Abstract: The invention is a system for measuring the braking force of a vehicle, whereby a wheel of a vehicle is supported by a pair of spaced rollers having axes that are generally parallel with the axis of the wheel. At least one of the rollers is driven at a constant speed by a circulatory hydraulic fluid system which includes a hydraulic motor. The energy expended by the hydraulic motor in maintaining a constant speed of the roller(s) is a function of the pressure of the hydraulic fluid on the inlet side of the hydraulic motor. This hydraulic fluid pressure is measured and recorded both before and after application of the vehicle's brakes.