Outline of an Automotive Brakes


In order to decrease the speed of a running vehicle and bring it to a stop, it is necessary to generate force to slow the rotation of the tires. When the driver operates the brake pedal, the brake device generates the force (road surface counterforce) that works to stop the tires and the force (inertia) working to keep the vehicle going is absorbed, thus stopping the vehicle. In other words, the energy (kinetic energy) of the tires working to rotate is converted into the heat of friction (thermal energy) by operating the brakes which works to stop the rotation of the tires. The vehicle must not only stop but must be able to stop in a way that reflects the intent of the driver. For example, the brakes must decrease the vehicle speed at the desired rate of the deceleration and stop in a relatively stable manner in a comparatively short distance during emergency braking. The main devices making up this stop function are the brake system such as the brake pedal, and the tires.

Brake System

There are two types of brake systems. The main brake system used when the vehicle is running is the foot brake system. There are drum brake and disc brake that are most commonly operated with hydraulic pressure. The parking brake system is used when leaving the vehicle is parked. The parking brake system operates the rear wheel brakes via wires or the like so that the vehicle does not move.

ABS (Anti-lock Brake System)

An ABS is a brake control unit that uses a computer control to automatically prevent the tires from locking due to emergency braking. This system raises the vehicle stability further and shortens the braking distance. Therefore, the tires do not lock up and the steering wheel can be steered even when the brake is depressed suddenly. The vehicle is kept in control, and can stop safely.

ABS with EBD

The “EBD” in the ABS with EBD is the abbreviation for Electronic Brake force Distribution or the Electronic Braking force Distribution control for the ABS. In addition to the conventional ABS function, braking force appropriate to the condition of the vehicle is distributed among the front and rear wheels and left and right wheels using the ABS brake hydraulic control unit.

BA (Brake Assist)

The BA is a system that assists brake

operation when drivers cannot apply

enough force on the brake pedal. Sudden

pressure applied to the brake pedal

is judged as an emergency stop, and a

larger amount of braking force is automatically


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