Three leather belts are used to transmit 15 KW from a 200 mm driver pulley running at 900 rpm to a 600 mm pulley. The coefficient of friction between the pulley and belt is 0.3. The distance between shafts is 0.6 m. Assume that the maximum allowable stress for belt material is 1.7 Mpa and the belt mass density is 900 Kg/m3 and for pulley rim is 7200 Kg/m3.