What holds the brake shoes away from the drum until brakes are applied?

The return spring is essential in a drum brake system as it plays a crucial role in maintaining the position of the brake shoes. When the brakes are not applied, the return spring pulls the brake shoes away from the drum, ensuring that they do not contact the drum when the vehicle is in motion. This helps prevent unnecessary friction, heat generation, and wear on the brake components, contributing to the overall efficiency and longevity of the braking system.

When the driver applies the brakes, hydraulic pressure from the wheel cylinder forces the brake shoes outward against the drum, effectively creating the friction necessary to slow down or stop the vehicle. Once the brakes are released, the return spring quickly retracts the brake shoes back into their resting position, ensuring that they are ready for the next braking event.

Understanding the function of the return spring helps clarify its importance in the braking system's operation, ensuring safety and effective vehicle control.