31 n733 5australiandraftonmaintenanceandrepair

Standards Australia Information in fields should be filled in if known or left as is.

Earth-moving machinery—Off-the-road wheels, rims and tyres –Maintenance and repair Part Title: Tyres Designation: AS 4457.2 Part Number: Supersedes Standard No:AS 4457–1997 AustralianORJoint: Australian Creation Date: 2006-06-20 Revision Date: Issue Date: September 2006 Committee Number: ME-063 Committee Title: Earth-moving Equipment Subcommittee Number: ME-063-00-01 Subcommittee Title: Wheels, rims and tyres Project Manager: Bob Maynard PMs Email Address: [email protected] WP Operator: Maynard/Tamara Project Number: 7940 Combined Procedure?: No Committee Doc No.: ME/063/06-008 Stage: SECOND COMMITTEE DRAFT Committee Reps: AUSTROAD

Australian Industry Group Construction and Mining Equipment Industry Group Department of Natural Resources and Mines, Qld Department of Primary Industries and Fisheries, Queensland Department of Primary Industries, Mine Safety (NSW) Motor Trades Association of Australia Safety Institute of Australia (Incorporated) WorkCover New South Wales

Additional Interests: Product Type AS Document Status Current Document Availability Private

DRAFT ONLY 2 DRAFT ONLY

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PREFACE This Standard was prepared by the Standards Australia Committee ME-063, Earth-moving Equipment at the request of users of earth-moving machinery, particularly those involved in major mining operations, and is supported by the inspectorates of Queensland, New South Wales and Western Australia. (?) These bodies have expressed their concern that wheels, rims and tyres for earth-moving machinery are being subjected to ever-increasing loads and forces. The origin of the forces is the larger, heavier trucks and payloads being introduced and the higher speeds these vehicles can achieve.

This Standard supersedes AS 4457—1997, Earth-moving machinery—Off-the-road rims and wheels—Maintenance and repair, which has now been revised into two parts.

The two parts of the AS 4457 series of Standards are as follows:

AS 4457 Earth-moving machinery–Off-the-road wheels, rims and tyres–Maintenance and repair Part 1: Wheel assemblies and rim assemblies Part 2: Tyres (this Standard)

The term ‘normative’ has been used in this Standard to define the appendix to which it applies. A ‘normative’ appendix is an integral part of a Standard.

The term 'informative' etc

The objective of this Standard is to provide all those involved in the earth-moving industry with information on the repair and correct maintenance of tyres used on earth-moving machinery


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FORWARD There are various hazards associated with tyres used on earth-moving equipment which, unless risk control is in place, can result in death or injury.

This Standard will note where the hazards exist, but this is not an exhaustive list. It is the responsibility of site management to ensure that all hazards are identified, and the appropriate risk controls put into place.

In some cases, the Standard will mention a generally accepted risk control but this still needs to be checked against overall risk management.

Fatalities and serious injuries have occurred when correct procedures for the repair, retreading and maintenance of tyres have not been followed. The use of badly repaired or retreaded tyres and the use of tyres that have not been maintained to high standards pose risks to persons operating earth-moving machinery and others and in order that this element of risk be minimized, some controls over the repair, retreading, maintenance and inspection of tyres are considered necessary.

Earth-moving tyres can be a cause of extremely hazardous conditions and are a major cost item. This Standard will give priority to eliminating hazard and controlling risks. However in many instances, the same recommendation will also be cost effective.


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CONTENTS

Page

PREFACE .................................................................................................................................. 2

FORWARD ................................................................................................................................ 3

SECTION 1 SCOPE AND GENERAL 1.1 SCOPE......................................................................................................................... 2 1.2 OBJECTIVE ................................................................................................................ 2 1.3 REFERENCED DOCUMENTS................................................................................... 2 1.4 DEFINITIONS............................................................................................................. 2

SECTION 2 MAINTENANCE OF IN-SERVICE TYRES(Practical maintenance) 2.1 SELECTION OF TYRE............................................................................................... 6 2.2 FITMENT INSPECTION ........................................................................................... 6 2.3 PERIODIC INSPECTION ........................................................................................... 6

SECTION 3 INSPECTION TO DETERMINE REPAIRABILITY 3.1 GENERAL................................................................................................................... 8 3.2 INTERNAL INSPECTION.......................................................................................... 8 3.3 EXTERNAL INSPECTION......................................................................................... 9

SECTION 4 REPAIR LIMITS 4.1 GENERAL................................................................................................................. 10 4.2 REPAIR LIMITS FOR BIAS PLY TYRES .............................................................. 10 4.3 IRREPARABLE DAMAGE TO BIAS PLY TYRES ................................................ 11 4.4 NUMBER OF REPAIRS TO BIAS PLY TYRES...................................................... 11 4.5 REPAIR LIMITS FOR RADIAL PLY TYRES ....................................................... 11 4.6 IRREPARABLE DAMAGE TO RADIAL PLY TYRES........................................... 11 4.7 NUMBER OF REPAIRS TO RADIAL PLY TYRES................................................ 11 4.8 DESTRUCTION OF UNREPAIRABLE TYRES ...................................................... 11

SECTION 5 REPAIR OF TYRES 5.1 REPAIR PRINCIPLES .............................................................................................. 12 5.2 MEASUREMENT OF DAMAGE ............................................................................. 12 5.3 DAMAGE AREA PREPARATION .......................................................................... 13 5.4 PATCH APPLICATION............................................................................................ 13 5.5 CURING.................................................................................................................... 14 5.6 INSPECTION AFTER CURING............................................................................... 15

SECTION 6 RETREADING OF TYRES 6.1 GENERAL ................................................................................................................ 16 6.2 DIMENSIONAL AND PHYSICAL REQUIREMENTS............................................ 18 6.3 ADHESION REQUIREMENT ................................................................................. 18 6.4 SPEED CATEGORIES FOR RETREADED OTR TYRES. ..................................... 19 6.5 ENVIRONMENTAL CONDITIONS ....................................................................... 19


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SECTION 7 MARKING OF REPAIRED AND RETREADED TYRES 7.1 REPAIRED TYRE IDENTIFICATION .................................................................... 20

SECTION 8 MAINTENANCE OF TYRES (Service records) 8.1 RECORDING ........................................................................................................... 21 8.2 SERVICE RECORD (LOGBOOK) ........................................................................... 21 8.3 RECORDED HISTORY ............................................................................................ 21 8.4 REPAIRS AND RETREADING................................................................................ 21 8.5 TRANSFER TO ANOTHER USER .......................................................................... 21 8.6 REPLACEMENT OF TYRE IDENTIFICATION ..................................................... 21

APPENDICES A EXAMPLE OF INSPECTION SHEET...................................................................... 23


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STANDARDS AUSTRALIA

Australian Standard Earth-moving machinery—Off-the-road wheels, rims and tyres –

Maintenance and repair

Part 2: Tyres

S E C T I O N 1 S C O P E A N D G E N E R A L

1.1 SCOPE

This Standard sets out the requirements for the identification, inspection, repair, retreading and maintenance, of off-the-road, pneumatic tyres for earth-moving machinery. It applies to tyres fitted to wheel assemblies and rim assemblies of not less than 600 mm (24 inches) nominal diameter.

1.2 OBJECTIVE

The objective of this Standard is to assist end-users repairers and retreaders of tyres and users of earth-moving machinery in minimizing the risk to health and safety of persons working on tyres used on earth-moving machinery.

1.3 REFERENCED DOCUMENTS

The documents below are referred to in this Standard:

AS 4457.1 Earth-moving machinery, Off-the-road wheels, rims and tyres – Maintenance and repairs, Part 1: Wheels and rims

AS/NZS

4360 Risk Management

1.4 DEFINITIONS

For the purpose of this Standard, the definitions given in AS 1973 and those below apply

1.4.1 Bead

the part of the tyre that is made to secure the tyre to the rim. This involves significant high tensile steel wires fashioned in a hoop shape that are encased in the tyre casing or carcass structure. This may involve 2 bead cores (in the case of a radial tyre) or multiple bead cores (for diagonal ply tyres).

1.4.2 Bead area

The area of a tyre below the rim line (at the bottom of the sidewall).

1.4.3 Belts

Two or more layers of substantially inextensible cord material embodied circumferentially within a tyre immediately outside the casing ply and under the tread. The cord angle relative to the tyre circumference is lower than that for the casing ply. Belts are used in radial ply tyres and form an integral structural component of the tyre construction.


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1.4.4 Bias ply tyre

A pneumatic tyre in which the ply cords in the tyre carcass are laid at alternate angles that are substantially less than 90 degrees to the centre-line of the tread.

1.4.5 Buffing

The preparation of the surface of the tyre prior to the application of cement and rubber.

1.4.6 Building

The application of rubber to the buffed and prepared surface of the casing or carcass.

1.4.7 Carcass

The multi cord layer structure and components of a diagonal ply tyre.

1.4.8 Carcass break up / separation

The detachment of the carcass plies from each other or the internal detachment of the plies resulting in a loss of structural strength.

1.4.9 Casing

The structure and components of a radial ply tyre.

1.4.10 Casing Ply

The major fixed dimension structural component of a radial ply tyre that is wrapped around the beads and extends to be contained beneath the belt structure. The strength of the casing ply has a major determination on the load carrying capacity of the tyre.

1.4.11 Cement

A solution of rubber, capable of being cured, compatible with the process in use, and used as a bonding agent in the repair and retreading of tyres.

1.4.12 Cementing

The application of rubber cement to the buffed surface of the tyre.

1.4.13 Cords

The individual strands when arranged parallel and encased in rubber form the structure of the tyre.

1.4.14 Crown

The portion of the tread between the shoulders of a tyre.

1.4.15 Curing

The application of controlled temperature and pressure for the duration necessary to transform the rubber from its plastic state to its elastic state.

1.4.16 Cushion gum

An uncured rubber compound used to assist adhesion between the buffed casing and the new tread.

1.4.17 Cut Damage

When the tyre experiences a cut into the tyre. This may be into the rubber, structure or through the rubber and structure.

1.4.18 Inflation Pressure

The measurement of force that is exerted on the inner surface of a tyre so as to tension the structure and to provide a vital element in the safe operation of the tyre.


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1.4.19 Inner liner

The layer which forms the inside surface of a tyre, and in a tubeless tyre retains the inflating medium within the tyre.

1.4.20 Injury

See Cut Damage.

1.4.21 Intermediate repair

Repair beyond that of a minor repair yet not affecting the structural integrity of the tyre.

1.4.22 Load index

A numerical code associated with the maximum load rating assigned to the tyre.

1.4.23 Major repair

Repair to a tyre that requires the installation of a structured internal patch.

1.4.24 Maximum load rating

The maximum load at which the tyre is designed to carry at a specific speed and inflation pressure.

1.4.25 Minor repair

Repair to a tyre that does not require the installation structure internal patch.

1.4.26 Patch

A non structured sealing form that is applies to a tyre or tube to prevent the loss of inflation pressure.

1.4.27 Repairable

A tyre that has suffered damage and is deemed safe for continued service once an appropriate repair is carried out.

1.4.28 Ply

A layer of substantially parallel, rubber-coated cords forming a structure which is part of the tyre casing or carcass.

1.4.29 Radial ply tyre

A pneumatic tyre in which the ply cords, which extend from bead to bead, are laid at substantially 90 degrees to the centre-line of the tread, the casing being stabilized by circumferential belts comprising two or more layers of substantially inextensible cord material.

1.4.30 Re-belting

A process of replacing damaged protector belts in radial ply tyres prior to retreading.

1.4.31 Retreading

A process of replacing the tread on a worn tyre.

1.4.32 Shall

Indicates that a statement is mandatory.

1.4.33 Should

Indicates a recommendation.

1.4.34 Shoulder

The transitional area of a tyre between the sidewall and the crown.


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1.4.35 Sidewall

The portion of a tyre between the shoulder and the bead area.

1.4.36 Sidewall rubber

A layer of rubber to protect the ply cords of the tyre casing or carcass from service damage.

1.4.37 Skiving

When repairing, the removal of damaged material by means of a bevelled cut.

1.4.38 Speed category

A symbol assigned to a tyre by a tyre manufacturer to denote the maximum safe vehicle speed for which the use of the tyre is rated.

1.4.39 Structural belt

The belts within a radial tyre that provides the containment of the casing ply so as to limit inflated dimension and to provide a stable foundation for the tread.

1.4.40 Structural Integrity

When the structure of the tyre is in condition and has the potential for continued safe service.

1.4.41 TKPH

A calculation used to determine the suitability of specific Off the Road Tyres for a given equipment application.

1.4.42 Tread

The portion of the tyre which comes into contact with the road.

1.4.43 Tread pattern depth

The distance from the bottom of the tread grooves to the top of the tread (excluding the tread wear indicators).

1.4.44 Tread rubber

A rubber compound specifically formulated to have the properties of heat, wear and cut resistance.

1.4.45 Tread wear indicator

A feature incorporated into the tread of a tyre to indicate when the tread has worn down to a predetermined minimum tread pattern depth.

1.4.46 Tubeless tyre

A pneumatic tyre designed for use without an inner tube.

1.4.47 Unrepairable tyre

When a tyre has suffered significant structural damage and is deemed un-safe for continued service.

1.4.48 Venting

A series of small diameter holes drilled into the carcass immediately above the rim line to provide the release of any air trapped within the carcass during the manufacturing process.


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S E C T I O N 2 M A I N T E N A N C E O F I N - S E R V I C E T Y R E S ( P r a c t i c a l m a i n t e n a n c e )

2.1 SELECTION OF TYRE

Tyres shall be selected in accordance with manufacturer's specifications and considering, but not limited to, the following points:

(a) Tyre load and speed

(b) TKPH rating

(c) Site conditions

(d) Type of earth-moving machinery

All tyres submitted for repair or retreading shall be inspected prior to any work being undertaken. An example of an inspection sheet for inspection of tyres is shown in Figure A1.

Tyres that do not contain a serial number shall not be fitted.

2.2 FITMENT INSPECTION

Prior to fitment of the tyre an inspection, internally and externally, undertaken by a competent person, should consider, but not be limited to, the following points:

(a) The tyre is in a sound state and suitable for fitment for the required application and position.

(b) The tyre is free of foreign objects and contaminants.

(c) Any previous repairs and markings.

(d) Site specific requirements.

2.3 PERIODIC INSPECTION

2.3.1 General:

Periodic inspections of fitted tyres shall be undertaken according to manufacturer's recommendations and site specific requirements and should include, but not be limited to, the following:

(a) Inflation pressure.

(b) Wear.

(c) Damage.

(d) Separation.

(e) Fatigue.


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2.3.2 Identification of tyre conditions

The following table identifies conditions that should be considered during the periodic inspection to determine serviceability.

Condition Identification Action Comment Sidewall Cut Structure not exposed Monitor Contained within

sidewall rubber Steel cords are

exposed mid ~ to bead (< 4 cords)

Monitor Schedule for removal & repair

Steel cords are exposed mid ~ shoulder

Schedule for removal Potential for repair (Hazard – Burst)

Exposed Belt Exposed top two belts Remove at this point Exposed beyond top 2

belts Schedule for immediate removal

Risk: structural integrity of tyre is reduced (Hazard – Burst)

Tread Detachment – Mechanical

< 3 lugs detached Re-locate to rear position

Belt structure sound

>= 3 lugs detached Continue to monitor Belt structure sound >= 3 lugs detached –

exposed top two belts Schedule for immediate removal

Weakened belt structure (Hazard – Burst)

Hot Tyre Inflation pressure increase > 25%

Continue to monitor Relocate to milder operation between 25 – 30% increase

Inflation pressure increase > 30%

Stand vehicle down 6 hours cool down period (Hazard – Burst)

Bead Bulge Steel cord is not visible

Continue to monitor

Steel cord is visible Schedule for immediate removal

Steel cord is damaged Isolate vehicle & stand for 6 hours

Deflate & remove tyre (Hazard – Burst)

Tread Detachment – Heat

Smell of burning rubber – stable shape

Deflate & remove from service

Transport speed <25km/hr

Smell of burning rubber – deformed shape

Isolate vehicle & stand for 6 hours

Deflate & remove tyre (Hazard – Burst)

Run Flat Inflation pressure > 60% of recommendation

Rectify & monitor Pressure checks every 8 hrs to verify

Inflation pressure < 60% of recommendation

Remove immediately for inspection

Inspect tyre – scrap if damaged (Hazard – Burst)

Deformed Sidewall Major cycle deformation

Isolate vehicle & stand for 6 hours

Deflate & remove tyre

External Power Source

Vehicle contact with external power source

Evacuate & isolate vehicle immediately – potential for tyre explosion

Allow to stabilise for 12 hours & remove tyre for inspection (Hazard – Explosion)

External Tyre Fire Tyre on fire Evacuate & isolate vehicle immediately – potential for tyre burst

Establish safety perimeter (Hazard – Burst)


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S E C T I O N 3 I N S P E C T I O N T O D E T E R M I N E R E P A I R A B I L I T Y

3.1 GENERAL Following an inspection undertaken according to Clause 2.3 if it is recommended that a tyre be removed for repair a further inspection should be undertaken to determine the action to be taken.

The following diagram shows a flowchart to assist in the decision making of the action to be taken:

Fi tment inspect ion (2.2 )

F i tment inspect ion (2.3 )

Repai r(Sect. 5 )

Inspect( )

Ref i t ( 2.2 )See a lso

AS 4457.1Clause 3.4

Scrap

Retread(Sect. 6 )

Scrap( )

Scrap( )

Leave inser v ice

Remove andre- inspect(Sect. 3 )

Ref i t

Inspect

ScrapRef i t( 2.2 )

FIGURE 1. INSPECTION AND REPAIR FLOW CHART FOR OTR TYRES

Tyres shall be removed from the wheel or rim assemblies before inspection. (See AS 4457.1)

Tyres shall be thoroughly inspected internally and externally and any tyres that have been treated inside with liquid puncture sealant, or other substances which impair the inspection process shall be thoroughly cleaned out for visual inspection.

Any existing repair shall be closely inspected and if its condition does not comply with the requirement of this Standard, the repair shall be removed and replaced.

An example of an inspection sheet is shown in Appendix A.

3.2 INTERNAL INSPECTION

The inner surface of the tyre must be inspected to verify that it is in sound condition and free of any foreign objects and contaminants. There should be no exposed casing or carcass plies, no significant cracking of the liner or deformations (if in doubt refer to manufacturer for review prior to taking action).


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3.3 EXTERNAL INSPECTION

The tread area, sidewalls and bead area must be inspected to verify that the structure of the tyre is in sound condition. Cut damage and areas of deformation must be carefully inspected to verify the extent of the damage to the structure of the tyre. Tyres beyond repair should be scrapped.

If a tyre does not contain a serial number, it shall not be repaired until the history of the tyre can be verified.


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S E C T I O N 4 R E P A I R L I M I T S

4.1 GENERAL

Whilst it is acceptable to repair tyres, any repair may reduce the tyres operating performance and consideration should always be given to the failure mode if the repair is unsuccessful and likely to place users at risk.

It is not acceptable to repair areas of the bead that are integral to the structure of the bead area.

Bias plyRadial p ly

Tread rubber

Crown

Bead(non-repa i rab le area )

Bead(non-repa i rable area )

Shoulder

Sidewal l

Shoulder

Sidewal lInnerl iner Tube

Flap

ValveChafer

Breaker(ny lon )

Carcasspl ies(ny lon )

Bead(stee l wi re )

Cas ing p ly( stee l )

Be l t( stee l )

Bead(stee l wi re )

FIGURE 2 CROSS-REPRESENTATION OF A RADIAL AND BIAS PLY TYRE AND TYRE AREAS

4.2 REPAIR LIMITS FOR BIAS PLY TYRES

4.2.1 Minor repairs

Minor repairs to otr bias ply and radial ply tyres are conducted on tyres having damage within the following limits:

Rubber only damage, with no structural damage to the carcass or casing, and without cut through damage.

4.2.2 Major repairs

Major repairs in tyres are conducted on tyres having damage exceeding that specified in Clause 4.2.1 such as cut through penetration, structural damage to the carcass, and not exceeding the repair limits of Clause 4.3.


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4.3 IRREPARABLE DAMAGE TO BIAS PLY TYRES

The following types of damage are not repairable:

(a) Major damage in the bead area shown in Figure 2

(b) Damage exceeding the repair limits of Clause 4.2

(c) Damage to the carcass involving carcass break-up or carcass separation.

(d) Inner liner deterioration e.g loose detachment, splits, cracks.

4.4 NUMBER OF REPAIRS TO BIAS PLY TYRES

Only one major repair is permitted in any quarter segment (more than 90° apart) of the tyre circumference. NOTE: There is no limit to the number of minor repairs.

4.5 REPAIR LIMITS FOR RADIAL PLY TYRES

4.5.1 Major repairs

Major repairs in tyres are conducted on tyres having damage exceeding that specified in Clause 4.2.1 such as cut through penetration, structural damage to the casing, and not exceeding the repair limits of Clause 4.6

4.6 IRREPARABLE DAMAGE TO RADIAL PLY TYRES

The following types of damage are not repairable:

(a) Major damage in the shaded area of the Figure 2.

(b) Damage exceeding the repair limits of Bridgestone Table (?)

(c) Damage to the casing involving casing separation and loose cords.

(d) Inner liner deterioration e.g. loose detachment, splits, cracks.

(e) Corrosion of the steel cords beyond the repairable limits in Bridgestone Table ?

4.7 NUMBER OF REPAIRS TO RADIAL PLY TYRES

Repairs shall not be conducted on tyres with damage that extends beyond the classifications of major repairs. Only two major repairs are permitted in any quarter segment (at least 45° apart) of the tyre circumference. The total number of major repairs in a tyre shall not exceed four.

There is no limit to the number of minor repairs.

4.8 DESTRUCTION OF UNREPAIRABLE TYRES

Tyres must be disposed of under EPA guidelines that apply to the user’s location (this may involve approval to dispose on site or may require off site disposal requirements).


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S E C T I O N 5 R E P A I R O F T Y R E S A tyre should be repaired to a standard that is safe for use in a nominated application. Repaired tyres must be used as instructed by the repairer.

5.1 REPAIR PRINCIPLES

5.1.1 General principles

The following principles shall be adopted, where applicable:

(a) Cavity and hole filling, and patch application, shall be conducted with the tyre in its normal relaxed condition (i.e. without distortion), and without trapping air.

(b) Where a mixture of solutions or compounds is used, compatibility shall be ensured, based on the recommendations of or in consultation with the repair material manufacturer.

(c) The selection of patches shall be in accordance with the tyre patch manufacturer’s recommendations.

(d) Materials shall be used in accordance with the processing instructions, damage limitations where applicable, storage conditions, and ‘use-by’ date (shelf life) specified by the repair material manufacturer.

(e) The bonding system shall be suitable for the application.

(f) All repair materials shall be capable of flexing compatibly with the carcass or casing when used in normal service (i.e. with tyre loads and inflation pressures appropriate to the tyre size and load index).

5.1.2 Preparation of damage for repairing

Following inspection of the tyre (see Section 2), the damaged area shall be prepared by skiving and buffing to maximize adhesion between the host tyre and the repair material. All foreign matter and contamination shall be removed.

5.1.3 Minor repair principles

All minor repairs shall be prepared by buffing out the damaged area and filling with a compatible rubber.

5.1.4 Intermediate repair principles

All intermediate repairs shall be prepared by skiving and buffing the rubber in the damaged area, trimming the damaged steel cords and filling with a compatible rubber.

5.1.5 Major repair principles

All major repairs shall be prepared by skiving and buffing the rubber in the damaged area, trimming the damaged steel cords, filling with a compatible rubber and applying a suitable reinforcing patch.

5.2 MEASUREMENT OF DAMAGE

5.2.1 General

All measurements of cut damage shall be taken after skive / buffing preparation to expose inner / outer casing or carcass at injury site. Reinforcing patch selection shall be made by consideration of ; the selection chart provided by the manufacturer, tyre history and application as well as the site environments. Custom (in house) manufactured patches i.e. uncured for hot vulcanizing, should be constructed in accordance with thoroughly tested repair procedures.


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5.2.2 Bias ply tyres

For bias a ply tyres, the damage measurement after preparation shall be taken as shown in Bridgestone Table

5.2.3 Radial ply tyres—Crown and shoulder damage

For radial ply tyres, the damage measurement after preparation of crown and shoulder damage shall be taken as shown in Bridgestone Table (?)

5.2.4 Radial ply tyres—Sidewall damage

For radial ply tyres, the measurement after preparation of sidewall damage shall be taken both across and along the damaged ply cords as shown in Bridgestone Table.

5.3 DAMAGE AREA PREPARATION

The damaged area shall be prepared as follows:

(a) Gouge the damaged rubber to determine the extent of the damage.

(b) The damaged area shall then be prepared by gouging, cutting and buffing to remove the damaged area from either the tread or sidewall.

(c) Remove the structural damage of the carcass or casing and re-measure the injury dimensions to the casing or carcass to determine reparability. If these dimensions exceed the limits of repair (see Clause ?) the tyre should be scrapped.

(d) Produce a skive so that it provides ample area for the maximum adhesion of the replacement repair rubber.

(e) Buff the skived area to a suitable texture to maximise the adhesion of the replacement repair rubber.

(f) Measure the injury dimensions in the casing or carcass for patch selection purposes.

(g) Apply a coat of rubber bond solution to the prepared area.

(h) Fill the skive area with repair rubber compatible to the host tyre and which must be suitable for the service application. At this stage the rubber may be cured using a hot process.

All repair preparation shall be carried out with the tyre dried to remove moisture and cleaning solvents from the damaged area and its surroundings.

Care shall be taken to maintain complete cleanliness during operations. All loose and extraneous materials, e.g. buffing dust, wire particles and fluffed cords, shall be completely removed from prepared surfaces prior to cementing and patch applications. The use of a suction cleaner is recommended.

5.4 PATCH APPLICATION

The following procedure shall be taken for applying the repair patch:

(a) Select a suitable repair patch if required.

(b) Locate the patch centrally over the internal casing or carcass damage and the outline marked to establish the area where the inner liner needs to be removed.

(c) Remove the inner liner within the marked area.

(d) Buff the exposed rubber to a suitable texture to provide maximum adhesion.

(e) Clean the area. A suction cleaner is recommended.

(f) Apply rubber bonding solution to the prepared surface.


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(g) Apply the patch according to the manufacturers instructions.

The patch can then be cured using a cold process if the skived fill rubber has previously been cured. Alternatively the patch and the skived fill rubber area can be simultaneously cured by the hot process.

TO HERE

5.5 CURING

5.5.1 General

During the curing period, the tyre shall be in its relaxed, i.e. non-distorted shape. After curing, rubber used to repair areas of a tyre tread shall be repatterned as required.

5.5.2 Hot-curing

The complete hot-curing procedure shall be in accordance with the specification of the repair material manufacturer, and shall take into account the following:

(a) Thickness of the repair material.

(b) Cure rate of the repair material.

(c) Type of curing equipment to be used.

The temperature and pressure for curing shall be maintained throughout the curing period.

5.5.3 Hot Cure Simultaneous hot vulcanizing of tread / sidewall repair rubber and reinforcing patch.

(a) Suitable curing equipment specifically designed for the repair of OTR tyres i.e. sectional mould; air bag / harness system; autoclave

(b) Such equipment should be capable of maintaining curing temperature / pressure over the whole area of the internal / external repair area.

(c) Curing rate of rubber material i.e. minutes / millimetre should be as recommended by manufacturer.

5.5.4 Hot cure repair rubber (plug) / cold (chemical) cured patch system requiring

(a) Suitable curing equipment specifically designed for the repair of OTR tyres i.e. hydraulic / air spotters. NOTE: Use of mechanical jack truck / tractor spotters should be limited according to their ability to deliver sufficient curing temperature / pressure over the whole repair area i.e. small repairs in small OTR tyres > 25 inch.

(b) Curing rate of rubber material i.e. minutes / millimetre should be as recommended by manufacturer.

5.5.5 Cold curing (chemical) patch application

The complete cold curing procedure shall be in accordance with the specification of the repair material manufacturer. OTR tyre curing equipment should be suitable for use to apply pressure on the reinforcing patch after installation and ensure maximum contact and adhesion.

No mix and match of different brand repair patch and rubber shall be permitted.

Substantial curing time for chemical patches is recommended by manufacturers. Tyres should not be put into service before this time has elapsed. NOTE: Curing using a chemical process requires a period of not less than two days for complete curing, depending on the ambient temperature.


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5.6 INSPECTION AFTER CURING

5.6.1 Visual inspection of repair

All repairs shall be visually inspected after curing to ensure that the repair is free of defects or distortions which could affect the performance capability of the tyre, for the following:

(a) Uniform cure to correct hardness.

(b) Absence of trapped air under the patch.

(c) Distortion of repaired area.

For hot cured repairs, this inspection shall be carried out within 30 minutes of the completion of the cure.

Repairs which are unsatisfactory shall be rejected or redone, provided that the damage remains within the limits of Section 5.

5.6.2 Inspection of repair marking

Tyres shall also be inspected to ensure the following:

(a) Major repairs have been marked in accordance with Section 8; and

(b) For a tubeless tyre that has been repaired and then converted for use only as a tube type tyre, the word ‘TUBELESS’ has been removed from the tyre.

NOTE: 1 It is essential to remove the word ‘TUBELESS’ from the sidewalls of a tyre that has been

converted to a tube type as an indication to subsequent users that the tyre is no longer suitable for use as a tubeless tyre.

2 A tubeless tyre may be converted to a tube tyre when, during inspection before or after repair, it is found to have damage to the innerliner or bead area which could adversely affect its ability to maintain inflation pressure, provided that such damage would not pinch or chafe the inner tube. .

3 There should be no justification for fitting a tube to a tubeless tyre after repairing or retreading other than stated in Note 2.


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S E C T I O N 6 R E T R E A D I N G O F T Y R E S

6.1 GENERAL

Only OTR tyres satisfying the inspection requirements of Section 3 may be retreaded in accordance with the requirements of this Section.

6.1.1 Use of materials

Materials shall be used in accordance with the processing instructions, storage conditions, and ‘use-by’ date (shelf life) specified by the retread material manufacturer.

6.1.2 Buffing

The entire surface to be re-rubbered shall be uniformly buffed, and care shall be taken to prevent furrows, gouges, scorching, burning, or damage to cords, belts or breakers. The contour of the buffed area shall suit the tread profile and, where applicable, the mould to be used. Embedded foreign material shall be removed. Nail holes, tyre paint finishes, and small cuts through the tread shall be buffed out, except minor cuts not exceeding 6 mm in length which shall be probed and left unbuffed. All loose ends shall be trimmed back to the carcass (see Clause 6.1.4).

Any marking referring to Australian Standards or Standards Australia Certification shall be

removed.

6.1.3 Inspection after buffing

The casing shall be re-inspected after buffing for additional damage revealed or caused by the buffing process.

6.1.4 Buffing damage

(a) Diagonal ply OTR tyres

Buffing damage shall be confined to cords in the outer ply or breaker only.

(b) Radial ply OTR tyres

If, during buffing, localized lifting of the cords occurs at the edges of structural belts, the OTR tyre may be repaired by buffing away the loose wire filaments. However, if buffing damage reduces the overall width of a structural belt by more than 10 mm, it shall be replaced (see Clause 6.1.5) or the carcass discarded.

Steel cords exposed by buffing shall be cemented in accordance with Clause 6.1.7(b). A protective breaker is not a structural component of the OTR tyre and, if extensively damaged by service cuts or buffing, or separated from the structural belts, it may be completely removed. Replacement is optional.

6.1.5 Rebelting of radial ply OTR tyres

Rebelting is only permitted in radial ply OTR tyres.

If structural belts in radial ply OTR tyres are removed, they shall be replaced with belts of similar material and characteristics to the original belt, of width within ±10 mm, and cord angle within ±5°, of the original belt. Each replacement belt shall be placed with the same direction of lay as the original belt. OTR tyres treated by removal and replacement of a structural belt shall be marked in accordance with Clause 9.1.2(d).


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6.1.6 Repairs

Prior to retreading, any casing damage shall be repaired in accordance with Section 4. All previous unsatisfactory repairs shall be replaced. However, if after preparation the damage exceeds the repair limits of Sections 5, the casing shall be rejected.

6.1.7 Cementing

If cementing is required to ensure effective adhesion of the retread rubber, the OTR tyres shall be cemented with a solution specifically intended for rubber adhesion, and shall be free from moisture and foreign materials such as buffing dust, dirt, or other deleterious matter.

The following measures shall be observed during the cementing process:

(a) The cementing process shall be accomplished within 4 h of buffing, as buffed surfaces begin to oxidize as soon as they are exposed to the air and adhesion is seriously reduced. If a tyre has been left for more than 4 h before cementing, or if a blue or brown discoloration appears on the buffed surface, the tyre shall be re-buffed before cementing. Tyres not cemented must be built within 4 h.

(b) If steel cords are exposed during buffing, they should be cemented within 15 min (but certainly no longer than 4 h) with a solution specifically intended for rubber to steel adhesion before filling any indentations.

(c) After cementing, the cemented area shall be covered to prevent dust accumulation or contamination by foreign matter, e.g. water, oil.

(d) Tyres which lose building tack after cementing shall be recemented.

(e) Air lines connected to spray units or blow guns shall be fitted with traps to eliminate water and oil.

6.1.8 Building

The tread rubber shape shall be selected to suit the profile and tread pattern of the mould or, for precured tread rubber, the particular tyre.

Before application of the tread rubber, or cushion gum and tread rubber—

(a) The casing shall be free from contamination; and

(b) All buffing cavities shall be filled with a compatible rubber compound. NOTE: The addition of cover ply strips over the edges of belts of radial ply tyres prior to the application of the retread rubber is optional.

Where the tread rubber is applied in precured or camelback form, it shall consist of not more than four pieces per tyre, and be applied centrally. After application of the tread rubber, sufficient pressure shall be applied to its surface by rolling to cause adhesion to the cemented surface without entrapment of air. Joints or splices shall be matched by skiving or butting. To minimize imbalance in precure all sections must be applied evenly around the tyre cumferentially.

All edges shall be rolled and tight.

Where the tread rubber is applied in layers of a continuous strip that is fed directly from an extrusion machine, the profile shall be built up progressively to the selected shape.


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WARNING: EXCESSIVE DEPTH OF RUBBER EITHER IN THE FORM OF TREAD DEPTH OR UNDERTREADING GAUGE CAN ADVERSELY AFFECT PERFORMANCE AND DURABILITY OF A RETREADED TYRE.

6.1.9 Curing

A tyre repaired prior to retreading shall be cured as soon as is practical after completion of the repairing and building operations. The tyre shall be cured for a set period and at a temperature and pressure recommended by the tread rubber manufacturer for the particular compounds and equipment in use. The recommended temperature and pressure cycle shall be maintained throughout the curing period.

6.1.10 Venting

Venting of radial ply tyres is not recommended. If radial ply tyres are vented, venting shall be restricted to the bead area. Care shall be taken to prevent cord damage, or penetration of the innerliner. The maximum tool size used in the venting process shall be 2 mm in diameter.

6.1.11 Inspection after curing Within 1 h of the completion of cure for a OTR tyre in a mould or autoclave, a retreaded tyre shall show neither tread nor carcass separation on examination.

6.1.12 Final inspection

The retreaded tyre shall be inspected to ensure that—

(a) the tread is fully moulded and defined;

(b) the tread is placed centrally and straight, and is not distorted;

(c) the casing and bead are not creased or buckled; and

(d) the tyre marking complies with the requirements of Section 7.

Repairs which may be present in the tyre shall be inspected, and if found to be unsatisfactory shall be rejected and redone provided that the damage remains within the limits of Sections 5..

6.2 DIMENSIONAL AND PHYSICAL REQUIREMENTS

6.2.1 Rubber under the tread pattern

After moulding, there shall be a minimum of 10 mm for OTR tyres. Total undertread depth shall be not less than 10 mm, the maximum undertread depth shall not exceed undertread depth of 15 mm for all OTR tyres.

6.2.2 Tread wear indicators

The tread pattern shall incorporate at least four tread wear indicators spaced approximately equidistant around the circumference. Each shall provide a visual indication that the remaining tread in the vicinity of the indicator has a nominal depth of 5 mm. The indicator height moulded into the tyre shall be 5 mm above the base of the tread grooves.

6.2.3 Balance

The retreaded OTR tyre shall be capable of being balanced statically and dynamically by normal means.

6.3 ADHESION REQUIREMENT

When determined in accordance with Appendix A, the adhesion value between the new tread rubber and the buffed surface of the carcass shall be not less than 9 N/mm for all specimens from a single tyre.


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6.4 SPEED CATEGORIES FOR RETREADED OTR TYRES.

Tyres retreaded in accordance with this Standard shall have the following speed categories:

(a) OTR tyres Diagonal ply or radial ply—the original speed category of the tyre when new shall also apply to the retreaded tyre.

6.5 ENVIRONMENTAL CONDITIONS

To ensure maximum adhesion of the repair material, the following practices shall be adopted:

(a) All repair preparation shall be carried out with the tyre dried to remove moisture and cleaning solvents from the damaged area and its surroundings.

(b) Care shall be taken to maintain complete cleanliness during operations. All loose and extraneous materials, e.g. buffing dust, wire particles and fluffed cords, shall be completely removed from prepared surfaces prior to cementing and patch applications. The use of a suction cleaner is recommended.

(c) To ensure effective adhesion of the repair material, tyres shall be cemented, and be free from moisture and foreign material such as buffing dust, dirt, or other deleterious matter. The cementing process shall be completed within 4 h of buffing, as buffed surfaces begin to oxidize as soon as they are exposed to the air and adhesion is seriously reduced. Exposed steel cords in tyres shall be cemented within 15 mm with a solution specifically intended for bonding rubber to steel.

(d) Air lines connected to spray units or blow guns shall be fitted with traps to eliminate water and oil.


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S E C T I O N 7 M A R K I N G O F R E P A I R E D A N D R E T R E A D E D T Y R E S

7.1 REPAIRED TYRE IDENTIFICATION

In order to assist service personnel/end user during the installation of repaired OTR tyres, all OTR tyre repairs are to be categorised by preferred installation location and identifications must be branded by the repairer prior to releasing the tyre back in to service.

Identifications marks are to be clearly branded “X”, “XX” or "XXX" adjacent to the serial number on both sidewalls of the repaired tyre and should be of a minimum dimension of 40 mm.

The external “X” markings will identify the presence of a repair and the number of “X’s” the extent of damage suffered by the tyre. Service personnel will be assisted in their decision as to the suitability of a repaired tyre for particular wheel positions and which sidewall would be best positioned to face equipment chassis or the other tyre of a dual fitment.

7.1.1 SINGLE (X) MARKING

A tyre that has A Minor Repair shall be marked by a single "X" on the shoulder of the tyre and is suitable for fitment in any position with no restrictions.

7.1.2 DOUBLE (XX) MARKING

A tyre that has An Intermediate Repair shall be marked with "XX" and is the repair of damage that did not completely penetrate the tyre. The repaired tyre is not for front wheel position with the exception of motor graders and wheel dozers and the end user may exercise the option of facing the repair to the chassis. An additional XX be marked on the shoulder of the tyre adjacent to the repair.

7.1.3 TRIPLE (XXX) MARKING

A tyre that has A Major Repair shall be marked with "XXX" and is the repair of damage resulting from a full penetration of tyre casing. An internal reinforcing patch will be evident at the site of the damage. The repaired tyre is not suited to front wheel position with the exception of motor graders and wheel dozers and the end user may position the repair facing the chassis. An additional XXX shall be marked on the shoulder of the tyre adjacent to the repair.


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S E C T I O N 8 M A I N T E N A N C E O F T Y R E S ( S e r v i c e r e c o r d s )

8.1 RECORDING

For safe management of tyres and rims the following records must be maintained:

Tyre Inflation Pressure – should be recorded daily, weekly or monthly depending on operating severity.

Tyre Movements – it is necessary to record all tyre movements by life (distance/hours), disposition, condition, repair life and RTD.

8.2 SERVICE RECORD (LOGBOOK)

A service record (logbook) shall be provided, which is capable of being maintained current with details of the maintenance, service and repairs carried out on each tyre.

8.3 RECORDED HISTORY

The basis of any record system is the unique serial number that the manufacturer embosses onto one or both sidewalls.

For each individual tyre, a full history shall be maintained from first fitment to scrap, or transfer to another user.

The recorded history will detail, as a minimum, the following:-

(a) Date of fitment, and vehicle identification and wheel position.

(b) Date and accumulated hours or kms when tyre is removed.

(c) Reason for removal.

The recorded history will continue until the tyre is scrapped or transferred to another user.

8.4 REPAIRS AND RETREADING

Full details of repairs and retreading shall be entered into the recorded history.

Minimum requirements areas follows:

(a) Identification of processing plant.

(b) Position and type of repair.

8.5 TRANSFER TO ANOTHER USER

The next user will be given sufficient information to show:-

(a) The service life of the tyre.

(b) Repair and retread details.

Information which can provide information applicable to a mines operation may be omitted.

8.6 REPLACEMENT OF TYRE IDENTIFICATION

It is possible that the manufacturer’s serial number may be removed during the repair or retread process.

Where one side of the tyre still retains a legible serial number, then the other side will remain blank.


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When serial numbers on both sides have been removed, it is not permitted to apply a copy of the original serial.

In such a case, an identification number, applicable to the site will be cut or branded into both side walls.

The tyre history will note the change in tyre identifiers.


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APPENDIX A

EXAMPLE OF INSPECTION SHEET An example of an inspection sheet for inspection of tyres is shown in Figure A1.

NATIONWIDE TYRE REPAIRS INSPECTION SHEET Reference No:

Pre-fitting Inspection Sheet:

Inspection Date:

Inspection start and finish times:

Inspected by Signed

Equipment needed External Tread

1. Separation in tread 2. Abnormal wear pattern 3. Large cuts to belt package 4. Rocks lodged in tread 5. Penetrations 6. Deformation or lifting of repairs

Further action or follow up

External Sidewall 1. Separation or bulging 2. Cuts 3. Deformation or lifting of repairs

.

External Bead 1. Distortion of the bead 2. Wear or chunking of bead sealing surface 3. Exposed bead wire 4. Wear on side ring mating surface

Internal 1. Separation or bulging 2. Liner lift or splits 3. Deformation or lifting of repairs 4. Foreign material

This pre-fitting inspection sheet is to be used as a minimum guide for inspection of used tyres prior to fitting to rims or wheels. It does not cover tyre size, specification, inflation, load capacity or matching. This inspection sheet should also be used in conjunction with other NTR controls.

Additional Instructions:

If there is any doubt about the integrity of the tyre then the tyre should not be fitted to a rim or wheel. The tyre must be put in a secure area so it CANNOT be fitted until a full inspection by Nationwide Tyre Repairs is carried out and the approval has been given to fit.

FIGURE A1: TYPICAL TYRE INSPECTION SHEET

*** END OF DRAFT ***

Draft—For Committee Purposes Only ME/063/06-008

(Supersedes ) SECOND COMMITTEE DRAFT DRAFT Issued: September 2006

Project No: 7940 STANDARDS AUSTRALIA

Committee ME-063— Earth-moving Equipment

Subcommittee ME-063-00-01—Wheels, rims and tyres

DRAFT

Australian Standard

Earth-moving machinery—Off-the-road wheels, rims and tyres –Maintenance and repair Part : Tyres

INTRODUCTORY NOTE

Documents

31 n733 5australiandraftonmaintenanceandrepair