How to Calculate Gas Strut Position

how to calculate gas struts position

In our previous articles, we covered how to measure gas struts and how to install gas springs. Today, we’ll show you the gas spring installation calculation, as they say, Give a man a fish, and you feed him for a day. Teach a man to fish and you feed him for a lifetime.

The calculation method is also very simple and will be explained in three steps.

1. Determine the Extended Length

When choosing gas struts to keep the trunk, hood, fishing rod locker, windows, benches, or storage boxes open, let’s illustrate this with the example of opening the hatch to a 90° angle. For the gas spring extended length, we can estimate it to be about 60% of the hatch height, which should not be less than half of the door height. For example, if a hatch door is 30 inches high, then lift supports extended length of 15-18 inches are suitable.


2. Determine the Ideal Mounting Position

For gas shocks of various specifications, we have detailed the specific mounting position that we consider optimal in the installation instructions. In practice, it’s important to note that the installing position is not the only option, you can adjust them based on our needs and different situations. In general, the distance from the upper installation point to the hinge (a) should be shorter than the distance from the door’s center point to the hinge (b).

3. Determine the Force

After determining the gas spring’s extended length and mounting position, we can calculate and confirm the required gas spring force.

To ensure gas struts last longer, it’s important to select a pair that distributes force evenly and avoids strain. In the figure below, we have marked some installation points.
A refers to the top mounting point of the shock;
B refers to the installation point of the box hinge;
M refers to the center point of the door height.

Additionally, you can refer to the explanations of the labeled letters in the lower left corner of the image.
The letter ‘a’ represents the distance from the top installation point A to the box hinge (B);
The letter ‘b’ represents the distance from the center point (M) of the door height to the box hinge (B). This distance is equal to half of the door height;
The letter ‘c’ represents the distance from the bottom installation point to the hinge (B);
The letter ‘G’ refers to the gravity of the door, expressed in Newtons, i.e. G = mg = m * 9.81. It is important to note that the units for ‘a’, ‘b’, and ‘c’ are all in millimeters. The calculation formula is F = G * b / (c * 2).

How to Calculate Gas Strut Position? Using the fomula will help you choose the right gas strut.

Next, I will demonstrate the calculation using an example. Suppose we have a cabinet with a door height of 18 inches / 457.2mm and a weight of 10kg. We need to place it 1/3 of the door height from the hinge. The measurements are: a = 6 inches / 152mm, b = 1/2 * door height = 9 inches / 228.6mm, c = 5 inches / 127mm.
Therefore, L 1= 60% * 18 = 10.8; L 2 = 50% * 18 = 9.
Thus, we can choose a support rod with a length between 9 and 10.8 inches. F = 10 * 9.81 * 228.6/ (127*2 )=22425.66/254= 88.29N

From the given information, we require gas struts that have a force of at least 88N or higher. In this case, we can directly choose a pair of Apexstone 10-inch 100N gas springs, which will help us easily lift the cabinet door.

Please understand that there is a margin of error in this calculation result. We have practiced it extensively and consider this method quite reliable. It can help you choose the right gas struts for effective door lifting, even if you lack prior experience. If you have any questions, please don’t hesitate to email us at [email protected], we’re here to discuss and assist you.

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