Given the diameter of a pulley and its number of revolutions per minute,
to find the circumferential velocity of the pulley or the speed of
ropes, belts, etc., driven thereby.
Set diameter of pulley in inches on C to 3·82 on D, and over revolutions
per minute on D read speed in feet per minute on C.
EX.—Find the speed of a belt driven by a pulley 53 in. in diameter and
running at 180 revolutions per minute.
Set 53 on C to 3·82 on D, and over 180 on D read 2500 ft. per minute
on C.
EX.—Find the speed of the pitch line of a spur wheel 3 ft. 6 in. in
diameter running at 60 revolutions per minute.
Set 42 in. on C to 3·82 on D, and over 60 on D read 660 ft. per minute
on C.
Given diameter and number of revolutions per minute of a driving pulley,
and the diameter of the driven pulley, to find the number of revolutions
of the latter.
Invert the slide and set diameter of driving pulley on Ɔ to given number
of its revolutions on D; then opposite diameter of any driven pulley on
Ɔ read its number of revolutions on D.
EX.—Diameter of driving pulley 10 ft.; revolutions per minute 55;
diameter of driven pulley 2 ft. 9 in. Find number of revolutions per
minute of latter.
Set 10 on Ɔ to 55 on D, and opposite 2·75 on Ɔ read 200 revolutions on
D.