In a drum brake system, the rotational action of the brake shoes activates the self-adjuster linkage when the brakes are applied and the vehicle is _________

In a drum brake system, the self-adjuster linkage is designed to maintain the optimal position of the brake shoes relative to the drum. When the brakes are applied and the vehicle is moving in reverse, the rotation of the brake shoes causes the self-adjusting mechanism to engage and adjust the position of the shoes. This adjustment is necessary because when brakes are used while reversing, the shoes tend to wear unevenly, and the self-adjuster compels them to return to the ideal adjustment for effective braking.

During forward movement or when braking occurs in either direction, the self-adjuster typically does not activate in the same way, as its primary function is to react to movements in reverse. This ensures that the brakes continue to function efficiently over time, maintaining a consistent distance between the brake shoes and the drum, which is critical for effective braking performance. Therefore, the correct choice captures the specific condition under which the self-adjuster is engaged in a drum brake system.