Brakes are the device we use for slowing down or stopping the motion of a vehicle and also to keep it from starting to move again. So, it seems little doubt that the car brakes are the most important safety system when driving a vehicle. Most non-commercial road vehicles use a system called "Friction braking". Friction brakes on vehicles will store the heat in the rotating part, which is the drum or disc during the braking application and then releases it gradually to the air. There are several different types of brakes, but the "disc" brake is the most common system in use in most passenger cars nowadays.
Types of Brakes
The Disc brake - a mechanical device used for slowing or stopping the rotation of a wheel. The brake disc, otherwise known as the "rotor", is made of cast iron in most cases, and is connected to the wheel or the axle. It looks like a metal circle.
To stop the wheel from turning, "friction" material, in this case the brake pads, which are mounted in a device called a brake caliper, is then forced, either mechanically, hydraulically or pneumatically, against both sides of the disc.
The friction created by the pad grabbing the disc then causes the disc and the attached wheel to slow down or to stop. Disc brakes have a much greater stopping performance than the older system of drum brakes, and are more reliable. This would be similar in principle to bicycle brakes, but with mechanical assistance added to the force of your foot on the brake pedal.
The Drum brake – this is a brake in which the friction is caused by a set of shoes or curved pads that will press against the inner surface of a rotating drum. The friction part of the brake, in this case called a "brake shoe" instead of a "brake pad", pushes out against the drums interior curve. The drum is connected to the rotating wheel. Drum brakes are sometimes still used in vehicles now days, but not often. The only reason they are still used is because of the weight and the cost advantages.
The Rest of the Braking System
Most brakes on cars now are what are called "Power" brakes, and driven by a hydraulic braking control system. This arrangement connects the brake pedal to the braking mechanism by s system that uses hydraulic fluid, typically some type of light-viscosity petroleum oil. It transfers pressure from the controlling unit, usually the brake pedal controlled by the vehicle’s driver, to the actual brake mechanism (disc or drum brake) that is at the wheel of the vehicle to slow it down or bring it to a stop.
Most hydraulic brake systems that are found on automobiles make up part of the "Power" in power braking systems and consist of:
- The brake pedal
- A "Master" cylinder containing hydraulic fluid.
- Hydraulic lines going out to the brakes
- A "slave cylinder" to keep hydraulic pressure even
- And the braking unit(s)