Patent GB-1284498-A (GB)
Title: Recorder and computer type brake analyzer and method
IPC: G01L5/22
Filed: 1970-03-25
Abstract: 1284498 Testing vehicle brakes CLAYTON MFG CO 25 March 1970 [27 March 1969] 14405/70 Headings G1N and G1W An apparatus for testing vehicle brakes comprises means for rotating a pair of wheels, means for measuring the brake effort of each wheel and means for measuring the degree of application of the brake actuator. In Fig.1, the wheels are driven by electric motors 21 and 22 via rollers 15 and 17, and the brake effort is measured by pneumatic weighing units 38 and 39, Fig.2 (not shown) which produce an output pressure on lines 48 and 49 respectively, proportional to the reaction torque on the housings of the motors 22 and 21. The two output pressures are indicated on gauge 78 and recorded on two tracks of sheet S, while the difference between the two pressures is indicated at 79 and recorded on a third track. A device 52 mounted on the brake pedal produces a pressure signal proportional to the force applied to the brake pedal which pressure is indicated at 77 and recorded on a fourth track of sheet S. Alternatively a pressure porportional to the degree of brake application may be derived from the brake hydraulic circuit Fig.3 (not shown). In Fig.4, the output pressures are converted into electrical signals by transducers 111, 112 and 124 which may comprise rheostats, and the electric signals are passed to recorder 110 and a computer 140 which signals the condition of the brakes by comparison with standard valves. In Fig.5 (not shown) the pneumatic weighing units are omitted and electrical signals proportional to the reaction torques of the motors are derived from rheostat units 38a and 39a, while a brake pressure signal is produced by transducer 175 actuated either via hydraulic pressure or directly from the brake pedal. In Fig.5A (not shown) the brake effort is measured by measuring the power passed to the motors via pick-up coils 253-256. In Fig.5B (not shown) the brake effort is measured by measuring the speed drop of the motors using tachometer generators. In Fig.6 a unit for testing two pairs of wheels shown and signals representing the brake efforts of the individual wheels, the difference between the brake efforts of the two front and two back wheels respectively and the difference between the brake efforts of the front wheels and back wheels are recorded. Instead of recording the brake efforts of each of a pair of wheels, the brake effort of one of the wheels and the difference in the brake efforts may be recorded. The recorded results may be compared with a suitable illuminated grid or mask Fig.7 (not shown) to indicate the condition of the brakes. Hydraulic or pneumatic motors or internal combustion engines may be used in place of the electric drive motors. A preferred method of testing brakes comprises recording the brake efforts while carrying out the following sequence of brake application: rotate the wheels to determine the rolling resistance, gradually apply moderate pressure to the brakes and maintain the pressure for a time, gradually release the brakes, rapidly apply a moderate pressure to the brakes and rapidly release them, gradually apply a high pressure to the brakes, maintain the pressure for several seconds and release the brakes.