1. Bucket types
There are many types of excavators, including mini excavators, compact excavators, diggers, backhoe loaders, hydraulic excavators, cable-operated excavator, front-end loaders, wheel excavators, crawler excavators, amphibious excavators, walking excavators, power shovels, dragline excavators, harbour cranes and bucket-wheel excavators.
They are all equipped with at least one bucket.
The main function of the bucket is to transport bulk material from a pile, quarry or mine for further transportation or downstream operations.
Common materials include minerals, ores, stones, sand, gravel, clay, coal, cereals, woodchips, cement, ash, salt and chemicals.
Some buckets are filled by pushing the bucket through the bulk material (as face shovels and loader buckets), some are pulled towards the excavator (as backhoes and draglines).
Most of the buckets are emptied by tipping, but some by opening the rear door (as face shovels and dippers).
The most common buckets are hydraulic excavator backhoes and wheel loader buckets.
2. How to calculate bucket capacity
Struck capacity is the volume capacity of the bucket after it has been struck at the strike plane. The strike plane passes through the top back edge of the bucket and the cutting edge.
Heaped capacity is the struck capacity plus the volume of excess material heaped on the bucket.
There are two common definitions of heaped capacity:
- The heaped capacity of excavator buckets and backhoes are mostly defined with a 1:1 angle of repose (according to standards ISO 7541, ISO 7546, PCSA 37-26, SAE J296/742b).
- The heaped capacity of loader buckets are defined with a 1:2 angle of repose (according to standards ISO 7541, ISO 7546, PCSA 37-26, SAE J296/742b and CECE V1).
Fill Factor is the percentage of an available heaped capacity of a bucket that is actually used. For example, a fill factor of 80 percent for a bucket means that 20 percent of the rated volume is not being used to carry material. Buckets often have fill factors over 100 percent.
The fill factors are affected by the bucket design, including the bucket penetration, breakout force, rack back angle, bucket profile and ground engaging tools.
In addition, the bulk material itself has a large influence on the fill factor. A stickier material, such as moist loam, forms easier a good heap than dry, poorly blasted rock.
3. Hydraulic excavator machine classes
The machine classes are based on the machine operating weight. The larger machine, the higher capacity to carry a large bucket and a large load.
Table of hydraulic excavator machine classes (PDF).
4. Excavator bucket sizes
The excavator buckets comes in many functions and sizes.
The General Purpose buckets are the most common.
Bucket size
The following graphs give an indication of bucket sizes for General Purpose buckets (GP) based on the excavator machine sizes.
Bucket dimensions
The following graphs gives an indication of bucket width and weight for a GP bucket, based on the bucket volume.
5. Wheel loader machine classes
The machine classes are based on the machine operating weight. The larger machine, the higher capacity to carry a large bucket and a large load.
Table of wheel loader machine classes (PDF).
6. Loader bucket sizes
The loader buckets comes in many functions and sizes.
The General Purpose buckets are the most common.
Bucket size
The following graphs give an indication of bucket sizes for general purpose buckets (GP) based on the wheel loader sizes.
Bucket dimensions
The following graphs gives indications of bucket widths of loader buckets, based on the bucket volume.
7. Ground engaging tools (GET) classes
The ground engaging tools (GET) classes, such as bucket teeth systems, are based on the machine operating weight and break-out-force. All numbers are indications.
Table of ground engaging tools (GET) classes.
The information in this report is only applicable to SSAB’s products and should not be applied to any other products than original SSAB products.
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