Overview
ISO 7451:2007 specifies a standardized method for estimating the volumetric ratings of hoe-type and grab-type buckets used on hydraulic excavators and backhoe loaders. The standard defines how to calculate a conventional bucket capacity by dividing the complex material shape inside a bucket into simple geometric elements based on the bucket’s internal dimensions and representative top volumes. ISO 7451 is intended for comparative rating and publication as a rated capacity - it is explicitly not intended to represent true/operational capacity. (Not applicable to cable excavators.)
Key topics and technical requirements
- Measurement basis: Internal bucket dimensions and representative volumes at the top of the bucket (strike plane or strike surface).
- Geometry method: Complex material shape is decomposed into simple geometric shapes to compute volumes.
- Primary volume components:
- Struck volume (Vs) - material volume beneath the strike plane/surface.
- Top volume (Vt) - additional volume above the strike plane that contributes to rated capacity.
- Displaced volume (Vm) - for grab-type buckets, the volume occupied by operating mechanism (subtracted from top volume).
- Dimensional definitions: Key dimensions are defined (X, Y, W, strike plane/surface, side surface areas) to ensure repeatable measurement.
- Special rules and exclusions:
- Ignore projecting parts (tooth supports, removable tips, side cutters, gussets) when assessing volumes.
- Include shielding and true indentation of the leading edge where specified.
- Buckets must be positioned with the defined plane (cutting edge to backsheet contact) horizontal during measurement.
- Expression and commercial designation:
- Volumetric rating Vr = Vs + Vt, expressed in cubic metres or litres.
- Commercial capacity designation shall lie within ±3% of the calculated value.
Applications and users
ISO 7451 is practical for:
- Bucket and equipment manufacturers preparing technical data sheets and product comparisons.
- Test labs and performance engineers conducting capacity estimations and standard tests.
- Procurement, fleet managers, rental companies and specifiers comparing bucket options across machines.
- Design and application engineers selecting bucket types for earth-moving, trenching and loading tasks.
Using ISO 7451 helps ensure consistent, comparable bucket capacity figures across product ranges and marketplaces.
Related standards
- ISO 6165:2006 - referenced for earth-moving machinery terms and basic type definitions.
Keywords: ISO 7451, volumetric ratings, bucket capacity, hoe-type bucket, grab-type bucket, hydraulic excavator, backhoe loader, struck volume, top volume, displaced volume.
Open preview (PDF)Earth-moving machinery — Volumetric ratings for hoe-type and grab-type buckets of hydraulic excavators and backhoe loaders
