A gear stick (also gearstick, gear lever, selection lever, shift stick and gear shifter) is the lever used to change gear in a vehicle, such as an automobile, with manual transmission or several common forms of automatic transmission.
The device is used to change gear; in a manual transmission vehicle this will normally be done whilst depressing the clutch pedal with the left foot to disengage the engine from the drivetrain and wheels. Automatic transmission vehicles, and those with continuously variable transmission gearboxes, do not require a clutch pedal.
Gear sticks are most commonly found between the front seats of the vehicle, either on the centre console (sometimes even quite far up on the dashboard), the transmission tunnel, or directly on the floor. Some vehicles, especially older models, have a column shift where the lever is mounted to the steering column; typical examples include the Saab 96, Citroen 2CV and Renault 4. The Bentley Mark VI had its gear lever to the right of the right-hand drive driver's seat, alongside the driver's door, where it was not unknown for British cars to also have their handbrake. (Left-hand drive models received a column shift.)
In some modern sports cars, the gear lever has been replaced entirely by "paddles", which are a pair of levers, usually operating electrical switches (rather than a mechanical connection to the gearbox), mounted on either side of the steering column, where one increments the gears up, and the other down.
The gear knob and switches
The gear knob (or shifter knob) is at the end of the gear stick; it forms the handle of the gear stick. Typically the gear knob includes a diagram of the shift pattern of the gear selection system; i.e. the positions to which the gear stick should be moved when selecting a gear. In some older manual transmission vehicles it may incorporate a switch to engage an overdrive; in some automatic transmission vehicles it may incorporate a switch to engage a special mode such as a sports mode. Both of the above-mentioned switches may also be found on the console or on steering column stalks instead.
Many automatic transmission vehicles have extra controls on the gear stick, or very close by, which modify the choices made by the transmission system depending on engine and road speed; for example, "sports" or "economy" modes which will broadly speaking allow, respectively, for higher and lower revolutions per gear, before changing up.
Some specialist vehicles have controls for other functions on the gear stick. The Land Rover Freelander introduced a button for that company's Hill Descent Control system feature, which uses the brakes to simulate the function of a low-ratio gearbox in steep descents.
Secondary gear levers
In some traditional four-wheel drive "off-road" vehicles there can be a second gear lever which engages a low-ratio gearbox, used on tough terrain. Further, similar-looking levers may: switch between two- and four-wheel drive, or engage differential locks; these are not "gear levers" however.
The "shift pattern" refers to the layout of the gears. In a typical manual transmission car, first gear is located forwards, and to the left. In many trucks and some sports cars it is instead in a "dog leg" position, back and to the left. There is usually a spring-loading to return the stick to the central position. Reverse gear is commonly positioned in the best choice of location to avoid accidental engagement.
A typical manual transmission vehicle, with (for example) five forward gears, will thus have seven possible positions: the five forwards gears, reverse gear, and a central "neutral" position. Some vehicles have a special button to prevent accidental engagement of reverse. Others require that the lever be lifted, pressed down, or moved with extra force to engage reverse.
Automatic transmissions traditionally have had a straight pattern beginning at the most forward position with "park" (which locks up the transmission), and running through reverse, neutral, drive (all gears available), and then the lower gears (often three or two more positions, each locking out a successive upper gear), with the rear-most position allowing first gear only. More modern automatic transmissions have employed a "J-gate" (pioneered by Jaguar) where some gears are on the left-hand "arm", some on the right, and there is a sideways movement at the rear of the pattern.
Some modern gearboxes such as the Alfa Romeo Sportronic have a traditional automatic shift pattern to the right, with a special position to the left in which movement of the stick forwards and backwards increments the gears up and down respectively.
A rare fault sees the gear stick and gear box in general completely shift, re-aligning where the gears are located. This places first gear where third usually is, and second, third and fourth where fourth, fifth and reverse normally are, respectively. This leaves no room for fifth gear or reverse, subsequently making the car unable to use these gears at all. The Mitsubishi Magna TR is most known for doing this.Template:Fact