AXXIS Disk Brakes

AXXIS Disk Brake

The disc brake is a device for slowing or stopping the rotation of a wheel. A brake disc (or rotor in U.S. English), usually made of cast iron or ceramic, is connected to the wheel or the axle. To stop the wheel, friction material in the form of brake pads (mounted in a device called a brake caliper) is forced mechanically, hydraulically, pneumatically or electromagnetically against both sides of the disc. Friction causes the disc and attached wheel to slow or stop.

The design of the disc varies somewhat. Some are simply solid cast iron, but others are hollowed out with fins joining together the disc's two contact surfaces (usually included as part of a casting process). This "ventilated" disc design helps to dissipate the generated heat and is commonly used on the more-heavily-loaded front discs.

Many higher performance brakes have holes drilled or cast through them. This is known as cross drilling and was originally done in the 1960's on racing cars. Brake pads will outgas and under use may create boundary layer of gas between the pad and the disc hurting braking performance. Cross drilling was created to provide the gas someplace to escape. Although modern brake pads seldom suffer from outgassing problems, water residue may build up after a vehicle passes through a puddle and impede braking performance. For this reason, and for heat dissipation purposes, Cross Drilling is still used on some braking components. Discs may also be slotted, where shallow channels are machined into the disc to aid in removing dust and gas. Some discs are both drilled and slotted.

Slotted discs are generally not used on standard vehicles because they quickly wear down brake pads, however, this removal of material is beneficial to race vehicles since it keeps the pads soft and avoids vitrification of their surfaces.


A Mountain Bike Disc brakeOn the road, drilled or slotted discs still have a positive effect in wet conditions because the holes or slots prevent a film of water building up between the disc and the pads. Poorly-made cross drilled discs (such as those made by simply drilling through a plain faced disc) may crack at the holes under use due to metal fatigue.

New technology now allows smaller brake systems to be fitted to bicycles, mopeds and now even mountain boards. The market for mountain bike disc brakes is very large and has huge variety, ranging from simple, mechanical (cable) systems, to highly expensive and also powerful, 6-pot hydraulic disc systems, commonly used on downhill racing bikes.

Disc brake discs are commonly manufactured out of a material called grey iron. The SAE maintains a specification for the manufacture of grey iron for various applications. For normal car and light truck applications, the SAE specification is J431 G3000 (superseded to G10). This specification dictates the correct range of hardness, chemical composition, tensile strength, and other properties that are necessary for the intended use.

Historically brake discs were manufactured throughout the world with a strong concentration in Europe, and America. During the period from 1989 to 2005, manufacturing of brake discs has migrated predominantly to China. Today, almost 90% of brake discs and brake drums are manufactured in China and exported globally.

For More Information, Please visit: http://en.wikipedia.org/wiki/Disc_brake