A steam donkey, or donkey engine, is a steam-powered winch once widely used in logging, mining, maritime, and other industrial applications. Steam-powered donkeys were commonly found on large metal-hulled multi-masted cargo vessels in the later decades of the Age of Sail on through the Age of Steam, particularly heavily sailed skeleton-crewed windjammers. A donkey used in forestry, also known as a logging engine, was often attached to a yarder for hauling logs from where trees were felled to a central processing area. The operator of a donkey was known as a donkeyman.
Name Steam donkeys acquired their name from their origin in sailing ships, where the "donkey" engine was typically a small secondary engine used to load and unload cargo and raise the larger sails with small crews, or to power pumps. They were classified by their cylinder type – simplex (single-acting cylinder) or duplex (a compound engine); by their connection to the winches (or "drums") – triple-drum, double-drum, etc.; and by their different uses. A good deal of the cable-logging terminology derived from 19th-century merchant sailing, as much of the early technology originated in that industry. Common logging terms include high-lead yarder, ground-lead yarder, loader, snubber, and incline hoist.
History
In logging
John Dolbeer, a founding partner of the Dolbeer and Carson Lumber Company in Eureka, California, invented the logging engine in that city in August 1881. The patent (number: 256553) was issued April 18, 1882. On Dolbeer's first model, a 46-metre (150 ft), 110-millimetre (4.5 in) manila rope was wrapped several times around a gypsy head (vertically mounted spool) and attached at the other end to a log. The invention of the steam donkey increased lumber production by enabling the transport of trees that would previously have been left behind because they were too large to move. They also enabled logging in hot or cold weather, which was not previously possible with the use of animal power. Later, the invention of the internal-combustion engine led to the development of the diesel-powered tractor crawler, which eventually made the steam donkey obsolete. Though some have been preserved in museums, very few are in operating order. A great number still sit abandoned in the forests.
Design A logging donkey consists of a steam boiler and steam engine, connected to a winch mounted on a sled called a donkey sled. The donkeys were moved by simply dragging themselves with the winch line, originally hemp rope and later steel cable. They were used to move logs, by attaching lines to the logs and hauling them. The larger steam donkeys often had a "donkey house" (a makeshift shelter for the crew) built either on the skids or as a separate structure. Usually, a water tank, and sometimes a fuel oil tank, was mounted on the back of the sled. In rare cases, steam donkeys were also mounted on wheels. Later steam donkeys were built with multiple horizontally mounted drums/spools.
Use
In the simplest logging setup, a "line horse" would carry the cable out to a log where its tree had been downed. The cable would be attached, and, on signal, the donkey's operator (an 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 it would be transferred for onward shipment by railroad, road or river – either send down a flume, loaded onto boats, or floated directly in the water, often becoming part of a large log raft or "boom". Later, a "haulback" drum was added to the donkey, where a smaller cable could be routed around the "setting" and connected to the end of the heavier "mainline" to replace the line horse. A donkey was moved by attaching one of its cables to a tree, stump or other strong anchor, then dragging itself overland to the next yarding location. In Canada, and in particular Ontario, the donkey engine was often mounted on a barge that could float and thus winch itself over both land and water. Log booms would be winched across water with the engine, after which it would often be reconfigured with a saw to mill the timber.
Operator
A logging donkey would be operated by an engineer called since about 1920 a donkey puncher. In later times the donkey puncher was too far away from the end of the line for verbal communication, so whistle codes were developed similar to those used by tug boats employing steam whistles. The whistle operator was known as a whistle punk, who was placed between the men attaching the cables (choker setters), and the donkey puncher, so that he could see the choker setters. When the cables were attached, a series of whistle blows signaled the donkey to begin pulling and the choker setters to stay out of harm's way. The process was a closely orchestrated sequence of actions, where mistakes were often fatal and where good men stood in line for the jobs. Although the steam engine, and its whistle, have been replaced by gasoline and diesel engines, the whistle codes are still used in many current logging operations. The whistle has been replaced largely with airhorns.
Other uses Steam donkeys were also found to be useful for powering other machines such as pile drivers, slide-back loaders (also known as "slide-jammers", cranes which were used to load logs onto railroad cars and which moved along the flat-bed rail cars that were to be loaded), and cherry pickers (a sled-mounted crane used for loading, onto railroad cars, logs that a grading crew had cut down). Sailing fishing vessels on the North sea operated vertical steam-driven capstans called 'the donkey' to haul fishing lines and nets, some of which are still operating today, even though converted to compressed air. Some steamboats used a steam-driven donkey hoisting-engine with capstan, ropes and strong poles (spars) to move "walk" the boat over or away from reefs and sandbars. An auxiliary engine on a sailing craft (which does propel the vessel) is still sometimes informally known as "the donk".
Preserved examples
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