Most manufacturers of composite friction materials do not possess adequate facilities to test their products dynamically. A practical solution is to simulate the braking process in the laboratory mechanically by means of a disc brake dynamometer. The authors describe a control-system design for the dynamometer. The function of the control system is to maintain a constant braking torque for the testing of brake blocks. A constant braking torque is necessary to create a realistic simulation of the true situation. A driver of a motor car continually varies the force exerted on the brake pedal while braking in order to maintain a constant deceleration of his vehicle. In this case, the driver is the controller who subconsciously adjusts the force on the brake pedal to compensate for the natural variations in the value of the friction coefficient of the brake block material. Therefore, by controlling the dynamometer's breaking torque, it is possible to determine the dynamic change in the friction coefficient of the material under test. After describing the control system philosophy and the design criteria, the authors discuss the pressure controller in detail.
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