Garter Springs

Garter Springs for Uniform Radial Tension

Garter springs are closely wound extension springs whose ends are joined together to form a closed spring ring.

When the spring ring is expanded during installation, the garter spring attempts to contract again. This creates a uniform inward-acting tension around the entire circumference. Garter springs are therefore particularly suitable for rotary shaft seals, sealing elements and other circular applications.

They can, for example, press a sealing lip continuously against a shaft while compensating for wear, dimensional changes or changes in the sealing material.

Use the product table above to select a suitable garter spring by spring body diameter, wire diameter, installed inside diameter, active length and internal initial tension.

Meaning of the Specifications in the Product Table

The internal initial tension F0 is a characteristic of the straight spring body. It does not directly correspond to the radial contact force acting on a shaft or sealing lip after installation.

The actual radial force also depends on the installed diameter, the amount of expansion, the spring geometry and the installation conditions.

How to Select the Right Garter Spring

Consider the following points when selecting a garter spring:

1. Determine the installed diameter: Select the inside diameter Di to suit the intended installation dimension.

2. Check the available space: Make sure that the outside diameter Da of the spring body fits into the existing groove or mounting space.

3. Consider the expansion: Determine how far the spring ring will be expanded in relation to its original diameter during installation.

4. Select the initial tension: A higher internal initial tension may result in a greater tensioning effect. However, the actual radial force must be assessed for the specific installation.

5. Check the operating conditions: Consider temperature, humidity, contact with media and the required service life.

6. Check the connection: The spring ends must be securely joined after installation and must not separate under load.

A garter spring should not be selected solely on the basis of the shaft diameter. The geometry of the sealing lip, the installation groove and the required contact force must also be considered.

Cutting and Installing Garter Springs

Garter springs are available in various standard lengths. Depending on the version, they can be shortened and then joined to form a closed ring.

Shortening the spring changes both the installed ring diameter and the force characteristics. The required length should therefore be determined from the desired installation diameter before the spring is cut.

It must also be checked whether the intended end connection can still be produced safely after shortening. The connection point should be fully closed after installation and must not have any sharp edges that could damage the surrounding component.

Stainless Spring Steel 1.4310

The garter springs in the Febrotec standard range are manufactured from stainless spring steel 1.4310, also known as X10CrNi18-8.

The material provides good corrosion resistance for many industrial applications and humid environments. It has limited suitability for permanent contact with seawater or media containing high levels of chloride.

Due to cold forming during spring manufacture, the material may be slightly magnetic. At elevated or very low temperatures, the required spring force, load duration and environmental conditions must also be considered.

Typical Applications of Garter Springs

Garter springs are commonly used in:

• rotary shaft seals,

• sealing lips and sealing elements,

• shaft and piston seals,

• small electric motors,

• circular tensioning and retaining devices,

• electrical contacts and connectors,

• movable clamping jaws,

• drive and transmission components.

In rotary shaft seals, the garter spring helps maintain uniform contact between the sealing lip and the shaft. This can partially compensate for wear and for temperature- or ageing-related changes in the sealing material.

Custom Garter Springs

In addition to the standard dimensions available from stock, garter springs can be manufactured according to individual requirements.

Customisable characteristics include:

• wire diameter,

• outside diameter of the spring body,

• active length,

• installed ring diameter,

• internal initial tension,

• material,

• connection of the spring ends.

For a technical enquiry, please provide information about the required installed diameter, available installation space, required tensioning effect, materials of the adjacent components and operating conditions.

Frequently Asked Questions About Garter Springs

What is the difference between a garter spring and a conventional extension spring?

A conventional helical extension spring transmits force between two attachment points. A garter spring, in contrast, is joined to form a closed ring and generates a radial tension acting around the circumference.

What does the installed inside diameter Di mean?

The value Di describes the inside diameter of the closed spring ring in its joined, unexpanded condition. When the spring is installed on a larger diameter, it is extended and generates an inward-acting tension.

Is the internal initial tension F0 the same as the radial contact force?

No. F0 describes the internal tensile preload of the spring body. The radial contact force in the installed condition also depends on the installed diameter, the amount of expansion and the installation conditions.

Can garter springs be shortened?

Depending on the version, garter springs can be shortened and then reconnected to form a ring. However, this changes the installed diameter and the force characteristics. The required length should therefore be determined before cutting.