1.1 The Parts of an Air Brake System

Air brakes use compressed air to apply the brakes. The key parts:

• Air compressor — pumps air into storage tanks; driven by the engine.
• Governor — controls when the compressor pumps, cutting out around its set maximum pressure and cutting back in as pressure drops.
• Air storage tanks — hold enough air to stop safely even if the compressor fails.
• Brake chambers and slack adjusters — convert air pressure into mechanical force at each wheel.

Drain water from air tanks daily unless the vehicle has automatic drains — water and oil can fail the brakes.