A 900-rpm electrical motor shaft drives the input shaft of an air compressor that operates between 15 to 20 minutes every hour. The compressor is rated at 5.7 and runs at an angular velocity of 62.8 / under smooth operating conditions. Select a suitable pair of 20 pressure angle spur gears to transmit the required power to the compressor. Also calculate the centre distance between shafts. Hint: 1Rev = 2 Radian