A Volute spring is a compression spring

Spring (device)

A spring is an elastic object used to store mechanical energy. Springs are usually made out of spring steel. Small springs can be wound from pre-hardened stock, while larger ones are made from annealed steel and hardened after fabrication...

 in the form of a cone (a Volute

Volute

A volute is a spiral scroll-like ornament that forms the basis of the Ionic order, found in the capital of the Ionic column. It was later incorporated into Corinthian order and Composite column capitals...

). Under compression, the coils slide past each other, thus enabling the spring to be compressed to a very short length in comparison to what would be possible with a more conventional helix

Helix

A helix is a type of smooth space curve, i.e. a curve in three-dimensional space. It has the property that the tangent line at any point makes a constant angle with a fixed line called the axis. Examples of helixes are coil springs and the handrails of spiral staircases. A "filled-in" helix – for...

 spring.

The shape of the initial spring steel (or other material) is a "V", with the ends of the V at either end of the wound spring (which forms a distorted cylinder, of wider diameter at the centre), and the bottom point of the V at the centre.

Such springs can frequently be found as a component of garden secateurs. Short posts anchored in each side of the handles, and inserted into each narrow end of the spring, retains the spring in position.