Parking brake

In road vehicles, the parking brake, also known as a handbrake is a mechanism used to keep the vehicle securely motionless when parked. Although it is also called the emergency brake (e-brake), that is an incorrect term as it will not stop a car in an emergency. The mechanical leverage, the size of the brake shoes inside the rotor "hat" on many vehicles with rear disc brakes, are insufficient to effectively stop the vehicle. Parking brakes often consist of a pulling mechanism attached to a cable which is connected to two wheel brakes. In most vehicles, the parking brake operates only on the rear wheels, which have reduced traction while braking. The mechanism may be a hand-operated lever, a straight pull handle located near the steering column, or a foot-operated pedal located with the other pedals.

In manual transmission vehicles, the parking brake is engaged to help keep the vehicle stationary while parked, especially if parked on an incline. As an extra precaution, some drivers may also put their car in gear (either in first or reverse) in case the parking brake fails.

While automatic transmission vehicles have a "Park" gear with a parking pawl that immobilizes the transmission, it is still recommended to use the parking brake, as the pawl in the gearbox could fail due to stress or another vehicle striking the car, causing it to roll.

When parking on an uphill gradient, it is recommended that the front wheels face away from the curb. This would prevent the car from rolling into the roadway by using the curb to block the front passenger tire in the event of a parking brake failure. Similarly, on a downhill gradient, the front wheels should face the curb for the same reason, and the wheels should face to the side of the road on which vehicles are driven on an uncurbed road regardless of orientation. In a manual transmission, leaving the car in first gear (or in reverse if pointing downhill) is also advised, as the engine will prevent the car from rolling if the parking brake fails.

The parking brake in most vehicles is still completely mechanical. Traditionally engaged by pulling a lever, the cables manually engage part of the car's braking system, usually the rear disk or drum brakes. The mechanical nature allows the driver to apply the brake even if the main hydraulic brake system fails.

Pictograph symbols and/or lights may be used to indicate the location of a parking brake, its application or release.

In manual and automatic transmission vehicles, the parking brake can also be used for various driving situations which require the vehicle to be momentarily stopped. For example, the brake can be engaged when moving off an uphill slope, as this allows the driver to hold the accelerator and clutch pedals steady without the vehicle rolling backwards. Other common situations is when the vehicle is stopped at a traffic light, a pedestrian crossing, or simply waiting to turn in front of oncoming traffic. The parking brake would ensure the car is secure, should another vehicle come into physical contact from behind, causing the car to jolt forward. It is not recommended to use the parking brake when the vehicle is in-motion, unless there is a problem with the main brakes, as this can lock the back wheels and cause a skid. This is known as a handbrake turn, which is often performed in street racing and rallying to initiate rear wheel drift.

In the event of hydraulic brake failure, the parking brake can be used to slow a vehicle. In such cases, the lever should be slowly engaged to prevent locking up the wheels.