Final answer:
Leading/trailing drum brakes use return springs to move brake shoes away from the drum, hold-down springs to secure the shoes, and adjuster springs to maintain proper clearance. These brakes operate based on Pascal's principle, with power brakes using a motorized pump for added efficiency.
Step-by-step explanation:
The leading/trailing type drum brake system commonly utilizes a variety of springs designed to perform specific functions. These include: return springs, hold-down springs, and adjuster springs. The return springs are used to pull the brake shoes away from the drum after the braking force is released, ensuring the brakes do not drag. Hold-down springs secure the brake shoes to the backing plate, allowing the shoes to move in a controlled manner while preventing them from pulling away or rattling. Adjuster springs maintain tension within the self-adjusting feature of the brakes, ensuring that the correct shoe clearance is consistently kept as the brake shoes wear down.
This system operates on Pascal's principle, which is applied in hydraulic brakes. When a driver exerts force on the brake pedal, that force is amplified through a lever and subsequently through the hydraulic system, providing even pressure to each wheel cylinder. If the vehicle is equipped with power brakes, a motorized pump assists in exerting most of the work in the system, increasing efficiency and reducing the physical effort required by the driver.