What is an Emergency Brake?

Mary McMahon
Mary McMahon

An emergency brake, commonly referred to as an e-brake or parking brake, is a specialized independent braking system for a driver to use in an emergency. It is also used as a parking brake to prevent a car from rolling when it is stopped and turned off, because it is a purely mechanical system, rather than a hydraulic one. It is an important part of the safety systems for a motor vehicle, and can make a significant difference in some emergency situations.

The emergency brake is designed to function even when there is total brake failure.
The emergency brake is designed to function even when there is total brake failure.

The setup of an emergency brake is simple; a cable connects to the braking mechanism in the rear wheels, and it attaches to a lever near the driver's seat which he or she can pull to engage the emergency brake. As the lever ratchets back, the cable tightens, setting the brake, and the lever cannot release until a button on the lever is pressed or it is turned, depending on how the brake is set up. The most common type in passenger vehicles is a lever located between the driver and passenger seats, which can be applied by either party, highly useful if a driver is incapacitated. Some cars have a knob located under the dashboard which must be pulled and turned, while other vehicles use a separate pedal which is higher than the other pedals and off to the side.

In a car with an automatic transmission -- the system of gears that changes at various driving speeds -- the "Park" setting helps keep the vehicle from rolling.
In a car with an automatic transmission -- the system of gears that changes at various driving speeds -- the "Park" setting helps keep the vehicle from rolling.

In a car with drum brakes, the emergency brake cable commonly connects directly to the rear brakes along with the hydraulic line for the conventional braking system. Many cars with disc brakes have a separate drum brake which serves as the emergency brake. In some cases, cars with disc brakes attach the emergency brake line to a screw which can apply pressure to the piston of the disc brake, causing the car to stop.

It is recommended that drivers set the emergency brake when parking to prevent runaways, regardless as to how steep the parking space, along with setting the car in the lowest gear or using the "Park" setting on an automatic transmission. If a car should pop into gear while parked, it can roll away and do serious damage. If a driver is parking on a hill facing up and there is a curb, the driver should also curb his or her wheels by turning them so that they face out into the street. If the emergency brake should fail, the car will roll back into the curb and stop. If there is no curb, the driver should face the wheels to the side of the road so that the car will roll off the road. If parking on a steep downhill incline, the wheels should be faced towards the side of the road or the curb.

Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a wiseGEEK researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

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Discussion Comments

anon150124

What is the loud bang sound if you accelerate from a stop when the parking brake is on?

rbrown

your car will probably not move or your tires will burn up.

anon16421

Should the emergency or parking brake be put on every time you park the car? I have heard this adjusts the brakes and is good for maintenance.

anon12882

Danny in Boston

If you drive with the emergency brake on, you will wear out the emergency brake very quickly and with even more use, you would wear down the rotor as well.

Depending on how strongly you apply the emergency brake and how strongly you accelerate, you may not be able to move much at all.

I can't think of any logical reason why someone would want to drive with the emergency brake on. It offers no benefit and will cause wear/damage very quickly.

anon3996

What happens if you drive with the emergency brake on?

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