A car in motion has a lot of kinetic energy, which is energy of motion. To stop a car, the brakes have to get rid of that kinetic energy. They do so by using the force of friction to convert that kinetic energy into heat.
How Braking Works
The brake pedal pushes a piston into a hydraulic fluid-filled master cylinder when you press the pedal. The hydraulic fluid is squirted into wider cylinders located next to each wheel's brakes via a system of pipes.
The hydraulic system multiplies the force exerted by your foot on the brake pedal so that the brakes are applied, and the car stops. As far as brakes themselves are concerned, they usually fall into one of two categories: disc brakes or drum brakes.
On the front wheels of many modern cars, there are disc brakes, and on the rear wheels, there are drum brakes. The more expensive models may have disc brakes on all four wheels as part of the standard equipment. The drum brakes are found on the four wheels of very old or very small cars.
It is the brake discs, the brake calipers, and the brake pads that make up disc brakes. A hydraulic fluid is injected into the brake caliper when the brake pedal is depressed. This causes the brake pad to press against the disc when the brake pedal is depressed. In the brake pad, friction is generated when the brake pad rubs against the brake disc, which is converted into heat as the kinetic energy of the brake pad is converted into energy.
Is there a lot of heat? There is a lot! When a car is speeding, the brakes can heat up to 950 degrees Fahrenheit or more if you stop it. Having to withstand high temperatures, brake pads must be made of materials that will not melt at such high temperatures in order to be able to withstand such heat. Composite materials, alloys, and ceramics are some of the special materials that can be used.
The friction used by drum brakes is slightly different from that used by disc brakes. There are two parts that make up the drum brake, which are the brake drum and the brake shoes. Turning the wheel spins the hollow drum. Brake shoes with friction linings are pushed against the brake drum by a hydraulic cylinder when the brake pedal is depressed, creating friction and slowing the vehicle.
ABS And Parking Brakes
During deceleration, anti-lock braking systems (ABS) limit, apply, and release pressure on a wheel. With this system, maximum stopping force can be applied without skidding or the brakes locking up. Each time your vehicle's ignition is turned on, the ABS tests itself. For whatever reason, the ABS shuts off if a defect is detected, allowing the normal braking system to operate. In the event of a defect in the ABS system, the driver will receive a warning light.
Parking brakes are lever mechanisms used to hold vehicles in parked positions. In the vehicle's rear brake system, it activates braking components.
In town, you may need to use your brakes more often than on the highway, not to mention that you may need to use them to stop your vehicle immediately in an emergency. Motorists should therefore maintain effective vehicle braking systems at all times.
Would you like to know how a car works and how it is maintained? Visit KeepDriving to learn more on why your car shakes when driving.