Friction is the mechanism used to convert kinetic energy into heat in a brake system. Friction is the resistance of motion between two objects that are in contact with each other. If friction at the friction surface is reduced to an unacceptable level, the ability to convert kinetic energy into heat will also be reduced. When a reduction in the friction at the friction surface occurs as the result of heat it is called Friction Fade. When friction fade occurs in a hydraulic brake system, the pedal will still feel hard to the driver, but he will notice a difference in the braking response of the vehicle. For air-braked vehicles, when friction fade occurs, the driver may report the pedal going to the floor.
Brake friction is affected by the temperature at the friction surface. The heat/friction profile is different from lining to lining and can be linear or curvilinear. Either brake lining friction can gradually decline (linear) as heat builds in the brake, or alternatively, lining friction can build-up until it reaches a peak, then quickly begins to decrease (curvilinear). Generally a linear heat friction relationship is more desirable because its fade is gradual and predictable.
Brake friction is affected by the temperature at the friction surface. The heat/friction profile is different from lining to lining and can be linear or curvilinear. Either brake lining friction can gradually decline (linear) as heat builds in the brake, or alternatively, lining friction can build-up until it reaches a peak, then quickly begins to decrease (curvilinear). Generally a linear heat friction relationship is more desirable because its fade is gradual and predictable.