Brake System Basics

Your vehicle’s brake system is made up of two types of systems: hydraulics and friction materials.

The hydraulic system consists of the master cylinder, the brake lines, hoses, wheel cylinders and calipers. The friction materials are either pads (with disc brakes) or shoes (with drum brakes).

How Your Brakes Work

When pressure is applied to the brake pedal, the master cylinder creates hydraulic pressure which pushes brake fluid to the wheel brakes. That pressurized brake fluid travels through steel brake lines and high pressure rubber hoses. The wheel cylinders and calipers apply pressure to the friction materials - either the pads or shoes, depending on whether your vehicle has disc brakes or drum brakes - causing your vehicle to stop.

The diagram on this page provides a cut-away view of a vehicle's brake system.

Common Signs Your Brakes May Need Repair or Replacing

  • Reduced response. As a driver, there is no scarier sensation than applying the brakes and feeling the pedal touch the floor with no resistance. The cause of this problem is usually a leak of some kind; most likely a fluid leak or air leak in the brake hose. Should your brakes fail, slow the vehicle as quickly as possible by applying the emergency brake. Or you can drive carefully into the grass, gravel or rumble strips on the shoulder of the road. Call for assistance right away and do not drive your vehicle until the problem has been assessed by a qualified brake services technician.
  • Vibration. Warped rotors often cause a vibrating or pulsating sensation when the brakes are applied.
  • Pulling. In most cases, when your vehicle pulls to one side of the road it is a problem that can be resolved with a wheel alignment. However, in some cases, the brake linings wear unevenly or your brake fluid has been contaminated with a foreign substance. If you notice pulling, make sure your vehicle is thoroughly examined for brake issues. 
  • Noise. If you hear a loud, metallic sound when you apply the brakes, it could mean that your brake pads need to be turned or that they’ve worn down completely and need to be replaced.