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A number of methods and types of equipment have been developed to measure a heavy vehicle's braking forces both for use as an inspection tool and for diagnosis of brake system problems. The systems and procedures evaluated included a vehicle deceleration test, a road transducer plate, roller dynamometers, a flat plate tester, a breakaway torque tester, and an infrared brake temperature measurement system. Evaluations of these devices have been conducted to ensure that the results produced are meaningful. In general, the devices compare very well and, in most cases, were found to be useful in determining the status of a brake system.

A vehicle test procedure for determining the adhesion utilization properties of braking systems has been developed. The procedure requires minima instrumentation and equipment. It was applied to 19 passenger cars over a range of conditions and the effects of factors such as load, center of gravity height, speed, parasitic drag, engine braking, drive configuration (front or rear), brake conditioning, and tire properties on adhesion utilization were determined. The vehicles were also subjected to a series of stopping tests on six different surfaces to evaluate the degree of correlation between predictions from the adhesion utilization curves and actual performance. Frictional properties of the tires from 11 of the vehicles were measured on the surfaces to aid in this correlation study.

Currently there are no adequate standards or regulations that address the performance of aftermarket replacement brake linings to insure that the use of these materials does not degrade vehicle braking performance from the original equipment (OE) design intent level. This paper discusses the results of an evaluation of a large sampling of aftermarket linings available for the rear brake of a specific model passenger car and shows that many of these linings have significantly different performance than the OE material. The paper also shows how this deviation can adversely affect vehicle braking efficiency or the ability of the brake system to utilize available tire/roadway friction without locking wheels and losing control.