High Performance Drum Brake Assembly for Automotive Braking Applications 2003-01-3306
Different types and sizes of hydraulic drum brake designs viz., two leading sliding shoe, leading-trailing sliding shoe, floating abutment sliding shoe are in existence today catering to the increasing vehicle weight applications. On an end requirement basis and by the cost benefit ratio, either of the above designs with appropriate brake size (diameter) is selected for a given vehicle application. Increasing wheel cylinder size and brake size proportional to the requirement also needs bigger actuation systems and poses packaging constraints within the available wheel sizes.
A High performance drum brake assembly is developed from the basic hydraulic, leading-trailing, sliding shoe brake design, which can substantially increase the brake output torque for a given hydraulic input pressure or reduce the required pipeline pressure to realize the current rated torque. The brake assembly has a new lever pivoted on the leading shoe web with one end resting on the wheel cylinder piston and the other end on the strut assembly. This lever touches the piston instead of the leading shoe web and receives input from the pressurized wheel cylinder.
Upon actuating the wheel cylinder assembly, the lever rotates about its pivot point and pushes the strut assembly. The trailing shoe now receives two inputs viz., one from the wheel cylinder and the other from the strut assembly, which is mechanically actuated by the new lever. The reaction from the trailing shoe is passed via the strut assembly as an input to the leading shoe. The wheel cylinder input and the strut reaction force together acting on the pivot, results in almost twice the force acting on the leading shoe. Prototype samples incorporating the new design is developed and validated on inertia dynamometer.