A double acme thread screw, 4 in. in diameter, is used to exert a force of 24,000 lb. in a shaft-straightening press. Th

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A double acme thread screw, 4 in. in diameter, is used to exert
a force
of 24,000 lb. in a shaft-straightening press. The assembly is
lubricated, thus
giving a coefficient of friction of 0.05 at the threads and 0.10 at
the collar. The
system is supported by a collar with 3 in. mean radius. For the
problem,
determine:
(a) Lead angle, degrees
(b) Determine the total torque, ft-lbf, for raising the load
(c) Determine the total torque, ft-lbf, for lowering the load
(d) Determine the efficiency for raising the load