What can excessive use of the service brakes lead to?

Answer: C — Expansion of the brake drums

Excessive use of the service brakes can lead to the expansion of the brake drums. When brakes are applied frequently and for extended periods, the friction generated creates a significant amount of heat. This heat can cause the brake drums to expand. If the temperature rises too high, it might also lead to brake fade, where the brakes lose their effectiveness due to the changes in the system caused by heat. Understanding this process is critical for safe vehicle operation, as it highlights the importance of monitoring brake usage, especially in heavy traffic or hilly areas. The expansion of the brake drums can potentially compromise braking performance, leading to unsafe driving conditions. Proper maintenance and awareness of how braking systems work are essential to avoid such issues.