Denignuut make a neat dimensioned sketch of a muff coupling which is used to connect twislesl shaila rummuting $50$ kW at $350$ r$.$p$.$m$.$ The material for the shafts and key is plain carbon need for Which allowable siwar and crushing stresses may be taken as $40$ MPa and $80$ MPa respectively. The material for the muff la cast iron for which the allowable shear stress may be assumed as $15$ MP