CALCULO CAPACIDAD BALDE PALA HIDRAULICA

The following method of calculating the capacity of Buckets for Hydraulic Excavators is

representative of the method used by most O.E.M. Heavy Equipment Manufacturers.

Similar methods are used for Rating Buckets for Wheel Loaders.

Our page, Buckets for Hydraulic Excavators shows samples of some of the many different

shapes and style of buckets. Our section Hydraulic Excavator Bucket Terminology defines

some of the many terms used in discussing these products.

The Society of Automotive Engineers publishes standards that define Bucket Capacities for

Wheel Loaders and other machines. For detailed information contact SAE directly on their

Web site and ask for:

• SAE Standard J296 - "Excavator Hoe Bucket Rating"

EXCAVATOR HOE BUCKET RATING

1. Purpose – The purpose of this standard is to provide a uniform method for determining

the SAE rated capacity for hoe buckets. The calculations are based on the inside physical

dimensions for the bucket only, without use of optional side cutters, spill guards, teeth, or

other accessories and without regard to bucket action provided by any specific machine.

2. Scope – This standard applies to hoe buckets on all excavators with a hoe attachment.

3. Definitions

3.1 SAE struck capacity is the volume of the bucket after it has been struck at the strike

plane. The strike plane shall pass through the top back edge of the bucket and the cutting

edge. (See Fig.1.)

Variance (whether angular or curved protrusions) of side plates leading edge beyond the

strike plane, dimension C1, shall not be used to increase volume VS shall be that bounded

by the strike plane and the inside contour of the bucket. If the bucket is open between the

mounting holes, this opening shall not be a factor in determining the volume. (See Fig.1)

Variance (whether angular or curved indentations) of the side leading edge from the strike

plane, dimension C2, should be no greater than D/12 for the purpose of calculating capacity

where "D" represents the bucket opening. (See Fig.1)

If dimensions C2 is greater than D/12, the volume V8 must be calculated by using the actual

volume of the bucket when it has been struck across the strike surface. (See Fig.2)

3.2 SAE rated capacity is the sum of the SAE struck capacity and the material heaped on

the bucket at a 1:1 angle of repose. (See Fig. 1 and 2.) This in no way implies that the hoe

must carry the bucket oriented in this attitude, or that all material will naturally have a 1:1

angle of repose.

VR = VS + VE

3.3 Definitions of terms used in the equations:

VS = SAE struck capacity

VR = SAE rated capacity

VE = excess material heaped at 1:1 angle of repose

D = bucket opening

3.4 SAE struck capacity shall be according to the following table:

Range of Rated Sizes Increments

English Metric English Metric

Under 7 ft3

7 ft3 up to 0.5 yd

3

0.5 up to 3 yd3

3 yd3 and over

Under 0.2m3

0.2 up to 0.4 m3

0.4 up to 2.3 m3

2.3 m3 and over

.05 ft3

1 ft3

0.125 yd3

0.25 yd3

0.01 m3

0.02 m3

0.1 m3

0.2 m3

The SAE rated capacity shall be in the same range of rated sizes and increments as for the

SAE struck capacity.

If the calculated capacity falls below a rated size by more than 2%, use the next lower rated

size.

4. Width – When bucket width is specified, both a "bucket width" and a "cutting width"

should be stated.

4.1 The "bucket width" is measured over the sides of the bucket at the lower lip without

teeth or side cutters attached. (See WB, Fig. 3.)

4.2 The "cutting width" is measured over the teeth or side cutters. (See WC, Fig. 3.)

Fig. 1 - BUCKET CAPACITY, TYPE A

Fig. 2 - BUCKET CAPACITY, TYPE B

Fig. 3 - BUCKET WIDTH

BUCKET PAYLOAD

An excavator’s bucket payload (actual amount of material in the bucket on each digging

cycle) is dependent on bucket size, shape, curl force, and certain soil characteristics, i.e.,

the fill factor for that soil. Fill factors for several types of material are listed below.

Average Bucket Payload = (Heaped Bucket Capacity) 2 (Bucket Fill Factor)

Material Fill Factor Range

(Percent of heaped bucket capacity)

Moist Loam or Sandy Clay A — 100-110%

Sand and Gravel B — 95-110%

Hard, Tough Clay C — 80-90%

Rock — Well Blasted 60-75%

Rock — Poorly Blasted 40-50%

NOTE: For bucket fill factors for hydraulic excavators, see Bucket Rating - Wheel Loaders section.

See our section on Bucket Terminology - Hydraulic Excavators for more information.

CALCULO CAPACIDAD BALDE CARGADOR FRONTAL

FRONT END LOADER BUCKET RATING

1. This discussion describes a method for determining the average volume of an average

material carried by the bucket of a front end loader. The calculations used result in a

realistically conservative heaped volume. They are based on physical dimensions of the

bucket only without regard to bucket action provided by any specific machine. It has been

determined that for rating purposes, a nominal heaped load will have a 2:1 angle of repose

when the bucket is oriented as shown in Figs. 1 and 2. This in no way implies that the

loader linkage must carry the bucket oriented in this attitude, or that all materials will

naturally have a 2:1 angle of repose.

2. Rated capacity shall be expressed in cubic yards for all sizes ¾ cu yd or over, and in

cubic feet for all sizes under ¾ cu yd. It shall be stated as the "Nominal Heaped Rating."

3. Rated capacities shall be stated in intervals of 1 cu ft for buckets under ¾ cu yd, 1/8 cu

yd for buckets from ¾ to 3 cu yd, and ¼ cu yd for buckets over 3 cu yd.

4. Measurements and calculations are outlined in the Figs. 1 and 2. All linear measurements

are in inches and the resulting volumes are in cubic inches. These are to be converted to

cubic feet or cubic yards as specified above. If the calculated value falls below a given

rating interval by more than 2%, the next lowest interval shall be deemed to be the rating.

EXAMPLE: A calculated value of 1.95 cu yd is under 2 cu yd by more than 2% and,

therefore, the proper rating on the basis of the measurements and calculations is 1-7/8 cu

yd.

5. To determine the rated capacity it is necessary to first determine the struck capacity. It is

defined as the volume of material retained in the bucket after a heaped load is struck by

drawing a straight edge across the width of the bucket with one end of the straight edge

resting on the cutting edge and the other end resting on the uppermost portion of the bucket

back sheet or spill guard. (See SAE J731.) For buckets with spill guards the struck capacity

can be expressed by the following equation:

V8 = AW – 2/3a2b

where:

A = cross section area at the center of the bucket; sq. in.

W = average inside width of the bucket; in.

a = height of the spill guard at the center of the bucket

normal to the strike line; in.

b = length of opening at the center of the bucket; in.

For buckets without spill guards, the struck capacity is

expressed as follows:

V’ = A’W

Where:

A’ = cross section area at the center of the bucket; sq. in.

If struck capacity is shown in addition to the nominal heaped rating, it should be shown

decimally to three significant figures.

NOTE: Where the terms A or A’ occur, they may be determined on an accurately drawn

layout by use of a planimeter or by accurately cutting a template to fit the bucket profile.

The template must be placed in a plane normal to the bucket back sheet and equidistant

from corresponding points of the bucket side sheets.

Bucket Heap Diagram

6. Using the 2:1 angle of repose of the heaped material, the rated capacity is expressed as

follows:

Vr = Vs + b2W/8 – b

2/6(a + c)

Where c is the length on a normal to the strike line. On one end it is determined by the

assumed crest of the material. On the other end it is determined by the intersection with a

line from the bit or cutting edge tip to the base of the spill guard.

For buckets without spill guards, the rated capacity is expressed as follows:

Vr = Vs + b2W/8 – b

3/24

7. This method applies primarily to regular buckets having parallel sides and a cutting edge

parallel to the edge of the spill guard or back sheet. Moderately clipped spill guard corners

will introduce no appreciable errors.

8. The addition of any auxiliary guard to protect against spillage of material which might

injure the operator will not be included in bucket capacity calculations. It is recommended

that such a guard be of "see through" construction.

BUCKET FILL FACTORS

Loose Material Fill Factor

Mixed Moist Aggregates 95-100%

Uniform Aggregates up to 3 mm (1/8") 95-100

3 mm-9 mm (1/8"-3/8") 90-95

12 mm-20 mm (1/2"-3/4") 85-900

24 mm (1") and over 85-900

Blasted Rock

Well Blasted 80-95%

Average Blasted 0 75-90

Poorly Blasted 0 60-75

Other

Rock Dirt Mixtures 100-120%

Moist Loam 100-110

Soil, Boulders, Roots 80-100

Cemented Materials 85-95

NOTE: Loader Bucket Fill Factors are affected by bucket

penetration, breakout force, rackback angle, bucket profile and

ground engaging tools such as bucket teeth or bolt-on

replaceable cutting edges.

NOTE: For bucket fill factors for hydraulic excavators, see

Bucket Rating - Hydraulic Excavators section.

Bucket Terminology

Wheel Loaders Link to: Bucket Terminology - Hydraulic Excavators

As in other parts of the heavy equipment industry, there are numerous terms used to

describe the same thing. We've picked on some of the common terms and their synonyms

that are used when describing Wheel Loader Buckets. Wherever possible we have used hot

links to pictures and diagrams to graphically define terms instead of using written

definitions.

Link to our page Wheel Loader Buckets for descriptions and photos of many different types

of buckets or to our Field Worksheet page for a handy form to be used when gathering

information to establish the capacity.

Bucket Types

IMAC Optional

General

Purpose

• Standard

Bucket

• Basic

Bucket

• Common

Bucket

Heavy

Duty

• Rock

• Extreme

Service

Light

Material

• Sand

• Woodchip

• Coal

Flat Bottom • Standard

Bottom

Wedge

Bottom

• Sloped

Floor

• Tapered

Bottom

• "Cat" Style

Cutting Edges

IMAC Optional

Straight

• Straight

Lip

• Standard

Edge

Spade

Nose • Vee Lip

Semi

Spade • Semi-Vee

Bucket Parts

IMAC Optional

Base Edge • Lip

• Cutting

Edge

Shell • Back

• Body

Side Plates

Spill Guard • Spill

Board

Corner Bit

Side Bar • Side

Cutter

• Side Edge

Lugs

• Ears

• Hinge

Plates

Frog

• Box Beam

• Torque

Beam

• Backbone

Skid Bar • Wear

Plate

Heel Plate • Wear

Plate

Adapter and

Tooth

Side Wear

Plate

• Cheek

Plate

Wedge Bottom Construction

Wedge Bottom Construction

Skid Bar &

Heel Plate Showing

plus

Extra Intermediate Wear Bars

Flat Bottom Construction

Flat Bottom

Straight Edge

c/w Bolt on Adapters & Teeth

featuring

"Corner Guard" outside adapters

Base Edge Types

Wheel Loader Buckets

Our section entitled Rating Wheel Loader Buckets describes the most common method of

rating these products. Be sure to turn there and study it to learn more.

Field Worksheet Wheel Loader Bucket Measuring

Print this page and use it to record all the information needed to properly calculate the

capacity of Wheel Loader Buckets according to the Bucket Rating Standard published on

this Web site or in SAE's Standard - J742b.

Our Wheel Loader Bucket Terminology page is useful when trying to define the details of a

bucket. Look it over and see if it helps you with your next bucket project.

Equipment needed: Straight Edge, 2 foot carpenters square, tape measure, level, inclinometer, a copy

of this diagram and for big buckets, an extra pair of hands.