How Does the Brake Pump Work?
2 Answers
The working principle of the brake pump is that when the brake is pressed, the piston inside the master brake cylinder is subjected to the thrust from the brake pedal, which then acts through the push rod. Below are the relevant introductions: 1. Hydraulic Brake Master Cylinder: The hydraulic brake master cylinder transmits brake fluid through tubing to the pistons of each brake slave cylinder, causing the brake pads to create friction with the inner surface of the brake drum, thereby achieving the braking effect. 2. Pneumatic Brake Master Cylinder: The working principle of the pneumatic brake master cylinder is to act as a valve. The difference is that after braking, the hydraulic brake master cylinder controls the brake fluid to return to the reservoir. Vehicles equipped with air brakes usually have large air storage tanks, and after braking, the air is directly discharged, which explains why the exhaust sound of large trucks is so loud.
Having driven for over a decade, I can say the principle of a brake master cylinder is quite straightforward—when you press the brake pedal, it pushes a piston inside the master cylinder (also called the main pump) forward via a linkage. As the piston moves, it compresses the brake fluid inside, creating high pressure. This pressurized fluid is then sent through the brake lines to the braking components at each wheel, such as the wheel cylinders in drum brakes or the calipers in disc brakes, forcing the brake pads against the rotors or drums to slow or stop the car. The key lies in the hydraulic system: brake fluid is virtually incompressible, so the pressure is transmitted directly without losing force. If the cylinder leaks or the fluid level is low, the brakes will feel spongy—I’ve experienced this on the highway and had to pull over immediately to check the reservoir. Regular fluid changes and bleeding the system can prevent major issues, ensuring the brakes remain responsive and reliable.
