What is a Clockspring?

In motoring terminology, a clockspring is a coiled connector mechanism that supplies power and switching inputs to the steering wheel of an automobile. This mechanism allows the wheel to turn throughout its range of motion while maintaining the connections between the airbag, horn, and steering mounted switches. A clockspring is typically a spring loaded reel with a length of round or ribbon cable wound onto it, one end of which plugs into a socket on the steering wheel and the other connected to the car's circuits. The cable supplies the airbag with power and interfaces with any other switches on the steering wheel. When the wheel is turned in either direction, it pulls the cable off the reel against spring pressure, and when it is turned back to the neutral position, the spring winds the cable back onto the reel.

Advances in automobile technology have seen an increasing number of ancillary switching functions and equipment mounted on vehicle steering wheels. The ability to control many of the functions in a vehicle commonly accessed during driving without losing contact with the wheel, or having to look away from the road, certainly does make sense. Increased focus on driver safety has also seen the installation of safety equipment such as airbags in most newer car steering wheels. Getting power to and from all of these steering wheel mounted gadgets poses a problem, though, due to the constant turning of the wheel.

Older vehicles generally only had a horn button or ring on the wheel which drew its power from a simple copper slip ring and carbon brush system. Catering to complex switching functions and power supplies requires something more sophisticated, though, and led to the introduction of the clockspring. This device is typically mounted inside the steering column and consists of a circular casing with a length of flat or round cable spooled up inside. One end of the cable is static and is connected to the vehicle's circuitry. The other end plugs into a socket on the steering wheel boss and can retract to keep up with steering wheel movement.

The spool onto which the cable is wound is typically spring loaded which allows the spool to feed cable when the wheel is turned and to automatically rewind the cable when the wheel returns to its neutral position. Although most clockspring assemblies have excellent service life cycles, they do sometimes require replacement. This is a job best left to a professional unless the car owner is really handy technically. Clockspring units used to supply driver airbags with power generally require replacement after bags deploy due to localized melting of connectors caused by the gas conversion process.