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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.