Lockable Gas Springs

Locking Gas Springs for Stepless Positioning

Locking gas springs combine the supporting force of a conventional gas spring with the ability to lock continuously at any position within the stroke. They can assist with lifting, lowering or adjusting a movable component and then hold it at the required position.

An internal valve is operated by a release pin. While the release pin is pressed, the piston rod can move in or out. When the release mechanism is released, the valve closes and the gas spring locks in its current position.

Locking gas springs are suitable for adjustable seats, backrests, treatment tables, desks, machine covers, control panels and medical equipment. A suitable release system is also required, such as a direct lever or Bowden cable.

Use the product table above to select a suitable version by piston rod diameter, cylinder diameter, length, stroke, extension force, valve, series and connection thread.

Meaning of the Specifications in the Product Table

The extension force F1, locking force and release-pin operating force are separate values. All forces relevant to the application must be checked for safe design.

How the Locking Function Works

When the valve is open, gas or the internal operating medium can flow between the working chambers. The piston rod can then move while the gas spring partially balances the weight of the application.

When the release pin is no longer operated, the valve closes. The internal flow is interrupted and the piston rod remains at the selected position.

The release system must be designed so that:

• the release pin is operated through a sufficient distance,

• the valve can close completely after release,

• no permanent residual actuation remains,

• the lever or Bowden cable operates without jamming,

• the operating force is suitable for the user.

An incorrectly adjusted release system may prevent the gas spring from moving freely or from locking reliably.

How to Select the Right Locking Gas Spring

Proceed in the following order:

1. Determine the installation lengths: Measure the distance between the mounting points in both end positions.

2. Define the required stroke: The required adjustment range must remain within the maximum stroke St.

3. Determine the extension force: Consider the weight, centre of gravity, lever arm, mounting position and number of gas springs.

4. Determine the locking force: Establish the maximum load that may act while the gas spring is locked.

5. Select the locking type: Decide whether slight elastic movement is acceptable or whether the position must be as rigid as possible.

6. Check the load direction: Determine whether the highest load acts in extension or compression.

7. Select the release system: Consider the operating travel, release force, available space and the required Bowden cable length.

8. Select the end fittings: Choose ball joints, eye ends or clevis ends according to the movement and connection thread.

9. Check the operating environment: Consider temperature, humidity, dust, cleaning agents and other surrounding media.

The required extension force cannot be determined from the weight of the movable component alone. The centre-of-gravity position, mounting points and installation angle have a major influence on the effective torque.

Difference from Standard Gas Springs and Locking Tubes

A standard gas spring supports movement but cannot hold the application at any chosen position within the stroke.

A locking tube mechanically secures a gas spring only in the fully extended end position. It cannot hold intermediate positions.

A locking gas spring can be moved within its adjustment range after the release mechanism is operated and then locked at the required position.

It is therefore the appropriate choice where stepless adjustment is required. If only the fully open position needs to be secured mechanically, a locking tube may be the more suitable solution.

Installation and Safety Recommendations

Locking gas springs are under high internal pressure and must not be opened, drilled, heated, welded or mechanically modified.

For reliable operation, we recommend:

• applying the load only in the axial direction,

• avoiding lateral forces, distortion and misalignment,

• using sufficiently articulated end fittings,

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

• providing separate mechanical end stops,

• not exceeding the maximum stroke,

• checking the release system throughout the complete stroke after installation,

• selecting the installation position according to the locking type.

Before commissioning, verify that the gas spring locks securely at every intended position and releases fully when operated.

Locking gas springs must not be used as the sole safety device without further assessment. If unintended lowering or closing could endanger people, additional mechanical safety measures are required.

Typical Applications

Locking gas springs are commonly used in:

• seat and backrest adjustment systems,

• medical treatment tables and therapy equipment,

• height- and angle-adjustable desks,

• machine covers and control panels,

• ergonomic workstations,

• rehabilitation and care products,

• furniture and adjustable beds,

• special-purpose and commercial vehicles.

The gas spring, release system, end fittings, brackets and mounting points must all be matched to the application.

Further information on design, calculation and installation can be found in our Gas Spring FAQ.

Frequently Asked Questions About Locking Gas Springs

Can a locking gas spring hold at any position?

In principle, it can lock continuously at any position within its usable stroke. However, the permissible load and remaining movement depend on the locking type and product design.

Is F1 the locking force?

No. F1 describes the extension force of the gas spring. The permissible locking force is a separate value.

What happens when the release pin is pressed?

The release pin opens the internal valve. This allows the piston rod to move. When the release pin is released, the valve closes and the gas spring locks in position.

Do I need a separate release system?

Usually, yes. Depending on the application, the gas spring may be operated using a direct lever, Bowden cable or another mechanical release system.

Can a locking gas spring be used as an end stop?

No. The application requires separate mechanical end stops and sufficient stroke reserve.