An engine produces 222 hp at 3628 rpm If the tractive force

An engine produces 222 hp at 3628 rpm. If the tractive force the vehicle produces is 400 lbf, calculate the torque the engine produces, in ft-lbf, when vehicle is at constant speed.

Solution

1 horse power (hp) = 33000 ft-lbf/min.

also the expression for power is given by , P= 2*pi*N*T

where P is power in ft-lbf/min, N is speed in rpm and Tis torque in ft-lbf

therefor substituting the given data, we have

222*33000=2*3.14*3628*T , from this T= (222*33000)/(2*3.14*3628)=321.25 ft-lbf

tractive force of the vehicle is superfluous data

or

if the engine develops variable tractive force, then the crank diameter is requied to compute the torque