A steering wheel knob is a device that affixes to the steering wheel of an automobile or other vehicle. This knob can spin independently of the wheel, allowing a user to put his or her palm on the knob and spin the steering wheel quickly. In many parts of the world, the use of a steering wheel knob in street-legal automobiles is illegal, though the device can often be used on work vehicles, tractors, and heavy machinery. Using the knob allows a person steering a vehicle to make quick turns, which is especially handy if the vehicle is being operated in a tight or restrictive area.
Before the advent of power steering, the popularity of the steering wheel knob was much greater, though the knobs were never especially popular among motorists. They were often used in work trucks to help make quick steering easier on the non-power steering trucks, and they are still in use primarily on forklifts in warehouses. Forklift operators are likely to need to make several tight turns in a row, making the steering wheel knob a useful accessory for this application. Tractor trailer drivers may also use a knob on the wheel when trying to turn quickly.
The purpose of the steering wheel knob is to make turning the wheel with one hand easier and quicker. The user can place his or her palm on the knob and turn the wheel rapidly. In many countries throughout the world, this design is considered dangerous, and many countries have therefore made the use of such knobs illegal for use in automobiles driven on roads. For an extended period of time, these knobs were popular among street racers who wanted maneuverability through city streets. This activity is usually illegal. The knobs can, however, be used for machinery or vehicles that are driven on construction sites or other areas not considered public roads.
One of the applications in which the knob is considered legal is for handicapped persons. The knob can be used by a person with one arm to make steering of a vehicle easier; people with other disabilities may be able to use the knob as well, although certain clearances are usually necessary for the person to use the knob legally. The knob can be problematic for some drivers because it protrudes from the wheel, meaning a person is likely to encounter the obstruction during normal turning, or during emergency maneuvers.