Enter Gas Strut Details
Example Data Table
| Application | Lid mass | CG distance | Lid bracket | Body offset | Open angle | Struts | Typical aim |
|---|---|---|---|---|---|---|---|
| Toolbox lid | 12 kg | 300 mm | 190 mm | 100 mm x 80 mm drop | 70 degrees | 2 | Light assisted lift |
| Machine guard | 28 kg | 520 mm | 320 mm | 180 mm x 130 mm drop | 75 degrees | 2 | Stable open hold |
| Vehicle hatch | 38 kg | 610 mm | 360 mm | 210 mm x 160 mm drop | 80 degrees | 2 | Controlled opening |
Gas Strut Sizing Guide
A gas strut looks simple, yet its size depends on leverage. The lid weight is only one part of the job. Mounting positions, opening angle, center of gravity, and safety margin all change the required force. This calculator combines those details in one workflow. It helps you compare brackets before you drill holes.
Why Geometry Matters
A strut does not lift straight up. It pushes along its own center line. The useful lifting effect is the moment created around the hinge. A longer perpendicular distance from the hinge gives better leverage. A poor bracket angle wastes force. That is why two struts with the same rating can feel different on the same hatch.
Formula Used
The calculator first converts the entered mass into weight force. Weight equals mass multiplied by gravity. Closing torque equals weight multiplied by the center of gravity distance and the cosine of the open angle. The strut torque arm is found from the cross product between the lid bracket radius and the strut force direction. Required force equals closing torque plus friction torque, divided by the number of struts, torque arm, and efficiency. The final recommendation applies the selected safety factor and temperature correction.
Stroke and Length Check
The tool also estimates closed and open strut lengths from the body bracket and lid bracket locations. Stroke is the difference between those lengths. A small reserve is useful, because real brackets, ball ends, and tolerances need room. Always confirm the final selection with the strut maker and hardware drawing.
How to Use This Calculator
Enter the lid mass, hinge to center of gravity distance, lid bracket distance, body bracket offset, and opening angle. Choose the number of struts and your safety factor. Add friction torque when seals, hinges, or locks create extra resistance. Press calculate. Review the recommended force, extended length, compressed length, and stroke. Export the result when you need a record for a workshop sheet or client file.
Design Notes
Use this result as a design estimate. Gas springs vary by manufacturer, end fitting, temperature, and orientation. Avoid mounting a strut where it can bind at either end of travel. Check clearance through the swing. Fit paired struts symmetrically when possible.
FAQs
1. What does this gas strut calculator estimate?
It estimates force per strut, open length, closed length, stroke, torque, and a rounded ordering force based on lid weight and bracket geometry.
2. What is center of gravity distance?
It is the distance from the hinge to the balance point of the lid. For a uniform rectangular lid, it is usually near half the lid length.
3. Why does bracket position change the force?
The strut force acts along its own line. A better perpendicular moment arm gives more lifting torque, so less gas spring force is needed.
4. Should I use one strut or two struts?
Two struts are often better for wide lids. They reduce twisting, share load, and help the hatch move evenly during opening and closing.
5. What safety factor should I use?
A factor from 1.1 to 1.3 is common for estimates. Use more margin when hinges are stiff, loads vary, or safety is critical.
6. Why is temperature included?
Gas spring force changes with temperature. Cold conditions can reduce available force, so the calculator can increase the ordered force estimate.
7. Is the calculated stroke the catalog stroke?
No. The calculated stroke is the geometric travel. Add reserve, then choose a catalog stroke that provides enough travel without bottoming out.
8. Can this replace manufacturer drawings?
No. Use it for planning and comparison. Final selection should be checked against manufacturer data, end fittings, clearance, and installation limits.