Brakes
Your car’s brakes use a hydraulic system, including the master cylinder, disc brake calipers (disc brakes), wheel cylinders (drum brakes), hydraulic lines and hoses, and combination/proportioning valve. When you push on the brake pedal, the force of your leg generates hydraulic pressure in the master cylinder, which then flows through the hydraulic lines and hoses to the wheel cylinders and calipers. The hydraulic force applies pressure through the wheel cylinders and calipers, forcing the brake shoes against the drums (drum brakes) and the pads against the rotors (disc brakes). Cars and light trucks also have a parking brake, which mechanically activates the rear brakes of the vehicle through a cable. This is also sometimes referred to as the emergency brake. In the early 1960’s, cars began using split hydraulic systems and tandem master cylinders. Essentially, this divided the hydraulic system into two separate systems (front and back), ensuring proper hydraulic and braking on one side of the system, if a leak developed on the other side. In the 1980’s, some carmakers began to use diagonally split systems, which took safety a step further. Instead of splitting the system into front and rear, the system was now hydraulically divided into left-rear/right-front and right-rear/left-front. By maintaining one front and one rear brake, the result is more balanced braking when the system develops a leak. By law, all of today’s cars are required to use some type of hydraulically split system.
Inspecting Your Brakes
Master Cylinder
The master cylinder, heart of the brake system, contains a reservoir for brake fluid. It is located on the firewall and should be checked periodically to ensure the proper fluid level.
Brake Lines
Attached to the master cylinder, steel brake tubing runs to all four wheels. Brake lines should be inspected for rust, which can lead to leaks. If the lines are damaged they should be replaced.
Brake Hoses
Rubber brake hoses run from the brake lines to the brake calipers and wheel cylinders. Constant exposure to road grime, dirt, salt and other elements can cause the rubber to become brittle and crack, leading to brake failure.
Linings and Pads
The pads and brake shoe linings should be checked periodically for uneven or excess wear, glazing, or saturation from brake fluid or grease.
Calipers and Wheel Cylinders
Brakes are activated by brake fluid pressure from the master cylinder pushing a piston located in the caliper or wheel cylinder against the pad or shoe. A leak can cause erratic braking or brake failure.
Bearings and Seals
Wheel bearings should be inspected and lubricated periodically. Worn wheel bearings, which can cause faulty steering as well as erratic braking, should be replaced.
Parking Brake
The parking brake should be adjusted periodically.
ABS sensors and controller
Your ABS system is electronically controlled. This system detects problems of which, some can be self-corrected, while others will shut down the ABS system, which causes the ABS light on the dash to be illuminated. Some problems are recorded in the vehicles computer for the technician's reference when servicing the braking system.
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