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Steam donkey, or donkey engine, is the common nickname for a steam-powered winch, or logging engine, widely used in past logging operations, though not limited to logging. They were also found in the mining, maritime, and nearly any other industry that needed a powered winch. Donkeys were often attached to a yarder.
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: high-lead yarder, ground-lead yarder, loader, snubber, incline hoist, etc. A good deal of the cable-logging terminology derived from 19th-century merchant sailing, as much of the early technology originated from that industry.
A logging engine comprised at least one powered winch around which was wound hemp rope or (later) steel cable. They were usually fitted with a boiler and usually equipped with skids, or sleds made from logs, to aid them during transit from one "setting" to the next. 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, on which were wound heavy steel cable instead of the original rope.
This describes the use of a steam donkey for logging operations. In the simplest setup, 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). Later, a "haulback" drum was added, where a smaller cable could be routed around the "setting" and connected to the end of the heavier "mainline" to replace the line horse.
If a donkey was to be moved, one of its cables was attached to a tree, stump or other strong anchor, and the machine would drag 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 and it would often be reconfigured with a saw to mill the timber.
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 150-foot, -inch 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 internal-combustion engine led to the development of the diesel-powered tractor crawler, which eventually put an end to the steam donkey. Though some have been preserved in museums, very few are in operating order. A great number still sit abandoned in the forests.
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.
An auxiliary engine on a sailing craft (which does propel the vessel) is still sometimes informally known as "the donk".
A functioning steam donkey is on display and occasionally operated at Fort Humboldt State Historic Park in Eureka, California. A non-functioning steam donkey accompanied by a plaque explaining the history of the machine is on permanent display at Grizzly River Run, an attraction at Disney California Adventure Park. Another collection of steam donkeys is located at the Point Defiance Park, Camp 6 Logging Museum located in Tacoma, Washington. The collection includes various steam donkeys, including one of the last very large ones built, and others at various stages of restoration.
Another steam donkey is on display along an interpretive trail at the Sierra Nevada Logging Museum in Calaveras County, California, an indoor open-air museum about the Sierra Nevada logging industry and history.
On August 1, 2009, a Steam Donkey was officially unveiled at McLean Mill National Historic Site in Port Alberni, British Columbia. It is now the only commercially operating steam donkey in North America. On that occasion, due to extreme fire risk, demonstrations of the donkey were not performed, but the logs hauled by previous test runs of the donkey (and had been loaded onto a truck) were dumped into the McLean Mill millpond, representing the first steam-powered commercial logging operation in North America in decades. This machine continued to operate after R. B. Mclean shuttered the steam-powered McLean Mill site in 1965. It ran until 1972 and was abandoned on site. It was restored by the Alberni Valley Industrial Heritage Society in 1986 for Expo 86 and, more recently, was re-certified for commercial use at McLean Mill. Agreements have been made with forestland owner Island Timberlands (owned by Brookfield Asset Management) to log, mill, and sell trees and lumber from the surroundings of McLean Mill.
A wide-face steam donkey (called that because the width of the drum is greater in proportion to that in later machines) has been operational at the Tillamook County Pioneer Museum in Tillamook, Oregon, since the early 1980s. Manufactured by the Puget Sound Iron & Steel Works in the early 1900s, this donkey was abandoned in the woods when the Reiger family finished logging their land in about 1952. The steam donkey was rescued and restored from 1979 to 1981. It was donated to the Pioneer Museum by the Ned Rieger family and has been on display on the Museum grounds.
A vertical steam capstan called "donkey" for hauling fishing lines and nets is preserved on the museum fishing vessel Balder in the historic harbour of Vlaardingen (near Rotterdam), the Netherlands.