A square-threaded power screw with single thread is used to raise a load of 13,750 lb. The screw has a mean diameter of 1 in. and four threads per inch. The collar mean diameter is 1.75 in. The coefficient of friction is estimated as 0.1 for both the thread and the collar.
(a) What is the major diameter of the screw?
(b) Estimate the screw torque required to raise the load.
(c) If collar friction is eliminated, what minimum value of thread coefficient of friction is needed to prevent the screw from overhauling?