The NEG'ATOR extension spring represents the most basic, yet most versatile, type of constant force springs. It is a prestressed flat strip of spring material which is formed into virtually constant radius coils around itself or on a drum. When deflected, the spring material straightens as it leaves the drum. This straightened length of spring actually stores the spring's energy through it's tendency to assume its natural radius.
The full rated load of the spring is reached after being deflected to a length equal to 1.25 times its diameter. Thereafter, it maintains a relatively constant force regardless of extension length. Load is basically determined by the thickness and width of the material and the diameter of the coil.
Fatigue life of NEG'ATOR springs ranges from 2,500 cycles to over a million cycles depending upon the load and size of the spring. Working deflections of 50 times the drum diameter can be achieved. A wide variety of mounting configurations can be used such as cavity mounts, multiple spring mounts, etc., depending on the application. End connections can also be varied to fit the design situation. Hunter's own experienced engineers can help you select a spring design to meet your space, life cycle, load and operation requirements.
