A load of 10,000 lb is carried by a 2.5-in. single-thread Acme screw of standard proportions. The pitch is 1/3 in. and the pitch diameter is 2 1/3 in. The OD of the collar is equal to 4 in., and the ID is equal to 1.25 in.
(a) For, μ1 = μ2 = 0.15, find the horsepower required to rotate the screw if the weight is to be raised at the rate of 10 fpm.
(b) What is the efficiency when the friction of both the screw and collar is considered? What is the efficiency if the collar friction is made negligible by use of an antifriction bearing?
(c) Find the horsepower required to lower the load at the same rale.
(d) What horsepower will raise the load at the given rale when the collar is supported on a ball thrust bearing for which μ2 = 0.003? Let the collar radius be the same as for the plain bearing. What will the efficiency now be?
(e) Find the pitch of the thread at which overhauling will take place, using a ball thrust bearing. The pitch diameter is the same.
(f) Suppose the screw is made with pilch just sufficient to overhaul. What will be the efficiency for the screw alone?
(g) If the minimum major diameter of the screw is 2.483 in. and the maximum minor diameter of the nut is 2.183 in., find the minimum length of the nut that must be engaged if the compressive stress on the projected area of the threads is equal to 600 psi.
(h) If the minimum minor diameter of the screw is 2.130 in., find the average value of the compressive stress at the root of the thread. What is the bearing pressure for the collar?
We need at least 10 more requests to produce the solution.
0 / 10 have requested this problem solution
The more requests, the faster the answer.