Air Brake Systems are used on heavy vehicles. An air brake system actually covers three separate systems including service brake, parking brake and emergency brake. Air brake system works through converting air pressure energy into mechanical force. Various components of air brake system work together to reach this mechanical energy.
How it works
Air brake systems use air pressure to apply the brakes. When you step on the pedal, the compressed air moves through lines to the brake chamber. The air pressure inside the brake chamber moves up the diaphragm causing the piston (pushrod) to move which in turn pushes the slack adjuster. The slack adjuster turns the camshaft. The camshaft turns the s-cam, which in turn pushes the brake shoes apart to the brake drum. The friction created because of the contact of brake shoes and brake drum, slows down the wheels and stops the vehicle. (picture 1)
Here are a number of parts engaged in air brake system
The air compressor pumps the air into the air tanks to maintain the proper level of air pressure to power the air brake system.
The air tanks are used to store the compressed air to allow the brakes to work even if the compressor stops working.
Air dryer is installed between the air compressor and the air tank. It removes moisture, oil and contaminants from the air which is leading its way through the lines to the air tank.
AIR BRAKE CHAMBER
Brake chambers convert the energy of compressed air of compressor into mechanical force. An air brake chamber contains diaphragm, spring and pushrod. When the brake pedal is applied, compressed air fills the brake chamber and the diaphragm moves pushing the pushrod out. (picture 2)
Slack adjuster is connected to the pushrod through the clevis. It regulates the distance between the brake shoes and the brake drum. When the pushrod is pushed out, the slack adjuster turns the s-cam which in turn pushes the brake shoes apart (picture2).