Use the Constant Force

You might have noticed how your seat belt keeps working at its best capacity, even after years of use and sudden stops you have to make on the road.  This is mainly possible due to the use of constant force springs in seat belts. These springs are very common and you can find them in many other items, ensuring their proper function.


Constant force springs are pre-stressed, flat strips of metal. When extended, they resist the loading force applied to them. They are used when there is the need of a spring that can withstand a constant load. These springs don’t obey Hooke’s Law, that says that the force needed to extend or compress a spring by a distance is proportional to that distance (F=kX). In these springs, the force of motion is constant, and they have barely any limit to their extension speed.

How Can They Be Used?

These springs’ durability and stress resistance make them perfect for several industry uses like gym equipment, electric motors, hair dryers, toys, and other equipment that require a constant force. In industries like aerospace and medical device manufacturing, durability and safety are one of the most important factors in spring development and building.

This is why our highly-skilled engineers are trained to choose the right materials for spring building, taking into consideration the stress, temperature, and also risk of corrosion that the material might face. Our constant force springs are commonly made from texture rolled carbon steel, or from stainless steel.

Installation Procedures

Several installation procedures are possible due to the versatility that these springs provide. Cavity mounting is a common way to fit constant force springs, as it is an inexpensive assembling process. However, despite its low costs, it has high-friction levels and diminishes the spring’s lifespan.

Spool mounting involves minimising the sliding friction by the use of a spool around the axis; the spool ensures that the consistent shape will lessen the extension, and as such it prolongs the spring’s lifespan.

Dual assembly mounts two or more constant force springs side by side, attaching them with coil strips. It doesn’t add stability due to the decreased extension length but the two springs installed together will create more force.

Here at European Springs we always ensure that our products are high-quality and made to your own specific needs. If you want more information about any of our services, contact us on 0208 663 1800. Alternatively, you can also find us on Facebook and Twitter to keep up to date with our news.

European Springs

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