What is the function of the wheel cylinder in a brake system?

The function of the wheel cylinder in a brake system is to expand the brake shoes against the brake drum. When the driver applies the brakes, hydraulic fluid is forced into the wheel cylinder, which has two pistons inside it. As hydraulic pressure builds up, these pistons move outward, pushing the brake shoes against the inner surface of the brake drum. This contact generates the friction needed to slow down or stop the vehicle.

This functionality is critical because it directly contributes to the effectiveness of the braking system, ensuring that the vehicle can be safely and reliably brought to a stop. In systems utilizing drum brakes, the wheel cylinder plays an essential role in translating hydraulic pressure into linear force that acts on the brake shoes.