extension springs

In extension springs, initial tension matters. When creating your design, you want to take into account the initial tension your spring will need.

What is Initial Tension in Springs

Initial tension is the tension that is already present between the coils in extension springs. It is the internal force that keeps extension springs compressed and holds their coils tightly together. Only when an external force is applied to the spring can the coils be separated and the spring flexed. When the tension is released, the coils separate. When the force lets up, the coils come together and allow the spring to compress once again and return to rest.

How to Calculate Initial Tension in Springs

You can calculate the initial tension (IT) of a spring by subtracting the product of its rate (R) and the distance it travels (T) from its load (L). As an equation, it can be written as:

IT= L- R(T)

If you are replacing springs in your application, you can calculate the initial tension you will need for new springs by measuring the initial tension of your current springs.

Things to Consider

  • Unlike compression springs, extension springs do not have a hard line where they will stop to prevent an overload. If the load is too great, the spring will continue to extend.
  • You can have an extension spring that has a stopping point, it’s called a drawbar spring.
  • Incorporate body length and outside diameter into your design.
  • There are many spring end types to choose from.

Get a Quote on the Extension Springs You Need

Initial tension is just one of the many factors that you can choose when requesting a quote on your extension springs. Whether you know all the specifications you need in a spring, just a few, or none at all, we can help you design and manufacture springs that will perfectly fit your product or application. Request a quote today.