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LA40 QR Damper - Quick Release with Comfort

To help improve ergonomics for care staff and to help increase comfort for bedbound patients, LINAK® has developed a unique internal damper function for the linear actuator LA40 QR.

This actuator is often used to adjust the backrest in multiple types of healthcare beds, where the Quick Release function can be essential in emergency situations. The damper helps staff retain the emergency lowering of the backrest while at the same time ensuring a quick, yet comfortable lowering experience for the patient.

What to consider when testing the LA40 QR Damper in your healthcare application

  • We recommend a minimum 30-minute cool-down period between activations
  • The type and size of testing weights will affect the performance of the actuator
  • The position of weights on the backrest will affect the performance of the actuator
  • Using weights instead of a real person will give different test results as the damper is designed for real life use


What is the recommended duty cycle of an LA40 QR Damper to be respected in order to have the same performance each time it is activated?

A cool-down time of minimum 30 minutes is recommended (recommended 60 minutes) between each activation for reliable test results. If this is not respected, the damping feature will be reduced as the heat inside the damper increases. This will result in a faster angular lowering speed of the back rest since there is less resistance in the total actuator system.

What is the effect of using the LA40 QR Damper with very high intermittence/frequency?

This will result in faster angular speed, since there is less resistance in the total actuator system. This will also cause the liquid inside the damper to get too hot and will eventually solidify and the damper will break.

Can dead weights be used to test the LA40 QR Damper performance?

Please note that the position and the use of the dead weights have a significant impact on the performance of the LA40 QR Damper.
The most realistic test results can be obtained by using a real person as test subject on the application.

Dead weights can be used to test the LA40 QR Damper on the application, if the weight distribution of these on the frame is ensured to be as close as possible to the weight distribution of a person.
Avoid unrealistic placing of the dead weights. This could for example be placing all dead weights on the top or middle part of the back frame. If doing so, retraction will be much faster.

Note that the dead weight will always have a faster lowering speed compared to person weight due to the different weight distribution on the bed frame's kinematic.

Does the damping resistance increase with more load?

No, the damper resistance always applies a constant resistance moment. This means that with a higher load on the frame, a higher lowering speed will be obtained.

Should the LA40 QR Damper be tested on an air giraffe or on a pneumatic system?

LA40 QR Damper should not be tested on an air giraffe or on a pneumatic system. Testing in this way will lead to inaccurate test behaviour/results.

Please be aware that you need an external application feature to stop the fast movement, the mechanical end stop inside the actuator is not designed to stop any Quick Release movement.

Why does the back rest of the application lower too fast?

If the recommended cooling time between each activation is not observed, the lowering speed will be faster each time the damper is activated. If the actuator is subjected to a higher load than specified, it will result in higher lowering speed.

Why does the back rest of the application lower too slowly?

This could be due to a low load on the actuator, but not a specifically low load on the application, for instance high back frame angle on the bed. In this way, the damper may not engage at all or engage with some intermittences.

What is the minimum weight required on the backrest to activate the damper?

Due to the different mechanical kinematics of each application and the spindle pitch, it is not possible to indicate a minimum weight to be placed on the frame that will activate the damper. Instead, the force on the actuator can be indicative and a force of between 750 - 1300 N is needed to activate the damper.

What will activate the damping function?

The damper will engage with a mix of acceleration and at a high spindle rotation speed.

Does the rotary damper travel along the spindle as the actuator extends and retracts? Is its travel distance limited mechanically in any way? Is it constantly rotating as the actuator is moving?

The damper is connected and rotates with the same speed as the spindle at all times.

When the stroke movement reaches a speed that is high enough, it will engage the damping feature.

The damping feature is not limited to any stroke position, it can be activated at all stroke positions.

What type of damper is used in LA40 QR Damper? Could another type of damper be used?

There is only one type of damper, which is a damper filled with silicone oil.

Is it possible to adjust the coupling point to a specific stroke position?

No, this is not possible. The coupling point is related to lowering speed and not stroke length.

What happens if the coupling mechanism of the damper breaks down?

If it breaks down, the remaining actuator functions will work as normal, and there is therefore no added safety hazard. However, there may be unexpected noises during movement depending on how the mechanism fails.

Does the damping function have any impact on the lifetime usage?

No, the damping feature follows the standard QR lifetime usage.

Why can a clicking sound be heard when the damper engages?

This sound is standard when engaging the damper. The damper is built on a sling clutch principle, where the damper resistance load is transferred between two metal parts resulting in a clicking sound every time the damper activates.

Does LA40 QR Damper make more noise than an LA40 QR?

The damping feature does not make any additional noise compared to LA40 QR version.

When the damper feature engages, a low clicking sound can be heard. If the load is too light, the damping feature will disengage and will engage again when the speed is high enough.

A clicking sound will occur every time the damper feature engages.

Are there any 3D models to better visualise how the actuator functions?

Yes, for internal use. Please contact the Sales Application Engineer responsible for supporting your subsidiary for further information.


LA40 data sheet

View the data sheet as an online magazine or download the PDF.

LA40 QR Damper - quick release with comfort

With the LA40 Quick Release with Damper you improve safety for care staff and increase comfort for bedbound patients.

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