Gas Struts with Welded Ends

Gas Springs with Welded Eye Ends

Gas springs with eye ends support the controlled opening, lifting, holding and lowering of flaps, lids and movable components. The Nitrider® W series has permanently welded eye ends at both ends and can therefore be mounted directly onto suitable pins or brackets without additional end fittings.

The gas spring contains pressurised nitrogen, which generates an extension force and pushes the piston rod outwards. An oil filling lubricates the seals and, depending on the installation position, can also provide damping near the end of the stroke.

Gas springs with eye ends are particularly suitable as replacements for existing gas springs with fixed connection dimensions. Use the product table above to select a suitable version by dimensions, stroke, eye diameter, spring force and reference number.

Meaning of the Specifications in the Product Table

A matching reference number makes it easier to find a replacement. However, the length L, stroke St, eye diameter B and spring force F1 should still be compared with the existing gas spring before replacement.

How to Select the Right Gas Spring

Proceed in the following order:

1. Check the existing gas spring: Look for a manufacturer or article number printed on the cylinder. Use the “Replacement for” column to search for a matching reference number.

2. Measure the extended length: Measure the distance between the mounting points with the gas spring fully extended.

3. Determine the stroke: Establish the difference between the extended and compressed lengths.

4. Check the eye diameter: The holes in the eye ends must fit the existing mounting pins.

5. Compare the spring force: Where possible, select the same force in newtons as the existing gas spring.

6. Check the installation space: Make sure that the cylinder and piston rod have sufficient clearance throughout the complete movement.

7. Check the mounting points: The eye ends must sit on the pins without distortion and must be able to align with the movement.

A gas spring should not be selected by length alone. Even small differences in stroke, spring force or mounting geometry can significantly change the opening and closing behaviour.

Spring Force and Force Characteristics

The value F1 stated in the product table is the nominal force near the fully extended position. When the piston rod is compressed, the gas inside the cylinder is compressed further. The spring force therefore increases over the stroke.

Friction also occurs between the piston rod, seal and guide. The force required to compress the gas spring is therefore slightly higher than the force with which it subsequently extends.

The required spring force depends on more than the weight of a flap. The following factors are also important:

• position of the centre of gravity,

• distance between the centre of gravity and the hinge,

• position of the mounting points,

• installation angle of the gas spring,

• desired operating force,

• use of one or two gas springs.

For a direct replacement, the same spring force should normally be selected. For a new design, the required force must be calculated using the complete installation geometry.

Comparison with Gas Springs with Threaded Connections

With gas springs featuring threaded connections, the end fittings can be changed and adapted to different mounting arrangements. The eye ends of the W series are permanently attached to the gas spring.

This design offers several advantages:

• no additional end fittings are required,

• fixed and clearly defined installation length,

• quick and straightforward installation,

• fewer individual components,

• suitable as a replacement for existing gas springs with eye ends.

However, the eye ends cannot be replaced with another type of connection. Where the hole diameter or mounting geometry does not match the application, a gas spring with threaded connections is usually the more flexible solution.

Installation and Safety Recommendations

Gas springs are under high internal pressure. They must not be opened, drilled, heated, welded or mechanically modified.

For reliable operation, we recommend:

• installing the piston rod pointing downwards in the closed position wherever possible,

• applying the load only in the axial direction,

• avoiding lateral loads, misalignment and distortion,

• using suitable mounting pins with smooth, burr-free surfaces,

• allowing sufficient lateral clearance for the eye ends,

• protecting the piston rod against scratches, dirt and paint,

• providing sufficient stroke reserve,

• not using the gas spring as a mechanical end stop.

Two gas springs are often installed symmetrically on wide or heavy flaps. The mounting points must be designed so that both gas springs are loaded as evenly as possible.

Where accidental closing could endanger people, an additional mechanical safety device must be provided. A standard gas spring is not a self-locking safety support.

Temperature and Service Life

The nominal force is specified at a defined reference temperature. As the temperature rises, the gas pressure and extension force increase. At lower temperatures, the force decreases.

Service life depends strongly on the actual operating conditions. Dust, dirt, lateral loads, damaged piston rods, frequent operation and significant temperature fluctuations may cause premature wear or loss of force.

The piston rod should therefore be kept clean and must not be treated with grease, adhesive or aggressive cleaning agents.

Custom Spring Force and Returns

The gas springs are filled to the spring force selected when ordering. This creates an individually configured product.

The length, stroke, eye diameter and spring force should therefore be checked carefully before ordering. Gas springs filled to a customer-specific force generally cannot be returned or exchanged for a different force rating.

Further information about design, selection, installation position and maintenance can be found in our Gas Spring FAQ.

Frequently Asked Questions About Gas Springs with Eye Ends

What does length L mean?

L is the fully extended length between the mounting points of the two welded eye ends.

Can the welded eye ends be replaced?

No. The eye ends are permanently attached to the gas spring. Gas springs with threaded connections are more suitable where interchangeable end fittings are required.

Can I replace a gas spring using only the reference number?

The reference number is an important guide. However, the length, stroke, eye diameter and spring force should also match the existing gas spring.

Can the gas spring be used as an end stop?

No. The application requires separate mechanical end stops and sufficient reserve before the maximum stroke is reached.

Why should the piston rod point downwards?

This installation position helps lubricate the seal and may improve end-of-stroke damping.