Question

A cross bar of a planer weighing 9 kN is raised and lowered by means of two square threaded screws
of 40 mm outside diameter and 6 mm pitch. The screw is made of steel and nut of phosphor bronze
having 42 mm height. A steel collar bearing with 30 mm mean radius takes the axial thrust. The
coefficient of friction at the threads and at the collar may be assumed as 0.14 and 0.10 respectively.
Find the force required at a radius of 120 mm of a handwheel to raise and lower the load. Find also the
shear stress in the nut material and the bearing pressure on the threads.

Answer 1