What can cause brake fade in air brake systems?

Brake fade in air brake systems primarily occurs due to excessive heat build-up from prolonged braking. When brakes are applied continuously, especially in situations like descending long grades or frequent stopping in traffic, the brake components can overheat. This excessive heat can lead to a loss of effectiveness, as the friction materials may become less able to create the necessary grip to slow down or stop the vehicle.

As brake components heat up, the air brake system can also experience changes in the viscosity of brake fluids or the characteristics of the braking materials, leading to diminished braking performance known as brake fade. Understanding this phenomenon is critical for drivers, especially those operating large vehicles, as it emphasizes the importance of allowing brakes to cool and managing braking techniques to prevent overheating.

The other options do not directly contribute to brake fade. For instance, frequent use of emergency brakes may not necessarily result in fade but could point to an over-reliance on that system. Low tire pressure affects traction and handling rather than directly influencing brake effectiveness. Driving on wet surfaces can change how brakes perform but does not lead to the thermal issues associated with brake fade.