Procedure for the Inspection, Repair, And Component Replacement on the Frames of Certain

Instrucción Especial Procedure for the Inspection, Repair, and Component Replacement on the Frames of Certain Off-Highway

Trucks/Tractors{7000, 7051}

Número de medio -REHS0541-18 Fecha de publicación -22/09/2014 Fecha de actualización -22/09/2014

i05934619

Procedure for the Inspection, Repair, and Component Replacement on the Frames of

Certain Off-Highway Trucks/Tractors{7000, 7051}

SMCS - 7000-023-CS ; 7051-023-CS

Off-Highway Truck/Tractor:

784B (S/N: 5RK1-UP)

784C (S/N: 2PZ1-UP)

785 (S/N: 8GB1-UP)

785B (S/N: 6HK1-UP)

785C (S/N: 1HW1-UP; APX1-UP; 5AZ1-UP)

785D (S/N: MSY1-UP)

789 (S/N: 9ZC1-UP)

789B (S/N: 7EK1-UP)

789C (S/N: 2BW1-UP)

789D (S/N: SPD1-UP; SHH1-UP)

793 (S/N: 3SJ1-UP)

793B (S/N: 1HL1-UP)

793C (S/N: CBR1-UP; 4AR1-UP; ATY1-UP; 4GZ1-UP)

793D (S/N: FDB1-UP)

Introduction

This Special Instruction contains general information and procedures that can be referenced when you repair the chassis of the machines that are listed above. Each repair will be unique. You may need to modify the procedures in some situations.

Read the entire special instruction. Understand the information before you perform any procedures. Understand the information before you order any parts.

Note: Some of the components that are necessary in order to complete procedures in this Special Instruction may not be available through the normal parts system. In some cases, special orders are required.

Note: For additional information regarding repairing cracked frames contact the subsidiary service engineer, the plant service

engineer and the plant product analyst.

ReferenceSpecial Instruction, REHS2346, "Weld Repair Procedure for the Rear Axle A-Frame and Rear Axle Housing on 785, 789, and 793 Off-Highway Trucks".

When you need to remove components in order to repair the chassis, refer to the appropriate Disassembly and Assembly Manual.

Table 1

Disassembly and Assembly Manuals

Sales Model Machine Systems Power Train

784B SENR5678 SENR5677

784C SENR1500 SENR1490

785 SENR4020 SENR4010



785C HAA SENR1500 SENR1490

785D KENR8312 KENR8308

789 SENR3404 SENR3430



789D SENR1534 UENR1065

793 SENR4917 SENR4907


793C (S/N: 4AR) SENR1463 SENR1462

793C (S/N: CBR, ATY, 4GZ) RENR2535 SENR2534

793D RENR8332 RENR8328

NOTICE

Do not allow any dirt or foreign material to get into the hydraulic system

during assembly, connection of lines, when components are filled with fluid,

or during any maintenance operation.

NOTICE

Care must be taken to ensure that fluids are contained during performance

of inspection, maintenance, testing, adjusting, and repair of the product. Be

prepared to collect the fluid with suitable containers before opening any

compartment or disassembling any component containing fluids.

Refer to Special Publication, NENG2500, "Dealer Service Tool Catalog"

for tools and supplies suitable to collect and contain fluids on Cat products.

Dispose of all fluids according to local regulations and mandates.

Personal injury or death can result from improper lifting or blocking.

When a hoist or jack is used to lift any part or component, stand clear of the area. Be sure the

hoist or jack has the correct capacity to lift a component. Install blocks or stands before

performance of any work under a heavy component.

Approximate weights of the components are shown. Clean all surfaces where parts are to be

installed.

Table 2

Approximate Weights of Unloaded Machines

Sales Model Weight

784B, 784C 88.903 kg (196,828 lb)

785, 785B, 785C, 785D

102.965 kg (227,891 lb)

789, 789B, 789C, 789D

130.634 kg (288,728 lb)

793, 793B, 793C, 793D

147.417 kg (325,000 lb)

Table 3

Approximate Weights of Components

Part

Number Part Name Part Name (Modifier) Weight Sales Model

119-4726 Tube Rear Cast Cross-Tube

297 kg (655

lb)

793, 793B, 793C, 793D

125-7017 Support Center Cross-Tube

1370 kg (3020

lb)

793, 793B, 793C, 793D

8X-0898 Rail Rail - 785, 785B, 785C, 785D

8X-2648 Rail Rail

290 kg (640

lb)

789, 789B, 789C, 793, 793B, 793C,

793D

320-5333 Rail Rail

382 kg

(842lb)

789D

320-5334 Rail Rail

382 kg

(842lb)

789D

6G-6499 Shaft (Ball) Lower Mounting for the Hoist

Cylinder

93 kg (205 lb)

785, 785B, 785C, 785D, 789, 789B,

789C, 789D

8X-1213 Shaft (Ball) Lower Mounting for the Hoist

Cylinder

110 kg (245

lb)

793, 793B, 793C, 793D

120-6765 Support Right Side Tail Casting

1026 kg (2262

lb)

793, 793B, 793C, 793D

120-6764 Support Left Side Tail Casting

910 kg (2006

lb)

793, 793B, 793C, 793D

8X-2376 Plate Inside Rear Window Plate

37 kg (82 lb) 793, 793B, 793C, 793D

5T-8671 Bracket

Assembly Steering Box

350 kg (775

784B, 784C, 785, 785B, 785C,

785D

lb)

5T-6243 Bracket


382 kg (842

lb)

789, 789B, 789C, 789D

8X-2283 Bracket


375 kg (830

lb)

793, 793B, 793C, 793D

Important Safety Information

The following information is an explanation of various labels that are found in this document.

Warnings

The warning label informs the technician that an injury or death can occur as a result of a condition that may exist.

Notices

A notice informs the technician that component damage can occur as a result of a condition that exists.

Notes

A note contains general information for the technician about the operation that is being performed.

Proper repair is important to the safe operation and the reliable operation of this machine. This document outlines basic recommended procedures. Some of the procedures require special tools, devices, or work methods.

Before you perform any repairs or before you perform any maintenance, read all safety information. Understand all

safety information before you perform any repairs or before you perform any maintenance.

Safety information is provided in this document and on the machine. If these hazard warnings are not heeded, bodily injury or

death could occur to you or other persons.

The "Safety Alert Symbol" that is followed by a "Signal Word" identifies a hazard. "DANGER", "WARNING", and "CAUTION" are "Signal Words".

Ver imagen

Illustration 1 g00008666

The signal word "WARNING" has the following meanings:

Pay Attention !

Become Alert !

Your Safety Is Involved !

The message that appears under the safety alert symbol explains the hazard.

Operations or conditions that may cause product damage are identified by "NOTICE" labels on the machine and in the service information.

The person that services the machine may be unfamiliar with many of the systems on the machine. Use caution when you

perform service work. Special knowledge of the systems and of the components is important. Before you remove any component,

or before you disassemble any component, obtain knowledge of the system and knowledge of the component.

Caterpillar cannot anticipate every possible circumstance that might involve a potential hazard. The safety information in

this document and the safety information on the machine are not all inclusive. You must determine that the tools,

procedures, work methods, and operating techniques are safe. You must determine that the operation, lubrication,

maintenance, and repair procedures will not damage the machine. Also, you must determine that the operation,

lubrication, maintenance, and repair procedures will not make the machine unsafe.

Basic Precautions

Improper operation, lubrication, maintenance or repair of this product can be dangerous and

could result in injury or death.

Do not operate or perform any lubrication, maintenance or repair on this product, until you

have read and understood the operation, lubrication, maintenance and repair information.

Always observe the list of basic precautions that follows:

Safety Signs

Safety signs include the items that follow: signs, information plates and decals. Read all "Safety" signs on the machine before

operating, lubricating, or repairing the machine. Understand all "Safety" signs on the machine before operating, lubricating, or

repairing the machine. Replace any safety signs that are in the conditions that follow: damage, unreadable and missing.

Protective Equipment

When you work around the machine, always wear protective equipment that is required by the job conditions. Protective

equipment includes the items that follow: hard hat, protective glasses and protective shoes. In particular, wear protective glasses

when you use a hammer or when you use a sledge hammer. When you weld, use the appropriate protective equipment that is

required by the job conditions. Protective equipment for welding includes the items that follow: gloves, welding hood, goggles and apron. Do not wear loose clothing or jewelry that can catch on parts of the machine.

Mounting and Dismounting

Use steps and handholds when you mount a machine. Also, use steps and handholds when you dismount a machine. Before you

mount the machine, clean any mud or debris from steps, walkways, or work platforms. Always face the machine when you use

steps, handholds, and walkways. When you cannot use the accesses on the machine, use ladders, scaffolds, or work platforms to perform safe repair operations.

Specifications for Cables, Chains, and Lifting Devices

Use approved cables, chains, and lifting devices in order to lift components. Refer to the manufacturer's weight's in order to

determine the application when you select the following items: cable, chain and lifting devices. When you lift a component, the lift angle is critical. Refer to the Illustration that follows in order to see the effect of the lift angle on the working load limit.

Note: The lifting devices that are shown in this publication are not Caterpillar parts.

Note: Ensure that the hooks are equipped with a safety latch. Do not place a side load on the lifting eyes during a lifting operation.

Ver imagen


Lift angles for lifting slings.

(A) The load capacity is 100% of the working load limit for the sling.

(B) The load capacity is 86% of the working load limit for the sling.

(C) The load capacity is 70% of the working load limit for the sling.

(D) The load capacity is 50% of the working load limit for the sling.

Hot Fluids and Parts

To avoid burns, be alert for hot parts on machines which have been stopped and hot fluids in lines, tubes and compartments.

Be careful when you remove filler caps, breathers, and plugs on the machine. Hold a rag over the cap or plug in order to prevent being sprayed by pressurized liquids. When the machine has been stopped, the danger of hot fluids is greater.

Corrosion Inhibitor

Corrosion inhibitor contains alkali. Avoid contact with the eyes. Do not allow corrosion inhibitor to contact the skin for extended

periods of time. Avoid repeated contact with the skin. Do not drink corrosion inhibitor. In case of contact, immediately wash skin

with soap and water. For contact with the eyes, flush the eyes with large amounts of water for at least 15 minutes. Seek medical

attention.

Batteries

Do not smoke when an inspection of the battery electrolyte level is made. Never disconnect any charging unit circuit or battery

circuit cable from the battery when the charging unit is operating. A spark can cause an explosion from the flammable vapor

mixture of hydrogen and oxygen that is released from the electrolyte through the battery outlets. Do not allow battery electrolyte

to contact skin or eyes. Battery electrolyte is an acid. In case of contact with battery electrolyte, immediately wash the skin with

soap and water. For contact with the eyes, flush the eyes with large amounts of water for at least 15 minutes. Seek medical

attention.

Pressurized Items

1. Always use a board or a piece of cardboard when you check for a leak. Leaking fluid under pressure can penetrate body

tissue. Fluid penetration can cause serious injury and possible death. A pin hole leak can cause severe injury. If fluid is

injected into your skin, you must get treatment immediately. Seek treatment from a doctor that is familiar with this type of injury.

2. Relieve all pressure in air, oil, or water systems before any lines, fittings, or related items are disconnected or removed.

Always make sure that all raised components are blocked correctly. Be alert for possible pressure when you disconnect any device from a system that utilizes pressure.

3. Fuel lines that are damaged and fuel lines that are loose can cause fires. Lubrication lines that are damaged and

lubrication lines that are loose can cause fires. Hydraulic lines, tubes, and hoses that are damaged can cause fires.

Hydraulic lines, tubes, and hoses that are loose can cause fires. Do not bend or strike high-pressure lines. Do not install

lines which have been bent or damaged. Check lines, tubes, and hoses carefully. Do not use your bare hand to check for

leaks. If fluids are injected into your skin, you must get treatment immediately. Seek treatment from a doctor that is familiar with this type of injury.

4. Pressure air or water can cause personal injury. When pressure air or water is used for cleaning, wear a protective face

shield, protective clothing, and protective shoes. The maximum air pressure for cleaning purposes must be below 205

kPa (30 psi). When you use a pressure washer, keep in mind that the nozzle pressures are high. The nozzle pressures

are frequently above 13790 kPa (2000 psi). Follow all of the recommended practices that are provided by the manufacturer of the pressure washer.

Welding Specifications and Qualifications

Protect yourself and others; read and understand this warning. Fumes and gases can be

dangerous to your health. Ultraviolet rays from the weld arc can injure eyes and burn skin.

Electric shock can kill.

Read and understand the manufacturer's instruction and your employer's safety practices. Keep

your head out of the fumes. Use ventilation, exhaust at the arc, or both, to keep fumes and gases

from your breathing zone and the general area. Wear correct eye, ear and body protection. Do

not touch live electric parts.

Refer to the American National Standard Z49.1, "Safety in Welding and Cutting" published by

the American Welding Society, 2501 N.W. 7th Street, Miami, Florida 33125: OSHA Safety and

Health Standards, 29 CFR 1910, available from U.S. Dept. of Labor, Washington D.C. 20210.

Note: Personal breathing protection should be worn by the personnel that are welding. Personal breathing protection will prevent

fumes from entering the lungs of the person that is welding. Use a 237-5181 Respirator for breathing protection.

Qualifications

Welders must be qualified for the appropriate type of weld that is being performed. Welders must be qualified for the appropriate

position of weld that is being performed. Welders must be qualified for the welding process that is being utilized: Shielded Metal

Arc Welding (SMAW), Flux Cored Arc Welding (FCAW) and Gas Metal Arc Welding (GMAW). Refer to American Welding

Society (AWS) D1.1 Structural welding code-steel or equivalent nationally or Internationally recognized code or standard for

guidance on welder qualification testing requirements. The welders must have used the process at some time within the last 6 months. The welders must complete the process of certification if the welders have not used the welding processes for 6 months.

Proper Welding Procedure on Machines and Engines with Electronic Controls

Proper precautions are necessary to prevent damage to electronic controls. When you weld on a machine with electronic controls,

use the steps that follow:

1. Turn off the engine. Put the key start switch in the OFF position.

2. If the machine has a battery disconnect switch, open the switch. If the machine does not have a battery disconnect

switch, disconnect the negative battery cable at the battery.

3. Connect the ground cable for the welder directly to the actual machine component that will be welded. Attach the

clamp for the ground cable as close as possible to the area that is being welded. This precaution will reduce the chance

of damage from welding current to the components that follow: bearings, hydraulic components and electrical components.

Note: Do NOT use electrical components as a ground point for the welder. Do NOT use ground points for electronic components as a ground point for the welder.

4. Protect the wiring harnesses from the welding spatter.

Area Preparation

The area to be welded shall be clean, dry, and free of the following contaminants:

Oil

Grease

Paint

Dirt

Rust

Any fluids or moisture

All welding shall be conducted on base material heated and maintained at a minimum temperature of 15.6° C (60° F).

Note: Heating instructions (preheat, interpass, and postheat) for any specific repair shall override the minimum 15.6° C (60° F) requirement.

Note: Heat distortion of the base metal is possible when you weld. Avoid excessive heating of the base metal.

Attach the welding ground cable directly to the base metal. Protect machined surfaces from sparks. Protect the machined surfaces from the welding spatter.

Welding Electrodes and Parameters

Flux Cored Welding Electrode for the FCAW Process

Use the Flux Cored Arc Welding (FCAW) with E71T-1 H8 (ANSI/A5.20) welding electrode and the manufacturer's shielding

gases that are specified (typically 75% argon and 25% carbon dioxide). The H8 implies that the electrode is designed to provide

less than 8 ml/100 g of diffusible hydrogen in the weld deposit. The weld that is deposited by the flux cored welding electrode

will have the following minimum mechanical properties:

Table 4

Mechanical Properties from Flux Cored Welding Electrode That Is Classified as "ANSI/AWS A5.20 E71T-1 H8"

Tensile Strength

480 MPa (70000 psi)

Yield Strength

400 MPa (58000 psi)

Elongation 22%

Impact Toughness 27 J @ -18 °C (20 ft lb @ -0 °F)

The tables that follow show the recommended parameter ranges for out of position welding in the field for two different flux

cored welding electrode diameters.

Table 5

Welding Current for Flux Cored Welding Electrode that Is

1.2 mm (0.045 inch)

Wire Feed Rate Voltage Amperage

7620 mm (300 inch) Per Minute to

10,160 mm (400 inch) Per Minute

24 to 28 190 to 240

Table 6

Welding Current for Flux Cored Welding Electrode that Is

1.4 mm (0.052 inch)

Wire Feed Rate Voltage Amperage

5080 mm (200 inch) Per Minute to

6350 mm (250 inch) Per Minute

23 to 27 180 to 220

Note: The settings listed above are recommendations which are based on experience for welding in the horizontal, vertical-up,

and overhead positions. Slight changes in the voltage and amperage may be necessary due to welding position and various

formulations by different electrode manufacturers. It is acceptable to use higher parameters than specified for welding in the flat

position.

Use a polarity setting of DC reverse polarity. Remove the slag after each pass of the welding electrode. The fast freezing

characteristics of flux cored welding electrode increases the possibility of evolving gas that is trapped in the weld. Control the

size of the weld in order to reduce the possibility of evolving gas that is trapped in the weld. The maximum size weld per pass should be equivalent to that of a 8.0 mm (.32 inch) fillet weld.

Low Hydrogen Electrodes for the SMAW Process

As an alternate process or when wind conditions are a factor, use SMAW and low hydrogen electrodes that meet the following requirements.

Table 7

Mechanical Properties of Welds from Low Hydrogen Electrodes That Are Classified as "ANSI/AWS A5.1 E7018"

Tensile Strength

480 MPa (70000 psi)

Yield Strength

400 MPa (58000 psi)

Elongation 22%

Impact Toughness 27 J @ -29 °C (20 ft lb @ -20 °F)

Low hydrogen electrodes must be stored in an electrode oven at 120 °C (250 °F). If low hydrogen electrodes get damp, scrap the

low hydrogen electrodes or recondition the low hydrogen electrodes to the manufacturer's specifications.

The table that follows shows the settings for the welding current based on electrode diameter.

Table 8

Welding Current for Low Hydrogen Electrodes

Diameter Amperage Rating

3.2 mm (1/8 inch) 105-155

4.0 mm (5/32 inch) 130-200

4.8 mm (3/16 inch) 200-275

Use a polarity setting of DC reverse polarity. Remove the slag after each pass of the welding electrode. The width of the weld

should not exceed two times the electrode diameter.

Arc Welding Electrodes for the GMAW Process

The table that follows lists the mechanical properties of welds that are deposited by the GMAW Process.

Table 9

Mechanical Properties of Welds from Gas Metal Arc Welding Electrodes That Are Classified as "ANSI/AWS A5.18

ER70S-6"

Tensile Strength

480MPa (70,000 psi)

Yield Strength

400 MPa (58,000 psi)

Elongation 22%

Impact Toughness 27J @ -30 °C (20 ft lb @ -20 °F)

The use of the GMAW process for field repairs is only recommended for certain conditions. Whenever the GMAW

process is appropriate, specific parameters and equipment will be defined.

Weld Inspection and Acceptance Criteria

Table 10

Defect Name ISO 6520 Defect

Reference Number Remarks Defect Limit

Cracks - Longitudinal,

Transverse, Radiating,

Crater, Disconnected,

Branching

1011, 1012, 1013,

1014, 1023, 1024,

1031, 1033, 1034,

1045, 1046, 1047,

1051, 1053, 1054,

1061, 1063, 1064

-- Not Permitted

Crack - Transverse 1021 Hard Surfacing Welds Only Permitted

Crack - Transverse 1021 Joining Welds Not Permitted

Porosity 2011, 2012, 2014,

2017

Maximum Diameter for a Single Pore

1 mm (0.040 inch)

Maximum Pores in Any

300 mm (11.81 inch) Length of Weld 6

Maximum Number of Pores in Any

50 mm (2.0 inch) of Weld Length for

Welds Less Than

300 mm (11.81 inch) in Length

1

Clustered Porosity 2013 Maximum Length of Cluster in Any

Weld

3 mm (0.120 inch)

Elongated Cavities 2015

Maximum Height or Width

3 mm (0.120 inch)

Maximum Length for Any Single

Discontinuity

25 mm (1.00 inch)

Maximum Length in Any Weld 10% of Weld Length

Elongated Cavities 2016

Maximum Dimension of Any Single

Cavity

3 mm (0.120 inch)

Maximum Total Length of Affected Area

in Any Weld

10% of Weld Length Not to

Exceed

25 mm (1.00 inch)

Shrinkage Cavities 2021, 2024, 2025 Maximum Diameter or Length

1 mm (0.040 inch)

Slag or Flux

Inclusions

3011, 3012, 3014,

3021, 3022, 3024

Maximum Height or Width

1mm (0.040 inch)


Discontinuity

25 mm (1.00 inch)


Oxide Inclusions 3031, 3032, 3033 Maximum Height or Width

1mm (0.040 inch)


Discontinuity 25 mm (1.00 inch)


Puckering (Oxide

Inclusion - Aluminum) 3034 -- Not Permitted

Metallic Inclusion 3041, 3042, 3043 -- Not Permitted

Lack of Fusion 4011, 4012, 4013

Visual (Breaking the Surface) Not Permitted

Subsurface Maximum Height or Width

1mm (0.040 inch)

Subsurface Maximum Length for Any

Single Discontinuity

25 mm (1.00 inch)


Lack of Penetration 402, 4021

Maximum Reduced Penetration

10% of Nominal

Penetration Not to Exceed

1mm (0.040 inch)

Maximum Allowed Total Length of

Reduced Penetration 10% of Weld Length

Undercut 5011, 5012, 5013,

5014, 5015

Maximum Depth Measured From Plate

Surface - Any Length

0.5 mm (0.020 inch)

Excess Weld Metal -

Groove Weld

Reinforcement

(Convexity)

502

Any Length --

Weld Face Width

5 mm (0.20 inch) or Less

1 mm (0.040 inch)

Weld Face Width Over

5 mm (0.20 inch) But Less Than

10 mm (0.40 inch)

1.5 mm (0.060 inch)

Weld Face Width Over (10 mm)(0.40 inch)

But Less Than

20 mm (0.80 inch)

2 mm (0.080 inch)

Weld Face Width Over

20 mm (0.80 inch) But Less Than

30 mm (1.20 inch)

3 mm (0.120 inch)

Weld Face Width

30 mm (1.20 inch) and Over

4 mm (0.160 inch)

Excess Weld Metal -

Fillet Weld Convexity 503

Convexity Affects Weld Toe Angle,

Reducing Fatigue Life 90 Degrees

Weld Toe Angles of 135 Degrees and More

Are Better --

Defect Limits Expressed as Minimum Toe

Angles Allowed --

Excess Penetration 5041, 5042, 5043

Without Drawing Limitation

2 mm (0.080 inch) (Any

Length)

With "Melt - Thru" and "Flush" Weld

Symbols

1 mm (0.040 inch) (Any

Length)

With "Melt - Thru" and "Grind Flush"

Symbols

Not Permitted (After

Grinding)

Incorrect Weld Toe 505 When 1E2995 Applies (Expressed as a Toe

Radius Rather Than a Toe Angle)

3 mm (0.120 inch)

Minimum Radius

Overlap 5061, 5062 Expressed as Minimum Toe Angle 90 Degrees

Fillet Weld Leg Size -

Undersize --

Applies to Either Weld Leg Measured

Independent of the Other --

Maximum Undersize

1 mm (0.040 inch)

Maximum Length of Undersize Weld

10% of Total Weld Length

If At Least 10% of Total

Weld Length is at Least

1 mm (0.040 inch) Over

Nominal Size, Otherwise,

No Undersize Length is

Permitted

Fillet Weld Leg Size -

Oversize --

Applies to Either Weld Leg Measured

Independent of the Other --

Maximum Oversize +25% (max

3 mm (0.120 inch))

Conformance to Design - Fillet Weld Leg

Sizes May be Oversized (Within Defect

Limitations or Beyond) Without Correction

Provided the Excess Does not Interfere

with Satisfactory End Use of the

Component (i.e., Distortion, Fit-Up

Interference, etc.)

--

Fillet Weld - Linear

Length when specified at

less than the length of the

joint

--

Weld Size ≤

6.5 mm (0.256 inch)

±

6.5 mm (0.256 inch)

Weld Size ≥

6.5 mm (0.256 inch)

±

12.5 mm (0.492 inch)

Fillet Weld Throat Size -

Undersize 5213

Nominal Size (0.7 x Leg Size) Not

Inclusive of Penetration Beyond the Weld

Root

Not Permitted

Weld Crater Only - Maximum Undersize

2 mm (0.080 inch) MAX -

and Not to Exceed 20% of

Specified Throat, Not

Inclusive of Penetration

Beyond the Weld Root (0.7

x Leg Size)

Incompletely Filled

Groove Weld 511

Careful Consideration Needs to be Given

When Plate Mismatch is Apparent Not Permitted

Weld Depth Must be Maintained as a

Minimum --

Root Concavity on Open

Root Groove Welds 515, 5013

Maximum Depth measured From Plate

Surface or Tube Inner Surface - Any

Length

0.5 mm (0.020 inch)

Poor Restart (Tie - In) 5171, 5172

Measured in Terms of Excess Weld Metal

(Fillet Weld Convexity) or Overlap on

Groove Welds, Lack of Fusion, or

Insufficient Throat

--

Excess Weld Metal on Fillet Welds, Defect

Limits Expressed as Minimum Toe Angles

Allowed

90 Degrees

Overlap on Groove Welds, Defect Limits

Expressed as Minimum Toe Angles

Allowed

90 Degrees

Lack of Fusion - Visual Maximum Length

Per Restart

3 mm (0.120 inch)

Insufficient Weld Throat Not Permitted

Stray Arc Strike 601 -- Not Permitted

Slag Residue 615

SMAW, SAW, FCAW, GMAW Not Permitted

GTAW

Silicon Residue Permitted

Unless Removal Specified

by Drawing Note

Combined

Discontinuities --

Total Maximum Combined Length of All

Imperfections in a Weld, Expressed as a

Percent of Total Weld Length

15%

(No Single Type of Imperfection Can

Exceed the Limits for That Single Type of

Imperfection)

--

In order to verify the quality of the weld, refer to Figure 27 from Caterpillar Specification 1E99 which is shown above in Table

10.

General Weld Repair

1. Remove any components that prevent access to the cracked weld.

2. Refer to the ""Area Preparation" " section in this Special Instruction.

3. Use dye penetrant (PT) or magnetic particle (MT) in order to identify the extent and/or length of the necessary repair.

4. Protect machined surfaces from sparks and weld debris.

5. Ensure that the base material is at a minimum temperature of 15.6° C (60° F) before welding. Ensure that a minimum temperature of 15.6° C (60° F) is maintained throughout the entire welding procedure.

6. Cracks in the weld and sound metal which are 50.8 mm (2.0 inch) beyond each end of the crack shall be removed by air

carbon arc torch or grinder. Caution should be used to avoid excessive removal of the surrounding base material. Areas

that are gouged by air carbon arc torch shall be later ground and cleaned prior to welding in order to remove all carbon

absorption or contamination. Gouged areas requiring rewelding shall have a root radius of not less than 5 mm (0.20

inch) and a Single V - 60 degree included angle joint preparation to allow the welder reasonable access to reinstate the weld.

7. Use dye penetrant (PT) or magnetic particle (MT) to inspect the gouged and ground area in order to ensure that the crack has been removed before welding commences.

8. Repair the prepared groove utilizing the recommendations provided in the ""Welding Electrodes and Parameters" "

section in this Special Instruction.

9. Clean the weld area. Inspect the area that was welded. All weld quality shall conform to specifications in the ""Weld

Inspection and Acceptance Criteria" " section in this Special Instruction.

Walk-Around Inspection of the Frame for the 784B, 784C, 785, 785B, 785C, 785D, 789,

789B, 789C, 789D, 793, 793B, 793C, and 793D Off-Highway Trucks

This Special Instruction provides information on the areas of the frame assembly that should be inspected for cracks. The

following areas are covered in this Special Instruction: castings, welded joints, pump and motor mounts, mounting pads for the

fuel tank, mounting hangers for the fuel tank, mounting pads for the hydraulic tank, mounting hangers for the hydraulic tank and the fabricated assemblies.

Note: The Operation and Maintenance Manual identifies the intervals for maintenance inspection. The conditions of the site, the

payloads, and the haul road conditions may affect the maintenance interval. Site managers should monitor these intervals accordingly. Site managers should adjust these intervals accordingly.

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Typical truck frame

(A) Bracket Assembly (Steering box)

(B) Superstructure

(C) Support (Center cross-tube)

(D) Support (Tail casting)

(E) Support (Rear cross-tube)

(F) Rear motor mount

(G) The casting that forms the mounting location for the front suspension cylinder

(H) Fuel/hydraulic tank support

(J) Supports for the hoist cylinder

(K) Pin bores for the control rod

Inspect the Support (Rear Cross-Tube)

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1. Inspect the welds that are used to hold the rear cross-tube to the tail castings.

2. Inspect the rear of the support (rear cross-tube).

3. If any cracks are found in the rear cross-tube, refer to ""General Weld Repair" " section in this Special Instruction. If

the crack cannot be repaired, refer to ""Rear Cross-Tube Replacement for the 793 Off Highway Trucks" " section in this Special Instruction.

Inspect the Tail Casting

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1. Inspect the welds that hold the tail casting to the support (rear center).

2. Inspect the welds that hold the tail casting to the side rails.

3. Inspect the area around the body pin bore for cracks.

4. Inspect the pin bore for the suspension cylinder for wear. This area can only be inspected if the pins have been removed. Refer to Disassembly and Assembly Manual.

5. Inspect the area around the pin bore for the suspension cylinder for cracks.

6. Inspect the bore and the area around the bore that is for the body retaining pin.

7. Repeat this inspection on the other side of the frame.

8. If any cracks are found in the tail casting, refer to ""General Weld Repair" " section in this Special Instruction. If the

crack cannot be repaired, refer to ""Tail Casting Replacement for 793 Off Highway Trucks" " section in this Special

Instruction.

Inspect the Side Rails

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1. Inspect the welds that hold the frame rails to the tail castings.

2. Inspect the side rails.

3. Inspect the welds that hold the side rails to the support for the suspension cylinders.

4. Inspect the welds that hold the support for the hoist cylinders to the frame rails.

5. Inspect the welds that hold the support for the cab to the frame rails.

6. Inspect the welds that hold the center tube to the frame rails.

7. Inspect the weld on the plates that make up the rails.

8. Inspect the welds that are used on bosses and plates that are attached to the side rails. Carefully inspect the welds that are used to hold on the brackets for the fuel tank and the hydraulic tank.

9. Inspect the welds that hold the plates that are used for the rear motor mounts.

10. If any cracks are found, refer to the ""Frame Rails Repair" " section in this Special Instruction for the procedure that is needed to repair the problem.

Inspect the Center Cross-Tube

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1. Inspect the welds that hold the outside brackets to the frame rails. Inspect the welds that hold the center tube to the two

outside brackets.

2. Inspect the center cross-tube.

3. Inspect the welds on any of the bosses, the plates, and/or the brackets that are positioned on the center cross-tube.

4. If any cracks are found in the center cross-tube, refer to ""General Weld Repair" " section in this Special Instruction. If the crack cannot be repaired, refer to the ""Center Cross-Tube Replacement 793 Off-Highway Truck" " section.

Inspect the Support for the Hoist Cylinders

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1. Inspect the welds that hold the center tube between the two supports.

2. Inspect the support for the hoist cylinder.

3. Inspect the front strut support.

4. Inspect the welds that hold the supports to the frame rails.

5. Inspect the weld that holds the mounting ball to the supports.

6. Inspect the ball for wear.

7. Inspect the welds that are used on any bosses or plates.

8. If any cracks are found, refer to ""General Weld Repair" " section in this Special Instruction. If the ball cannot be

repaired, refer to ""Ball Replacement for the Lower Connection of the Hoist Cylinders" " section in this Special Instruction.

Inspect the Front Strut Support

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1. Inspect the weld that holds the side rails to the strut support.

2. Inspect the front strut support.

3. Inspect the welds that are used to hold the center tube to the two strut supports.

4. Inspect the weld that is used on the brackets for the steering cylinders.

5. Inspect the welds that are used on any bosses or plates.

6. If any cracks are found refer to ""General Weld Repair" " section in this Special Instruction. If the crack cannot be

repaired, refer to Special Instruction, REHS0172, "Front Strut Frame Casting Replacement" for the procedure that is needed to repair the problem.

Inspect the Front Side Rails and the Bumper

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1. Inspect the weld that holds the front side rails to the strut supports.

2. Inspect the weld that is used to hold the front side rails to the bumper.

3. Inspect the weld that is used on the front motor mount.

4. Inspect the welds that are used on the vertical supports in the front.

5. Inspect the welds that are used on any bosses or other plates and brackets.

6. If any cracks are found refer to ""General Weld Repair" " section in this Special Instruction.

Inspect the Upper Superstructure

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1. Inspect the welds that are used to hold the superstructure to the vertical support.

2. Inspect the welds that are used to hold the superstructure to the side rails in the rear.

3. Inspect the welds that are used to hold the front suspension cylinders to the superstructure.

4. Inspect the welds that hold the superstructure to the frame rails.

5. Inspect the welds that are used on any bosses or other plates.

6. If any cracks are found, refer to ""General Weld Repair" " section in this Special Instruction. If additional information is needed, refer to Special Instruction, REHS0452, "Superstructure Repair".

Frame Management/Repair Philosophy

Frame life, as it relates to fatigue, is a function of many variables that include payload, application (condition of haul roads and

load/unload zones), speed, maintenance, and repairs. Frame cracking can be a result of many of these variables. Over the life of

the machine, frame cracking is an expected event in most circumstances. Understanding and managing all of these variables is a

part of general machine maintenance. General machine maintenance is essential to ensuring fully acceptable life of the frame.

Proper frame management practice should include the following: maintenance and repair, documentation and trending. Local

conditions and/or age of equipment may dictate adjustments to your requirements.

Documentation

1. Any cracks that are identified at inspection or repair should be measured. Any cracks that are identified at inspection or

repair should be documented. This information should be retained for future inspections and trending. Crack

documentation history can show that where cracks are reoccurring, time to propagate, and to what degree of severity.

2. A crack found at inspection should be marked and dated with paint/etch as to identify any crack growth at future inspection that is specified by the Operation and Maintenance Manual.

3. Utilize a crack inspection checklist with identified call out locations on the frame in order to help in the documentation

process. Table 11 shows an example of a crack inspection checklist. The checklist example provides a sequential walk-around inspection which includes a table for capturing locations, comments, and lengths, of cracks.

4. It is important to maintain a database of fleet frame crack status. The repair labor and downtime requirements for the

fleet should be included in this database.

Maintenance and Repair

1. Conduct a full frame inspection as per the inspection requirements listed in this document and your Operation and Maintenance Manual.

2. Clean the frame prior to inspections.

3. Utilize an inspection diagram. A walk-around inspection diagram with weld joint locations is included in this document.

4. When evaluating frame cracks for repair, crack documentation and trend history can assist in determining potential

crack growth and speed. The sites crack trend data history can determine the priority in completing the repair. If the

sites crack trend data history predicts the crack growth speed to be low risk, then the crack would then be scheduled for

repair at the next scheduled opportunity/preventative maintenance. If the work sites crack trend data history predicts the crack growth speed to be high risk, then the crack should be repaired immediately.

Trending

1. Data collected from the crack history documentation reveals crack tendencies.

2. Evaluating tendencies enables site-specific identification and rankings of crack severity/importance.

3. The frequency of crack reoccurrences can be identified through the trending process.

Table 11

Frame Inspection Checklist

Date

Equipment

Number

SMU

Inspector

Item Area OK Cracked Comments - Length -

Location

1 RH Front Frame Rail/Support

2 RH Upper Strut Mount

3 K Frame RH

4 RHR Engine Mount

5 Front Hydraulic Tank Mount

6 Rear Hydraulic Tank Mount

7 RH Side Torque Tube and Transition to Frame

Rail

8 RH Hoist Cylinder Mount

9 RH Rear Frame Rail

10 RH Tail Casting

11 LH Tail Casting

12 LH Rear Frame Rail

13 LH Hoist Cylinder Mount

14 Rear Fuel Tank Mount

15 Front Fuel Tank Mount

16 LH Side Torque Tube and Transition to Frame

Rail

17 A Frame Mount

18 LHR Engine Mount

19 K Frame LH

20 LH Upper Strut Mount

21 LH Front Frame Rail/Support

22 Cross-Tube

23 RH Fore/Aft Rail

24 RH Fore/Aft Transition

25 LH Fore/Aft Transition

26 LH Fore/Aft Rail

Note: Fill in all areas of the checklist and circle cracked areas on the diagrams.

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Inspection Intervals

Inspections of the frame assembly for cracks should be conducted during regular maintenance intervals. Some of the areas that

need to be inspected are blocked by one or more components. If the component that is blocking the frame is removed, an

inspection of that area should be performed. It is therefore important to take advantage of the opportunity to inspect those parts of

the frame assembly that are exposed whenever components are removed. As an example, when the hydraulic tank is removed, the

area behind the hydraulic tank should be cleaned and inspected. Cracking on one machine may indicate closer focus in that area

for the rest of the fleet. Refer to Table 12 for the Operation and Maintenance Manual for the off-highway truck/tractor that is being worked on.

Table 12

Operation and Maintenance Manual

Off-Highway Truck/Tractor Manual Number

784B SEBU6517

784C SEBU7176

785 SEBU6092

785B SEBU6517

785C S/N:(1HW, APX, 2PZ) SEBU7173

785C S/N:(5AZ) SEBU7176

785D SEBU8350

789 SEBU6039

789B SEBU6518

789C SEBU7174

789D SEBU8242

793 SEBU6333

793B SEBU6519

793C S/N:(4AR) SEBU6995

793C XQ S/N:(CBR, ATY, 4GZ) SEBU7175

793D SEBU7792

Prepare the Work Area

1. Before you start to work on the machine, disconnect the battery. Attach a Do Not Operate tag in the operator compartment.

2. When possible, make all repairs with the machine parked on a level, hard surface. When you work on the machine or

when you work under the machine, block the machine in order to prevent the machine from rolling. Select an

appropriate site in order to repair the chassis. Select an area that is flat, smooth, and drained. Make sure that there is sufficient space for the items that follow: machine, components, tools and lifting devices.

3. Do not work on any machine that is supported only by lift jacks or a hoist. Always use hardwood blocks or jack stands

to support the machine before performing any service or disassembly. Always make sure that the maximum load capacity of the jack stands is greater than the weight of the machine.

4. Make sure that the work area around the machine is made safe. Become aware of hazardous conditions that may exist.

If an engine is started inside an enclosure, make sure that the engine exhaust is properly vented.

5. Before you start a repair, be sure that all protective devices are properly installed and that all protective devices

function correctly. When a guard must be removed or a shield must be removed in order to perform the repair work, use extra caution.

6. Always use tools that are in good condition. Before you perform any service work, understand the intended use of the tools.

7. Replace all fasteners with fasteners of the same part number. Do not use a lesser quality fastener if replacements are necessary.

8. Prepare to stop an engine that has had a recent overhaul. Prepare to stop an engine that has a fuel system that has

recently been worked on. If the engine has not been assembled correctly, the engine can possibly overspeed. If the fuel

settings are not correct, the engine can possibly overspeed. Overspeeding can cause bodily injury, death, or property damage. Prepare to shut off the fuel and the air supply to the engine in order to stop the engine.

9. Be careful when you remove cover plates. Gradually back off the last two bolts or the last two nuts that are located at

opposite sides of the cover or the device. Pry the cover loose in order to relieve any spring or other pressure, before you completely remove the last two bolts or the last two nuts.

10. When you make repairs that require welding, have appropriate reference information. Welding should only be

performed by personnel that are adequately trained. Personnel should be knowledgeable in welding procedures. Make sure that all repairs that require welding comply with the ANSI/AWS standards.

11. Do not damage wiring during removal operations. When you install the wiring, do not damage the wiring. The wiring

can be damaged in operation by the conditions that follow: contact with sharp corners, rubbing against objects and contact with hot surfaces. Do not connect the wiring to a line that contains fluid.

12. Tighten connections to the correct torque. Make sure that all heat shields, clamps, and guards are installed correctly in

order to avoid excessive heat, vibration, or rubbing against other parts during operation. Shields that protect against oil

spray onto hot exhaust components in the event of a line, tube, or seal failure must be installed correctly.

13. Do not operate a machine if any rotating part is damaged or if any rotating part contacts any other part during

operation. Any high speed rotating component that has been damaged or altered should be checked for balance before

reusing. Before you start the engine, make sure that all protective devices are properly installed. Before you operate the

machine, make sure that all protective devices are functioning correctly.

14. Use extra caution when you service the rubber belts. Follow all safety instructions in the appropriate manuals. Wear protective glasses. Block the machine in order to prevent the machine from moving.

15. When you unload components, place the components near the machine. Leave enough space around the machine in

order to maneuver lifting devices. Carefully inspect the parts. Ensure that all parts are undamaged. Organize the parts

for assembly.

16. The repair of the chassis will be easier if the machine is clean. Use a steam cleaner to clean the truck. Be careful with the steam cleaner. Do not damage electrical wiring or cab windows.

Casting Replacement that Forms the Mounting Location for the Front Suspension

Cylinder on the Axle Frame for 784B, 785, 785B, 789, 789B, 793, 793B, 793C and 793D

In order to replace the casting that forms the mounting location for the front suspension cylinder on the axle frame, refer to Special Instruction, REHS0172, "Off-Highway Tractor and Truck Front Strut Frame Casting Replacement".

Install the Field Retrofit for the Superstructure of 789, 789B, 789C, 789D, 793, 793B, 793C

and 793D Off-Highway Trucks

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In order to install the field retrofit for the superstructure, refer to Special Instruction, REHS0452, "Weld Repair Procedure for Field Retrofit of Large Off-Highway Truck Frame Superstructure".

Repair of the Rear Motor Mount Castings

Repair Cracks

1. Remove the necessary components in order to gain access to the castings for the rear motor mounts.

2. Thoroughly clean the area around the castings for the rear motor mounts .

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Rear motor mount

3. Inspect the welds and castings for the rear motor mounts.

4. If you find a crack, use an air carbon arc to gouge out the crack. Taper the ends of the gouged area in order to provide a

smooth transition to the base metal. Gouge out at least 50.8 mm (2.0 inch) past the end of the crack. Use a grinder to

smooth the gouged area.

5. Use some liquid dye penetrant to inspect the gouged area in order to ensure that the crack has been removed.

Note: Use the SMAW process and "E7018" welding electrode for all welds. As an alternate process, the FCAW

process can be used with "E71T-1 H8" welding electrode.

6. Weld the gouged area until you reach the original profile.

Additional Fillet Welding of the Rear Motor Mounts

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(A) 50.8 mm (2.00 inch)

(B) 50.8 mm (2.00 inch)

(C) Additional fillet weld

1. Start at the lower corners of the castings for the rear motor mounts and use an air carbon arc torch to remove 50.8 mm

(2.0 inch) of the horizontal 12.0 mm (.47 inch) fillet welds (A) that secure the motor mounts to the frame. Taper the ends of the gouged area in order to make a smooth transition into the existing weld.

2. Start at the lower corners of the castings for the rear motor mounts and use an air carbon arc torch to remove 50.8 mm

(2.0 inch) of the vertical 12.0 mm (.47 inch) fillet welds (B) that secure the motor mounts to the frame. Taper the ends of the gouged area in order to make a smooth transition into the existing weld.

3. Start at the end of the gouged areas and apply a 12.0 mm (.47 inch) fillet weld across the bottom of the motor mounts.

Continue the weld around the corner. Continue the welds into the vertical fillet welds at the sides of the motor mounts.

Note: Do not start the weld at the bottom corners of the motor mounts and do not stop the weld at the bottom corners of the motor mounts.

4. After you have repaired the welds at the corners of the motor mounts, apply an additional fillet weld (D) over the

existing fillet weld. Apply the fillet weld all the way around the motor mount. Refer to Illustration 16 in order to determine the profile of the new fillet weld (D) .

Note: Ensure that there is at least an 8.0 mm (.32 inch) radius of transition at the toe of the weld. If necessary, grind the radius.

Center Cross-Tube Support) Replacement for the 793C and 793D Off-Highway Trucks

Prepare the Frame in Order to Remove the Support (Center Cross-Tube)

1. Remove the body from the truck. Remove any components that prevent access to the center cross-tube.

2. Clean the area around the center cross-tube of the items that follow: oil, grease, dirt and paint.

Note: You must stabilize the area near the center cross-tube before you remove the center cross-tube.

3. Before you stabilize the frame, prepare to take measurements for reference. Record reference dimensions from the mounting holes for the A-frame to the frame rails. Record reference dimensions in order to position the tank support.

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(1) Square tubing

4. Obtain two pieces of 101.6 mm (4.0 inch) square tubing (1) with 6.35 mm (.25 inch) thick walls. The square tubing should be long enough to extend between the frame rails.

5. Weld the square tubing between the frame rails. Refer to Illustration 17. Weld around each end of the square tubing (1).

Use 8.0 mm (.32 inch) fillet welds.

6. Use the steel bar stock that is 25.4 mm (1.0 inch) thick and 101.6 mm (4.0 inch) wide to make diagonal braces.

7. Place supports under the front half of the truck and place supports under the back half of the truck. Place the supports

under the frame rails on each side of the truck.

Remove the Existing Support (Center Cross-Tube)

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(A) Top rail

(B) Window plate

(C) Window plate

(D) Window plate

(E) Tank support

(F) Support (Center cross-tube)

1. Cut section (A) from the top rail at each side of the frame. Section (A) should begin at the joint between the frame rail

and the casting for the rear pedestal of the superstructure. Refer to Illustration 18.

Note: Record the length of the opening that remains after you remove section (A) .

2. Remove the window plates (B, C, D, and) the tank supports (E) from the sides of the frame rails.

Note: Save the tank supports (E). The tank supports will be used again.

3. Remove the existing center cross-tube (F) .

4. Measure approximately 1128 mm (44.4 inch) forward from the rear welded joint of the former center cross-tube in

order to locate a mark on the inside window plate. The mark will be used to cut an opening for the new 125-7017

Support (Center Cross-Tube) .

5. Cut the inside window plates in order to make an opening for the new center cross-tube.

Install the New Support (Center Cross-Tube)

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(G) New center cross-tube

Note: Use the SMAW process and "E7018" welding electrode for all welds that secure the new cross-tube. As an alternate process, the FCAW process can be used with "E71T-1 H8" welding electrode .

1. Set the new 125-7017 Support (Center Cross-Tube) (G) in place. Use the reference dimensions that were recorded

earlier to position the center cross-tube.

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8X-2648 Rail

2. Fabricate new top rails. Trim an 8X-2648 Rail . Grind a 30 degree bevel at each end of the 8X-2648 Rail .

Note: Maintain a root opening of 5.0 mm (.20 inch) at each end of the new section of rail.

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Support plate

(H) Cut in order to fit.

(J) 150 mm (5.9 inch)

(K) 300 mm (11.8 inch)

(L) 30 mm (1.2 inch)

(M) 500 mm (19.7 inch)

(N) 10 mm (.4 inches)

3. Use steel that is 20 mm (.79 inch) thick to fabricate a support plate for the new section of frame rail. The steel must

meet ASTM specification "A572". Refer to Illustration 21.

Note: As an alternative, cut the former support plate from the former rail. If the former support plate is undamaged, use the former support plate again.

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New top rails

(P) 1071.0 mm (42.16 inch)

4. Use 12.0 mm (.47 inch) fillet welds to secure the support plate to the 8X-2648 Rail . Weld along the sides of the

support plate and weld along the angles of the support plate. Do not weld across the end of the support plate.

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5. Tack weld the new top rails in place. Use two 50 mm (2.0 inch) bevel welds (W6) to secure the new sections of top rail

in place.

6. Tack weld the new center cross-tube in place.

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(G) New center cross-tube

7. Use welds (W1) to secure both rear edges of 125-7017 Support (Center Cross-Tube) to the vertical supports within the

frame rails. Weld to the contour that is shown in Illustration 25.

8. Use 16.0 mm (.63 inch) fillet welds (W2) to join the rear edges of the top rails to both sides of the vertical supports within the frame rails.

9. Use 12.0 mm (.47 inch) fillet welds (W3) to join the top and bottom edges of the 125-7017 Support (Center Cross-

Tube) to the top and bottom frame rails. Weld from the inside of the frame rails.

10. Use 16.0 mm (.63 inch) fillet welds (W4) to secure the fore and aft edges of the 125-7017 Support (Center Cross-Tube) to the inside window plates of the frame rails.

Note: Maintain a 10.0 mm (.40 inch) root opening. Do not extend the weld (W4) into the grooves for the horizontal welds (W5). The forward edge of the new center support requires an 8X-0597 Backup Strip .

11. Use 16.0 mm (.63 inch) J-groove welds (W5) to secure the top and bottom edges of the 125-7017 Support (Center Cross-Tube) to the top and bottom frame rails. Weld from the outside of the frame rails.

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Window plate (Y)

(R) 669.0 mm (26.34 inch)

(S) 1829.0 mm (72.00 inch)

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Window plate (X)

(U) 669.0 mm (26.34 inch)

(T) 612.0 mm (24.1 inch)

(V) 13.0 mm (.51 inch)

12. Use steel that is 16.0 mm (.63 inch) thick to fabricate two new outside window plates (Y) and (X) for each frame rail.

The steel should meet ASTM specification "A572". Trim the window plates in order to fit in the frame rails.

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(E) Tank support

(Y) Window plate

(X) Window plate

13. Position window plate (Y) and window plate (X) on the frame.

14. Use 16.0 mm (.63 inch) J-groove welds (W7) to secure the new outside window plates (Y) and (X) in place.

15. Position the tank supports that were removed earlier.

16. Use 8.0 mm (.32 inch) fillet welds to secure the tank supports to the frame rails. Grind a 5.0 mm (.20 inch) radius at the toe of the fillet weld. Refer to the ""Tank Supports Field Repair Procedure" " in this Special Instruction.

Complete the Installation of the New Support (Center Cross-Tube)

1. Remove the square tubing that was installed in order to brace the frame.

2. Grind the areas near the intersection of welds to a smooth contour.

3. Paint the areas that were repaired.

4. Install the components that were removed from the truck.

Frame Rails (Repair)

Table 13

Frame Rails

Off-Highway Truck/Tractor Part Number (1)

785 8X-0898

789 8X-2648

793 8X-2648

( 1 ) (Bulk) Must be cut to length.

1. Remove the body of the truck. Refer to Disassembly and Assembly, "Body and Canopy - Remove".

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View of the left outside frame

(A) Bevel groove weld

(B) Tank mount

(C) J-groove

(D) Window plate

2. Support the truck frame. Remove the fuel or the hydraulic tank. Use jacks on both sides of the frame rail that is cracked. Raise the frame until the crack is closed.

3. Remove all of the hardware that will be affected in the area near the center tube. Save all hardware. Record some

reference dimensions from the front mount for the fuel tank to the rear mount for the fuel tank. These measurements will be used to relocate the front tank mount.

4. Remove bracket (B) for the front fuel tank by using a arc gouge. Angle the cuts toward window plate (D) away from

the tank mount. Use care when cutting as the tank mount will be reused. Remove window plate (D) by using the carbon

arc gouging along the dotted line shown in Illustration 29. Angle the cut toward window plate (D) away from the top

and the bottom rails. The top and bottom weld joints have a backing plate (C) for the J-groove. When you cut the

window, try not to damage the plates. The vertical weld joints are bevel joints that have a gusset backing. Do not cut into the gusset.

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Clean weld joints and prepare weld joints.

(C) J-groove

(E) 45 degree bevel with a 2 mm (0.08 inch) land

5. After window plate (D) is cut and removed, grind off all of the old weld. Use a grinder in order to prepare the joints of

the weld to the original profile. This is shown in illustration 30. Be sure that the weld joints are free of oil, carbon, slag, or foreign material.

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Frame rail

(F) Inside frame rail

(G) Crack

6. Inspect the top and bottom rails (F) for cracks. Refer to Special Instruction, SEHS9091 for a reference. If cracks are

located, cut out the crack from the inside of frame rail (F). Weld the cut out areas and grind the area smooth. Back

gouge the repair as shown in Illustration 31. Weld the area that was gouged and grind the area smooth. Inspection of

the rail should be done in order to ensure that the rail is free of cracks. The Ultrasonic inspection procedure should be

used in order to inspect the repair. Use an angle beam transducer that is set up for mild steel. The weld should be checked from each side. Any internal feature should be repaired.

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Inside window plate

(H) Bulkhead

(D) Inside window plate

(I) Backup strip

7. Inspect the center cross-tube for cracks. If the tube is cracked, the tube must be repaired. Refer to ""Support (Center

Cross-Tube) Replacement" " section in this Special Instruction. Inspect inside window plate (D) in front of the center

tube. If the window plate is cracked, the window plate must be removed. The weld seam to the rear of the truck has a

backup strip (I). Remove the backup strip (I) and all of the old weld. For the 785 and 789 trucks, inside window plate

(D) will need to be cut at the gusset (bulkhead) (H) at the location shown in Illustration 32 and a weld seam created. For the 793 truck, cut on the weld seam.

Note: The J-groove seams that run along the frame, top, and bottom of the window plate, will need to be removed.

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Reinforcement plates

8. Fabricate the required reinforcement plates that are shown in Illustration 33. Use ASTM A572 grade 42 or 40 steel.

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Outside window plate

9. Fabricate the required window plates that are shown in Illustration 34. Use ASTM A572 grade 42 or 40 steel.

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Backup strip

10. Fabricate the required backup strips that are shown in Illustration 35. Use ASTM A572 grade 42 or 40 steel.

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Inside window plate for 793 Off-Highway Truck

(ZZ) 16.0 mm (0.63 inch)

(ZY) 671.5 mm (26.44 inch) or 677.5 mm (26.67 inch)

(ZX) 669.0 mm (26.34 inch) or 672 mm (26.46 inch)

Note: Measure the length and width of the window plate prior to removal in order to determine the dimensions that are

appropriate for your truck.

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(ZW) 16.0 mm (0.63 inch)

(ZV) 1735.0 mm (68.31 inch) or 1570.0 mm (61.81 inch)

(ZU) 594.0 mm (23.39 inch) or 597.0 mm (23.50 inch)



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(ZT) 14.0 mm (0.55 inch)

(ZS) 1626.5 mm (64.04 inch) or 1461.5 mm (57.54 inch)

(ZR) 521.0 mm (20.51 inch) or 524.0 mm (20.63 inch)



11. Fabricate the required inside window plates that are shown in Illustration 36, Illustration 37, or Illustration 38. Use ASTM A572 grade 42 or 40 steel.

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Welding the reinforcement plate

(J) Reinforcement plate

(K) 12 mm (0.47 inch) fillet

(L) Weld groove

(M) Existing weld

(N) Groove weld with 12 mm (0.47 inch) fillet

12. After the crack in the bottom rail is repaired, position the plate and tack weld reinforcement plate (J). Weld

reinforcement plate (J) that is shown in illustration 39. Visually inspect the welds. The welds shall be free from cracks, porosity, undercut, and incomplete fusion. Grind the groove weld flush.

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Welding of the inside window plate

(O) 16 mm (0.63 inch) Fillet

(P) Bevel groove

13. Position the plate and tack weld the inside window plate. The root openings on the sides of the plate need to be a

minimum of 6 mm (0.24 inch) in order to allow for proper fusion of plate corners. Equalize the root opening between

the top and the bottom. Tack weld the window plate. Locate backup strip (I) and tack weld backup strip (I). Weld the

vertical seams (R). Weld the top and bottom J-grooves. After the groove welds are welded around the window plate,

weld a 16 mm (0.63 inch) fillet on the (bulkhead to window) on the inside of the rail. Slag each pass and make sure all

tie-ins are complete. The welds around the window plate should be inspected using ultrasound.

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Welding the outside window plate

(Q) 8 mm (0.32 inch) Fillet tig dressed

(R) Vertical grooves

(S) Bottom grooves

14. Locate and tack weld the outside window plate with a minimum of 6 mm (0.24 inch) root openings on the sides. Weld

the vertical seams (R). Weld the top and bottom horizontal groove weld (S). Slag each pass and make sure all tie-ins

are complete. The welds around the window plate should be inspected with ultrasound. Locate the bracket for the fuel

tank and tack weld the bracket for the fuel tank with the recorded reference dimensions. Refer to ""Tank Support Field

Repair Procedure for the 785, 785B,785C, 785D, 789, 789B, 789C, 789D, 793, 793B, 793C and 793D Off-Highway

Trucks" " for the correct welding size on the tank supports. Blend, grind, and paint as needed.

Tank Support Field Repair Procedure for the 785, 785B,785C, 785D, 789, 789B, 789C,

789D, 793, 793B, 793C and 793D Off-Highway Trucks

This procedure covers the field repair of cracks and to enhance fatigue life of the tank support welds for the 785, 789, 793, Off-Highway Trucks.

Repair Procedure

Table 14

Tank Support

Fuel Tank Bracket Hydraulic Tank Bracket

Front Bracket Rear Bracket Front Bracket Rear Bracket

784 6G-7438 6G-7439 8W-4293 8W-4293

785 6G-7438 6G-7439 8W-4293 8W-4293

789 8W-5359 8W-5354 5T-6465 5T-6464

789D 347-6511 347-6510 5T-6465 5T-6464

793 8X-2571 8X-2572 8X-5936 8X-5936

Use the direct current electrode positive (DC reverse polarity) polarity setting and remove the slag after every pass. The weld

pass shall not exceed two times the electrode diameter.

When the base metal temperature is below 0.0 °C (32 °F), the base metal shall be preheated to 21 °C (70 °F) and this minimum temperature maintained during cutting or welding.

Clean the area to be welded from oil, grease, paint and dirt. Attach the welding ground cable directly to the center tube assembly. Protect all machined surfaces from sparks or spatter produced by the welding, chipping and /or grinding operations.

The weld shall be free from cracks, porosity, undercut and incomplete fusion. All welds quality shall conform to ANS/AWS 14.3 or Caterpillar Specification 1E99.

Welding parameters will vary due to weld position and the manufacturer of welding electrode. For 1.3 mm (0.052 inch) diameter electrode typical welding parameters.

Use the direct current electrode positive (DC reverse polarity) polarity setting and remove the slag after every pass.

Repair Cracks

Begin the repair by removing any cracks with the carbon arc gouging method, or grinding. Cracks must be removed to sound

metal prior to welding. Verify that the crack has been removed by the use of dye penetrant or magnetic particle inspection. Be

sure to clean the prepared groove before welding. Weld repair the prepared groove by using passes that do not exceed two times

the electrode diameter. If the alternate welding process is selected, the welding pass size should not exceed 8 mm (0.31 inch) fillet weld volume. Remove the slag after each weld pass in order to avoid the possibility of slag inclusions.

Clean and inspect the weld repair. The weld shall be free from cracks, porosity, undercut and incomplete fusion. All welds

quality shall conform to ANS/AWS 14.3 or Caterpillar Specification 1E99.

Tank Support

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After the crack has been repaired, weld a small bead 6 mm (0.24 inch) around the toe of the existing weld as shown in Illustration

42. Use a small grinder to blend the toe of this weld (B) to approximately a 5 mm (0.2 inch) radius as shown in Illustration 42.

This will create a smooth transition from the weld to the rail, therefore reducing the stress concentration. Use a small grinder in order to grind the top of plate (A) to a gradual radius. This will create a smooth transition from the weld to the tank support.

Outside Window Plates Repair for 784B and 784C Tractors, 785, 785B, 785C, 785D, 789,

789B, 789C, 789D,793, 793B, 793C and 793D Off-Highway Trucks

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(A) Inside window plate

(B) 100 mm (4.0 inch)

1. Start at the tail casting and remove the inside window plate (A). Remove an additional 100 mm (4.0 inch) (B) from the

remaining window plate.

Note: When you remove the window plate, do not cut into the tail casting.

2. Locate the crack in the outside window plate. Gouge out the crack from both sides of the plate.

Note: Use the SMAW process and "E7018" welding electrode for all welds. As an alternate process, the FCAW process can be used with "E71T-1 H8" welding electrode.

3. Weld one side of the crack. Gouge out the remaining side of the crack. Weld the remaining side of the crack. Grind the welds down to the original profile.

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4. Add an 8.0 mm (.32 inch) fillet weld (W1) to the toe of the 12.0 mm (.47 inch) fillet weld that joins the outside window

plate and the tail casting. Grind the 8.0 mm (.32 inch) fillet weld to a radius of 5.0 mm (.20 inch).

Note: You may need to remove the pistol plates in order to gain access to the 12.0 mm (.47 inch) fillet weld.

5. Position the inside window plate and the backup plate.

Note: If necessary, install the pistol plates first. Use a 12.0 mm (.47 inch) fillet weld to secure the pistol plates to the frame rail and to the tail casting. Maintain a 3.0 mm (.12 inch) root opening.

6. Apply a 16.0 mm (.63 inch) J-groove weld around the inside window plate from the outside of the frame rail. Extend

the 16.0 mm (.63 inch) J-groove weld 100 mm (4.0 inch) along the top and along the bottom of the frame rail past the

vertical joint in the window plates.

7. Use a 16.0 mm (.63 inch) bevel weld to join the inside window plates.

Rear Window Plate Replacement Near the Tail Casting of 784B and 784C Tractors, 785,

785B, 785C, 785D, 789, 789B, 789C, 789D, 793, 793B, 793C and 793D Off-Highway Trucks

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(A) Outside window plate

(B) 100 mm (4.0 inch)

1. Start at the tail casting and remove a section (A) of the window plate from the outside of the frame rail. Remove an

additional 100 mm (4.0 inch) (B) from the remaining window plate.


Note: The section of window plate that is removed should be the same size as the inside window plate.

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(C) Inside window plate

(D) 100 mm (4.0 inch)

2. Start at the tail casting and remove the inside window plate (C). Remove an additional 100 mm (4.0 inch) (D) from the

remaining window plate.


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(E) New outside window plate

3. Position a new outside window plate (E) and a backup plate.

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4. Use a 12.0 mm (.47 inch) fillet weld (W1) to secure the new outside window plate to the tail casting.

Note: Grind the toe of the 12.0 mm (.47 inch) fillet weld to a 5.0 mm (.20 inch) radius.

Note: Illustration 48 does not show the pistol plates. If necessary, remove the pistol plates in order to gain access to weld (W1) .

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5. Apply a 16.0 mm (.63 inch) J-groove weld (W2) around the new outside window plate from the outside of the frame

rail. Extend the 16.0 mm (.63 inch) J-groove weld 100 mm (4.0 inch) along the top and along the bottom of the frame rail past the vertical joint in the window plates.

6. Use a 16.0 mm (.63 inch) bevel weld (W3) to join the outside window plates.

7. Position the inside window plate and the backup plate.

Note: If necessary, install the pistol plates. Use a 12.0 mm (.47 inch) fillet weld to secure the pistol plates to the frame rail and to the tail casting. Maintain a 3.0 mm (.12 inch) root opening.

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8. Apply a 16.0 mm (.63 inch) J-groove weld (W4) around the inside window plate from the outside of the frame rail.

Extend the 16.0 mm (.63 inch) J-groove weld 100 mm (4.0 inch) along the top and along the bottom of the frame rail

past the vertical joint in the window plates.

9. Use a 16.0 mm (.63 inch) bevel weld (W5) to join the inside window plates.

Rear Cross-Tube Replacement for 793, 793B, 793C, and 793D Off-Highway Trucks

Prepare the Frame in Order to Remove the Rear Cross-Tube

Note: The rear cross-tube can be replaced with the body on the truck or with the body off the truck. If you leave the body on the

truck, the body must remain in the DOWN position while the cross-tube is replaced.

1. Clean the area around the rear cross-tube of the items that follow: oil, grease, dirt and paint.

Note: You must stabilize the area near the rear of the frame before you remove the rear cross-tube. Stabilize the area

near the rear frame in order to maintain the alignment of the bores for the body pins. You can weld braces on the rails

of the frame in order to stabilize the frame. Do not weld the braces too close to the bores for the body pins in order to prevent distortion.

2. Before you stabilize the frame, prepare to take measurements for reference. Use a punch to mark the four locations that

follow:

o Mark the rear of the right tail casting directly behind the bore for the body pin.

o Mark the rear of the left tail casting directly behind the bore for the body pin.

o Mark the rear of the left tail casting directly behind the bore for the pin for the suspension cylinder. o Mark the rear of the right tail casting directly behind the bore for the pin for the suspension cylinder.

3. Record the measurements that follow:

o Measure the distance across the tail castings above the bores for the body pins. Measure the distance from the

outside of the castings.

o Measure the distance from the top left punch mark to the bottom right punch mark.

o Measure the distance from the top right punch mark to the bottom left punch mark.

o Measure the distance between the bottom two punch marks.

4. Remove parts that are exposed and remove parts that could be damaged by the repair procedure. Remove the items that

follow: rear lights, backup alarm, lubrication lines and wiring harnesses. Cut the light bar off the cross-tube. Save the light bar in order to install the light bar on the new rear cast cross-tube.

Note: Record measurements for the location of bosses that will be removed.

Brace the Frame When the Body Is Off

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(A) Frame rail

(B) Square tubing

(C) Steel bar stock

1. Weld braces on the frame rails of the truck in order to maintain the alignment of the pivot pin bores for the body. Apply

one set of braces ahead of the cross-tube. The braces should consist of the material that follows:

o Obtain two pieces of 101.6 mm (4.0 inch) square tubing (B) with 6.35 mm (.25 inch) thick walls. The square

tubing (B) should be long enough in order to extend across the frame rails.

o Obtain two pieces of steel bar stock (C) that are 25.4 mm (1.0 inch) thick and 101.6 mm (4.0 inch) tall. The

steel bar stock should be as long as the square tubing.

2. Place one piece of square tubing (B) across the top of the frame rails. Weld the square tubing (B) in place. Start the weld and stop the weld at least 25.4 mm (1.00 inch) away from the edge of the frame rails (A) .

3. Place the second piece of square tubing (B) across the bottom of the frame rails (A). Weld the second piece of square

tubing (B) in place directly below the first piece of square tubing (B). Start the weld and stop the weld at least 25.4 mm (1.00 inch) away from the edge of the frame rails (A) .

Note: Adjustable spreader bars can be used in place of the square tubing (B). Refer to Illustration 53. Use the screw

adjustment to adjust the width of the spreader bar. When you use spreader bars, weld the pads to the inside of the frame

rails. Start the weld and stop the weld at least 25.4 mm (1.00 inch) away from the weld at the edge of the frame rails (A).

4. Use the steel bar stock (C) that is 101.6 mm (4 inch) wide to make diagonal braces between the two pieces of square tubing (B). The diagonal braces are shown in option 1 of Illustration 51.

Note: You can fabricate the diagonal braces from a single plate that is 25.4 mm (1.00 inch) thick. A diagonal brace that is made from a single piece of plate is shown in option 2 of Illustration 51.

5. Install braces behind the cross-tube. The brace should consist of the material that follows:

o Obtain two pieces of 101.6 mm (4.0 inch) square tubing (B) with 6.35 mm (.25 inch) thick walls. The square

tubing (B) should be long enough in order to extend across the frame rails.

o Obtain two pieces of steel bar stock (C) that are 25.4 mm (1.0 inch) thick and 101.6 mm (4.0 inch) tall. The material should be as long as the square tubing.

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(A) Frame rail

(E) Square tubing

(F) Steel bar stock

6. Place one piece of square tubing (E) across the top of the tail castings above the pivot pin bores for the body. Weld the

square tubing (E) in place.

7. Place the second piece of square tubing (E) at the bottom of the tail castings between the upper mounts for the rear suspension cylinders.

8. Use the steel bar stock (F) that is 101.6 mm (4.0 inch) wide to make diagonal braces. Weld the braces on the tail

castings from the pivot pin bores for the body to the upper mounts for the rear suspension cylinder. The diagonal braces

are shown in option 3 of Illustration 52.

Note: You can fabricate the diagonal braces from a single plate that is 25.4 mm (1.00 inch) thick. A diagonal brace that is made from a single plate is shown in option 4 of Illustration 52.

Brace the Frame When the Body Is On

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(A) Frame rail

(B) Spreader bar

(C) Steel bar stock

1. Weld braces on the frame rails of the truck in order to maintain the alignment of the pivot pin bores for the body. Apply

one set of braces ahead of the cross-tube. The brace should consist of the material that follows:

o Obtain four spreader bars (B) with pads for welding. The spreader bars (B) should have a screw adjustment in

order to extend across the frame rails.

o Obtain two pieces of steel bar stock (C) that are 25.4 mm (1.0 inch) thick and 101.6 mm (4.0 inch) tall. The

material should be as long as the spreader bars.

2. Place two spreader bars (B) across the top of the frame rails. Weld the pads of the spreader bars (B) in place. Start the weld and stop the weld at least 25.4 mm (1.00 inch) away from the weld at the edge of the frame rails (A) .

Note: Use the jam nuts to secure the screw adjustment.

3. Place the second set of spreader bars (B) across the bottom of the frame rails (A). Weld the second set of spreader bars

(B) in place directly below the first set of spreader bars (B). Start the weld and stop the weld at least 25.4 mm (1.00 inch) away from the weld at the edge of the frame rails (A) .

Note: Use the jam nuts to secure the screw adjustment.

4. Use the steel bar stock (C) that is 101.6 mm (4.0 inch) wide to make diagonal braces between the spreader bars (B). The diagonal braces are shown in option 1 of Illustration 53.


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(A) Frame rail

(B) Spreader bar

(C) Steel bar stock

(H) Shims

5. Install braces behind the cross-tube. The brace should consist of the material that follows:

o Obtain a piece of 101.6 mm (4.0 inch) square tubing (B) with 6.35 mm (.25 inch) thick walls. The square

tubing (B) should be long enough in order to extend across the frame rails (A) .

o Obtain two pieces of steel bar stock (C) that are 25.4 mm (1.0 inch) thick and 101.6 mm (4.0 inch) tall. The material should be as long as the square tubing.

6. Place the shims (H) between the inner flanges of the body for the pivot pin bores and the tail castings. The shims will prevent the tail castings from distorting when the new cast cross-tube is installed.

7. Place the piece of square tubing (B) at the bottom of the tail castings between the upper mounts for the rear suspension cylinders.

Note: Adjustable spreader bars can be used in place of the square tubing (B). Refer to Illustration 54. Use the screw

adjustment to adjust the width of the spreader bar. When you use spreader bars, weld the pads to the inside of the tail

castings.

8. Use the steel bar stock (C) that is 101.6 mm (4.0 inch) wide to make diagonal braces. Weld the braces on the tail

castings from the pivot pin bores for the body to the upper mounts for the rear suspension cylinder. Refer to option 3 of Illustration 54.


Remove the Existing Rear Cross-Tube

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New 119-4726 Tube

(J) Length of cross-tube

1. Use a grinder in order to make the ends of the new 119-4726 Cross-Tube square. Use a grinder to restore the chamfer at

the ends of the 119-4726 Cross-Tube . Measure the length (J) of the new cross-tube. Record the measurement (J) .

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(K) Distance from centerline of frame to cut

(M) Width of opening

2. Establish the center line of the existing cross-tube. Mark a line that is a distance (K) from each side of the center line of

the existing cross-tube. Calculate the distance (K) from the formula that follows.

K = (J ÷ 2) + 9.6 mm (.38 inch)

Note: The distance (M) between the outer two lines on the existing cross-tube should be 19.0 mm (.75 inch) wider than

the length (J) of the new cross-tube.

3. Before you cut the cross-tube from the truck, support the existing cross-tube.

4. Cut the existing cross-tube from the truck.

Note: A second cut may be needed on the existing cross-tube in order to provide clearance for removal.

Note: Make sure that the opening (M) is no more than 19.0 mm (.75 inch) wider than measurement (J) .

5. Grind the surface of the transition area until the surface is flush and square. Clean debris away from the inside surfaces of the casting.

Position the New 119-4726 Cross-Tube for Installation

Prepare The Backup Plates

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Backup plate

1. There are four backup plates that are used with the 119-4726 Cross-Tube . Cut each backup plate into two pieces along the length of the backup plate.

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(N) 40.0 mm (1.57 inch)

2. Obtain eight pieces of steel that can be used to hold the backup plates in position. The steel should have the dimensions

that follow:

o 3.0 mm (.12 inch) thick

o 25.4 mm (1.00 inch) wide o 203.20 mm (8.00 inch) long

3. Make a 90 degree bend in the steel. Refer to Illustration 58.

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Backup plate and strip

4. Weld one steel strip to each piece of backup plate. Refer to Illustration 59.

Note: Before you weld the steel strip in place, refer to Illustration 60 in order to calculate the position of the steel strip.

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(P) Total length of cross-tube and backup plates

5. Install the backup plates in the new cross-tube. Use the steel strips to hold the backup plates in position.

Note: When the backup plates are positioned in the new cross-tube, the total length (P) of the cross-tube and backup plates must fit within the opening. When the correct length has been established, tack weld the steel strips in place.

Prepare the Locator Bars in Order to Hold the New Cross-Tube in Position

1. Obtain eight steel bars in order to support the new cross-tube. The bars should have the dimensions that follow:

o 12.7 mm (.50 inch) thick

o 50.8 mm (2.00 inch) wide o 203.2 mm (8.00 inch) long

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Rear cross-tube with backup plates and support bars

2. Weld one locator bar on the top of the new cross-tube at each end of the new cross-tube. Weld the locator bars centrally

on the cross-tube. Allow the locator bars to extend beyond the ends of the new cross-tube. The end of the locator bar,

that extends beyond the end of the cross-tube, will support the cross-tube when the cross-tube is suspended in position.

3. Weld one locator bar on the back side of the new cross-tube at each end of the new cross-tube. Weld the locator bars

centrally on the cross-tube. Allow the locator bars to extend beyond the ends of the new cross-tube. The end of the locator bar, that extends beyond the end of the cross-tube, will locate the cross-tube in the fore and aft position.

Set the New Cross-Tube in Place

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1. Position the new cross-tube in the opening. The new cross-tube should hang from the castings that protrude from the

frame rails. The raised letters on the cross-tube should face toward the front of the machine.

Note: It may be necessary to grind on the locator bars in order to position the cross-tube centrally in the opening.

Note: The new cross-tube weighs approximately 297 kg (655 lb).

2. After the cross-tube is positioned, weld additional locator bars at the top of the cross-tube. Weld additional locator bars

on the side of the cross-tube. Weld the locator bars on the same side as the existing locator bars. At one end of the cross-tube, weld the locator bars to the castings. The casting protrudes from the frame rail.

Note: Secure the new cross-tube to the frame rail on only one side. When the secured side is welded, the opposite end is free in order to float.

3. On the end of the cross-tube that is secured to the frame, cut the tack welds on the steel strips that hold the backup

plates. Slide the backup plates into position. Tack weld the backup plates to the cross-tube. Remove the steel strips that

held the backup plates.

Weld the New 119-4726 Cross-Tube in Place

1. Use the SMAW process and "E7018" welding electrode in order to permanently weld the end of the new cross-tube that

is tack welded to the frame. Use two welding operators that start on opposite sides of the secured end of the cross-tube.

Start the welds at the bottom center of the cross-tube and end the welds at the top center of the cross-tube. Stagger the

starts and the stops. Fill the grooved area to a depth of 40.0 mm (1.57 inch). Before you proceed, complete all welding at the secured end of the cross-tube.

Note: The FCAW process can also be used with "E71T-1 H8" welding electrode.

2. Allow the welded end of the cross-tube to cool to a temperature of 38 °C (100 °F). While the welded end cools, slide

the backup plates at the other end of the cross-tube.

3. Use the SMAW and "E7018" welding electrode in order to weld the four corners on the unsecured end of the cross-

tube. Weld approximately 76.2 mm (3.00 inch) from the center of each corner in both directions. Fill the corners to a depth of 26.7 mm (1.05 inch).


4. Heat all four corners until the corners are a dull red color. Maintain the dull red color between 2 minutes and 3 minutes. Allow the corners to cool to a temperature of 38 °C (100 °F).

Note: The heat treat process will minimize the shrinkage of the cross-tube.

5. Gouge out the welds at the corners. Finish welding the cross-tube in place. Fill the grooved area to a depth of 40.0 mm (1.57 inch).

Complete the Installation of the New Rear Cross-Tube

1. Carefully remove the fixtures that braced the frame. Grind excess welds until the welds are flush. Fill any gouges.

2. Install the light bracket on the new cross-tube. Weld the new bosses on the cross-tube. Refer to the recorded

dimensions.

3. Measure the distances between the punch marks. Compare the measurements to the measurements that were taken previously.

Note: The distance between the punch marks can be 4.5 mm (.17 inch) shorter than the recorded measurement. The shorter measurement should not affect the pivot pin bores for the body.

Note: In some cases, the pivot pin bores may need to be repaired in order to install the body.

4. Paint the area that was repaired.

5. Install the components that were removed earlier.

Rear Support Assembly Replacement

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1. Start by removing the body and supporting the frame rail with jacks.

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2. Next the main rail needs to be braced. Cut two pieces of steel tubing to a length of 102 X 102 X 6 mm (4 X 4 X 1/4

inch).

3. Weld the two braces (2) between the two frame rails. Weld the brace ends (3) with a 6 mm (0.24 inch) fillet welds.

4. Make some reference measurements from the rear pivot holes to the rail and scribe a line on the rail. Record these measurements. The recorded measurements will be used to locate the new rear support assembly.

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5. Remove both rear window plates (1) by cutting around the weld seams.

6. Angle the cuts toward the window plate so that minimal damage is done to the rail. Make sure that the support assembly is safely supported before you cut the assembly loose.

7. Finishing removing the rear support assembly by cutting the inside fillet weld that joins the outside window to the rear casting.

8. Cut weld joints (5) at the top and bottom of the rails. Also, cut welds (6) that is located on the inside on the top and

bottom.

9. After the welds are cut loose, remove the rear support assembly. Prepare the weld joints by grinding the joints to the original profile.

10. Be sure to remove all paint, oil, grease, slag, weld metal, and dirt.

11. Position the new rear support assembly near the frame. Use the recorded reference dimensions to locate the new rear support assembly.

12. Tack weld the assembly into position. Weld the outside window plate to the rear casting on the inside of the rail use a

10 mm (0.4 inch) fillet weld. Weld a 10 mm (0.4 inch) weld on the inside along the rear casting to the rail on the top and bottom as shown in Illustration 65.

13. Next weld the 29 mm (1.14 inch) top and bottom J-groove welds. Alternate between the top and the bottom.

14. Position and tack weld two 2G-7521 Strips (7) to each window (1) .

.

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15. Make strips (7) tack welds from the groove side of assembly.

16. Next tack two 115-3311 Plates to each rail. Weld the vertical 10 mm (0.4 inch) bevel weld joint on both inside window plates. Weld the outside vertical J-groove joints.

17. Next weld the 10 mm (0.4 inch) J-groove around the inside windows.

Note: Make sure that all welds are tied in properly.

18. Clean and visually inspect all welds. The welds should be free from cracks, porosity, undercut, and incomplete fusion. Remove the cross bracing and repair the rails.

19. Grind, blend, and paint as needed. All groove welds should be ultrasonically tested for soundness.

Tail Casting Replacement for 793, 793B, 793C and 793D Off-Highway Trucks

This procedure shows the replacement of the right side tail casting. Similar procedures are required for the left side tail casting.

1. Remove the body from the truck. Remove any components that prevent access to the rear body pivot casting.

2. Support both rear frame rails with jacks.

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(A) Square tubing

(B) Square tubing

(C) Inside window plate

3. Obtain two pieces of 101.6 mm (4.0 inch) square tubing (A) with 6.35 mm (.25 inch) thick walls. The square tubing

should be long enough in order to extend between the frame rails.

4. Obtain two additional pieces of 101.6 mm (4.0 inch) square tubing (B) with 6.35 mm (.25 inch) thick walls. The square

tubing should be 1059 mm (41.7 inch) long. The square tubing will form braces between the rear cross-tube and the bracing between the frame rails.

5. Refer to Illustration 67 in order to brace the rear frame rails with the square tubing.

Note: Position square tubing (A) approximately 140 mm (5.5 inch) from the edge of the inside window plate.

6. Remove the 8X-2376 Window Plate (C) from the inside of the frame rail.

Ver imagen


(D) Pistol plate

(E) Pistol plate

7. Remove the 8X-2686 Plate (D) and the 8X-0463 Plate (E) from the inside of the frame rail.

8. After you make sure that the tail casting is supported, cut the tail casting away from the frame rail and from the rear cross-tube.

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(F) Backup plate

(G) Backup plate

9. After you remove the damaged tail casting, remove the two 9P-1037 Backup Plates (F) from the frame rail. Also,

remove the four 120-6766 Backup Plates (G) from the rear cross-tube.

10. Clean the edges of the joints at the frame rail. Clean the edges of the joints at the rear cross-tube. Remove slag and carbon deposits.

11. Position two new 9P-1037 Backup Plates in the frame rail. Tack weld the backup plates in place.

12. Position four new 120-6766 Backup Plates in the rear cross-tube. Tack weld the backup plates in place.

13. Position the new tail casting in place on the frame rail and on the rear cross-tube. Align the unfinished pivot pin bore of the new tail casting with the pivot pin bore of the existing tail casting.

Note: The reference dimension between the outer edges of the tail castings is 2085.0 mm (82.09 inch).

14. Tack weld the new tail casting in position.

Note: Use the SMAW process and "E7018" welding electrode for all welds. As an alternate process, the FCAW process can be used with "E71T-1 H8" welding electrode.

15. Weld the new tail casting to the rear cross-tube. Alternate the welds between the top of the rear cross-tube and the

bottom of the rear cross-tube in order to prevent distortion. Also, alternate the welds between the front side of the rear

cross-tube and the back side of the rear cross-tube in order to prevent distortion.

16. Weld the new tail casting to the top of the frame rail and to the bottom of the frame rail.

17. Install the pistol plates. Position the 8X-2686 Plate (D) and the 8X-0463 Plate (E) inside the frame rail. Use a 4K-7004

Bar to connect the two plates.

Note: Grind the plates in order to fit the frame rail and the new tail casting. Maintain a 3.0 mm (.12 inch) root opening.

18. Use a 12.0 mm (.47 inch) fillet weld in order to secure the 8X-2686 Plate (D) and the 8X-0463 Plate (E) to the frame rail and to the tail casting. Weld the joint between the plates.

19. Tack weld a new 8X-2688 Backup Plate in the frame rail for the inside window plate.

20. Position the 8X-2376 Window Plate on the inside of the frame rail. Use a 16.0 mm (.63 inch) fillet weld in order to join the inside window plate to the existing side plate of the frame rail.

21. Use a 16.0 mm (.63 inch) J-groove weld to join the inside window plate to the tail casting and to the frame rails.

Note: Do not start the weld on the radius and do not stop the weld on the radius. Stagger the starts and stops.

22. Use a 16.0 mm (.63 inch) J-groove weld to join the outside window plate to the tail casting and to the frame rails.

Note: Do not start the weld on the radius and do not stop the weld on the radius. Stagger the starts and stops.

23. Machine the pivot pin bore of the tail casting to a diameter of 149.93 mm (5.903 inch).

Note: Align the pivot pin bore with the pivot pin bore of the tail casting on the opposite side of the frame.

Procedure to Repair the Bracket Assembly (Steering Box) on the 793C S/N:ATY and 793D

Note: Removal of the engine is required for performing the Advanced Repair. Refer to Disassembly and Assembly Manual,

SENR1461, "3516B Engine Supplement for 793C Off-Highway Truck" and Disassembly and Assembly Manual, RENR8334, "793D Off-Highway Truck Engine Supplement " for procedure to remove and install the engine.

Ver imagen


View of the general area of repair

(A) Bracket assembly (steering box)

(B) Support assembly

The following procedure applies to the repairs of cracks located in the J-groove welds connecting the steering box to the support

castings. Refer to Illustration 71.

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View of crack present in the weld joint

Illustration 71 represents a typical crack that can occur in the weld joint between the bracket assembly (steering box) (A) and

support assembly (B). The crack shown in Illustration 71 is a fatigue crack that has initiated from the root of the weld and

propagated up through the weld and along the length.

Note: The following information provides details about the weld joints and the base material.

Ver imagen


Cross sectional view of J-groove weld joints



Illustration 72 depicts the J-groove weld joint design that is present on all four sides between bracket assembly (steering box) (A)

and support assembly (B). As shown, support assembly (B) contains an inherent (or integral) backing for the weld joint.

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Cross sectional view of corner joints

Illustration 73 depicts the corner joint connection that is common on all four sides. Fillet welds are specified at this location (12

mm (0.47 inch) x 20 mm (0.79 inch).

Table 15

Material Type and Thickness

Part Number Description Material Type Thickness

8X-2272 Bracket ASTM A27 70-40

25 mm (0.98 inch) (1)

8X-2273 Plate ASTM A572 Gr 42

25 mm (0.98 inch)

8X-2274 Plate ASTM A572 Gr 42

20 mm (0.79 inch)

8X-3566 Support ASTM A27 65-35 Varies

8X-3567 Support ASTM A27 65-35 Varies

( 1 ) Nominal

Note: The cast bracket plate has been quenched and tempered to obtain higher mechanical properties than listed.

Basic Repair Procedure for the Bracket Assembly (Steering Box)

Ver imagen


View of probable crack initiation site and propagation path to the surface



(C) Crack

1. Excavate the full length and depth of crack (C) .

The depth of the crack will likely be the full thickness of the adjacent plate on bracket assembly (steering box) (A).

Therefore, the crack will likely be 20 mm (0.79 inch) to 25 mm (0.98 inch) deep depending on the side of bracket assembly (steering box) (A) .

Note: There is likely to be small gap between the underside of the plate and the integral backing of support assembly (B) (shown in Illustration 72).

2. Verify that the crack has been removed via magnetic particle (MT) or dye penetrant (PT) testing.

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View of crack excavated



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View of excavation prepared for welding



(D) 60 degree minimum included angle

(E) 6 mm (0.24 ch) minimum

3. Gouge, grind, and prepare the area to provide suitable access to the root of the joint.

Note: Gaps at the joint root (especially at the corners) should be reduced by building up with weld metal and

blend sanding.

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View run on/off tab examples

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View of run on/off tab used in repair process

4. For repairs made on plates with open ends, attach run on/off tabs in order to place weld starts on tabs and outside of

finish weld. Lack of fusion defects associated with weld starts will then be non-existent when tabs are removed.

5. Inspect all welds visually to ensure that all weld quality meets or exceeds the requirements in the ""Weld Inspection and Acceptance Criteria" " section.

NOTICE

Use caution when removing run on/off tabs. Avoid gouging or grinding

adjacent base material.

6. Remove the run on/off tabs and sand the corners to a generous radius.

Ver imagen


View of completed repair

7. Paint repaired area as needed. Illustration 79 shows a completed repair.

Advanced Procedure to Repair the Bracket Assembly (Steering Box)

Note: Removal of the engine is required for performing the Advanced Repair. Refer to Disassembly and Assembly Manual,

SENR1461, "3516B Engine Supplement for 793C Off-Highway Truck" and Disassembly and Assembly Manual, RENR8334, "793D Off-Highway Truck Engine Supplement " for procedure to remove and install the engine.

If required, perform ""Basic Repair Procedure for the Bracket Assembly (Steering Box)" " before removing the front

plate.

In order to extend the life of the J-groove weld joints and correct the root gap issues, access to the inside of the bracket

assembly (steering box) is required.

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View of the front plate on the bracket assembly (steering box)


(B) Front plate

1. Document and scribe lines for all hardware presently located on front plate (B) .

NOTICE

Use caution not to damage the hardware. Hardware can be reused.

2. Remove all hardware from front plate (B) .

3. There is an internal fillet weld connecting the four sides of bracket assembly (steering box) (A) along the length. Remove the center section of front plate (B) first.

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View of front plate

(B) Front plate

(C) 30 mm (1.18 inch)

4. Measure 30 mm (1.18 inch) from the edge of the weld on front plate (B) and mark a cut line. Refer to Illustration 81.

Note: The 30 mm (1.18 inch) is to avoid damaging the integral backing strip of the support assembly.

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View of bracket assembly (steering box) with front plate partially removed


Note: One access has been obtained you will be able to see the internal fillet welds and the inside surface of the top and

bottom plates of bracket assembly (steering box) (A). Refer to Illustration 82.

5. Gouge/excavate the J-groove welds connecting the remnants of the front plate to the support assembly.

6. Gouge/excavate the corner fillet welds connecting the top and bottom plates to the remaining part of the front plate.

Ver imagen


View of bracket assembly (steering box) with front plate partially removed


7. Continue gouging/cutting the remaining of front plate material (and internal fillet weld) until removed from the top and

bottom plates. Refer to Illustration 83.

8. Once inside, locate the weld root of the J-groove (externally) on three sides (top/bottom/rear).

Ver imagen


View of the locations to excavate to locate weld root

9. Use arc/air gouging and grinding to remove part of the integral backing strip to locate the weld root and prepare the

joint for welding.

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View before excavation

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View after excavation

10. Back gouge to sound metal (D) .

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View of prepared area

11. Grind and sand gouged areas to smooth rough edges and remove any carbon and slag residue.

Note: Tungsten carbide burring tools will need to be used in the corners in lieu of grinders/sanders.

12. Visually inspect (with the aid of a good light source) to verify that sound metal has been reached and there are no

discontinuities present to hinder a quality root pass. If anything appears suspicious, then verify with either magnetic particle (MT) or dye penetrant inspection (PT).

Note: Perform Step 9 through Step 12 on both sides (left and right) before welding.

Ver imagen


View of offset

13. Measure offset (D) between the inside surface of the adjacent plate of bracket assembly (steering box) and the inside

surface of the integral backing strip on the support assembly. Refer to Illustration 88Record the offset dimensions.

Note: Offset will be used to determine fillet weld size.

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View of welding progression

14. Weld the root pass as shown in Illustration 89. Vertical progression is uphill and no starts or stops are allowed in the corners. Weld the root pass on one side and then the other side.

Note: Use a balanced welding technique in order to equalize the welding distortion between the two sides. For

example, weld the root pass on the left side and the weld the root pass on the right side. Continue this sequence for each succeeding pass until the groove (excavation) portion is filled.

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View of no weld area previously specified

15. Prior to finishing the weld joint between the support assembly and the bracket assembly (steering box), the fillet weld

that is internal to the bracket assembly (steering box) will need to be modified.

Illustration 90 shows that the internal fillet weld from the factory does not extend all the way to the edge, but is stopped short by 100 mm (3.94 inch).

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View of the internal fillet weld size

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View of the drain hole in the bracket assembly (steering box)

16. Extend the fillet weld until the fillet weld connects at the corners with the previous welds applied. The size of the fillet

weld is 10 mm (0.40 inch) as shown in Illustration 91. Do not weld the drain hole shut.

Note: Grind the existing weld start/stop to minimize lack of fusion before starting the fillet weld that extends into the corner.

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View of full penetration groove weld with fillet weld transition

17. The offset was measured in Step 13. This dimension determines the size of the fillet weld that will be added over the

partial J-groove weld in Step 14, and the fillet weld that was completed in Step 16.

Example: If the offset is 10 mm (0.40 inch), then the fillet weld over the J-groove weld will be a 10 mm (0.40 inch) by

10 mm (0.40 inch) fillet weld. The fillet weld size will vary depending on the offset. Illustration 93 depicts the expectation of the full penetration groove weld and fillet weld.

Note: Use the same welding progression and balanced welding technique in reference to Illustration 89.

18. Visually inspect all welding and ensure that all weld quality meets or exceeds the requirements in the ""Weld Inspection and Acceptance Criteria" " section.

19. Blend sand all weld starts/stops and any transitions.

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View of prepared edges and surfaces for welding

20. Prepare the edges of the plates and surfaces of the J-groove preparations on the support assembly. Repair any divots or

gouges by welding and sanding. Refer to Illustration 94.

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Dimensions for fabrication of front plate

(E) 1090 mm (42.91 inch)

(F) 355 mm (13.98 inch)

(G) 20 mm (0.79 inch)

21. Use the dimensions in Illustration 95 in order to fabricate a new front plate. Use ASTM A572 Grade 42 material.

Ver imagen


Determine if gap exists


(H) Gap measurement

(J) front plate

22. Fit the fabricated front plate (J) to bracket assembly (steering box) (A) and check for interference or gaps. If gaps exist

between the bottom side of front plate (J) and the integral backing strip on support assembly (B), record the measurement and build up the support assembly casting accordingly. Refer to Illustration 96.

Note: Gaps should be less than 2 mm (0.079 inch)

Ver imagen


View of support assembly casting built up


(H) Gap measurement

23. Build up support assembly (B) casting by welding to a dimension slightly higher than gap measurement (H) .

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View of support assembly casting sanded to profile

24. Blend sand excess weld material to achieve a smooth J-groove profile with minimal gap.

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View of J-groove minimum requirements


(J) Front plate

(K) 20 mm (0.79 inch)

(L) 45 degree bevel

25. Install front plate (J) and ensure desired fit-up has been achieved. The minimum face opening for a J-groove should be

approximately 20 mm (0.79 inch). Refer to Illustration 99.

Ver imagen


View of optional single V groove

(J) Front plate

26. If access to the root is difficult, grind a bevel (15 to 20 degree) on front plate (J) to increase access. Refer to Illustration

100.

27. Secure front plate (J) in place using 6 mm (0.24 inch) by 50 mm (1.97 inch) fillet welds on all four sides.

28. Attach run on/off tabs as discussed in Step 4 in the ""Basic Repair Procedure for the Bracket Assembly (Steering Box)" ".

29. Weld the root pass at each of the four weld joints before proceeding with the second and third weld passes.

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View of the direction/progression of welding for fillet welds

30. The progression for the J-groove welds will be vertical up. The direction for the top and bottom fillet welds are shown

in Illustration 101. Start each weld pass in the middle and terminate at the end of the joint.

Note: Grind the weld start in the middle to minimize lack of fusion before starting the fillet weld going in the opposite direction.

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View of weld sizes

(J) Front plate

31. Finish weld front plate (J) using the weld sizes shown in Illustration 102.

Note: Use a balanced welding technique in order to equalize the welding distortion between the four sides. Do not weld

more that two passes at one joint before the next.

32. Inspect all welds visually to ensure that all weld quality meets or exceeds the requirements in the ""Weld Inspection

and Acceptance Criteria" " section.

NOTICE

Use caution when removing run on/off tabs. Avoid gouging or grinding

adjacent base material.

33. Remove the run on/off tabs and sand the corners to a generous radius.

34. Locate and reattach all miscellaneous hardware that was document and removed in Step 1 and Step 2.

35. Paint repaired area as needed.

Steering Box Replacement or Replace the Bracket that is on the Steering Box

The steering box can be replaced or the bracket that is on the steering box can be replaced. To replace the complete steering box,

the engine must be removed. The bracket can be replaced without removing the engine. In either case, a new steering box is needed in order to complete the repair.

Table 16

Part Numbers for Replacement of the Steering Box

Model Part Number

784B, 784C, 785, 785B, 785C, 785D 5T-8671

789, 789B, 789C, 789D 5T-6243

793, 793B, 793C, 793D 8X-2283

Complete Steering Box Replacement

1. Remove any components that prevent access to the center steering box.

2. Support both front frame rails with jacks.

3. Measure the distance from the bore diameters in the steering box to the mounting locations for the front suspension cylinders. Record the measurements to use as a reference when you install the new steering box.

Ver imagen


Typical steering box

(A) Square tubing

(B) Steering box

4. Obtain two pieces of 101.6 mm (4.0 inch) square tubing (A) with 6.35 mm (.25 inch) thick walls. The square tubing

should be long enough in order to extend between the mounting locations for the front suspension cylinders.

5. Refer to Illustration 103 in order to place the square tubing (A) between the mounting locations for the front suspension cylinders.

Note: Use 8.0 mm (.32 inch) fillet welds in order to secure the square tubing (A) to the mounting locations for the front suspension cylinders.

6. Use an air carbon arc torch in order to remove the damaged steering box. Angle the torch toward the steering box in order to prevent damage to the mounting locations for the front suspension cylinders.

7. Clean slag and carbon deposits from the J-grooves on the mounting locations for the front suspension cylinders.

8. Use the reference dimensions in order to place the new steering box (B) in position.

Note: You may need to remove the cast backup strip on the J-groove in order to fit the steering box (B) in place. If you remove the cast backup strip, you will need to use separate backup strips.

9. Ensure that there is a 5.0 mm (0.20 inch) root opening around each end of the steering box (B) .

Ver imagen


(B) Steering box

(C) Hardware



10. Start the J-groove welds (W1) at both vertical joints at the front of the steering box (B). Fill the grooves to the halfway point.

11. Use J-groove welds (W2) to weld both vertical joints at the rear of the steering box (B). Fill the grooves completely.

12. Complete the J-groove welds (W1) at both vertical joints at the front of the steering box (B). Fill the grooves

completely.

13. Use J-groove welds (W3) to weld both joints at the bottom of the steering box (B). Fill the grooves completely.

14. Use J-groove welds (W4) to weld both joints at the top of the steering box (B). Fill the grooves completely.

15. Position any hardware (C) that was removed from the original steering box. Weld the hardware (C) in place.

16. Remove the square tubing (A) that was used to brace the frame. Grind the mounting locations for the front suspension cylinders to the original profile.

Table 17

Sizes for Welds

Model (W1) (W2) (W3) (W4)

784B, 784C, 785, 785B, 785C,

785D

20.0 mm (.79

inch)

25.0 mm (.98

inch)

25.0 mm (.98

inch)

25.0 mm (.98

inch)

789, 789B, 789C, 789D

20.0 mm (.79

inch)

20.0 mm (.79

inch)

25.0 mm (.98

inch)

25.0 mm (.98

inch)

793, 793B, 793C, 793D

20.0 mm (.79

inch)

20.0 mm (.79

inch)

25.0 mm (.98

inch)

25.0 mm (.98

inch)

Replace the Bracket that is on the Steering Bracket

The procedure can be performed without removing the engine. Replace the steering bracket whenever the bores are not within the

specifications. A new steering box is needed in order to complete the procedure. This procedure consists of the following

procedures: preparation of the new steering bracket, removal of the worn steering bracket, installation of the new steering bracket and welding of the new steering bracket.

Preparation of the New Steering Bracket

Note: The following trucks need an updated center arm and associated parts in order to use the steering box part numbers

referenced in Table 18. 785 (S/N: 8GB1-516) and 789 S/N:9ZC1-554. Refer to Service Magazine, SEPD0055, "New Bearing and

Shims Used Between Steering Arm and Frame Bracket" for additional information.

Table 18

Part Numbers for Replacement of the Steering Box

Model Part Number

784B, 784C, 785, 785B, 785C, 785D 5T-8671

789, 789B, 789C, 789D 5T-6243

793, 793B, 793C, 793D 8X-2283

Table 19

Sizes of Bevels and Sizes of Welds

Model B1 W1 W2 W3 W4 W5

784B, 784C, 785,

785B, 785C,

785D

10 mm (0.4

inch)

12.0 mm (0.47

inch)

25.0 mm

(0.98

inch)

10 mm (0.4

inch)

12.0 mm (0.47

inch)

25.0 mm

(0.98

inch)

789, 789B, 789C,

789D

10 mm (0.4

inch)

12.0 mm X 20 mm

(0.47 inch X 0.8

inch)

20 mm (0.8

inch)

10 mm (0.4

inch)

12.0 mm X 20 mm

(0.47 inch X 0.8

inch)

20 mm (0.8

inch)

793, 793B, 793C,

793D

10 mm (0.4

inch)

12.0 mm X 20 mm

(0.47 inch X 0.8

inch)

20 mm (0.8

inch)

10 mm (0.4

inch)

12.0 mm X 20 mm

(0.47 inch X 0.8

inch)

20 mm (0.8

inch)

1. Order a new steering box. Refer to Table 18.

Ver imagen


2. Remove the casting (1). Use air carbon arc to gouge the fillet welds (A) from the outside corners. Gouge the fillet

welds (B) from the inside corners. Protect the bores from sparks or from grinding material during the removal

procedure. Also protect the bores during the cleanup procedure. Refer to Illustration 105. Remove the bracket from the

steering box. Do not cut into the casting with the gouging rod.

Note: The remaining plate steel will not be needed for this repair.

3. Once the bracket is removed from the steering box, clean the casting by removing all existing weld deposits with a grinder.

Ver imagen


4. Machine the bevel or grind the bevel (B1). The angle of the bevel is 45 degrees. Refer to Table 19 for the size of the bevels.

Removal of the Worn Bracket from the Existing Steering Box

Note: Be sure to protect all surfaces from sparks and grinding grit.

1. Remove all hydraulic lines and steering cylinders from the area around the existing bracket assembly.

2. The center arm will also need to be removed.

Ver imagen


3. Scribe a line (L1) from the center of the bore across the top of the steering box. Make a center punch on top of the

steering box. This will be used to locate the new bracket.

Ver imagen


4. Remove the worn bracket. Cut along line (C1) .

Note: For the weld seams (W2), angle the air carbon arc torch straight down in order to remove the weld deposit. Use caution so that the cast backup is not cut.

Note: The top and bottom seams are fillet welds (W1). The weld joints on the sides of the bracket are J-groove welds with a backup casting (W2). Refer to Table 19 for the size of the welds.

5. Clean the J-groove welds that are on the sides of the support castings. Do not gouge the cast backup strip. Clean the top

of the steering box of slag and bottom of the steering box of slag. Then prepare the square edge.

Installation of the New Bracket

Note: Ensure that the casting is beveled. Remove all foreign material from the weld joint.

1. Use the scribed line on top of the steering box to locate the center bore. Center the bore with the line. Adjust the casting

so that the top weld seams and bottom weld seams are equal. Locate the new casting.

2. Tack weld the bracket to the steering box and to the support castings.

Weld the New Bracket to the Existing Steering Box

Note: Perform the welding in order to distribute the heat. This will avoid excessive weld distortion. Complete the groove welds

before you begin the fillet welds. For example, place one pass on the top, one pass on the bottom, one pass of the right side, and

one pass on the left side. Repeat this process until the weld seams are complete. Remove the slag after each pass and do not allow the interpass temperature to exceed 205 °C (400 °F).

Ver imagen


1. Weld a bevel groove weld (W3) on the top of the casting and on the bottom of the casting. There is a notch on the

bottom of the casting that is designed to drain the casting. Do not weld over the drain hole (DH). Refer to Table 19 for

the size of the welds.

2. Once bevel groove weld (W3) is full, weld a fillet weld (W4) on the top of the casting and on the bottom of the casting. Again, do not weld over the drain hole (DH). Refer to Table 19 for the size of the welds.

3. Weld J-groove welds (W5) on both sides of the casting. Refer to Table 19 for the size of the welds.

Ver imagen


4. Smooth the welds from the support casting to the steering box. Place the tie-in at the corners. Blend the weld in order to

match the contour of the support assembly and of the steering box. Grind the welds (G1) at four corners smooth.

5. Locate any removed hardware. Weld the hardware in place.

6. Visually inspect all welds. The welds shall be free from cracks, porosity, undercut, and incomplete fusion. Blend the welds. If necessary, paint the components.

7. Reassemble all components that were removed in order to make the repair.

Ball Replacement for the Lower Connection of the Hoist Cylinder

1. Remove any components that prevent access to the ball.

Ver imagen


View of ball installation

(A) Ball

(B) Refer to Table 20.

(C) Refer to Table 20.

2. Use an air carbon arc torch to remove the worn ball (A). Angle the torch toward the ball in order to prevent damage to

the drop tube casting.

3. Clean the slag and the carbon from the casting.



4. Locate the new ball (A) in position. Refer to Illustration 111 and Table 20. Use three 8.0 mm (.32 inch) fillet welds that

are equally spaced to tack weld the ball in place. The tack welds should be 50.8 mm (2.0 inch) long.

5. Use multiple passes to complete the J-groove weld (W1) at the Ball (A). Refer to the Table 20 in order to determine the

size of the J-groove weld (W1) that is required for your machine. Weld each pass completely around the ball in order to minimize distortion.

Note: Cover the ball in order to protect the machined surfaces from damage due to welding.

6. Use a hand grinder in order to blend the weld between the ball and the casting. Paint the area around the new ball.

Table 20

Sales Model Part Number (A) Dimension (B) Dimension (C) Weld (W1)

785, 785B, 785C, 785D 6G-6499 Ball

271 mm (10.67 inch) -

35.0 mm (1.38 inch)

789, 789B, 789C, 789D 6G-6499 Ball

298 mm (11.73 inch) -

35.0 mm (1.38 inch)

793B, 793C, 793D 8X-1213 Shaft -

335 mm (13.19 inch)

44 mm (1.73 inch)

Replacing the Drop Tube Assembly on the 793C and 793D Off-Highway Trucks

Table 21

Required Parts

Item Qty Part Number Description

1 1 125-6968 Support As (1)

2 1 125-6969 Plate As

3 2 284-7988 Plates

4 1 8X-5939 Block

5 1 135-7627 Bracket

6 1 135-7641 Gusset

7 1 8X-2573 Bracket

8 1 8X-2574 Gusset

( 1 ) Also referred to as "Drop Tube As"

Note: The total combined weight of the components in Table 21 is approximately 1390 kg (3064 lb).

1. Disassemble as required to obtain unrestricted access to the drop tube-to-frame weld joint interfaces. Items to be

removed include the A-frame assembly, drive shaft, hydraulic tank, fuel tank, the hoist cylinders, and any hoses/tubes that may interfere with welding.

2. Plug all open hose and tube ends.

3. Remove all components from the top of the drop tube.

4. To avoid damage from weld and oxy-fuel cutting torch spatter, protect all exposed machined surfaces, hoses, tubes, and affected nearby components with flame proof blankets.

5. Support bottom of frame with suitable stands so that the frame is level in the transverse direction.

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(A) 80 mm (3.15 inch)

(B) Existing drop tube assembly

6. Layout cut lines 80 mm (3.15 inch) down from pad casting corner, both sides, two castings. Connect layout lines across

each casting end surface.

7. Using sling straps or choke chains, attach hoist to drop tube castings.

Note: The weight of existing drop tube assembly (B) and associated welded components is approximately 1390 kg (3064 lb). Be sure to use a suitable lifting device rated for this capacity.

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(B) Existing drop tube assembly

8. Using an oxy-fuel cutting torch with a tip capable of penetrating 45 mm (1.77 inch) steel thickness, carefully cut along

the lines laid out in Step 6.

Note: The torch cuts must be parallel with the bottom frame rail surface to prevent damage to the drop tube mounting pad surfaces.

9. After existing drop tube assembly (B) is free, remove from under truck frame.

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Arrows show the areas on the frame rail pad castings to grind smooth.

10. Remove slag. Then grind the casting faces smooth. Grind the weld metal only. Fill gouges as needed. Then grind flush.

11. Use a suitable tool to determine the flatness of the frame rail pad castings. Ensure that each frame rail pad casting is flat to within 5.0 mm (0.20 inch) in both directions.

Note: The casting faces are milled from the factory with a course "N" surface finish. Grind only the areas affected

during the cutting operation. There should be no need to grind the inner, undisturbed casting face surfaces.

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View of existing drop tube assembly (B) with original components

12. Take note of the original locations of items (C1), (C2), (D), and (E) on existing drop tube assembly (B) using whatever

measurements are necessary. Then use these measurements to locate and weld the new items to new drop tube

assembly (1).

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(1) New drop tube assembly

(2) Plate assembly

(W2) A 20 mm (0.79 inch) flare-bevel groove weld along top of plate assembly (2).

(W3) A 12 mm (0.47 inch) vertical fillet weld with 1.5 mm (0.06 inch) root penetration on both sides of each gusset. Weld in upward direction.

13. Using the measurements taken in Step 12, locate and weld plate assembly (2) to new drop tube assembly (1) .

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(3) Plates

(4) Block

(W4) An 8 mm (0.31 inch) fillet weld with 1.5 mm (0.06 inch) root penetration all the way around each plate (3).

(W5) A 12 mm (0.47 inch) flare-bevel groove weld along the top and bottom of block (4).

14. Using the measurements taken in Step 12, locate and weld plates (3) and block (4) to new drop tube assembly (1) .

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Arrows show where to grind chamfer.


15. Prepare new drop tube assembly (1) by removing paint from casting weld areas. Then grind a 2 mm (0.08 inch) to 3

mm (0.12 inch), 45 degree chamfer all around the top of both drop tube castings. The arrows in Illustration 118 show the areas to be ground to a chamfer.

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Left side view


(F) 548 mm (21.57 inch)

(G) 1464 mm (57.64 inch)

(H) 228 mm (8.98 inch)

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View J - J


(H) 228 mm (8.98 inch)

(K) 85 mm (3.35 inch)

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Right side view


(L) 622 mm (24.49 inch)

(M) 1489 mm (58.62 inch)

(N) 302 mm (11.89 inch)

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View P - P


(N) 302 mm (11.89 inch)

(R) 228 mm (8.98 inch)

16. Using a hoist with straps or choke chains raise new drop tube assembly (1) to the bottom of the frame. Support new

drop tube assembly (1) with jacks. Locate new drop tube assembly (1) from the centerlines of the upper hydraulic and

fuel tank brackets. Use the dimensions from Illustration 119, Illustration 120, Illustration 121, and Illustration 122 in order to position new drop tube assembly (1) correctly.

Note: The weight of new drop tube assembly (1) and associated welded components is approximately 1390 kg (3064

lb). Be sure to use a suitable lifting device rated for this capacity. If using an overhead shop hoist with chains, the use of a hook insulator is required.

17. Tack weld the assembly into position by using 25 mm (0.98 inch) long, heavy-duty tack welds all the way around each tube casting.

18. Clean slag from all tack welds and inspect.

Note: No weld overlap or crater cracks allowed.

19. Prepare the weld joints for root passes by feather grinding the ends of the tack welds.

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White arrow shows view of root pass.


20. Weld root pass all the way around each tube casting. Maintain the same direction of weld travel for the fore-aft (side) weld joints and the transverse (front and rear) weld joints.

21. Remove hoist, clean root passes, and inspect.

Note: Visually inspect subsequent weld passes and repair as needed.

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Left side view


(W6) A 30 mm (1.18 inch) J-Groove weld


(W8) A 20 mm (0.79 inch) J-Groove weld on the inside and the outside of each tube casting

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Right side view





22. Use a 30 mm (1.18 inch) J-Groove weld on the front of each tube casting. Weld until 50% full, alternating every two or three passes from side to side.

Note: Transverse (front and rear) weld passes shall wrap around corners, starting, or terminating in the fore-aft (side)

weld joints.

23. Slag each weld pass.

24. Use a 40 mm (1.57 inch) J-Groove weld on the rear of each tube casting. Weld until 33% full, alternating every two or three passes from side to side.

Note: Transverse (front and rear) weld passes shall wrap around corners, starting, or terminating in the fore-aft (side) weld joints.

25. Feather grind the ends of the transverse (front and rear) weld passes.

26. Use a 20 mm (0.79 inch) J-Groove weld on the inside and the outside of each tube casting. Weld until 50% full, alternating every two or three passes from side to side.


28. Clean all welds and prepare joints for finish welding.

29. Use a 30 mm (1.18 inch) J-Groove finish weld on the front of each tube casting. Finish weld the remaining 50%, alternating every two or three passes from side to side.

Note: Transverse (front and rear) weld passes shall wrap around corners, starting, or terminating in the fore-aft (side) weld joints.


31. Use a 40 mm (1.57 inch) J-Groove weld on the rear of each tube casting. Weld until 66% full, alternating every two or

three passes from side to side.

Note: Transverse (front and rear) weld passes shall wrap around corners, starting, or terminating in the fore-aft (side)

weld joints.

32. Feather grind the ends of the transverse (front and rear) weld passes.

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View of finish weld (W8)



33. Use a 20 mm (0.79 inch) J-Groove finish weld on the inside and the outside of each tube casting. Finish weld the

remaining 50%, alternating every two or three passes from side to side.


35. Use a 40 mm (1.57 inch) J-Groove finish weld on the rear of each tube casting. Finish weld the remaining 33%, alternating every two or three passes from side to side.

36. Clean all welds.

37. Inspect and repair the finish welds as needed.

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Left side view of transverse (front and rear) finish welds



(S) Finish grind contour for (W6)

(T) Weld contour before grinding for (W6)


(U) Finish grind contour for (W7)

(V) Weld contour before grinding for (W7)

38. Grind all transverse (front and rear) finish welds to the contours shown in Illustration 127.

39. Grind the front and rear ends of the fore-aft (side) finish welds flush approximately 75 mm (2.95 inch) from each end. Blend around each corner to the transverse (front and rear) finish welds.

Note: No sharp corners allowed.

40. Remount the hydraulic tank to the right side of the truck, supporting the bottom of the hydraulic tank with a hydraulic jack. Snug the mounting bolts and caps.

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(5) Bracket

41. Assemble new bracket (5) to the hydraulic tank with regular mounting hardware.

42. Lower the hydraulic jack allowing bracket (5) to touch the RH side of new drop tube assembly (1) .

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(5) Bracket

(X) Bracket (5) angle as measure from the horizontal is 20 +/- 2 degrees.

43. Check the bracket angle and rotate bracket (5) in order to duplicate the original angle. The angle as measured from the

horizontal should be 20 +/- 2 degrees.

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(5) Bracket

(W9) A tack weld all the way around the inside of the slot in bracket (5).

44. While maintaining angle (X) which is shown in Illustration 129, tack weld bracket (5) to the RH side of new drop tube

assembly (1) .

Note: Tack weld around the inside of the slot in bracket (5) only. Do not tack weld around the perimeter of bracket (5) .

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(5) Bracket

(6) Gusset

(W10) Tack welds attaching gusset (6) to bracket (5) and new drop tube assembly (1).

45. Locate and tack weld gusset (6) to the RH side of new drop tube assembly (1) and to bracket (5). Tack weld both on the top and on the bottom of gusset (6) .

46. Remove the hydraulic tank from the truck.

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(5) Bracket

(W11) A 25 mm (0.98 inch) weld with 2.5 mm (0.10 inch) root penetration all the way around the inside of the slot in bracket (5).

47. Weld around the inside of the slot in bracket (5) .

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(5) Bracket

(6) Gusset

(W12) A 15 mm (0.59 inch) weld with 2.5 mm (0.10 inch) root penetration on the top and bottom of gusset (6).

48. Weld gusset (6) to the RH side of new drop tube assembly (1) and to bracket (5). Weld both on the top and on the bottom of gusset (6) .

49. Remount the fuel tank to the left side of the truck, supporting the bottom of the fuel tank with a hydraulic jack. Snug

the mounting bolts and caps.

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(7) Bracket

50. Assemble new bracket (7) to the fuel tank with regular mounting hardware.

51. Lower the hydraulic jack allowing bracket (7) to touch the LH side of new drop tube assembly (1) .

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(7) Bracket

(W13) A tack weld all the way around the inside of the slot in bracket (7).

52. Tack weld bracket (7) to the LH side of new drop tube assembly (1) .

Note: Tack weld around the inside of the slot in bracket (7) only. Do not tack weld around the perimeter of bracket (7) .

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(7) Bracket

(8) Gusset

(W14) Tack welds attaching gusset (8) to bracket (7) and new drop tube assembly (1).

53. Locate and tack weld gusset (8) to the LH side of new drop tube assembly (1) and to bracket (7). Tack weld both on the

top and on the bottom of gusset (8) .

54. Remove the fuel tank from the truck.

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(7) Bracket

(W15) A 25 mm (0.98 inch) weld with 2.5 mm (0.10 inch) root penetration all the way around the inside of the slot in bracket (7).

55. Weld around the inside of the slot in bracket (7) .

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(7) Bracket

(8) Gusset

(W16) A 25 mm (0.98 inch) vertical flare-bevel groove weld which is welded in the upward direction. (W16) welds the inboard side of bracket (7) to the

LH side of new drop tube assembly (1).

56. Weld vertically up along the inside of bracket (7) and the LH side of new drop tube assembly (1) .

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(7) Bracket

(8) Gusset

(W17) A 15 mm (0.59 inch) weld with 2.5 mm (0.10 inch) root penetration on the top and bottom of gusset (8).

57. Weld gusset (8) to the LH side of new drop tube assembly (1) and to bracket (7). Weld both on the top and on the

bottom of gusset (8) .

58. Repaint bare metal areas.

59. Reassemble all of the hardware that was removed prior to the repair.

Updating The A-Frame Mounting Area on the Center Tube for the 793 Truck

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Section view of center tube area

(1) Remove weld

(2) Fillet weld

1. Begin by removing any existing cracks by grinding or carbon arc gouging. Verify that the crack has been removed by

the use of dye penetrant.

2. Remove the existing 16 mm (0.63 inch) fillet weld (1) and cut a groove 12 mm (0.47 inch) deep with a 45 degree bevel as shown in illustration 140.

3. Clean the prepared weld joint by grinding. Make sure that all of the oil, dirt, and the dye penetrant is cleaned from the joint.

4. Weld the groove with small stringer welds. Weld a 16 mm (0.63 inch) fillet (2) over the groove. The toes on the fillet weld should have a smooth transition with no overlaps.

5. Visually inspect the welds. The weld should be free from cracks, porosity, undercut, the overlay, and incomplete fusion.

Suspension A-Frame Field Weld Repair for the Weld Joint for the 785, 785B, 785C, 785D,

789, 789B, 789C, 789D, 793, 793B, 793C and 793D Off-Highway Trucks

Note: For cracks in machined surfaces refer to Special Instruction, REHS2346, "Weld Repair Procedure for the Rear Axle A-Frame and Rear Axle Housing on 785, 789, and 793 Off-Highway Trucks".

Ver imagen


Welded joints for the A-Frame

1. Visually inspect the welded joints of the suspension A-frame for cracks. Also use some liquid dye penetrant in order to

inspect joints that may have cracks. As an alternative, you can use the magnetic particle inspection process to inspect

the welded joints.

2. Use one of the methods that follows in order to remove cracks.

o Grinding process o Air carbon arc torch

Note: Cracks that extend completely through the original weld should only be removed by the grinding process.

Completely remove the crack from the base metal. Use some liquid dye penetrant in order to inspect the ground

surfaces of the groove. Also, you can use the magnetic particle inspection process to inspect the ground surfaces of the

groove. When the crack is removed, the bottom of the groove should have an angle of 90 degrees in order to ensure sufficient penetration. The side walls of the groove should extend upward at an angle of 45 degrees.

3. Clean the area that will be welded.

4. Protect the machined surfaces from the weld spatter. Protect the machined surfaces from the sparks.

5. Attach the welding ground cable directly on the suspension A-frame.

6. Heat the base metal of the groove to a temperature of 150 °C (300 °F). Maintain the temperature of the base metal at 150 °C (300 °F) during the welding process.

7. Use the SMAW process and "E7018" welding electrode in order to fill the grooves that are left after you remove the

cracks. Remove the slag after every pass of the welding electrode.


8. Clean the welds. Inspect the repairs for the following defects:

o Cracks

o Porosity

o Undercut o Incomplete fusion

Note: Use some liquid dye penetrant in order to inspect the weld. Also, you can use the magnetic particle inspection process to inspect the weld.

9. Use a hand grinder to blend the weld flush at the corners to the profile of the casting.

Relocate the Mounting Block on the Suspension A-Frame of 793, 793B, 793C and 793D Off-Highway Trucks

in Order to Prevent Cracks

Ver imagen


Mounting block

Check the location of the mounting block at the front of the suspension A-frame. If the mounting block is located over the weld

bead that joins the center section of the A-frame and the right leg support, the overlap of the welds may cause cracks to develop.

Move the mounting block in order to correct the overlap.

1. Remove the existing mounting block.

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Fabricated mounting block

(A) 223.5 mm (8.80 inch)

(B) 20 mm (.80 inch)

(C) 45 mm (1.77 inch)

(D) 15 mm (.59 inch)

(E) 193.5 mm (7.62 inch)

(F) 22.5 mm (.89 inch)

(G) 10.53 ± .10 mm (.415 ± .004 inch) Diameter

2. Fabricate a new mounting block from steel that meets ASTM specification "A36". Refer to Illustration 143.

Ver imagen


Moved mounting block

(H) 112 mm (4.4 inch)

(J) 175 mm (6.9 inch)

(K) This is the starting point for the weld.

(L) This is the end point for the weld.

3. Use the SMAW process with "E7018" welding electrode in order to secure the new mounting block on the suspension A-frame. Refer to Illustration 144 in order to position the new mounting block.


Bearing Bore Field Repair for the Suspension A-Frame for 785, 785B, 785C, 785D, 789, 789B, 789C, 789D,

793, 793B, 793C and 793D Off-Highway Trucks

Ver imagen


Typical A-Frame

(A) Refer to Table 22.

(B) Refer to Table 22.

You can install a sleeve in order to salvage the bearing bore at the front of the suspension A-frame.

Note: The only option for wear is a sleeve. The entire a-frame must be replaced if wear is excessive or the a-frame has cracks at

the bolt holes. If the bore cannot be sleeved, the a-frame must be replaced. The nose is not a replacement option due to assembly, dimensioning, and machining requirements.

Table 22

Dimensions for Machining the Bearing Bore

Sales Model Dimension (A) Dimension (B) Part Number for the

Sleeve

785B, 785C, 785D

32.35 mm (1.27

inch)

215.86 ± .013 mm (8.498 ± .0005

inch)

184-6962

789B, 789C

32.35 mm (1.27

inch)

215.86 ± .013 mm (8.498 ± .0005

inch)

184-6962

793, 793B, 793C.

793D

21.12 mm (.83 inch)

234.92 ± .013 mm (9.249 ± 0.0005

inch)

184-6963

1. Remove the suspension A-frame from the center cross-tube of the truck. Remove the bearing from the bearing bore.

Ver imagen


Bearing bore that does not require welding

(C) Original bearing bore

(D) Worn area

(E) Bore for sleeve

2. If the largest diameter of the bearing bore that is elongated is less than the outer diameter of the sleeve, machine the

bearing bore to the dimension that is listed in Table 22. Refer to Illustration 146.

Note: If the largest diameter of the bearing bore that is elongated is greater than the outer diameter of the sleeve, you must replace the A-frame.

3. Lower the temperature of the sleeve to −45° ± 5°C (−50° ± 10°F).

4. Install the sleeve in the bearing bore of the suspension A-frame.

5. Lower the temperature of the bearing to −45° ± 5°C (−50° ± 10°F).

6. Install the bearing in the bearing bore of the sleeve in the suspension A-frame.

7. Connect the suspension A-frame to the center cross-tube of the truck.

Control Rod Bores Field Repair on Differential Housing and Main Frame for the 785,

785B, 789, 789B, 789C, 789D, 793, 793B, 793C and 793D Off-Highway Trucks

Repair Procedure

Ver imagen


(A) Main frame bore

(1) 2.5 degree

Ver imagen


(B) Differential housing bore

Begin the repair by cleaning the bore to be welded. Measure the bore so that amount of buildup can be determined. Use small 6

mm (0.24 inch) weld passes. Try to make each pass continuous. Make sure that all weld passes are tied-in and slag each pass. After welding, bore to the following dimensions as shown in Table 23.

Table 23

785 789 793

Frame Bore (A)

101.66 mm (4.0024 inch)

101.66 mm (4.0024 inch)

101.66 mm (4.0024 inch)

Differential Housing Bore B

101.66 mm (4.0024 inch)

101.66 mm (4.0024 inch)

101.66 mm (4.0024 inch)

Field Replacement of the 161-1249 Beam As on the 793C Off-Highway Trucks

Required Parts

Table 24

Required Parts

Item Qty Part Number Description

1 2 350-1599 (1) (3) (4) (5) Support As

2 1 350-1598 (1) (3) (4) (5) Cab Alignment Tool As

3 1 161-1249 (3) (4) (5) Beam As

4 1 8X-0514 (3) (4) (5) Plate

5 1 8X-0515 (3) (4) (5) Plate

6 2 8X-1986 (3) (4) (5) Plates

7 2 128-3200 (3) (4) (5) Plates

8 2 8X-1985 (3) (4) (5) Plates

9 1 8X-9176 (3) (4) (5) Plate

10 2 125-6974 (3) (4) Bracket As

11 1 247-6905 (4) (5) Bar

12 1 9R-2613 (3) (4) Weld Boss

13 1 091-9284 (4) Bar

14 1 8X-6100 (2) (5) Bracket As

15 1 9R-1733 (5) Boss

16 1 8X-6101 (2) (5) Bracket As

( 1 ) A nonserviceable part of the 353-4386 Cab Alignment Tool Gp ( 3 ) Used on S/N:4AR machines ( 4 ) Used on S/N:4GZ and ; S/N:ATY machines ( 5 ) Used on S/N:1HL machines ( 2 ) This part is canceled. Follow the instructions in this document.

Disassembly

Ver imagen


(17) Right beam assembly

(18) Transition casting on the right-hand side

(19) Rear pedestal on the right-hand side

(20) 161-1249 Beam As

(21) Rear pedestal on the left-hand side

(22) Holes for the ROPS cab

(23) 8X-0469 Support As

(24) Transition casting on the left-hand side

(25) Left beam assembly

(26) Front suspension cylinder

(27) 8X-0436 Support As

(28) Holes for the ROPS cab

(29) Front pedestals

Note: The engine does not need to be removed in order to perform this procedure. Alternate, temporary supports can be

used. This procedure shows the engine removed for clarity.

1. Disassemble the machine as required in order to allow open access to the 161-1249 Beam As (20). Both front

suspension cylinders (26) will remain in place. The support assembly (27) for the ROPS will remain in place. The

support assembly (23) for the ROPS will be removed. The support assembly (23) will be installed on the new beam

assembly.

2. Support the frame assembly so that beam assembly (20), beam assembly (25), and beam assembly (17) are reasonably level.

3. Document the location of the hardware that will be affected by the tooling on the beam assembly and the

transition casting for the left beam assembly and the right beam assembly.

Temporary Bracing

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1. Refer to Illustration 150. From steel that has a yield strength of 400 MPa (58015 psi), cut lengths of steel for temporary

bracing. As shown in Illustration 150, install the temporary bracing.

If possible, do not weld the temporary bracing to the corners of the left beam assembly and the right beam assembly or

the corners of the supports for the suspension cylinders. Weld only on the horizontal surfaces toward the center of the

beams or support castings in line with the major axis of the parts. The horizontal bracing will need to clear the jack clamp on the left beam assembly and the right beam assembly for the locating fixture of the beam assembly.

350-1599 Support As to Check the Height and Squareness of the Beam Assembly

Ver imagen


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(W1) two 6 mm (0.24 inch) fillet welds that are 25 mm (0.98 inch) long, 180 degrees apart on each boss

1. By using the bases of the two support assemblies (1), mark the location for the two 2J-3507 Full Nuts (30) on the back side of the left pedestal and the back side of the right pedestal.

Note: The two 2J-3507 Full Nuts (30) are part of the 350-1599 Support As . You will need to replace the nuts after the

procedure is completed.

Note: The approximate weight of each fixture is 890 N (200 lb).

2. Refer to Illustration 152. Weld the two nuts (30) to the back side of the left pedestal and the back side of the right

pedestal.

Note: Use the SMAW process and "E7018" welding electrode for all welds. As an alternate process, the FCAW process can be used with "E71T-1" welding electrode.

3. Install the top of the two support assemblies to the bases.

4. Loosen the lock nuts. Adjust the screws on the top of the support assemblies so that each screw barely contacts the beam assembly. Tighten the lock nuts.

5. Document the location of the hardware that will be affected by the tooling on the beam assembly and the

transition casting for the left beam assembly and the right beam assembly.

6. Remove the top of the two support assemblies from the bases. Leave both bases on the pedestals. You will install the top of the two support assemblies after the new beam assembly has been installed.

The 350-1598 Cab Alignment Tool As to Locate the Beam Assembly

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The 350-1598 Cab Alignment Tool As (2) is used in order to locate the position of the new 161-1249 Beam As (3). The

approximate weight of the fixture is 544 kg (1200 lb).

You can adjust three of the four pins in the 350-1598 Cab Alignment Tool As (2) in order to locate the cab according to the

dimensions that are on the print or you can adjust the fixture to the actual position of the holes in the frame. Set the pin locations

to the actual position of the holes in the frame.

The cab alignment tool assembly contains two bolts (31) that are jacks. One bolt supports the inside rear corner of the fixture near

the beam assembly that will be replaced. You adjust the bolt to the height of the beam assembly on the left side of the machine

after the fixture is in line with the position of the holes in the cab support. The other bolt supports the front of the fixture by the front left cab support.

Note: The 2 mm (0.08 inch) shim (32) is used to compensate for weld shrinkage in the transverse weld in the beam assembly.

When you establish the location of the bores for the cab supports, the shim should not be in the fixture. The shim must be in the fixture when you weld the new beam assembly into position.

Ver imagen


1. By using a suitable lifting device, position the 350-1598 Cab Alignment Tool As (2) over the holes (22), beam

assembly (25), the six holes in the rear cab support (23), the four bores in the front cab support (27) and holes (28) in the front pedestal. The approximate weight of the cab alignment tool is 544 kg (1200 lb).

2. Locate and lightly tighten the bolt for the nonadjustable pin that is located in holes (28). This is the pin that goes in the front pedestal.

3. Adjust the pin that is in holes (22) on the back, right corner of the fixture. Loosen the two bolts that fasten the bracket

to the frame. Loosen the two bolts that fasten the pin to the bracket. Adjust the bracket so the pin slides into the hole. Tighten the four bolts.

Note: If needed, loosen the locknut on the bolt that is used in order to adjust the height of the fixture. Raise the fixture

to remove the weight from the pin. Tighten the locknut. When the pin is positioned, loosen the locknut and lower the fixture to the correct height. Tighten the locknut.

4. Adjust the pin that is over the beam assembly on the back, left corner of the fixture. Loosen the two bolts that fasten the

bracket to the frame. Loosen the two bolts that fasten the pin to the bracket. Adjust the bracket so the pin slides into the hole. Tighten the four bolts.

5. Adjust the pin that is over the front, left corner of the fixture. Loosen the two bolts that fasten the bracket to the frame.

Loosen the two bolts that fasten the pin to the bracket. Adjust the bracket so the pin slides into the hole. Tighten the four bolts.

Note: If needed, loosen the locknut on the bolt that is used in order to adjust the height of the fixture. Raise the fixture

to remove the weight from the pin. Tighten the locknut. When the pin is positioned, loosen the locknut and lower the

fixture to the correct height. Tighten the locknut.

6. Verify that contact has been made between the fixture and the spot faces on the bores of the cab supports. Verify that the bolts for the pins have been tightened.

7. Remove the 350-1598 Cab Alignment Tool As from the machine. Set the fixture out of the way.

Marking the Transition Casting on the Left Beam Assembly and the Right Beam Assembly

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The transition casting on the new beam assembly is longer than the transition casting that was on the former beam assembly. In

order for the new beam assembly to work on older frames, you must shorten the back end of the right beam assembly 215 mm (8.5 inch) (A) .

Ver imagen


(B) 363 mm (14.29 inch)

(C) 415 mm (16.33 inch)

(D) The front face of the beam assembly

(E) 90 degrees

(F) Cutting line, all around the left beam assembly, even and square all around

(G) Remove the bracket before you cut the left beam assembly

1. By using the dimensions that are listed in Illustration 156, mark the cutting line (F) that you will cut on the back end of

the right beam assembly. Use a punch to mark the steel so that the line cannot be erased.

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2. The cutting line (F) on the left beam assembly is the back side of the weld joint all around the beam. By using an

oxyacetylene torch that is capable of piercing steel that is 30 - 40 mm (1.2 - 1.6 inch) thick, cut the transition casting

along cutting line (F). Cut the steel on the transition casting side of the line. Cut as little steel from the left beam

assembly and the right beam assembly as possible. If a weld joint is present, cut on the side of the weld joint that is toward the transition casting. This would be away from the two beam assemblies.

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3. By using an air carbon arc torch, remove the 16 mm (0.63 inch) fillet weld (34) from the left end of the pedestal that is

on the left side of the frame. Do not gouge deeply into the pedestal. Gouge into the bottom plate of the beam and gouge into plate (35) .

4. By using an air carbon arc torch, remove the 16 mm (0.63 inch) fillet weld (33) that is on the front and back of the

beam assembly between the pedestal and the beam assembly on the left side of the frame. Gouge into the bottom plate of the beam assembly not the pedestal.

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5. By using an air carbon arc torch, remove the 12 mm (0.47 inch) fillet weld (36) that is between the pedestal and the

beam assembly on the right side of the machine. Gouge into the bottom plate of the beam assembly not the pedestal.

6. By using an air carbon arc torch, remove the 16 mm (0.63 inch) fillet weld (37) that is on the front and back of the

beam assembly between the pedestal and the beam assembly on the right side of the frame. Gouge into the bottom plate of the beam assembly not the pedestal.

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7. By using an air carbon arc torch, remove the 12 mm (0.47 inch) fillet welds (38) that are toward the center of the frame

between the pedestals and the beam assembly on both sides of the machine. Gouge into the bottom plate of the beam assembly not the pedestal.

8. By using a suitable lifting device, remove the beam assembly from the frame. The beam weighs approximately 1250 kg (2755 lb).

Note: For S/N:1HL machines, be careful not to damage the 8X-6100 Bracket As (14) and the 8X-6101 Bracket

As (16) that are attached to the beam assembly. You must remove and save both bracket assemblies from the

beam. You cannot order both bracket assemblies through the Cat parts distribution system. You must attach

both bracket assemblies to the new beam assembly (3) .

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9. Clean the weld joints on both pedestals. When you clean the weld joints, take care in order to preserve as much of the

original edges of both pedestals as possible.

Installation of the New 161-1249 Beam As

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1. On the left beam assembly, trim the weld joint and the casting so that the faces (39) of the plates and the corners of the

plates are square.

2. Remove the slag from the trimmed end of the left beam assembly. Smooth both of the end surfaces of the beam assembly.

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3. The new transition castings are machined in order to accommodate the designs of the newer left beams and the newer

right beams that contain heavier plate material. You must build up the root (40) of the upper weld joint and the lower weld joint on both castings with approximately 6 mm (0.24 inch) of weld metal.

4. Weld the upper weld joint and the lower weld joint on both castings with two passes of weld metal. Grind the edges

smooth in order to provide a good fit with minimal gaps between the transition castings and the left beam and the right beam. Rotate the beam assembly and position the beam assembly as needed for each weld area.

5. Clean any paint, grease, or debris from the mounting face, tapped holes, and weld area of the support assembly for the cab.

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6. By using an appropriate lifting device, attach support assembly (23) to the left-hand side of the new beam assembly.

Use an impact wrench in order to fasten the bolts. The support assembly weighs approximately 260 kg (573 lb).

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7. By using a suitable lifting device, install beam assembly (3) to the frame. The beam weighs approximately 1510 kg

(3329 lb). Check the fit of the transition castings on the new beam assembly with the left beam assembly and the right

beam assembly.

8. Install the 2 mm (0.08 inch) shim (28) into the 350-1598 Cab Alignment Tool As (2) .

9. By using a suitable lifting device, install the 350-1598 Cab Alignment Tool As (2) into the bores of the beam assembly

(3) and the front pedestal. The approximate weight of the fixture is 544 kg (1200 lb). Snug the pins so that contact is made with the spot faces of the bores.

10. Check the fit for the transverse weld between the transition casting and the left beam assembly. A minimum root opening of 3 mm (0.12 inch) is needed. A face gap of 18 mm (0.71 inch) is needed.

11. Install the top of the two 350-1599 Support As (1) to check the height and squareness of the beam assembly. Adjust the beam as needed.

Tack Welding Procedure

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1. Apply one tack weld (42) to the outside of the pedestal on the left side of the frame and the new beam assembly and the

back side of the new beam assembly and the pedestal.

2. Apply one tack weld (41) to the bottom of the joint between the transition casting and the left beam assembly and to the bottom of the joint between the transition casting and the right beam assembly.

3. Apply one tack weld (43) to both sides of the inside of both of the pedestals and the new beam assembly.

4. Apply one tack weld (44) to the front of both sides of the pedestals and the new beam assembly.

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5. Apply one tack weld (45) to the top of the joint between the transition casting and the left beam assembly and to the top

of the joint between the transition casting and the right beam assembly.

6. Apply one tack weld (46) to both sides of joint between the transition casting and the left beam assembly and apply one

tack weld to both sides of joint between the transition casting and the right beam assembly.

7. Remove the 350-1598 Cab Alignment Tool As and the two 350-1599 Support As from the new beam assembly.

Remove the four nuts (26) from the back side of both pedestals.

Finish Welds

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(W2) A 12 mm (0.47 inch) bevel weld

1. Slag the tack welds and grind the ends of the tack welds.

2. Refer to (W2) in Illustration 168. Weld the right end of the new beam assembly to the pedestal on the right side of the

frame. Apply three weld passes to the parts. Slag each pass. In order to minimize distortion and residual stress, alternate

from the left side of the pedestal to the right side of the pedestal.

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(W3) A 16 mm (0.63 inch) fillet weld

(W4) A 16 mm (0.63 inch) bevel weld


3. Refer to Illustration 169. Locate plate (4). Tack the plate to the pedestal on the left side of the frame. Leave enough

space in order to apply a 16 mm (0.63 inch) bevel weld to the plate and to the pedestal.

4. Refer to (W5) in Illustration 169. Weld the hole in plate (4). Apply four passes. Slag each pass.

5. Refer to (W3) in Illustration 169. Weld the left side of plate (4) to the left side of the left pedestal. Apply four passes. Slag each pass.

6. Refer to (W4) in Illustration 169. Weld the right side of plate (4) to the pedestal. Apply four passes. Slag each pass.

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(W6) A 16 mm (0.63 inch) fillet weld on both ends of the plate (4)

(W7) A 12 mm (0.47 inch) fillet weld on the inside of both pedestals and the beam assembly

(W8) A 16 mm (0.63 inch) fillet weld on the back

(W9) A 16 mm (0.63 inch) fillet weld on the front of both pedestals

(W10) A 16 mm (0.63 inch) fillet weld on the right side of plate (5)

(W11) A 12 mm (0.47 inch) bevel weld on the left side of plate (5)

7. Locate plate (5). Tack weld the plate into position.

8. Refer to (W6) in Illustration 170. Weld both ends of plate (4) to the left side of the beam assembly. Apply four passes. Slag each pass.

9. Refer to (W10) in Illustration 170. Weld the right side of plate (5) to the left side of plate (4). Apply four passes. Slag each pass.

10. Refer to (W11) in Illustration 170. Weld the left side of plate (5) to the end of the beam assembly. Apply three passes.

Slag each pass.

Note: For the next three steps, alternate the welds from side to side. Do not weld one item then start the weld on the

opposite side. Balance the welding sequence. This will minimize weld distortion.

11. Refer to (W7) in Illustration 170. Weld the inside of both pedestals to the beam assembly. Apply three passes. Slag each pass.

12. Refer to (W8) in Illustration 170. Weld the back side of both pedestals. Apply four passes. Slag each pass.

13. Refer to (W9) in Illustration 170. Weld the front side of both pedestals. Apply four passes. Slag each pass.

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(W12) A 20 mm (0.8 inch) j-groove weld



14. Prepare the joints between the transition castings and the left beam assembly and the right beam assembly for root

passes. Grind the ends of the tack welds. Slag the welds completely.

15. Refer to (W12) in Illustration 171. By using a j-groove weld, apply the root pass in the four vertical joints between the

transition castings and the left beam assembly and the right beam assembly. Start toward the centerline of the frame, then move to the outside of the frame. Start on the bottom of the joints.

16. Refer to (W13) in Illustration 171. By using a j-groove weld, apply a root pass between the transition castings and the

left beam assembly and the right beam assembly on the top side. Start the welds toward the center of the frame and weld toward the outside of the frame.

17. Refer to (W14) in Illustration 171. By using a j-groove weld, apply a root pass between the transition castings and the

left beam assembly and the right beam assembly on the bottom side. Start the welds toward the center of the frame and weld toward the outside of the frame.

18. Refer to (W12) in Illustration 171. By using a j-groove weld, apply two passes in the four vertical joints between the

transition castings and the left beam assembly and the right beam assembly. Start toward the centerline of the frame.

Start on the bottom of the joints.

19. Refer to (W13) in Illustration 171. By using a j-groove weld, apply one pass between the transition castings and the left

beam assembly and the right beam assembly on the top side. Start the welds toward the center of the frame and weld toward the outside of the frame.

20. Refer to (W14) in Illustration 171. By using a j-groove weld, apply one pass between the transition castings and the left

beam assembly and the right beam assembly on the bottom side. Start the welds toward the center of the frame and weld toward the outside of the frame.

21. Repeat Step 18, Step 19, Step 20 until the beams are welded flush.

Note: The welds between the transition castings and the left beam assembly and the right beam assembly are to be

inspected by an ultrasonic flaw detection unit.

22. Clean the welds.

Installation of Hardware on the S/N:4AR Machines

As noted in the illustrations, install the parts that are listed in the following illustrations on the left beam assembly and the right beam assembly.

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The area of the transition casting and the right beam assembly

(6) Plates

(7) Plates

(8) Plates

(9) Plate

(W15) An 8 mm (0.32 inch) fillet weld using vertical welding on the outside of the two plates (7) and the two plates (8)

(W16) A 6 mm (0.24 inch) fillet weld on the two sides of both plates (6)

(W17) An 8 mm (0.32 inch) fillet weld using vertical welding on the two ends of plate (9)

As shown in Illustration 173, locate the parts. Tack weld the parts in position. Then, weld the parts in position as shown in

Illustration 172.

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The top of the transition casting and the right beam assembly

(6) Plates

(7) Plates

(8) Plates

(9) Plate

(H) 100 mm (3.9 inch)

(J) 326 mm (12.8 inch)

(K) 718 mm (28.27 inch)

(L) 199.5 mm (7.85 inch)

(M) 126.5 mm (5.0inch)

(N) 89 mm (3.5 inch)

Illustration 173 shows the location for plates (6), plates (7), plates (8) and plate (9) on the top, right part of beam assembly (3)

and the right beam assembly.

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A top view of the transition casting and the right beam assembly

(P) 2154.5 mm (84.82 inch)

(R) 194 mm (7.64 inch)

Illustration 174 shows the location of plate (6) from the plate on the front of the right beam assembly.

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(S) 15 mm (0.59 inch) at two places

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The inside of the area of the transition casting and the left beam assembly

(10) Bracket assembly

(T) 35 ± 5 mm (1.4 ± 0.2 inch)

(U) 760 mm (29.9 inch)

(W18) A 3 mm (0.12 inch) fillet weld on the two sides of bracket assembly (10)

Illustration 176 shows the location of one of the two bracket assembly (10). Locate the bracket assembly. Tack weld the bracket

assembly in position. Then, weld the bracket assembly in position.

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The top of the area of the transition casting and the left beam assembly


(V) 6 ± 5 mm (0.24 ± 0.20 inch) from the end of the other bracket assembly

(W) 70 ± 5 mm (2.76 ± 0.20 inch) from the center of the boss to the end of bracket assembly (10)

(X) 120 ± 5 mm (4.72 ± 0.20 inch) between the centerline of the bosses and the centerline of bracket assembly (10)


Illustration 177 shows the position of the second bracket assembly (10) that is positioned on top, left side of the beam assembly

(3). Locate the bracket assembly. Tack weld the bracket assembly in position. Then, weld the bracket assembly in position.

1. Clean the welds and inspect the welds. As needed, make repairs.

2. Remove the temporary bracing.

3. As needed, paint the machine.

4. Assemble the machine.

Installation of Parts on the S/N:4GZ Machines and the ; S/N:ATY Machines

As noted in the illustrations, install the parts that are listed in the following illustrations on the left beam assembly and the right beam assembly.

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(Y) 35 ± 5 mm (1.4 ± 0.2 inch)

(Z) 760 mm (29.9 inch)


Illustration 178 shows the location of one of the two bracket assembly (10). Locate the bracket assembly. Tack weld the bracket assembly in position. Then, weld the bracket assembly in position.

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(AA) 6 ± 5 mm (0.24 ± 0.20 inch) from the end of the other bracket assembly

(BB) 70 ± 5 mm (2.76 ± 0.20 inch) from the center of the boss to the end of bracket assembly (10)

(CC) 120 ± 5 mm (4.72 ± 0.20 inch) between the centerline of the bosses and the centerline of bracket assembly (10)


Illustration 179 shows the position of the second bracket assembly (10) that is positioned on top, left side of the beam assembly

(3). Locate the bracket assembly. Tack weld the bracket assembly in position. Then, weld the bracket assembly in position.

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The top of beam assembly (3)

(DD) 70.5 ± 3 mm (2.78 ± 0.12 inch)

(W22) A 5 mm (0.20 inch) skip weld that is 50.0 mm (1.97 inch) long on 200.0 mm (7.87 inch) centers

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A view of beam assembly (3) from the front

(EE) 871 mm (34.3 inch)

Position bar (11) as shown in Illustration 180 and Illustration 181. Weld the bar to the beam.

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A view of the top of the transition casting and the right beam assembly

(FF) 376 ± 5 mm (14.8 ± 0.2 inch)

(GG) 31 ± 5 mm (1.2 ± 0.2 inch)

(W23) An 8 mm (0.32 inch) fillet weld that is vertical up weld in two places

(W24) An 8 mm (0.32 inch) fillet weld in two places

(W25) A 3 mm (0.12 inch) fillet weld all around the boss

(W26) An 8 mm (0.32 inch) fillet weld that is vertical up in two places

(W27) An 8 mm (0.32 inch) fillet weld in two places

(W28) An 8 mm (0.32 inch) fillet weld that is vertical up in two places

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(HH) 391 ± 3 mm (15.40 ± 0.12 inch)

(JJ) 125 ± 5 mm (4.9 ± 0.2 inch)

(KK) 264.5 ± 1 mm (10.40 ± 0.04 inch)

(LL) 712 ± 1 mm (28.03 ± 0.04 inch)

(MM) 126.5 mm (5.0 inch)

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(NN) 50.0 mm (1.97 inch)

(PP) 15.0 mm (0.59 inch)

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The inside of the transition casting and the right beam assembly

(RR) 107 ± 5 mm (4.2 ± 0.2 inch)

Refer to Illustration 182. Locate and tack boss (12) to the bottom side of the right transition casting. Weld the boss into position.

Refer Illustration 182, to Illustration 183 and Illustration 184. Locate and tack plate (6) and two gussets (7) into position. Weld all three parts into position.

Refer to Illustration 182, to Illustration 183 and to Illustration 184. Locate and tack plate (13) and two gussets (8) into position. Weld all three parts into position.

Refer to Illustration 182, to Illustration 183 and Illustration 185. Locate and tack plate (9) into position. Weld the part into position.

Clean the welds and inspect the welds. As needed, make repairs.

Remove the temporary bracing.

As needed, paint the machine.

Assemble the machine.

Installation of Parts on the S/N:1HL Machines

As noted in the illustrations, install the parts that are listed in the following illustrations on the left beam assembly and the right

beam assembly.

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(W30) A 6 mm (0.24 inch) fillet weld from the edge of the casting to bracket assembly (16)


(W32) A 6 mm (0.24 inch) fillet weld from bracket assembly (14) to the corner of bracket assembly (16)

(SS) 312.3 ± 3.0 mm (12.30 ± 0.12 inch)

(TT) 81.5 ± 3.0 mm (3.21 ± 0.12 inch)

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(UU) 46.0 ± 3.0 mm (1.8 ± 0.12 inch) from the center of the holes for the rops cab

(VV) 111.9 ± 3.0 mm (4.4 ± 0.12 inch)

(WW) 35.0 ± 5.0 mm (1.40 ± 0.20 inch)

(XX) 230.0 ± 5.0 mm (9.06 ± 0.20 inch)


Refer to Illustration 186 and Illustration 187. Locate and tack bracket assembly (14), bracket assembly (16), and boss (15) into

position. Weld all three parts into position.

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The top of beam assembly (3)

(YY) 70.5 ± 3 mm (2.78 ± 0.12 inch)

(W34) A 5 mm (0.20 inch) skip weld that is 50.0 mm (1.97 inch) long on 200.0 mm (7.87 inch) centers

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A view of beam assembly (3) from the front

(ZZ) 871 mm (34.3 inch)

Position bar (11) as shown in Illustration 189 and Illustration 188. Weld the bar to the beam.

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A view of the top of the transition casting and the right beam assembly

(AAA) 376 ± 5 mm (14.8 ± 0.2 inch)

(BBB) 31 ± 5 mm (1.2 ± 0.2 inch)


Locate and tack boss (12) to the bottom side of the right transition casting. Weld the boss into position.

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The area of the transition casting and the right beam assembly

(6) Plates

(7) Plates

(8) Plates

(9) Plate

(W36) An 8 mm (0.32 inch) fillet weld using vertical welding on the outside of the two plates (7) and the two plates (8)

(W37) A 6 mm (0.24 inch) fillet weld on the two sides of both plates (6)

(W38) An 8 mm (0.32 inch) fillet weld using vertical welding on the two ends of plate (9)

As shown in Illustration 192, Illustration 193, Illustration, and194 Illustration 195 and locate the parts. Tack weld the parts in

position. Then, weld the parts in position as shown in Illustration 191.

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(6) Plates

(7) Plates

(8) Plates

(9) Plate

(CCC) 100 mm (3.9 inch)

(DDD) 326 mm (12.8 inch)

(EEE) 718 mm (28.27 inch)

(FFF) 199.5 mm (7.85 inch)

(GGG) 126.5 mm (5.0inch)

(HHH) 89 mm (3.5 inch)

Illustration 192 shows the location for plates (6), plates (7), plates (8) and plate (9) on the top, right part of beam assembly (3)

and the right beam assembly.

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A top view of the transition casting and the right beam assembly

(JJJ) 2154.5 mm (84.82 inch)

(KKK) 194 mm (7.64 inch)

Illustration 193 shows the location of plate (6) from the plate on the front of the right beam assembly.

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(LLL) 50.0 mm (1.97 inch)

(MMM) 15.0 mm (0.59 inch)

Illustration 194 shows the position of the two plates (6) from the top of the transition casting.

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The inside of the transition casting and the right beam assembly

(RR) 107 ± 5 mm (4.2 ± 0.2 inch)

Illustration 195 shows the position of plate (9) from the top surface on the transition casting.

Clean the welds and inspect the welds. As needed, make repairs.

Remove the temporary bracing.

As needed, paint the machine.

Assemble the machine.

Procedure to Strengthen the Weld Joint on the Center Tube on 785C and 785D Off-

Highway Trucks

ReferenceSpecial Instruction, REHS1841, "General Welding Procedures"

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(1) Tube

(2) Plate

A TIG toe dressing of the weld is now being carried out for the entire circumference of the interface of the Plate (2) and the tube

(1) on the frame assembly. This will provide an improved weld joint on the center tube of the frame assembly. The TIG toe

dressing can be applied to the interface of the Plate (2) and the tube (1) on any machine in order to strengthen the weld.

Refer to the above reference for the procedure to prepare the area for welding and for the procedure to clean the welds and

inspect the welds.

The following two methods can be used in order to strengthen the weld on the center tube of 785C Off-Highway Trucks and 785D Off-Highway Trucks:

TIG dressing of fillet welds for improved fatigue life

Burr grinding of fillet welds for improved fatigue life

The preferred method is TIG dressing. The second method can be performed in an emergency. The second method does not require an experienced welder or specialized equipment.

TIG Dressing of Fillet Welds for Improved Fatigue Life

Note: The fatigue performance is controlled by the profile of the weld toe. This applies to fabricated structures that have fillet

welded attachments to highly stressed members. The fatigue performance can be improved by altering the original welded toe

profile. This can be achieved by using several post weld treatment options. This procedure describes a method of using an electric arc to reduce adverse profiles and stress risers. This creates a seamless transition from one component to the next component.

Table 25

Required Equipment

Tool Description

GTAW (TIG) Power supply and a

torch.

The power supply must be capable of producing 225 amps (min. 60% duty cycle) with a

hand control or a foot control.

Shielding Gas 100% Argon and flow meter

Electrode

Lanthanated or

Ceriated or

Thoriated Tungsten

2.4 mm (0.09 inch) diameter

If needed:

ER70S-2 filler metal

1.5 mm (0.06 inch ) diameter

Grinder Pneumatic grinder or electric grinder with carbon steel wire wheel attachment

Grinding Wheel Aluminum oxide

Gauge Radius gauges

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Preparation of 2.4 mm (0.09 inch) tungsten electrode

(3) Striations or grinding marks

(A) 2 to 3 times the diameter

(B) 1/4 to 1/2 times the diameter

1. Cleanliness and preparation of tungsten electrode are the first steps in order to ensure that a proper TIG dressing is

achieved. All contaminants must be thoroughly removed from the fillet weld and the surrounding base metal. All rust,

dirt, oil, scale, and silicate islands must be removed. This can be accomplished quickly via a grinder with a carbon steel wire attachment.

2. Prepare a 2.4 mm (0.09 inch) tungsten electrode. Refer to the dimensions that are shown in Illustration 197. The

striatings should run parallel to each other.

3. Adjust the flow rate of shielding gas to 15 CFH. Adjust the current control to approximately 225 amps. If a ramp down

control is present on the power source, utilize the ramp down control to ensure that proper crater fill control is achieved.

4. A number of different techniques exist for TIG dressing. This is due to the variation of the contour of the fillet weld

toe. The contour of the fillet weld toe must be reshaped. Use a stringer or weave manipulation of the torch in order to

achieve a smooth radius of the weld. A minimum radius of 5.0 mm (0.20 inch) must exist between the base material

and the weld metal.

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Stringer technique

(C) 0 to 25 degrees work angle

Note: Use a 10 to 15 degrees push angle for the stringer technique.

5. Illustration 198 represents the stringer technique of welding. The center of the arc needs to be 0.0 to 2.0 mm (0.0 to 0.08 inch) from the weld toe into the base material.

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Weave technique

(D) 0 to 45 degrees work angle

(E) 3 mm (0.1 inch) Weave

Note: Use a 10 to 15 degrees push angle for the weave technique.

6. Illustration 199 represents the weave technique of welding.

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7. Illustration 200 represents a cross section view of a proper TIG dressed fillet weld.

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8. Illustration 201 and Illustration 202 demonstrate the expected results.

9. Once the TIG dressing is completed, the area needs to be cleaned and painted in order to prevent pitting due to corrosion.

Note: Poorly shaped fillet welds with 70 to 90 degrees transition angles will require several overlapping of TIG

dressing runs. Overlapping of the TIG dressing runs is required in order to properly stabilize the weld toe transition

area.

Note: TIG dressing can be conducted in the vertical position when you perform TIG dressing in a downhill

progression.

Note: Some undercuts will require the addition of filler metal. This can be accomplished by hand feeding ER70S-2 1.5

mm (0.06 inch diameter) into the weld pool. You then repeat the TIG dressing in order to achieve the desired toe radius and the desired profile.

Burr Grinding of the Fillet Welds for Improved Fatigue Life

Note: The profile or geometry of the weld toe controls the fatigue performance of fabricated structures. These fabricated

structures have attachments that are fillet welded to highly stressed members. Fatigue performance improvement can be achieved

through alteration of the original toe profile by several post weld treatment options. This procedure describes a method of using a

mechanical means in order to remove adverse profiles and adverse stress risers. This method creates a smooth transition from one

component to the next component.

Table 26

Required Equipment

Tool Description

Hand Held Grinder High speed, pneumatic, rotary, pencil grinder - 20,000 rpm

Compressed Air

621 kPa (90 psi) minimum

Tungsten Carbide Burr The burr should be conical shaped with approximate end diameter of

10.0 mm (0.39 inch).

Leather Welding Jacket

Leather Gloves

Safety Glasses

Face Shield

Radius Gauge

Bridge Cam Gauge

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Pneumatic rotary pencil grinder with burr

(4) Preferred shape of burr

1. Illustration 203 shows the preferred shape of burr.

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(F) 45 degrees

(G) 45 degrees

(H) Minimum depth of 0.8 mm (0.03 inch)

(5) Burr tool

(6) Direction of travel

(7) Weld

(8) Plate

2. The tip of burr should be located over the weld toe. The axis of the tool should be maintained at approximately 45

degrees to the parent plate. The axis of the tool should be inclined at approximately 45 degrees to the direction of

travel. Grinding should extend to a depth of 0.5 mm (0.02 inch) below the last visible traces of the weld toe resulting in

minimum depth of 0.8 mm (0.03 inch) and maximum depth of 1.0 mm (0.04 inch). The resulting ground surface should

be smooth without grinding marks running parallel to the weld, but 90 degrees to the weld. All traces of the original weld toe should not be visible via the use of a lower powered magnifying glass.

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3. The finished burr grinding should look like the Illustration 205.

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Documents

Procedure for the Inspection, Repair, And Component Replacement on the Frames of Certain