Tension Springs

What are Extension Springs?

Tension springs are often manufactured to carry an initial tension, allowing them to store energy and exert a ‘pull’ force when subjected to extension forces. The stored energy in the springs create resistance, and the spring tries to pull back to its original shape. The tensile stresses that an extension spring is exposed to are caused by axial loading and bending.
Tension spring functionality relies on the pull forces exerted by external forces, and as a consequence, extension springs have attachment points that enable them to have these pulling forces exerted. These are referred to as hook ends, and quite often, these come in the form of loops. Here at Metrol, our springs are subject to rigorous quality control to ensure you can have confidence they will operate well in your required application.

Tension Spring Applications

This type of spring is often used in loft hatch installations, garage doors, or products that use lever-based mechanisms to provide a return force.

Unalloyed Spring Steel and Stainless Spring Steel Options Available

Metrol manufacture tension springs using two main materials, unalloyed spring steel and stainless spring steel. When reviewing the range, tensions springs that use unalloyed spring steel have an Ln (the permitted extended length for dynamic load) that applies at 40°C. If this is abided, the relaxation (power loss over time) will stay at acceptable values for most applications. For unalloyed spring steel, if this temperature is exceeded or the springs have dynamic life demands (more than 10,000 cycles), they should not be loaded as far as the stated Ln. For stainless spring steel, the standard operating temperature that will maintain relaxation at accepted values is 150°C. Similarly to unalloyed spring steel manufactured springs, if stainless steel springs are used in temperatures above this or with dynamic life demands, loading must also not reach Ln. Following these guidelines will help you get the most from your springs, enhancing longevity and overall spring lifespan.

Please Read the Details Provided for the Individual Tension Springs

Take a look at the tension spring categories to find out more information, then select your desired wire diameter, free length and spring force using the filter option. You will find a PDF attachment available at the product level that will take you to our extension spring catalogue. Please make sure you are happy and understand the tolerances and suitability of the springs before purchasing. We are very happy to assist you if you require any further information or assistance.

Made-to-Order Springs

We can also design and create custom extension springs. Simply specify your spring type, then let us know your required technical information, and one of our friendly team will be in touch to discuss and refine your requirements.

Order Online Today

Providing the springs you need are in stock, you can expect Next Day or Express delivery for orders to the UK (working days only). We also provide international shipping via our DPD courier. We are confident we have what you’re looking for in our extension spring range, but if you can’t find an item, please contact us, and we will be happy to help.