General Purpose, or GP, buckets come with bucket teeth or in a no-teeth, smooth edge style. GP buckets excel at digging and trenching soft to medium materials such as gravel and dirt. The largest GP bucket for a standard, 20- to 22-metric ton unit has a 1.5 cubic-yard capacity.
The thicker steel used on heavy-duty buckets makes them a better choice than GP buckets for soils consisting of dense dirt, rock and clay mixtures. They have straight sides to reduce packing and speed up the load-dump cycle. The teeth on heavy-duty buckets must stand up to abrasive conditions.
Rock presents the toughest digging condition and holds the greatest potential for causing equipment failure, including cracked buckets and broken bucket teeth. Rock buckets feature the thickest reinforcing wear plates and wear strips available to extend bucket life. Some have ripper shanks and staggered teeth to cut through rock and dig simultaneously.
Ditch maintenance requires a special bucket that clears, rather than cuts, the ground surface. Ditch buckets are shallow and compact for work in confined space. They feature drainage holes and a no-teeth, flat front. One type of ditch bucket, the trapezoid bucket, slopes a ditch to a specific depth in one pass. Another, the hydraulic tilt bucket, provides automatic adjustment to slope angles.
Attachment manufacturers offer excavator buckets designed for specific applications. Examples include screening buckets to sort rock sizes, marine buckets for dredging, slab buckets to lift concrete slabs, coral buckets that perform the peeling needed to excavate coral rock, sharp-edged grading buckets with drainage holes and coal buckets for strip mining. Clamshell buckets used for clean-up on demolition and general excavation sites feature a hinge for clam-like opening and closing.