Brake Fade
Posted: Mon Nov 30, 2009 9:41 pm
This chart shows what happens when brake linings get hot.The friction provided by the linings decreases. The linings no longer offer the same resistance to the rotation of the drums, they get slick.
Organic brake linings are essentially composed of glue and a strengthening material, this used to be asbestos but today differant materials are used because asbestos is a health hazard. When the linings get hot, the glue softens and starts to melt and the linings get slick.
The phenomenon of brake fade is not just a matter of lining fade however. As the drum heats up it expands and moves away from the shoes. With an air brake system the stroke of the pushrod and thus the distance that the shoes can be moved out into the drum is limited. If the brakes are improperly adjusted, when they get hot it is possible to run out of stroke before the shoes make good contact with the drums.
- fade.JPG (27.86 KiB) Viewed 4489 times
The phenomenon of brake fade is not just a matter of lining fade however. As the drum heats up it expands and moves away from the shoes. With an air brake system the stroke of the pushrod and thus the distance that the shoes can be moved out into the drum is limited. If the brakes are improperly adjusted, when they get hot it is possible to run out of stroke before the shoes make good contact with the drums.