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What is a Rotor?

Felicia Dye
Felicia Dye

A vehicle's braking system plays an essential role in safe driving. A rotor, sometimes referred to as a disc, is an essential part of the disc braking system. There should be a brake rotor located on each end of each axle. When this part of the vehicle is in good condition, the rotor helps to ensure that the car stops in an effective manner. When this part is not in good condition, both driving and braking can be problematic and dangerous.

Rotors can often be visible without removing or changing any of the other parts on a vehicle. They can be viewed by looking through spaces in the rim of a vehicle's tire. The rotor is usually a dark metallic part that is flat, smooth, and round. It may appear to be striated. If it is worn, it may be possible to see or feel grooves in it.

A car's rotors can be changed with the help of a simple car jack.
A car's rotors can be changed with the help of a simple car jack.

The rotor is a piece of metal that interacts with a vehicle's brake pads. When a driver presses the brake pedal, an inside and outside brake of each wheel clasps a rotor. The harder the brake pedal is pressed, the tighter the grip should be. The tighter the grip is, the more the vehicle should stop.

In most circumstances, a rotor can be removed and replaced. Doing this, however, will require the removal of the tire. This means that it is usually necessary for the vehicle to be jacked up. It may also require the removal of the brake caliper, which is the contraption that holds the brake pads.

When the brake pedal is actuated, the oil or fluid is forced into the brake caliper, thrusting a series of pistons against the rotor.
When the brake pedal is actuated, the oil or fluid is forced into the brake caliper, thrusting a series of pistons against the rotor.

The rotor has a hole in center. Once any parts that may be obstructing it have been removed, the rotor should slide off the axle. A replacement can then be slid on. Replacing rotors should not be necessary every time brakes are replaced, but a person should expect to replace them periodically if he keeps a vehicle for an extended period.

Grooves in the rotor are one indication that its condition is deteriorating. If the grooves are not too deep, it may be possible to skim, or true, the part. This is done when it is removed and a machine is used to smooth the surface.

Rotors are located at the end of each axle.
Rotors are located at the end of each axle.

In some instances, people allow their rotors to deteriorate to a point where they cannot be skimmed. When this is the case, driving and braking the vehicle often become problematic. Braking is likely to involve inefficient stopping speeds and the sound of grinding metal. Metallic sounds and vibration of the steering wheel may be experienced while driving. Continuing to drive a vehicle in this condition can be dangerous.

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    • A car's rotors can be changed with the help of a simple car jack.
      By: iTake Images
      A car's rotors can be changed with the help of a simple car jack.
    • When the brake pedal is actuated, the oil or fluid is forced into the brake caliper, thrusting a series of pistons against the rotor.
      By: timur1970
      When the brake pedal is actuated, the oil or fluid is forced into the brake caliper, thrusting a series of pistons against the rotor.
    • Rotors are located at the end of each axle.
      By: Milos Stojiljkovic
      Rotors are located at the end of each axle.