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Maggard, James H.

"Rough and Tumble Engineering"

0000 by 33,000=17 1/2 horse
power.
Q. What is a high pressure engine?
A. It is an engine using steam at a high pressure and
exhausting into the open air.
Q. What is a low pressure engine?
A. It is one using steam at a low pressure and exhausting
into a condenser, producing a vacuum, the piston being under
steam pressure on one side and vacuum on the other.
Q. What class of engines are farm engines?
A. They are high pressure.
Q. Why?
A. They are less complicated and less expensive.
Q. What is the most economical pressure to carry on high
pressure engine?
A. From 90 to 110 pounds.
Q. Why is high pressure more economical than low
pressure?
A. Because the loss is greater in low pressure owing to the
atmospheric pressure. With 45 pounds steam the pressure
from the atmosphere is 15 pounds, or 1/3, leaving only 30
pounds of effective power; while with 90 pounds the
atmospheric pressure is only 1-6 of the boiler pressure.
Q. Does it require any more fuel to carry I00 pounds than it
does to carry 60 pounds?
A. It don't require quite as much.


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