A new test vehicle has been developed at HSRI to measure time histories of brake torque over-the-road at nearly constant velocity. Four truck air brakes where used in an initial test program which included tests to assess the influence of brake pressure, rubbing speed, and drum temperature on brake torque. Special tests were included to measure hysteric effects. The results from the program were used to develop a semi-empirical formula to simulate torque as a function of time during a spin-down process.
Abstract