1. A worm gear speed reducer has a right-hand triplethreaded worm made of hardened steel, a normal pressure angle of 20, an axial pitch of 0.25 inch, and a center distance of 2.375 inches. The gear is made of forged bronze. The speed reduction from input to output is 15:1. If the worm is driven by a -hp, 1200-rpm electric motor operating steadily at full rated power, determine the following, assuming the coefficient of friction between worm and gear to be 0.09: 1 2,
a. Number of teeth in the gear.
b. Pitch diameter of the gear.
c. Lead angle of the worm.
d. Relative sliding velocity between worm and gear .
e. Tangential force on the worm.
f. Tangential force on the gear .
g. An acceptable range for face width that should allow a nominal operating life of 25,000 hours. (Hint: See footnote 130 relating to equation (15-115).)
