Most compact hydraulic excavators have three distinct assemblies: house, undercarriage and workgroup.
House The house structure contains the operator's compartment, engine compartment,
hydraulic pump and distribution components. The house structure is attached to the top of the undercarriage via a swing bearing. The house, along with the workgroup, is able to rotate or slew upon the undercarriage without limit due to a hydraulic distribution valve which supplies oil to the undercarriage components.
Slew Slewing refers to rotating the excavator's house assembly. Unlike a conventional
backhoe, the operator can slew the entire house and workgroup upon the undercarriage for spoil placement.
Undercarriage The undercarriage consists of rubber or steel tracks, drive sprockets, rollers, idlers and associated components/structures. The undercarriage supports the house structure and the workgroup.
Workgroup The workgroup of a compact hydraulic excavator consists of the boom, dipper or arm, and attachment (e.g.
auger, bucket or breaker). It is connected to the front of the excavator's house structure via a swing frame that allows the workgroup to be hydraulically pivoted left or right to achieve offset digging for trenching parallel with the tracks. Certain manufacturers including Terex and Caterpillar (CAT) offer an extendable boom option, much like the extendable boom of a backhoe loader.
Independent boom swing The primary purpose of boom swing is for offset digging around obstacles or along foundations, walls or forms. A secondary use is cycling in areas too narrow for cab rotation. Independent boom swing is one of the major advantages of a compact excavator over other excavation equipment.
Backfill blade The backfill blade is used for grading, leveling, backfilling, trenching, and general dozer work. The blade can be used to increase dump height and digging depth depending on its position in relation to the excavator's workgroup, this makes it very versatile. It is also used to stabilize the machine while digging. ==Attachments==