Which part is responsible for the service brakes functioning properly?

The slack adjuster plays a crucial role in the proper functioning of the service brakes. It is a component of the air braking system that automatically maintains the correct distance between the brake shoe and the brake drum. When the brake pedal is engaged, the slack adjuster ensures that the brakes apply evenly and effectively by compensating for brake shoe wear. This adjustment is essential for maintaining optimal braking performance and ensuring safety while operating the bus. A well-functioning slack adjuster directly impacts the responsiveness and efficiency of the service brakes, making it vital for safe driving and compliance with regulations.