Masterzylinder

The master cylinder is a hydraulic component that converts mechanical input from the brake pedal into hydraulic pressure in the brake fluid circuit. It is the primary source of pressure that actuates the vehicle’s braking system and distributes force to the wheel brakes through brake lines.

Most master cylinders consist of a cylindrical metal body containing pistons and seals, a fluid reservoir, and outlet ports. In traditional single-circuit designs a single piston pressurizes the fluid; in modern vehicles a tandem or dual-circuit cylinder provides separate hydraulic circuits for redundancy.

Operation: When the driver presses the pedal, the piston moves within the bore, compressing brake fluid and raising pressure. This pressure is transmitted through the master cylinder’s outlet ports into the brake lines to operate wheel cylinders or calipers, creating braking force at each wheel. Bleeding air from the system is necessary for effective performance.

Absorbing variations: Some master cylinders integrate with anti-lock braking systems (ABS) or electronic stability control, and may include a brake fluid level sensor. Materials are typically steel or aluminum, and the internal seals are designed to withstand high hydraulic pressure and exposure to glycol- or silicone-based fluids depending on the system.

Maintenance and issues: Regular inspection of the reservoir, fluid level, and visible leaks is important. Brake fluid should be replaced according to the vehicle manufacturer’s schedule. A soft or spongy brake pedal, reduced braking performance, or visible leaks indicate a faulty master cylinder and require professional service.

See also: braking system, tandem master cylinder, clutch master cylinder, anti-lock braking system.