7. Two shafts made of plain carbon steel are connected by a rigid protective type flange coupling. The shafts are running at 500 r.p.m. and transmit 25 kW power. Design the coupling completely for over- load capacity 25 per cent in excess of mean transmitted torque capacity. Assume the following permissible stresses for the coupling components: Shaft-Permissible tensile stress = 60 MPa; Permissible shear stress = 35 MPa Keys Rectangular formed end sunk key having permissible compressive strength = 60 MPa Bolts-Six numbers made of steel having permissible shear stress = 28 MPa Flanges-Cast iron having permissible shear stress = 12 MPa Draw two views of the coupling you have designed. [Ans. d=45 mm; D = 90 mm]