The hour spring (slip ring) consists of two conducting windings. The spring is established on a steering column and a steering wheel. Thus at rotation of a steering wheel the continuous electric contact between modules of a safety cushion and system of passive safety is made.

For the correct work of an hour spring the steering wheel has to be correctly established on a steering column (combination of the central provision of the operated wheels and an hour spring). Otherwise the hour spring can be damaged.

Fig. 8.43. Hour spring

Fig. 8.44. Components of an hour spring