CONSIDERATIONS

Prior to the manufacture of any associated components, it is important that the required spring space envelope is ascertained.

Serious consideration should be given to life cycle requirements, so that critical ratios can be designed into the springs.

There are limits to the types of material which can be used to produce a clock type spring, ie - spring steel or stainless steel. The environment within which the spring is to operate must be considered carefully as it is not always possible to corrsively protect springs after manufacture.

The degree of angular movement required will effectivly define which type of spring will be required for a particular applpication.

APPLICATION - To both retract an electrical cable and keep it under tension during use in an application where the operational site for electrical equipment was at some distance from the power supply point.

PROBLEM - The extreme lengths of electrical cable required often created a hazard to the working environment through coiling and tangling, as well as time wasted in re-coiling it after use.

SOLUTION - George Emmott developed a close coiled clock type spring which, when placed within the housing over which the electrical cable fitted, solved the problem of loose cable during use and retracted easily, thereby saving operator time. The spring was designed so that no major build-up of tension occurred throughout the working length of the cable, which might cause operator fatigue. Furthermore, by careful selection of the spring material, particularly with reference to the strip edge condition, the clock type spring designed was capable of several thousand cycles.