Gas Springs & Fittings

CT-GS nitrogen gas springs (also called gas struts, gas props or lift supports) hold up lids, hatches, cabinet doors and machine guards with near-constant force over the whole stroke. Sizes in stock: 9.84 in (250 mm), 10 in, 12 in and 14.76 in (375 mm) extended, with forces from 50 to 500 N (about 11 to 110 lb), depending on size. 10 in and 12 in are sold as pairs; 9.84 in and 14.76 in are sold singly. CT-B1 ball sockets and CT-B2 ball studs are sold separately. Other CT-29 fittings, brackets, stainless springs and custom sizes are available by quote. Builders of RV storage bays, boat deck hatches, work-truck service bodies, lift-up cabinets and OEM equipment can send us their lid dimensions. Engineering checks force, stroke and mounting positions at no charge.

How to size a gas spring

1. Work out the force (N or lb)

Force per spring: F1 (N) = 9.81 × (RH × m) / (2 × N × X2) + 5. Here m is the lid mass in kg, RH is the opening length from hinge to free edge in m, X2 is the lever arm in m, and N is the number of springs. Round up to the next available force. A load of 1 kg is about 10 N, or 2.2 lbf. A 100 N spring is about 22 lb (10 kg).

Per-spring force for a lid on 2 springs: with N = 2, the formula becomes F1 = 9.81 × (RH × m) / (4 × X2) + 5. Worked example: a 10 kg lid with RH = 0.5 m and X2 = 0.1 m gives 9.81 × 5 / 0.4 + 5 ≈ 128 N per spring. Round up to the next available force (150 N), and order two. Figures are indicative. Send your dimensions to cs@conversionstech.com and engineering will verify them at no charge.

2. Pick extended length and stroke

Extended length is measured center to center with the rod fully out. Compressed length is the extended length minus the stroke. For a 90° opening, plan a stroke of about one-third of RH. Sizes sold here: 9.84 in (250 mm, 85 mm stroke), 10 in, 12 in and 14.76 in (375 mm, 165 mm stroke) extended. Stroke for the 10 in and 12 in springs is not listed, so measure your existing spring or ask us. Fittings add to the overall length, so measure your existing strut with its fittings on.

3. Choose end fittings

The 9.84 in and 14.76 in catalog springs have M6 threads on both ends. A ball socket (CT-B1) on a ball stud (CT-B2) suits lids and hatches, and both are sold separately. Eyelet and clevis fittings for machinery pins are available by quote from the CT-29 catalog.

4. Mount it right

Use two springs per lid to avoid side load. Mount rod down when you can, since this keeps the seal lubricated. Leave free movement at both fittings, and screw the fittings on completely where there's vibration. Don't paint, scratch or grip the rod. Don't use the spring as a dead stop.

5. Material for wet or corrosive spots

For marine decks, wet RV bays or food-service equipment, ask for stainless springs. They are available by quote.

Safety

A gas spring is not a safety component. If a failure could put someone's health or life at risk, add an independent locking mechanism.

Download the CT-29 Gas Springs & Fittings Catalog (PDF)

Gas spring FAQ

What is the difference between a gas spring, gas strut and lift support?

They're the same part. A gas spring (also called a gas strut, gas prop or lift support) is a sealed cylinder of pressurized nitrogen with a piston rod. It pushes out with near-constant force to lift and hold a lid, hatch or door.

How do I calculate the gas spring force I need?

Use F1 (N) = 9.81 × (RH × m) / (2 × N × X2) + 5. Here m is the lid mass in kg, RH is the opening length in m, X2 is the lever arm in m, and N is the number of springs. Round up to the next available force. Or send us your lid dimensions and engineering will check the numbers at no charge.

How do I convert Newtons to pounds for a gas strut?

1 kg is about 10 N, or about 2.2 lbf. A 100 N spring is about 22 lb (10 kg), and 500 N is about 110 lb (50 kg).

How do I measure a gas spring for replacement?

Measure extended length center to center with the rod fully out, then measure the stroke. Read the force in N if it's printed on the tube. Note the end fittings and thread size. Then match all three: length, stroke and force.

What sizes and forces do you stock?

Four extended lengths: 9.84 in (250 mm) at 50 to 250 N, 10 in at 50 or 100 N, 12 in at 200 or 250 N, and 14.76 in (375 mm) at 100 to 500 N. That is about 11 to 110 lb. Custom sizes, forces and colors are available by quote.

What end fittings are available?

We sell the CT-B1 angled ball-socket bracket and the CT-B2 threaded ball stud here. The other CT-29 end fittings and mounting brackets are available by quote at cs@conversionstech.com.

What gas strut should I use for an RV storage bay or boat hatch?

Use two springs per lid, one on each side, to avoid side load. Size the force with the formula or send us the lid details. Specify stainless for wet or corrosive locations. Ball socket fittings press onto the ball stud by hand, with no hammer or pliers.

Should a gas spring be mounted rod up or rod down?

Rod down when possible. It keeps the seal lubricated and extends service life. Store springs rod down too if you'll keep them longer than three months or in hot climates.

Why did my gas strut stop holding the lid?

Gas springs are wear parts and lose force over time. Damage, corrosion or paint on the rod can ruin the seal and cause fast failure. Side loading and over-extension also shorten their life. Replace them in pairs to the original length, stroke and force.

Are stainless steel gas springs available?

Yes, by quote. Ask for stainless for marine, food-service and corrosive environments.

Is a gas spring a safety device?

No. If a failure could put someone's health or life at risk, add an independent locking mechanism. That's the installer's responsibility.

Do you offer OEM and volume pricing?

Yes. We offer contractor, distributor and wholesale tiers, with net terms for qualified accounts, and OEM volume programs for one-off replacements and production runs alike. We reply within 48 hours at cs@conversionstech.com, and in-stock items ship same day from Oxnard, CA.