Gear stick
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.
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.
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.
A typical manual transmission vehicle, with five forward gears, will 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.
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 feature, which uses the brakes to simulate the function of a low-ratio gearbox in steep descents.
