Tractor Trailer Brakes

Hot brake lining reduces the friction provided by them resulting in decreased braking. The hot linings do not offer the same resistance to the rotation of the drums. Organic brake linings are composed of glue and a strengthening material, this. When the linings get hot, the glue softens and starts to melt and the linings get slick.

When the break drum heats up it expands and moves away from the shoes. In an air brake system the stroke of the pushrod is limited. The stroke is the distance that the shoes can be moved out into the drum. If the brakes are not adjusted carefully, the stroke could fall short when they get hot. Thus the shoes will fail making good contact with the drums. Air brake system is used in the heavy trucks. Brakes use friction to stop the vehicle (thus kinetic energy gets converted to heat). When an 80,000 lbs truck running at the speed of 60 mph is brought to a halt using brakes, the drum temperature raises to about 600 degrees F. This is very close to the safe operating temperature for the drums. Improper brakes do not equally distribute the load; this can raise the drum temperature to 800-1000 degrees F. This is not a safe operating temperature for the brake system.