How Does A Master Cylinder Work?

The master cylinder is the heart of the braking system on any vehicle. How does a master cylinder work? That’s just the subject of this article.

The brake system on any car is hydraulic in nature. This means that when you push on the brake pedal, brake fluid is put under pressure. The pressure builds up in milliseconds through the brake lines and is transferred to the wheels where the brake systems are engaged and you stop. The process of converting the downward stroke of the pedal into pressurized brake fluid is the job of the master cylinder.

The master cylinder is about the size of your hand and is found in the engine compartment. It tends to look like a “T” shape with a little tank on the top of it. The tank holds the brake fluid used for the system. The metal bar below the tank is where the action happens and contains pistons that move the fluid. In modern cars, you will see a wire module running up to the master cylinder. This feeds information to the cylinder and from the cylinder back to the driver’s compartment.

So, how does a master cylinder work? Well, there are different designs, but most now are two channel systems. This means there is one channel of fluid for the back wheels and one for the front. This duplicity means that if one channel fails, the car will not be completely without brakes. Let’s take a look at how one channel works.

The master cylinder proper looks like a small pipe. In it is a piston that moves horizontally. This piston moves down the pipe when you engage the brake pedal. This movement causes the brake fluid in the system to be “squeezed.” The squeezing action creates pressure. The pressure is transmitted down the brake lines that run to the front or back wheels. There, the pressurized brake fluid causes the braking action to occur.

This is obviously a very simple explanation, but it does the trick. The master cylinder on modern cars actually does much more. It has equalization monitors that keep the pressure between the back and front wheels adjusted for the most efficient stopping power. It monitors itself for leaks and communicates problems to the dashboard in the form of a brake light warning and, well, it does a host of things. Still, this is a basic description of how a mastery cylinder works.

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