A self-propelled truck of total mass 25 tonnes and wheel diameter 750 mm runs on a track for which the resistance is 180 N per tonne. The engine develops 60 kW at its maximum speed of 2400 r.p.m. and drives the axle through a gear box. Determine : 1. the time to reach full speed from rest on the level if the gear reduction ratio is 10 to 1. Assume the engine torque to be constant and a gearing efficiency of 94 per cent, and 2. the gear ratio required to give an acceleration of 0.15 m/s² on an up gradient of 1 in 70 assuming a gearing efficiency of 90 per cent. [Ans. 157 s; 20.5]

A self-propelled truck of total mass 25 tonnes and wheel diameter 750 mm runs on a track for which the resistance is 180 N per tonne. The engine develops 60 kW at its maximum speed of 2400 r.p.m. and drives the axle through a gear box. Determine : 1. the time to reach full speed from rest on the level if the gear reduction ratio is 10 to 1. Assume the engine torque to be constant and a gearing efficiency of 94 per cent, and 2. the gear ratio required to give an acceleration of 0.15 m/s² on an up gradient of 1 in 70 assuming a gearing efficiency of 90 per cent. [Ans. 157 s; 20.5]