The 'theoretical' performance of a horse whim will be based on the
definition of 'horsepower' of 330 pounds at 100 feet/min but this is defined
for a heavy 'brewery horse' and a 'pony power' of 220 pounds at 100 feet/min
might be more appropriate for a mine. (This latter is not too far away from
the 224-280 pounds at 75 feet/min which is quoted by Phil).
The depth of the lift would depend on the rope but a 3/4-inch diameter
manilla rope weighs 16-17 lbs/100ft (best figures I could find) and the
catalogue I used gave a safe working load of 695 lbs and strength of 4,860
lbs. This gives a maximum depth of around 1,500 feet just to raise the rope
alone with no load and 400-450 feet for a load of 150 lbs.
Regards
Richard
----- Original Message -----
From: "NEWMAN, Phil" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Saturday, October 04, 2008 9:22 PM
Subject: Limitations of the Horse whim
Dear List,
Can anyone offer suggestions for some reading on the subject of the maximum
operational depth of the horse whim, preferably from 18th-19th century
accounts? Clearly there are many variables involved, such as the weight and
nature of the load, strength of rope (I beleive hemp was preferred) and
number and size of horses etc. At later mines, where alternatives were
available, there was also the decreased efficiency of using it to hoist
from greater depth; Davies (1894, Machinery for Metalliferous Mines)
considers the machine only capable of lifting 2-2.5cwt at a rate of 75ft per
minute. To those working the apparatus there must have been an approximate
consensus at to a maximum depth, beyond which the horse whim would not
operate safely or efficiently.
Any thoughts or suggestions gratefully received.
Phil
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