3. A shaft transmitting 150 kW is to be connected to a coaxial shaft through cast iron flange coupling. The shaft runs at 120 rpm. The key and shaft are to be made of same material for which permissible shearing stress is 60 N/mm? and compressive strength is 120 N/mm?. The steel bolts may be subjected to maximum shearing stress of 26 N/mm?. Design protected type flange coupling.(30P)