The first thing that we probably think of when we hear the word rotors is helicopter blades. However rotor also refers to all kinds of rotating item and in this case rotors is the term used to distinguish brake discs.

What is a brake rotor? In simple terms it is the disc that is attached to the wheels of a vehicle such as a car or motorcycle. These rotors have pads which are designed to press against the surface of the rotors under appropriate stimulation to slow and stop the rotation of the disc. Therefore by using the force from a fixed object to affect a rotating object the movement is slowed and can also be stopped.

Rotors come in various sizes and styles. The most common is the solid circular type of various thicknesses. These are used mainly on the lower powered vehicles. Then there are drilled rotors, in which the holes are an aid to keeping the discs from overheating. However you can be sure that the holes do not promote wear on the disc pads and by helping the disc to stay at a temperature that is well below the overheating stage the life of the pads is increased. Another type of rotor is the ventilated disc. This is a type of disc that is quite thick with two solid sides that has vents situated in the metal between the discs. These vents have a fairly large area and they keep air flowing through the disc so that the rotors are kept much cooler.

All rotors share the same qualities: they rotate with the wheel that they are attached to, they have the specific purpose of assisting the braking force to stop a vehicle and they are for all intents and purposes circular in shape. However there are some that do have some kind of pattern on the outer edge. This decoration does not have too much of an effect on the function of the disc but it does minimise the surface area upon which the brake pads can provide braking pressure on. It is because of this factor that the patterned discs have to be larger than the recommended size of a normal disc so as to provide the same amount of braking power.

When fitting rotors there are some things that must be considered. The first is that they must be the correct size that is diameter and thickness and the mounting holes must be of the correct diameter and placement. Many types of rotors have a centre hole to aid correct placement, or dowels. Correct placement of the rotors is absolutely vital because if the rotor is not perfectly centralised it will cause an imbalance which will put extra stress in the wheels and attaching bolts. Fortunately this only becomes a real problem when the vehicle is at speeds that are much higher than the recommended speed limits. Rotors also require maintenance. They should be kept clean, and inspected at regular intervals for wear and possible cracking. Braking systems are designed to work with hydraulic fluid, air or cable actuation and they must not have any type of grease or oil on the surface.