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MANILA ROPE TRANSMISSION. 345
leaving the pulley and will wear out in a short time if the
pulley is left as it comes from the lathe tool. Sand and blow-
holes must also be avoided. The angle of groove is usually 45°,
and the rope is made to wedge into it, as shown in Fig. 3.
The usual shape of grooves for guide pulleys is shown in
Fig. 4.
FIG. 3.
N
[«-a-i f-a\»j j-ar-L{
Sjj
s-. u + + ^
X
3£ 1! II II II li
!-H
Q Vi * s °0
</ins. a ins. c ins. e ins. /ins. ^ins.
1 3 1 1 1
1
2 4 4 4 4
5
8 h A i
5
T6 li
3
4 ItV t T%
3
8 H
1 if 1
2"
3
8
1
2
2
1* 111 5 7 5 91
8 1(5 8 - -7
1* .2 3
4 2
3
4 3
lf 2 s
Z T6
7 9
H
8 16 8
2 25
-8 1 5 1 4
Fig. 4.
The best speed for ropes is from 1500 to 5000 feet per
minute. When the velocity of the rope exceeds 0000 feet per
minute the loss, due to the centrifugal force, is so great that it
will hardly pay to increase the velocity. The diameter of the
pulleys ought to be at least 50 times the diameter of the rope.
Transmission Capacity of Manila Rope.
A manila rope two inches in diameter, running over
properly-shaped pulleys at a speed of 5000 feet per minute, is
capable of transmitting 50 horse-power. The transmitting
capacity of the rope is in proportion to the square of its
diameter, and the power transmitted by the rope is in propor-
tion to its velocity; therefore, a one-inch rope, running 5000 feet
per minute, will transmit 12 ]/
2 horse-power, and the formula
will be
:
Horse-power = <*’ X * X 12.5
5000
which reduces to
Horse-power = 0.0025 X d 2
X v
d = Diameter of rope in inches.
v = Velocity of rope in feet per minute.
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