Brakes (Undercar Systems) Practice Test 2025 - Free Practice Questions and Study Guide

The correct answer is the secondary shoe because during the braking process, particularly in drum brake systems, the adjusting screw plays a key role in maintaining the proper positioning of the brake shoes relative to the brake drum. When the brakes are applied, the primary shoe is pushed against the drum, and the secondary shoe is affected by the force generated.

The adjusting screw, which is part of the brake assembly, is responsible for automatically compensating for wear of the brake shoes. When the vehicle brakes, the momentum causes the secondary shoe to be forced outward, moving it closer to the drum. This action is enabled and fine-tuned by the adjusting screw, ensuring that the secondary shoe is effectively energized to maintain contact with the drum during forward braking. By keeping the secondary shoe properly positioned, the overall effectiveness of the braking system is enhanced.

This function of the adjusting screw is crucial, as it allows the secondary shoe to provide a significant portion of the braking force in drum brake applications. The role of the other components in the choices, while important to the overall braking system, does not involve being directly energized by the adjusting screw in the context of forward braking.