Disc Brake System: Description and Operation

Upon application of the brakes, pressure is exerted equally against the bottom of the caliper piston and also against the bottom of the caliper cylinder bore. The pressure applied to the caliper piston is transmitted to the inner shoe and lining, forcing the lining against the inner rotor surface. The pressure applied to the bottom of the cylinder bore forces the caliper to slide or move on the mounting bolts inward toward the center of the vehicle. Since the caliper is one piece, this movement causes the outer section of the caliper to apply pressure against the back of the outer shoe and lining assembly, forcing the lining against the outer rotor surface. As pressure increases, the shoe and lining assemblies are pressed against the rotor surfaces with increased force, bringing the vehicle to a stop. When the brake pedal is released, line pressure is released and the seal and seal groove cause the piston to be slightly retracted, resulting in less drag on the rotor by both shoe and lining assemblies. Lining wear is automatically compensated for by the sliding action of the caliper.