The NEG'ATOR Constant Force 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 Constant Force 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 Constant Force Extension 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 Constant Force Extension Spring design to meet your space, life cycle, load and operation requirements.

The NEG'ATOR Constant Force Spring motor is a prestressed strip of spring material which is formed into a coil and stored on a small storage drum. The free end is then fastened to and backward wound onto a larger output drum-this is the "winding" portion of the Constant Force Spring's cycle. When the output drum is released, the spring will return to the storage drum to assume its natural curvature thus rotating the output drum and providing virtually constant torque.

The torque of a NEG'ATOR Constant Force Spring motor is dependent on many factors including material width and thickness, the natural radius of curvature and the diameters of the drums. These motors, due to their high operating stress, provide many advantages in motor size and life cycle at a given load. Optimal applications would require fatigue life between 2,500 and 35,000 cycles.

The Constant Force Spring output and long defection capability of the NEG'ATOR power package provides a practical and economical alternatives to electric motors, dead weights and power springs. This Constant Force Spring can provide up to 100 turns with little effect on torque output. Hunter Spring's design engineers will assist you in designing a motor to meet your size, load and life cycle requirements. Our engineers can also suggest mounting arrangements and stopping devices which can help optimize the performance or your overall product design.

The NEG'ATOR Constant Force Spring Extension Springs listed below are available from stock for immediate shipment from established distributors or directly from the factory. These Constant Force Spring Extension Springs can be used by designers to assist in the development of product prototypes of supplied in small production quantities.

All stocked Constant Force Spring Extension Springs are supplied in Type 301 stainless steel with hole punches in the free ends. The wide variety of sizes and load capacities available permit you to closely match a Constant Force Spring Extension Spring to your application at a considerable savings over a custom-designed spring (minor modification can be made when required).