Gas Struts: A Complete Engineering Guide 2026
Gas struts are self-contained pneumatic cylinders that provide a controlled extension force and damping effect, using compressed nitrogen to assist in lifting or holding a load. They consist of a cylinder, a piston rod, a piston assembly, and a seal, acting as a force-managed spring system that significantly reduces the effort required to manipulate heavy panels, hatches, or machinery guards.
⚡ In a Rush? Key Takeaways
- Standard industrial gas struts typically offer a cycle life of 50,000 to 100,000 cycles under normal operation.
- Force ratings are measured at 20°C; expect a 1.5% force drop for every 1°C decrease in temperature.
- Always replace struts in pairs to ensure balanced support and prevent asymmetric load-bearing on the hinges.
- Using our gas spring force calculator is the only accurate way to determine your required Newtons.
How Do I Accurately Measure Gas Struts for Replacement?
Measure the eye-to-eye length when fully extended, the stroke length of the rod, and the total diameter of both the body and rod.
What is the procedure for measuring extended length?
Extended length is the distance from the centre of one end fitting to the centre of the other when the strut is fully at rest.
To acquire an accurate measurement, you must place the strut on a flat surface and ensure it is fully extended. Use a digital caliper to measure from the centre point of the top end fitting to the centre point of the bottom fitting. If the strut is worn and won’t stay fully extended, you may need to apply manual pressure to simulate the fully open position before measuring.
How is the stroke length determined correctly?
Stroke is the total distance the rod travels, calculated by subtracting the compressed length from the fully extended length.
The stroke is the active working range of the gas strut, represented by the exposed portion of the rod when fully extended. Simply measure the exposed rod and add approximately 5-10mm to account for the internal stop. Accurate stroke length is vital for ensuring your application opens to the correct degree of travel.
What Parameters Govern Gas Strut Force Selection?
Force is calculated using the weight of your lid, the distance to the center of gravity, and the total number of springs installed.
How does mounting geometry affect the required force?
The distance of the mounting points from the hinge axis acts as a lever; the closer to the hinge, the more force is required to hold.
Geometry is the most overlooked factor in gas strut specifications. Placing the strut mount closer to the hinge pivot requires a higher Newton rating to achieve the same lifting capability. Conversely, moving the mount further away provides more mechanical advantage, allowing for a lower force spring.
Why does ambient temperature influence spring performance?
Nitrogen gas pressure changes with temperature, causing force output to fluctuate by roughly 3.3% for every 10 degrees Celsius variance.
Engineers must account for thermal drift when specifying components for outdoor use in the UK or cold storage. If your application operates in a sub-zero environment, a standard gas spring will underperform, potentially failing to hold the lid open entirely. You must specify a low-temperature grade seal and fluid if the working temperature drops below -20°C.
How Do I Diagnose Common Gas Strut Failures?
Common failure signs include visual oil leakage at the seal, corrosion on the piston rod, or the strut failing to hold the weight.
Why does my strut lose holding capacity over time?
Seal fatigue allows the internal nitrogen charge to leak slowly, resulting in a gradual loss of force that reduces the lifting power.
Gas springs are consumable components with a finite seal life. Even in high-quality units, a very slow diffusion of gas is expected over a 5-year period. Once the internal pressure falls below a specific threshold, the force will no longer be sufficient to counter the load, resulting in a ‘soft’ strut that drifts closed.
What should I check when a strut becomes seized?
Seized struts are usually caused by bent rods, severe corrosion on the rod surface, or internal mechanical failure of the piston.
- Check for visible nicks or scratches on the chrome rod surface.
- Verify the end fittings are not seized due to oxidation or road salt accumulation.
- Ensure the pivot points on the equipment lid are functioning freely.
- Inspect for mechanical damage to the cylinder body itself.
Frequently Asked Questions About Gas Struts
Most common inquiries involve interchangeability, DIY installation safety, and the reasons for using specific end fitting types.
Can I refill a gas strut that has lost pressure?
Gas struts are sealed units and cannot be recharged; they must be replaced entirely once the nitrogen charge has been depleted.
Do I need to replace one or both gas struts?
Always replace in pairs, as the surviving strut will likely fail shortly after due to similar age, stress, and fatigue cycles.
What are the benefits of using stainless steel struts?
316 stainless steel provides superior corrosion resistance for marine, coastal, or high-humidity food processing applications.
If you are unsure of your specific Newton requirement, consult our online force calculator to ensure your setup is safe for daily operation.
