or on the steering column, however electronic rotary dials and push-buttons have also been occasionally used since the 1980s, as well as push buttons having been used in the 1950s and 1960s by Rambler (automobile), Edsel, and most famously, by Chrysler. A few automobiles employed a lever on the instrument panel, such as the 1955 Chrysler Corporation cars, and notably, the Corvair. P-R-N-D-L positions Most cars use a "P-R-N-D-L" layout for the gear selector, which consists of the following positions: Park (P): This position disengages the transmission from the engine (as per the Neutral position) and a parking pawl mechanically locks the output shaft of the transmission. This prevents the driven wheels from rotating which typically prevents the vehicle from moving. The use of the hand brake (parking brake) is also recommended when parking on slopes, since this provides greater protection from the vehicle moving. The Park position is omitted on buses/coaches/tractors, which must instead be placed in neutral with the air-operated parking brakes set. Some early passenger car automatics did not have the Park feature, such as the pre-1960 Chrysler cars and the Corvair Powerglide. These cars also were started in Neutral and required the driver to apply a parking brake when parked. The park position usually includes a lockout function (such as a button on the side of the gear selector or requiring that the brake pedal be pressed) which prevents the transmission from being accidentally shifted from Park into other gear selector positions. Many cars also prevent the engine from being started when the selector is in any position other than Park or Neutral (often in combination with requiring the brake pedal to be pressed). Reverse (R): This position engages reverse gear, so that the vehicle drives in a backwards direction. It also operates the reversing lights and on some vehicles can activate other functions including parking sensors, backup cameras and reversing beepers (to warn pedestrians). Some modern transmissions have a mechanism that will prevent shifting into the Reverse position when the vehicle is moving forward, often using a switch on the brake pedal or electronic transmission controls that monitor the vehicle speed. Neutral (N): This position disengages the transmission from the engine, allowing the vehicle to move regardless of the engine's speed. Prolonged movement of the vehicle in Neutral with the engine off at significant speeds ("coasting") can damage some automatic transmissions, since the lubrication pump