Physics Photo of the Week
Farms of the
19th century needed much power to run mechanical equipment - saws,
churns, hay packing grinders, threshing in addition to work in the
fields. Horses were plentiful and versatile; gasoline engines and
tractors hadn't yet been developed, and steam engines were too
expensive for small family farms. This is a treadmill powered by
a horse walking in the "box" on an inclined conveyor. This unit
powered a reciprocating crosscut saw used to saw cordwood for heating
fuel and is part of the extensive collection of antique farm equipment
by Fred Webster of Coventry, Vermont.
At right is another treadmill with owner and
collector Fred Webster. The well-worn wooden treads on the
the horse walks on are clearly visible. I was lucky to have a
tour led by Fred of his exensive collection of antique farm
equipment. About six of us visiting people got into a horsepower
were able to power it - an interesting experience.
Fred Webster's mission in collecting these antiques is to document the
technological progress of farming equipment. Horse "sweeps" soon
replaced treadmills as more practical and more efficient. A sweep
consists of a long rod attached to a gear box. A horse (or team)
is hitched to the sweep rod and walks in a circle driving the gear box
that drives a
shaft to power stationary machinery such as a threshing machine, hay
press, or lift equipment. In the photo at left, the drive shaft
can barely be seen - it resembles a pipe in the upper center of the
photograph pointing away from the gears.
Animal powered machinery has been used for centuries. In the
development of steam power in the 18th century, the horse became the
"standard" unit of power. With similar devices as these machines,
James Watt was able to measure that a typical horse could hoist a 100
lb load a distance of 330 feet in one minute (33,000 ft-lbs/minute =
746 Watts). See
on horsepower for September 18, 2009.
Photo of the
published weekly during the academic year on Fridays by the Warren
Wilson College Physics
Department. These photos feature an interesting phenomena in
the world around us. Students, faculty, and others are invited to
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explanation. Atmospheric phenomena are especially welcome.
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