Calculate the required width b for the key of Problem if the link transmits a 60-lb force...

Calculate the required width b for the key of Problem if the link transmits a 60-lb force and the length of the key is . The allowable shear stress for the key is 4000 psi.

Problem

A control arm is keyed to a l-in.-diameter shaft and a link transmits a 40-lb force to the end of the arm, as shown. The key is . by . and has a length of . Find the shear stress in the key.