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Central function for your brake system

The brake master cylinder is the heart of the hydraulic brake control system: it converts pedal force into hydraulic pressure and distributes it evenly to the wheel brake cylinders. Any leakage, insufficient stroke or wear in the cylinder mechanism can have a negative impact on braking behavior and endanger safety.

Wide range of accessories in the store

Our range includes spare parts and accessories such as boots (bellows) for master brake cylinders, repair kits and complete master brake cylinders in various designs. These components enable both precise repair and complete replacement in the event of a defect or wear.

Master brake cylinder

What should you look out for when buying:

CYLINDER DIMENSION

Make sure that the stroke, piston diameter and length match the existing brake cylinder so that the pressure is generated correctly.

SEALING

Choose high-quality sealing sleeves or repair kits to prevent leaks and ensure long-lasting tightness.

ASSEMBLY

Check whether the replacement is possible with existing fixing points and whether all connection threads, holes and mechanical components are compatible – especially when replacing with a different design or a retrofit model.

The central control in the truck brake system
Although the master brake cylinder in its classic, hydraulic design is the centerpiece in many light commercial vehicles and older trucks, the central brake control in modern heavy-duty trucks is taken over by pneumatic components. The functional equivalent of the master brake cylinder here is the foot brake valve (or brake valve). This valve is the interface between the driver and the air brake system: it converts the mechanical force of the brake pedal into two separate, proportional pneumatic control pressures. The maximum precision of this valve is crucial in order to precisely modulate the high pressures (typically up to 12 bar) and ensure sensitive, safe deceleration of the entire vehicle combination (truck and trailer).

Safety through dual-circuit systems and redundancy
The central importance of the master brake cylinder or the foot brake valve lies in the safety architecture. All commercial vehicles must have a dual-circuit brake system that maintains the function of the other circuit even if one circuit fails. Hydraulic master cylinders for trucks are therefore designed as tandem cylinders that supply two independent pressure circuits. This design ensures that the master brake cylinder retains the remaining braking effect even in the event of a fault in one line. With the pneumatic foot brake valve, two separate control lines are also activated to control the front and rear brake circuits and the trailer brake system independently of each other. The perfect tightness and function of this component is therefore the most fundamental prerequisite for road safety.

Requirements for accessories
Regardless of the type of actuation, accessories in the truck sector must be extremely robust, as every component on the brake master cylinder has a direct influence on the braking distance and vehicle control. In the case of hydraulic cylinders, the sealing sleeves and pistons are more solidly dimensioned and must be able to withstand higher loads and longer service lives. In pneumatic systems, the mounting parts of the brake valve and the connected air lines must be absolutely pressure-resistant and vibration-resistant. The selection of spare parts of tested quality is essential to ensure that the legally prescribed braking performance and the reliability of the brake system are guaranteed at all times, even under maximum load and in long-distance traffic.

Expert FAQ: Everything about master brake cylinders, maintenance & brake pressure

The brake master cylinder converts the mechanical force of the brake pedal into hydraulic pressure and transmits this to the wheel brake cylinders via the brake lines.

In trucks and cars, it is usually designed as a tandem cylinder. It has two separate chambers (dual-circuit system) to maintain the braking force in the second circuit in the event of a leak in one brake circuit.

Typical symptoms are a “soft” brake pedal that can be depressed slowly to the floor, uneven brake pressure or visible leaks at the connections.

High-quality repair kits with new gaskets often help. However, if the inside of the cylinder housing is scored or corroded, a complete replacement is absolutely essential for safety reasons.

An incorrect diameter changes the transmission ratio. A piston that is too large requires more pedal force, a piston that is too small extends the pedal stroke dangerously.

Old brake fluid absorbs water (hygroscopic). This can lead to internal corrosion on the brake master cylinder and damage the sealing lips of the sleeves.

Yes, the brake system must be properly bled after every intervention in the hydraulic system, as air bubbles in the system prevent the transmission of brake pressure.

While the master brake cylinder generates hydraulic pressure, the foot brake valve in heavy trucks controls pneumatic compressed air circuits. However, the function as an “interface to the driver” is identical.

Your brake system back in top condition

With suitable cylinders, sleeves and repair kits, you can ensure that your vehicle brakes precisely and safely again. Simply select a model and order online!