What is Master Cylinder and Wheel Cylinder?

The master cylinder and wheel cylinder are the parts of the Hydraulic brake system. It is used to pressurize the hydraulic fluid and also helps to engage the brake properly. In this article, I will discuss the details of the master cylinder and wheel cylinder.


Master Cylinder and Wheel Cylinder

The master cylinder and wheel cylinder are found in the mechanical hydraulic brake system. In this system, the brake fluid is pressurized into the master cylinder and this pressurized fluid takes the action on the brake pads. Then the brake pads make a grip on the axle, and the vehicle stops.

There are connections and lines are made to run the fluids on the channels. The fluid pressurizes in the master cylinder and then this pressurized fluid travels through the lines and activates the pads on the wheel cylinder. In the wheel cylinder, there are also chambers ready with pistons that are connected to the brake pads.

The brake their fore engage and the vehicle stops. So, read the working and the details of the master cylinder and wheel cylinder.

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Master Cylinder

The master cylinder is the heart of the hydraulic brake system. It consists of two main chamber-the fluid reservoir which contains the fluid to supply to the brake system, and the compression chamber in which the piston operates.

The reservoir supplies fluid to the brake system through two ports. The larger port is called the filler and intake part and is connected to the hollow portion of the piston between the primary and secondary cups which acts as piston seals. The smaller port is called the relief, bypass of the compensating port which connects the reservoir directly with the cylinder and lines when the piston is in the released position.

The reservoir is vented to the atmosphere so that the atmosphere pressure causes the flow through the filler port. The vent is placed in the filler cap. The boot covers the push rod and the end of the cylinder to keep it free from foreign matter.

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Master Cylinder Working

When the brake pedal is depressed, the master cylinder piston moves forward to force the liquid under pressure into the system. The relief port is sealed out of the system. The liquid pressure is applied to the wheel cylinders, where it forces the wheel cylinder pistons outward. These pistons force the brake shoes out against the brake drum.

When the brake pedal is released, the return spring quickly forces the master cylinder piston back against the piston stop. Because the fluid in the lines returns rather slowly, a vacuum tends to form in the cylinder in front of the piston. This causes the primary cup to collapse to allow the liquid to flow from the reservoir through the filler port past the piston to fill the vacuum.

When the pedal is in the “off” position, the liquid may flow from the reservoir through the relief port in the master cylinder, supply lines, and wheel cylinder to make up for any fluid that may be lost or to compensate for the shrinking cooling of the liquid.

In this way, a complete column of liquid is always maintained between the master cylinder piston and wheel cylinder pistons.

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Wheel Cylinder

Among the master cylinder and wheel cylinder, the piston and the pressurized fluid work in both places. This is the second important component of the hydraulic brake system. It consists of two pistons that can move in opposite directions by the fluid pressure.

It is rigidly mounted on the brake shield or backing plate. The boots protect the cylinders from foreign substances. Bleeder valves are provided in the cylinder to permit air and liquid to be pumped out of the system during the bleeding operation.

The piston cups fit tightly in the cylinder against each piston and seal the mechanism against leakage of the brake fluid. A spring serves to hold the cups against the piston when the pressure decreases.

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Wheel Cylinder Working

When the brakes are applied the brake fluid enters the cylinder from a brake line connection inlet between the two pistons. It forces out the two pistons in opposite directions. This motion is transmitted to the brake shoes directly or through links forcing them against the brake drum, thus appalling the brake.

The copper-coated, tin-plated annealed steel tubing and flexible hoses are used to connect the master cylinder to wheel cylinders. The hoses are used to connect the lines to the front wheel cylinders to permit the front wheel to be turned.

Rear wheel cylinders are generally connected directly to a line fastened to the rear axle housing. The brake lines are attached directly or using brackets to the frame or axle housings.

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Importance of Master Cylinder and Wheel Cylinder

In a hydraulic brake system, the brakes are operated based on fluid. If the fluid operates normally without any pressure then the brakes will not work effectively. The pistons in the master cylinder and wheel cylinder are the main component that helps to pressurize and supplies the fluid in the channels.

This system works in a closed vacuum loop because air can damage the pressure of the liquid. This is called a spongy brake. Then the system needs to be calibrated to work effectively. The pressure generated by the master cylinder is taken to the wheel cylinder by force.

So, the importance of these two systems is much greater. heel cylinders ensure equal and balanced braking force distribution to each wheel. This helps maintain stability and prevent skidding during braking, especially in emergencies or when driving on uneven surfaces.

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The master cylinder and wheel cylinder are essential components of a hydraulic brake system, working together to convert driver input into braking force and ensuring safe and efficient vehicle deceleration. Proper maintenance and periodic inspection of these components are crucial for optimal brake performance and overall vehicle safety.

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