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  • Everything You Need to Know About Gas Struts

    What are Gas Struts used for? 

    Gas Struts are most often used to assist raising and lowering of hinged doors, such as on a ute canopy or overhead cabinets. They are also used in many other applications such as in office and transportation equipment.

    A black gas strut

    What Size Gas Strut Do I Need?

    Gas Strut Calculator:

    To figure out what Gas Strut you need, all you need to do is a simple calculation. This calculation is for a door opening to 90 degrees.


    If the width of your door is less than 1.5m:

    Height of your door ÷ 2 = Extended Length of the gas strut you need


    If the width of your door is more than 1.5m:

    Height of your door x 0.7 = Extended Length of the gas strut you need


    How to Measure Gas Strut Length?

    I already have one and I want to find one with a similar length. 

    1.  Meaure the extended length of your strut
    2.  Match it with the extended length (G) in Co-Mac's range of gas struts.
    3.  Because Co-Mac's gas struts are adjustable, you can calibrate them to what you need

    Co-Mac's gas strut length is measured from the centre of the ball joint at each end. If you want to replace an existing gas strut, measure the length of your strut from the centre of each ball joint.

    If your gas strut does not have ball joints, measure the length of the gas strut with no end attachments.

    How to Calculate Gas Strut Length modules/SP_webshop/ products.php?cat=1546?

    If you cannot find a gas strut with exactly the same size, find the closest size up or contact us

    There should always be 2 gas struts installed per door. This ensures that equal weight is on each end of the door when opening. Having only one gas strut on a door can warp or damage your hinge.

    Because of this it is also important to install 2 gas struts with the same length and pressure on both ends of the door. This means that both ends of the door open to the same height.

    Gas Strut Installation Made Simple:


    How to Install a Gas Strut?

    Warning: Gas struts can be dangerous, please take all health and safety concerns and precautions into account when installing the gas struts.

    Once you have found the gas strut in our range that will fit your door, it is time to install it.


    1. The first step is to carefully prop the door in the open position. For most hinged doors this will be 90° to the closed position. 
    2. On the gas strut chart, you will see a length at 90° (P) Measurement. This is the distance from the rotation point of the hinge to the top mounting point of the gas strut.  
      How to find the P dimension
    3. Mount the top of your gas strut at this point. It is important to mount your struts with the bigger tube at the top as shown above. 
    4. Once the top of the strut is mounted swing the bottom of the gas strut to the side of the body as shown below. Using it to determine where your bottom mounting point should be. Mount the bottom of the gas strut at this point. 
      Image showing how to find the bottom mounting point of the gas strut
    5. Once the gas struts are in place it should be safe to remove the prop holding the door open. The gas struts should now be holding the weight of your door. 
    6. Adjust the gas struts to suit the weight of your door. Co-Mac’s gas struts are adjustable, allowing you to let the pressure down until it suits the weight of your door.


    Using the provided Hex Key, quickly open and shut the valve at the top of the strut. One open and shut equals one pulse. We recommend releasing gas in short sharp pulses. Remember to do the same amount of pulses on each gas strut on your door. Test regularly to see if the struts have reached the right pressure.

    How to adjust a gas strut, quickly opening and closing the valve equals one pulse

    To avoid releasing to much gas we recommend adding a little weight to your door when adjusting the struts. Do 3-5 pulses on each side and test often to ensure you don’t let too much gas out of the strut. Remember, you can always let more gas out, but you can’t add it back in.


    I have let too much gas out of my struts, what should I do?

    If too much gas has been released from the struts, they will be too weak to open your door. If this happens you will have to send them back to Co-Mac to be re-gassed. We are only able to Re-Gas Gas Struts from our range.


    My Gas Strut will not compress, what should I do?

    If your gas strut will not compress you need to let more gas out of it. The pressure is too high for the strut to compress under the weight of the door.

    If all the gas has been released out of the strut and it still won’t compress it is likely that your struts have been overextended. This usually happens if wind has wrenched the door open, forcing the piston of the strut past the safety ring and jamming the strut in the open position. If this has happened you will need new struts as overextended struts are not safe to use.

    How to Calculate the Kg Needed In a Gas Strut?

    If you want to calculate the Kg needed in a Gas Strut please follow the instructions on this free PDF

    How to Calculate Kg Needed
    for a Gas Strut

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