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Air brake equipped vehicles

 

How air supplies braking force

Compressed air is air that has been forced into a small space. Compressed air has a higher temperature and pressure than decompressed air. If channelled or directed properly, compressed air will cause or exert a great force or pressure. This directed force makes an air brake system work.

Force can be generated by applying pressurized air to the diaphram of a brake chamber. The amount of force generated by the brake chamber depends upon:

  • Brake chamber diaphram area.
  • The air pressure applied to the diaphram.

The effect of increasing brake application pressure on a brake chamber having a 24 square inch diaphram as the application pressure is increased from 5 PSI (35 kPa) to 100 PSI, the force generated by the chamber increases from 120 lb (529 N) to 2400 lb (100672 N). Increased brake chamber force causes a harder application of the vehicle's brakes.

Braking force is further multiplied through the slack adjuster. The slack adjuster acts like a lever to multiply brake chamber force to the brake shaft. A Brake chamber force of 1000 lb (4459 N) is increase to 6000 lb in. (67885 N cm) through a six inch slack adjuster.


 


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