any mechanical or electrical device that transmits or modifies energy to perform or assist in the performance of human tasks

an excavator whose shovel bucket is attached to a hinged boom and is drawn backward to move earth

a power shovel to remove material from a channel or riverbed

a power shovel that is driven by steam

a power shovel that operates by being dragged by cables at the end of an arm or jib: used for quarrying, opencast mining, etc.

a continuous digging machine in large-scale open-pit mining operations (as in surface mining).