494
MOLESWORTH’S POCKET-BOOK
Steam-engine Governor.
L = Vertical height from plane of revolution to
point of suspension in inches.
R = Number of revolutions per minute.
_ 187-5 T /187-5V
K = —• • Li — I —7T— I •
Weight of Rim of Fly-wheel.
D = Mean diameter of rim in feet.
P = Total average pressure on piston in lbs.
S = Stroke in feet.
P S
W = Weight of rim in cwts. = •
a .. . „ . . . . 11'42W
Sectional area of rim m inches ———■ •
D = Stroke X 31 or 4 generally.
For engines with high expansion or with irre-
gular loads multiply W as found above by 1*5.
Some engineers make W = 100 lbs. for each indi-
cated horse-power.
In corn mills the velocity of the periphery of the
fly-wheel must exceed the velocity of the peri-
phery of the stones, to prevent back lash.
Weight of Fly-wheel Kim. (Another Rule.)
P = Pressure on piston in tons.
S = Stroke of engine in feet.
D — Mean diameter of rim in feet.
N = Number of revolutions per minute.
C = Constant varying from 3 to 4 in ordinary
engines, and rising to 6 when great
uniformity is required.
W = Weight of fly-wheel rim in tons.
-6366PSC/N\
W —------------I — I •
D \60/
Maximum safe velocity for cast iron = 80 feet
per second.