Truck Disc Brakes-Practice Makes Perfect

A hydraulic front disc brake for heavy trucks was introduced in 1975 to meet federal motor vehicle safety standard 121 (FMVSS 121). This paper addresses the design parameters utilized in the development of the energy absorbing medium, namely, friction material and rotor surface.

Friction material characteristics in terms of temperature, speed and pressure sensitivity are studied. Truck geometry is studied along with friction materials to evaluate the combined effects on stopping distances, resulting in a quick reference method for predicting the 60 MPH stopping distance of any straight truck configuration.

Rotor thermal stress and interface durability characteristics are also discussed.