Brake horsepower =
2-34. Rated Speed. The rated speed as
indicated in figure 2-65 is the speed at which the
governor in a military vehicle is set. The rated
speed usually is just under the maximum horse-
power speed. Operation over the rated speed,
causes disproportionate engine wear and
excessive fuel consumption.
2-35. Gross and Net Horsepower. The gross
horsepower of an engine is the amount of power
the engine delivers without any accessories or a
propel the automobile after the requirements of all
of the accessories have been deducted from the
Figure 2-63. Conversion of Torque to Work.
2-36. Indicated Horsepower. Indicated horse-
b. Torque can be substituted into the formula
power is the power developed inside of the engine
because it is equal to the length of the arm times
based on the pressure developed in the cylinders.
the scale reading. This yields:
It is always much higher than the brake horse-
power because it does not consider friction or the
6.28 x torque x engine rpm
inertia of the reciprocating masses within the
c. This can be simplified further by dividing
the 33,000 constant by the 6.28 constant. This
provides a formula that shows a direct torque-
Figure 2-65. Torque-Horsepower-Speed
Figure 2-64. Torque Output Versus Speed.