What Is A Brake Rotor?

The brake disc system is the most commonly used braking system on consumer cars. The brake rotor is a key part to that system. Okay, so what is a brake rotor?

There are two types of brake systems – drum and rotor. The rotor system is also often called a brake disc system. Regardless of the name, it is the primary choice on most modern cars. Why? It is very efficient at stopping the car and much better at dealing with the heat produced when that is being done.

The brake rotor is connected to the wheel or axle of the car. There is a rotor on each wheel although some cars will use a different drum system on the rear of the vehicle. Regardless, this rotor moves at the same rate as the wheel does. It is a large piece of metal that is roughly a quarter of an inch wide and perhaps a foot across depending on the particular car. It looks for all the world like a quarter sitting on its edge, but with the axle coming out of the middle.

The rotor has a pad system that fits down over its edge on one side of the rotor. The system sits in such a way that it pads rest on either side of the rotor. When the driver presses the brake pedal, the pads squeeze against both sides of the rotor. This is exactly what happens with the brakes on a bicycle. The squeezing motion creates friction and slows the rotor. As the rotor slows down, so does the wheel.

The brake pads cover only about 15 to 20 percent of the rotor surface. Why? This approach allows the rotor to spin through the air most of the time. This is important as it gives the rotor a chance to cool down. Too much heat can warp or wear out the rotor and pads to quickly. If the rotor gets sufficiently hot, the friction will actually be reduced and the driver will lose control. It is this design attribute that makes rotor systems superior to drum systems.

What is a brake rotor? It is the key part connected the wheel or axel that allows the brake system to slow the car. You can find brake rotors here:

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