Which part of the drum brake assembly is filled with brake fluid?

In a drum brake assembly, the component that is filled with brake fluid is the wheel cylinder. The wheel cylinder operates by using hydraulic pressure to expand the brake shoes against the inner surface of the brake drum, thereby creating friction to slow down or stop the vehicle. When the driver presses the brake pedal, brake fluid from the master cylinder is sent to the wheel cylinder, which forces the pistons within the cylinder to move outward. This movement activates the brake shoes, pressing them against the drum.

Understanding the function of the wheel cylinder is essential to grasp how hydraulic systems in drum brakes work. It is specifically designed to convert hydraulic pressure from the brake fluid into mechanical force, which is critical for effective braking performance.

Other components mentioned do not fill with brake fluid. The master cylinder is responsible for generating hydraulic pressure, while the brake rotor is part of disc brake systems and not applicable here. The caliper pertains to disc brakes as well, where it houses the brake pads and uses fluid pressure to clamp down on the rotor.