steam shovel

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A large, steam-driven machine for digging.
2. n. See power shovel.

Century Dictionary and Cyclopedia

1. n. A digging-, dredging-, or excavating-machine, driven by steam in its own engine from its own boiler: usually mounted on a car to run upon the rails of a track and used in mining, canal, and railway work. Called steam-navvy in England. It is essentially the same as the dredge, but is operated on land instead of from a boat. See cut at excavator.

Wiktionary

1. n. An industrial machine designed to effect a shovelling action through steam power.

GNU Webster's 1913

1. n. a machine with a scoop or scoops, operated by a steam engine, for excavating earth, as in making railway cuttings.

WordNet 3.0

1. n. a power shovel that is driven by steam