<P> Handbrake turns are often intentionally used in street racing and offroad rally racing to initiate rear wheel drift . In conditions near freezing where it is both wet and icy, the parking brake mechanics may freeze and be impossible to release until thawed . If only using the "park" function on a transmission to hold the car parked, there is no freezing problem . The parking brake is also used to keep a parked manual transmission car from unintentionally moving when it is parked on a hill . Even though it is possible to keep a parked manual transmission car in place by putting it in gear in the opposite direction of the slope (e.g., if parking pointing downhill, put the car in "reverse"), the parking brake is still typically used, as if the engine were to lose compression, the car could roll forward . As a further precaution, some driving instructors tell students to point the wheels of hill - parked standard transmission cars towards the curb . </P> <P> In vehicles with rear disc brakes, the parking brake either actuates the disc calipers (again, with much less force) or a small drum brake housed within the hub assembly (the inner circumference of the disc is often used instead of a separate drum). </P> <P> Hudson automobiles used an unusual hybrid hydraulic - mechanical dual - brake system which operated the rear brakes through the otherwise conventional mechanical parking brake system when a failure of the hydraulic system allowed the pedal to travel beyond its normal limit . </P> <P> A number of production vehicles, light and medium duty trucks, and motor homes have been made with a separate drum brake on the driveline; called a transmission brake . This has an advantage of being completely independent of other braking systems . This is effective when there are multiple driving axles, all driven wheels are braked at once . </P>

The parking brake controls the rear two wheels