How A Tractor Trailer Brake System Functions
The compressor is a device situated on the engine that takes in and compresses air to be used in the pneumatic system. This air is then held in the air reservoir.
When the brake is applied, the air then passes through the triple-valve system and air lines to the brake cylinder. In the cylinder, the pressure forces the spring to compress and the brake mechanics to engage.
This system is backward in terms of how hydraulic systems work, in that if a hydraulic system were to leak and lose pressure, the brakes would be unable to engage. However, if the pressure drops too low in an air brake system, the emergency brakes come on, and the brake won’t disengage.
While this is much safer in the event of an emergency, the system is bulkier and more cumbersome than a hydraulic system. Hence, regular cars and smaller vehicles use hydraulic brakes. Additionally, as air brakes are often used on trucks carrying heavy loads, many drivers will employ engine braking to reduce wear on the brake pads and maintain better control over the vehicle.
