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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.
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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.
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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.
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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.
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