An electric motor purchased by your employer surprisingly arrived without a keyway in the shaft. The motor has power rating of 7.5kW & 1,800rpm & has a shaft of Ø17mm. It will be used to drive a centrifugal pump using cast iron sheave. Design the square key to be used in the assembly based on maximum bearing & shearing stresses of 580MPA & 370MPA, respectively, and factor of safety of 5.

A rigid coupling with 30 inches of bolt circle diameter transmits a torque of 18,000 lb-in. The coupling material has a yield strength of 90,000 psi.  The coupling is fastened by six bolts.  Assume design factor of  N=3 Calculate the diameter of each bolt.