A gear knob,variously called shift knob, gear shift knob, or stick shift knob forms the handle for the gear shift knob. Typically the gear knob includes a diagram of the shift pattern of the gear selection system; i.e. the positions to which the gear shift knob 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. Manual shifters on the steering column, if having only three forward speeds, are typically called a "three on the tree." The lowest of these gears, if set at a much lower ratio than standard 1st-gear ratio, is often called a "granny gear."
5 speed gear shift knob of a manual transmission car.The shift pattern refers to the layout of the gears. In a typical manual transmission car, first gear is located to the left, and forwards. In many trucks and some sports cars it is instead in a "dog leg" position, to the left and rearwards. 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 occurrence.
This gear shift knob has been replaced entirely by "paddles", which are a pair of levers, operating electrical switches through 6 pins electrical wire connections,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. Rock the knob of a manual gearbox from side to side before starting the engine, to confirm that the gearbox is in neutral (starting the car in gear causes it to lurch forwards since the starter motor has sufficient torque to move the whole vehicle; this can be highly dangerous, especially if the parking brake is not firmly applied). Some cars require the clutch pedal to be depressed before the starter will engage, for the same reason. The latter practice is also useful in extremely cold conditions or with a weak battery, since it avoids the starter motor also having to turn over a gearbox full of cold and highly viscous oil.http://gear.shiftknob.net/products/gear%20shift%20knob%20for%20VOLVO20488063.html
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