HW 3 Flexible Machine Elements

19.1 Angle alpha = 3.185°; L = 442.2 inches.  Fc = 73.25 lb.  F2 = 224 
lb; F1 = 1776 lb. Hp = 169 HP.

19.14 u = 339 in/sec = 1695 fpm.  Fc = 3.57 lb.  mu = 0.2 / sin(18°) = 
0.647.  F2 = 42.9 lb; F1 = 257.1 lb.  Hp = 11.0 HP.  Therefore, need 3 
belts.

19.18 Shaft B turns at 720 rpm.  Alpha = 6.47°.  From Table 19.5a, find 
the rated HP for a 3" pulley as 0.06 HP at 500 rpm and 0.12 HP at 1000 
rpm.  Linearly interpolating, Hp = 0.06 + (720-500) * 
(0.12-0.06)/(1000-500) = 0.0864 HP, or 64.45 Watts.  Going to Table 
19.4 with a loss of contact of 2 Alpha = 13°, estimate the correction 
factor as 0.97, so rated power is really 62.5 W.  The input torque to 
shaft A will be 62.5 / (1800 rpm * 2pi rad/rev * 1min/60 sec) = 0.332 
Nm . The output torque on shaft C is 0.332 * (50/20) * (200/76) = 2.18 
Nm.  Finally, the belt length is 1.54 m.  THIS IS DIFFERENT FROM 
HAMROCK's GIVEN ANSWER.