Brakes are pretty much the most important safety device on your car. If you’ve ever partially lost your brakes in the past, you’ll agree that it’s not something you want to experience again. Inspecting your brakes twice a year for wear and damage can protect you and your passengers. Additionally, it will also help save you money by catching any damage before it becomes too costly.
Brake System Components That Can Fail
The master cylinder, the heart of the vehicle’s braking system, holds the brake fluid when it is not being delivered to the brakes through the brake lines. If brake fluid leaks because the master cylinder is worn or brake lines are plugged or broken, the fluid cannot be delivered, and the brake pads will become ruined.
The brake fluid itself can become dirty or contaminated as it draws rust-causing moisture and picks up other debris, or it can break down from excess heat. Clean brake fluid is either clear or slightly yellow, while dirty brake fluid may be brown or even black. Old and dirty brake fluid can damage ABS brake systems internally.
The brake lines connect to the master cylinder through a combination valve, which combines a metering and proportioning valve. It regulates the pressure on the front and rear wheels to make sure both sets of brakes are applied simultaneously. A malfunctioning combination valve may cause the wheels to lock up.
Brake pads and shoes can be made of ceramic, metal or organic materials, while the disc rotors and drums they press against are made of metal. Because the pads and shoes create friction to stop the car, they gradually wear down over time and may wear away completely, letting the metal of the calipers and cylinders they are attached to grind against the rotors and drums and damage them. Some pads have a metal strip attached that sounds a warning whistle when the pad becomes too worn, but this strip sounds only when the car is in motion and the brakes are not applied.
The brake system is actually composed of two kinds of systems---Hydraulics and Friction Materials. Here's what happens within these systems between the time your foot hits the brake pedal and your car stops.
When pressure is applied to the brake pedal, the master cylinder creates hydraulic pressure which pushes brake fluid to the wheel brakes.
Brake Lines and Hoses
Steel brake lines and high pressure rubber hoses are the avenues through which the pressurized brake fluid travels.
Wheel Cylinders and Calipers
These are the hydraulic cylinders that apply pressure to the friction materials, causing your car to stop.
Disc Brake Pads and Drum Brake Shoes
These brake linings are composed of high temperature materials that create the friction that stops your car.
Types of Brakes
Disc brakes consist of a Disc Brake Rotor, which is attached to the wheel, and a Caliper, which holds the Disc Brake Pads. Hydraulic pressure from the Master Cylinder causes the Caliper Piston to clamp the Disc Brake Rotor between the Disc Brake Pads. This creates friction between the pads and rotor, causing your car to slow down or stop.
Drum brakes consist of a Brake Drum attached to the wheel, a Wheel Cylinder, Brake Shoes and Brake Return Springs. Hydraulic pressure from the Master Cylinder causes the Wheel Cylinder to press the Brake Shoes against the Brake Drum. This creates friction between the shoes and drum to slow or stop your car.
The Parking Brake uses Cables to mechanically apply the brakes (usually the rear brake.) This is used to prevent the car from rolling when not being driven.
Anti-Lock Brakes: A System Built For Safety
Computer-controlled anti-lock braking systems (ABS) are a recently developed safety feature. When sudden stops are made, the ABS prevents wheel lock-up. The system is comprised of wheel-speed sensors that monitor wheel rotation, computer-controlled hydraulics that pulse the brakes on and off rapidly, and the on-board computer.