A compressor requires 120 kW to run at 240 rpm from an electric motor of speed 750 rpm, by means of a V-belt drive. The diameter of the compressor shaft pulley should not be more than 1000 mm while the centre distance between the shafts is 2000 mm. The belt speed should not exceed 25 m/sec.
Determine the number of V – belts required to transmit the power, if each belt has a cross sectional area of 375 mm2, density 1000 kg/m3 and an allowable tensile stress of 2.5 MPa. The pulley groove angle is 400 and coefficient of friction between the belt and pulley sides is 0.25.