Brakes and Traction Control: Description and Operation

STANDARD AND ANTILOCK BRAKING

GENERAL DESCRIPTION
The following description paragraphs describe several of the common components comprising the brake system.

MASTER CYLINDER
This master cylinder is a composite design for use in a diagonally split hydraulic system It incorporates the functions of the standard dual master cylinder plus it has a fluid level sensor switch and integral proportioners.

OPERATION OF DISC BRAKES
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.

OPERATION OF DRUM BRAKES
The anchor plate drum brakes are duo-servo design. In the duo-servo drum brake, the force that the wheel cylinder applies to the primary shoe is multiplied by the primary lining friction to provide a very high force applied to the secondary shoe. Torque from the brake shoes is transferred to the anchor pin and through the backing plate, to the axle flange. Adjustment is automatic when the brakes are applied while the vehicle is backing up.

PROPORTIONER VALVES
The proportioner valve limits outlet pressure to the rear brakes after a predetermined master cylinder pressure has been reached. This is used when less rear apply force is needed to obtain optimum braking.

FLUID LEVEL SENSOR
The master cylinder is equipped with a fluid level sensor located in the side of the master cylinder reservoir. This sensor will activate the red "BRAKE" light if a low fluid condition is detected. Once the fluid level is corrected the "BRAKE" light will go out.