What is used to stop a vehicle in a drum brake system?

In a drum brake system, shoes are the components that actually make contact with the inside surface of the drum to create friction, which slows down or stops the vehicle. When the brake pedal is pressed, hydraulic pressure forces the brake shoes outward against the drum. The friction generated between the shoes and drum is what brings the vehicle to a stop.

While pistons play a role in applying pressure to the shoes, they are not the components that make direct contact with the braking surface. Calipers are found in disc brake systems, not drum brakes, and while fluid is necessary for the hydraulic system to operate, the shoes are specifically responsible for the actual stopping of the vehicle. Therefore, the correct answer highlights the function of the shoes in the drum brake system.