Maximum Spring Extension Equation

Definition: The maximum spring extension of a tension spring is the elastic limit the spring is able to achieve due to the proportion of its physical dimensions.

Our spring calculator, Spring Creator, is able to calculate your tension spring’s elastic limit using a maximum spring extension equation which has been added into its calculating software. This value on our calculator is known as Maximum Safe Travel Considering Hook Stress (TravelmaxHS). By making the distance traveled of your spring longer than this value, thus exceeding its elastic limit, you will cause the extension spring to take a set.

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Maximum Spring Extension

Besides the Maximum Safe Travel Considering Solid Height, there is an additional value called Maximum Safe Travel. The difference between the two is that one of the values considers the stress being applied on the hooks as your spring is extended while the other value is the amount of travel you would be able to achieve out of your spring if you were to remove the hooks.

Assisting Diagrams

maximum spring extension example

The amount stated in Maximum Safe Travel Considering Hook Stress is calculated by considering the tightness of the coil forming the hook as well as the tensile strength of the material selected. These values amongst others are what makes our extension spring calculator automatically calculate the stress one the hook after a certain amount of load.

If you want to get the additional amount of travel shown in the Maximum Safe Travel section, you must get rid of the hooks. So how do you extend the spring if you took the hooks off? There are two options, use bolts as hooks or weld the spring ends to the pieces which will be extending them. The way to use bolts is by screwing the bolt into the spring’s inner diameter. Make sure that the bolt’s diameter is a bit larger then the extension spring’s inner diameter so that the coils will be tight around it thus causing it to stay in place and not slip out.

extension spring travel chart

The amount of distance your spring will be able to travel consists of how stressed it is. How stressed your spring will be is based on the proportion of its dimensions. For example, if you have spring with a tight spring index (large wire diameter in proportion to the coil diameter) or a spring that has little coils within its body length, you might have a strong spring but also under a lot of stress which will affect its elasticity. The travel chart shows you what adjustments you can make to your spring in order to get more travel out of it. The spring index diagram shows you what a small index and a large index look like.

large and small extension spring index