31.6.
Calculation of Equivalent Weight,
We
Now, tractive effort available at the road wheels = Tractive effort to overcome road resistance + Tractive effort for acceleration.
Example 31.3. A supercharged road-racing automobile has an engine capable of giving an output torque of949Nm, this torque being reasonably constant over a speed range from 96 km I hr to 257.5 kmlhr in top gear. The road wheels are of 0.76 m effective diameter and the back axle ratio is 3.3 to 1. When travelling at a steady speed of 160 kmlhr in top gear on a level road the power absorbed is 55.2 kW. The vehicle weights 9344 N. The four road wheels each weighs 397.3 N and have a radius of gyration of 0.255 m. The moment of inertia of the engine and all parts
forward of the differential is 16.5 Nm .
Assuming that the resistance in N caused by windage and road drag varies as the square of speed, determine the time taken for the speed to rise from 96 to 257.5 kg/hr in top gear at full throttle on an up-grade of 1 in 30.
