Question 1

What is a gas spring?

Accepted Answer

A sealed cylinder containing nitrogen gas under pressure and a small amount of oil. The gas pushes against a piston to produce a near-constant extension force, and the oil damps the movement at the end of the stroke so the panel does not slam. Unlike a coil spring, the force stays roughly the same across the whole travel.

Question 2

How do I work out the force I need?

Accepted Answer

Use the calculator. It needs the panel length, its weight, and the distance from the hinge to the centre of gravity, then works out the force per spring from a moment balance about the hinge. Guessing from a similar installation rarely works, because force depends on where the brackets sit as much as on the weight.

Question 3

What is the difference between a standard and a lockable gas spring?

Accepted Answer

A standard spring pushes continuously and holds the panel only at full extension. A lockable spring holds at any point along the stroke until a release valve is actuated. Use lockable for anything a person works underneath — machine guards, engine hatches, hospital beds — where the panel must not drop.

Question 4

One spring or two?

Accepted Answer

Two, for anything wide. A single spring on a wide panel twists it and loads the hinges unevenly. As a rule of thumb, panels wider than about 600 mm should use a pair, sized so each carries half the load.

Question 5

How long should the spring be?

Accepted Answer

Extended length usually works out at 55–70% of the panel length, with the bracket on the panel about 20% of its length out from the hinge. If your geometry gives a much shorter spring, the wall bracket is probably too close to the hinge — that reduces leverage and forces you into an unnecessarily strong spring.

Question 6

Which material should I choose?

Accepted Answer

Steel for indoor and protected outdoor use. Stainless 304 for freshwater marine, washdown, and food processing. Stainless 316 for saltwater and anything permanently weather-exposed — it resists chloride pitting, which is what destroys a rod seal in a marine environment.

Question 7

How do I measure a spring I am replacing?

Accepted Answer

Measure the extended length pin-to-pin — centre of one mounting hole to centre of the other, fully extended. Then measure the compressed length the same way, or the exposed rod length. Finally measure the rod diameter with calipers; it will be 6, 8, 10, or 14 mm. Those three figures identify almost any spring. The Replacement Finder does the matching.

Question 8

Why did my old spring fail?

Accepted Answer

Usually the rod seal. A pitted or scratched rod destroys the seal as it passes through, and the gas escapes. Corrosion is the most common cause outdoors, which is why stainless is worth the extra cost in marine and road-salt environments. Springs also weaken gradually — losing perhaps 10% of force over their service life is normal.

Question 9

Does temperature affect the force?

Accepted Answer

Yes, by roughly 3% for every 10 °C. A spring sized in a warm workshop feels noticeably weaker outdoors in a Canadian winter. Above 80 °C a standard seal pack starts to fail, so under-hood applications need a high-temperature build.

Question 10

Should I replace both springs at once?

Accepted Answer

Yes. A new spring working against a tired one loads the hinges unevenly and the panel sits crooked. Springs are inexpensive relative to the labour of fitting them, so replace in pairs.

Question 11

Which way up should a gas spring be mounted?

Accepted Answer

Rod down, wherever possible. The oil pools at the bottom of the cylinder, and keeping the rod at the low end means the seal stays lubricated. Mounting rod-up shortens service life.

Question 12

What are typical lead times?

Accepted Answer

Catalogue sizes in steel usually ship within one to two weeks. Custom force ratings, stainless, and high-temperature builds are typically three to four weeks. Tell us your deadline when you request a quote and we will confirm.

Resources

Sizing a gas spring

Finding a replacement

Building an assembly

Frequently asked questions

Still not sure?