Available in unalloyed steel. Minimum order value of £15+VAT. Shipping to the UK only.

extension spring turn bolts

Extension Springs with Turnable Bolts

Our extension springs with turnable bolts allow you to use the spring to its maximum potential without running the risk of breaking. Extension springs are ideal for keeping resistance, especially when linked to components with bolted ends.

You can apply either the extension springs with turnable loops or this series of extension springs with turnable tapered bolts, which can be mounted directly in a threaded bore or fitted with an end mounting.

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As tension spring manufacturers, we can give you guidance on the best product for your application. Please contact us using our online form or directly by calling us on 01604 499332.


TC = No of active coils
R = Spring Rate
F0 = Initial force


EN 10270-1-SH

Max load length and temperature:

Maximum load length EL applies for static or pseudo static loaded springs operating at temperature up to about 40°C. The relaxation, i.e. the power loss over time, will then stay within acceptable values for most applications. At higher operating temperatures or dynamic life demands, more than 10,000 cycles, the spring should not be loaded as far as EL. Maximum permitted operating temperature of unalloyed spring steel EN10270-1-SH is about 120 °C.

To calculate the spring force at a certain length, multiply the travel in mm by the rate (R) + the initial force (F0).

1 kp = 9.80665 Newtons, 1 Newton = 0.10197 kp