Gas struts or springs are used in caravans and RVs for helping to lift and hold heavy things like the roof of a pop-top or an island beds for storage.

There are many types of Gas Struts and it is important to use the right one. This is a quick guide to help you choose.

The main things that vary between the Struts are the Strength, the Extended Length, and the Compressed Length. Other things that may be a choice are the Shaft size and the Ball Joint size. The most commonly used ball joint on RV's are 10mm.

On this website we name our Struts with a format like:
Gas Strut, 525mm > 305mm, 350N, 8mm Shaft with 10mm Ball Joint Ends.

In this case the
Extended Length = 525mm
Compressed Length = 305mm (Extended - Stroke)
Strength = 350N (which is about 35kg)

How To Install.

In the below example the uncompressed strut is 130mm. The position of the fixed end is around 130mm from the hinge point.

If the strut can compress by 50mm then the moving end can be mounted upto 50mm from the hinge. The further away from the hinge point the less it will open but the push will be stronger.

How To Work Out What Strength You Need.

If you are replacing an existing strut the strength (N) should be printed on the strut you have. Otherwise...

The easiest way to guess the lifting weight required for a gas strut, is to use a set of bathroom scales, and length of timber.

Pick the position where you think the gas strut will be located and place the timber and scales there. This will show you the weight that is being applied in that position. If for example the scales read 20kgs then you need at least a 200N (20kgs x 10) strut to hold the weight.

Remember to take into consideration any extra weight such as a matress.

It is important to select the correct length of strut that will open to the desired height, but also allow the stroke to fully close.

Advanced: The Scientific Method.

For those who would like to try a more mathematical approach to working out the strength then please study the formulas presented.

F1 = G x XG
F2 = A x F1 x LS

Z = length of lid from pivot (hinge) point in millimetres.
XG = Centre of Gravity in millimetres.
G = The weight of the lid in Newtons. 1Kg is 9.8N (Round this to 10 Newtons).
LS = Radius of Gas Spring Force in millimetres.
A = Number of gas springs per application. We recommend using two for most applications such as island beds