Besides the compression spring, everybody is familiar with the extension spring. The most people could for instance imagine a spring of a trampoline.

As the term extension spring already indicates, this spring is being loaded with extension. The length of the spring increases under influence of a force, and after the removal of this force the spring will return back to its original position.

In order to be able to use these extension springs, loops should be assembled to the spring. These are the ends of a spring, with which the spring can be attached. There are several opportunities for this, therefore, take a look at ‘’Characteristics’’ (below) and the pictures alongside.


Extension springs are also known for their wide range of applications. Certain explicit examples which speak to our visualisation are listed below;

• Trampolines
• Door-springs
• Fitness-tool
• Agricultural machines
• Garage doors
• Machines in general


For extension springs, the same applies as for the majority of spring types manufactured from wire, namely that they are nearly always produced from spring steel quality. The most common materials remain 1.1200 (high carbon spring steel) and 1.4310 (Stainless Steel-spring steel). For other opportunities concerning materials, we refer you to the special page; Material choice.


The most attractive feature of an extension spring is not the spring body itself but rather the way the edges are finished. This determines the manner in which the spring is mounted. There are already lots of different variants to be seen on the pictures whereby it is not particularly the case that the ends should be the same. These springs are, in other words, not always symmetrical.

The most common finishes are the German loops, English loops, double loops, or coned swivel loops. Without getting to detail it must have been said that there are many possibilities concerning these coned swivel loops. Again, this is also to be seen on the pictures.

Extension springs are produced (semi-)automated. Where the majority of extension springs with the wire thickness range of 0,2-10 mm is manufactured, we have the opportunity to process wire/rod to a thickness of about 25 mm.