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constant force spring

Constant Torque Springs

Our range of high-quality Constant Torque Springs

The constant force spring (or constant torque spring) consists of strip material, which has been shaped and pre-tensioned into a tightly wound roll.

The spring is used in a linear movement and produces almost constant force throughout its deflection. The maximum load of the spring is reached after being deflected to a length equal to 1.25 times its diameter — it can undergo a constant force regardless of the extension length.

Fitting a Constant Force Spring

Constant force springs can be fitted in a number of ways and extended partly or completely. There is practically no limit on extension speed and acceleration.

During long extensions, the spring must be laterally guided to prevent movement in a sideways direction. Suitable play on each side is 0.5–1.5 mm.

When fitting on a bearing or conduit, the spring can be located using its own force providing that sufficient strip length remains on the bearing. If there is no operating extension limit in the application, we recommend that a screw or rivet is used to secure the inner end of the spring.

Fitting on a bearing and conduit

Our standard springs and slide bearings are normally supplied separately. Fitting is done by loosening the outer end of the spring and winding it onto the bearing (securing it if necessary), after which the complete spring is wound onto the bearing.

Constant force springs for general use based on imperial dimensions. These springs are normally fitted on bearings. If the spring is placed directly onto a shaft, the chosen shaft diameter must afford sufficient play on the inner diameter to prevent the spring from locking onto the shaft.

Spring life

The life of the spring is determined by the relation between the diameter of the spring and the thickness of the material. See information for the relevant item. For applications demanding a higher number of oscillations, the spring must be changed once the recommended number of oscillations has been reached. Spring life is not time-dependent, it is only determined by the number of oscillations made.

15 000 oscillations
1 kp = 9.80665 Newtons, 1 Newton = 0.10197 kp

Contact Our Experienced Team Today

As constant torque spring manufacturers, we’re best placed to advise you on the use or application of our products. If you need guidance, please don’t hesitate to contact us using our online form or directly by calling us on 01604 499332.


T = Strip thickness
F = Spring force in Newtons
* May vary in order to comply with the force specification.


Stainless steel: EN 10270-3-1.4310