Extension springs

Extension springs

trekveren tekening

Besides compression springs, extension springs are the most common springs and come in all types and sizes. The basic principle of a extension spring is simple; under the influence of a tensile strength the spring becomes longer and after removing the strength, the spring will go back to its normal position (elastic deformation). This simple mechanical principle has thus ensured that extension springs are widely used and are being used in all kinds of applications. Extension springs are usually manufactured from spring steel (1.1200 – and 10270-1) or from INOX 302 (1.4310 and 10270-3) but of course also other materials can be used.


Spring calculation

The tensile strength that can be generated by a spring depends on the material used and the dimensions. The details lead to the spring constant that indicates the strength per mm of elongation:

c = slide modulus x d⁴/(8 x Dm³ x nw) (Click on the arrow for an explanation)
c = spring constant [N/mm compression]
slide modulus = material dependent
d = wire thickness
Dm = diameter center to center (of the wire)
nw = active windings

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Extension springs are usually fitted with “fixed loop ends”, these loop ends are directly attached to the spring-body by machines. There are several standard possibilities for this, the most commonly used being “German and English loop ends”. The way in which the spring is attached in a system (“loop end” or the suspension) is the weakest point of the spring and therefore the type of suspension or “loop end” depends on the desired lifespan and tension (static/dynamic).


Extension springs from stock

Most standard extension springs are supplied directly from stock and can easily be ordered from our web shop. Please note: all standard extension springs delivered from stock are fitted with a closed “German loop end”. Feel free to fill in our contact form if you have any questions about our spring from stock.

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Custom made extension springs

In addition to our complete stock programme, Alcomex provides the possibility to have extension springs produced custom made. All “custom made” springs are fully adapted to your specific application. If necessary, these springs are fitted with a coating or undergo a surface treatment to make them suitable for your application. The short changeover times of our modern machinery make it possible to also produce custom made lengths in small series, against a competitive price. Contact our technical team. They will be happy to give you advice.

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