Prony Brake

This was a device designed by Gaspard de Prony to measure horsepower in 1821. This is the KowCo variant, made mostly from 80/20 extrusions. After attaching the engine to the flat belt pulley behind the force display the hand crank wheel is turned which clamps the brake pads onto the wheel which creates the breaking action. This actuates the force scale. The rotation of the shaft drives the flyball which indicates the RPM on the scale. Continuing to clamp down on the brake will eventually slow down the engine. At this time the force value is used to calculate the horsepower. In this case use:

HP = (Arm Length * RPM * Force)/5252