March April 2005
 

 

 

 

THE DOLBEER DONKEY ENGINE

By Kurt Glaeseman

The refurbished Dolbeer Donkey Engine was the mechanical replacement for animals that were used to haul logs out of the woods. Invented in 1881 by Eureka naval engineer John Dolbeer, this small steam engine was called a "donkey," after a ship’s auxiliary engine. Dolbeer’s theory was that a small, high-pressure steam engine could turn, through sets of gears, a capstan-like spool or drum that could reel in rope attached to a log.

Volunteer Jerry Harmon, from Mount Shasta, does a brief check.

In appearance it was a woodburning boiler that powered a single piston engine. Stabilized on heavy wooden skids, the donkey could pull even the heaviest of logs. This particular Dolbeer Donkey was first used by the King River Lumber Company in Fresno County and dates back to the 1890s. It was abandoned when logging operations ceased in 1929 and escaped the scrap metal pile during World War II. It was recovered and restored to operating condition in the early 1970s.

John Nichols, retired Forester, holds a water wheel fashioned from a tin can lid. Steam hits the wheel and makes it turn, causing a red bicycle light to flash on.

Today it is on loan from the Sequoia National Forest and is operated regularly by members of the Northern California Chapter of the Society of American Foresters. At first it was used to ‘yard’ or haul logs to the head of a skidroad, but when rope was replaced by sturdier wire cable, logs were "roaded" long distances from one donkey to another. Donkeys became specialized: Two- and three-drum donkeys were used to haul in logs over high wires, to load logs onto railroad cars, and to bring logs to river or lake landings.

John Nichols shows how steam turns the water wheel improvised from a tin can lid.

A converted lighter with a donkey engine that turned a stern wheel was used to herd large rafts of logs downriver. John Nichols, a retired forester from Oakland, and volunteer Jerry Harmon give a brief lecture, answer questions, and then fire the Dolbeer Donkey up so that it produces steam. To illustrate to the audience how energy can be generated, Nichols has fashioned a water wheel from a tin can lid. This is attached to a bicycle generator. The steam hits and turns the water wheel, and a rudimentary turbine is in operation. The light goes on immediately. What caused the death of these donkeys? The internal combustion engine paved the way for a new stage of "progressive" logging, and today we stare in wonder at this historical marvel.

TW

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This page was last updated on Tuesday, April 19, 2005