Clocksprings – sometimes also called ETU’s (Electrical Transmission Units) – play a critical role in driver safety. Located inside the steering wheel, clocksprings provide transmission of electrical signals and power between the fixed steering column and the rotating airbag unit inside the steering wheel. Initially clocksprings provided 2 electric lines for airbag applications; today they are highly advanced multifunctional units accommodating the increasing functionality being added to steering wheels. The clockspring uses flat (mainly laminated) cables to activate airbags and connect control buttons for infotainment applications. Other functions such as horn, cruise control and transmission gear selectors may also be integrated into the steering wheel control system. A clockspring can incorporate up to 18 electrical lines plus additional higher current slip-ring slider contacts for steering wheel heating.

The typical components of a clockspring include:

 • Housings - usually made from unfilled polymers, such as POM or PBT for low friction and noise
   characteristics.
 • Terminals and lead-frames
 • Airbag (squib) connectors, headers and cable assemblies
 • Flexible flat cable (FFC)
 • Foils for noise reduction - required to meet increasing customer expectations for lower noise
   levels within the vehicle.