What is the purpose of a relief valve in a brake system?

The purpose of a relief valve in a brake system is primarily to compensate for thermal expansion. In braking systems, particularly hydraulic systems, the fluid can heat up during the operation due to friction, which causes thermal expansion. If the pressure of the fluid increases too much due to this heating, it can lead to a system failure. The relief valve allows for the excess pressure to be released, maintaining the integrity of the brake system and preventing potential damage. By allowing the fluid to expand in a controlled manner, the relief valve helps ensure consistent performance and reliability of the braking system under varying temperatures and load conditions.

While the other options address important aspects of brake systems, they do not accurately represent the core function of the relief valve. The relief valve's main role is to manage pressure related to thermal expansion specifically, rather than directly addressing system failures, enhancing braking speed, or preventing fluid contamination.