Steam donkey, or "donkey engine" is the common nickname for a steam-powered 'hoist' widely used in logging operations. They were also found in the mining, maritime, and nearly any other industry that needed a powered winch.
A steam donkey's boiler powered a winch around which was wound hemp rope or (later) steel cable. They were usually equipped with skids, or sleds made from logs, to aid them during transit from one "setting" to the next.
For use in logging operations, a "line horse" would carry the cable out to a log in the woods. The cable would be attached, and, on signal, the steam donkey's operator (engineer) would open the regulator, allowing the steam donkey to drag or "skid" the log towards it. The log was taken either to a mill or to a "landing" where the log would be transferred for onward shipment by rail, road or river (either loaded onto boats or floated directly in the water).
Steam donkeys powered other machines including, logging, timber,and lumber saws, pile drivers, slide-back loaders (also known as slide-jammers), and cherry-pickers (a sled-mounted crane used for loading logs, that a grading crew had cut down, onto railroad cars).