Manufacture of tension springs

Loop springs

Tension springs are helical springs which oppose an axial force the elongation of the spring. They are shortest when at their free length. Very often, the coils of tension springs are joined at rest. To exert a force on a tension spring, its ends are fitted with eyelets or hooks. In addition to cylindrical tension springs, conical hourglass-shaped or convex barrel-shaped tension springs are also manufactured.

Home | Springs | Tension springs

Tension spring applications

German and English loops

Tension springs are generally fitted with loops or hooks, the choice of which depends on space constraints and fixing requirements. There are two main categories of ends: German loops (single or double, with the start on one side) and English loops (centred in the axis of the spring). CGR can help you choose the most suitable fastening method.

Tension spring specifications

Spring preload

The preload of a tension spring is the initial tension inside the spring when it is at rest, i.e. unstretched. Unlike a compression spring, which begins to act as soon as it is crushed, a tension spring requires a certain minimum force to be applied before it begins to stretch. Pre-tensioning eliminates mechanical play between the spring and the mechanical parts, improves the precision of the system, and increases its durability and resistance to premature fatigue.
CGR relies on its STRAIN advanced research laboratory to develop specific technical solutions for the complex problems of dimensioning and manufacturing tension springs.

I have a project

FAQs

1How do you choose the right tension spring?

Choosing the right tension spring depends on your application's required load, extension, available space, operating environment, and durability requirements. The right spring is defined by its dimensions, spring rate, material, and end configuration to ensure reliable performance throughout its service life. For demanding industries, a custom-engineered solution is often the best choice. We work with customers from the design stage to develop tension springs that meet their exact technical and manufacturing requirements.

2What is the initial tension of a tension spring?

The force supplied by a compression spring and tension spring is from a torsion effect. In tension springs because they are close coiled, we can apply a pre-torsion opposite the direction of applied load giving an initial load to overcome before the deflection starts. We call this Initial tension.

3What type of loop is best suited for heavy loads?

There are a few tactics we can employ for heavy loads or safety critical applications. We can block the spring from overextending, have a fail to safe design or as in the mooring lines for yachts utilize a compression spring when loads are unpredictable.

4How can the fatigue resistance of tension springs be improved?

We would study the stress characteristics and stress map the application. From this study we can use a number of solutions to improve fatigue life.

5What are the best materials for corrosive environments?

The choice of material to make the spring from is down to the environment the spring operates. We have materials used on ships at sea, chemical facilities, nuclear power plants, sour gas, engines, inside the human body, the list is as varied as the world and space is diverse. Each environment has its challenge with an engineered material solution for the spring maker to choose.