ABSTRACT
This chapter examines power digging equipment which includes hydraulically operated excavators and cable-operated draglines and clamshells. Dragline excavators are used when there is a need for extended reach in excavating or when material must be excavated from under water. Clamshell excavators provide the means to excavate vertically and also can be used to excavate from under water. Backhoe excavators are machines with buckets mounted on the end of a boom with the bucket opening facing the machine operator. If the backhoe is used to lift pipe into the excavated trench, the operational efficiency must be adjusted to consider only that portion of time the excavator is actually digging the trench. Draglines mounted on tracked cranes can operate over soft ground conditions that would not support hydraulic excavators. Draglines are used to load hauling units, such as trucks, or create stockpiles. The digging reach and the operating radius of a dragline are considerably greater than for a front shovel or backhoe.
