Gas Springs for Wall Beds

Application Guide — Furniture & Wall Beds

Gas Springs for Wall Beds

Lift support engineered for Murphy bed and wall-bed frames — for furniture OEMs, hardware-kit assemblers, and procurement teams sourcing matched, long-life springs.

OEM & Aftermarket Supply

Paired & Force-Matched

Custom Force & Stroke

Engineering Support Available

 

Sizing a Wall Bed Spring Is a Force Window, Not a Single Number

Gas springs for wall beds must be sized to a force window, not a single number: high enough to assist the bed up as it closes, but low enough that it rests down on its own when open. Push the top of that window and the bed drifts up off the floor when no one is on it. Miss the bottom and it drops the last few inches with a bang. For a typical queen — frame plus mattress in the 45–70 kg (100–155 lb) range — that usually means two matched springs, each carrying several hundred newtons, with the exact value set by hinge geometry rather than weight alone. Pull the bed down at the end of the day and it should glide the last stretch under control. Fold it up in the morning and it should rise with two fingers, then sit tight against the wall. When the spring is right, nobody thinks about it. When it’s wrong, you get the two complaints we hear most: a bed that won’t stay down, and a bed that feels heavy or jerky halfway through the arc. Both are force-window problems, and both are fixable on paper before any tooling is cut.

The Force Window: Stay Down When Open, Lift When Closing

A wall bed has two behaviours that pull the spring force in opposite directions. Open and flat, the bed must hold itself on the floor — so the spring must not fully cancel the weight at that position. Folding up toward the wall, the bed needs real assistance — so the spring must supply most of the lift through the rest of the arc. The art is sizing one spring to do both. The reason this works at all is geometry. The bed pivots through roughly 90°, and the load torque it puts on the hinge follows the cosine of the arm angle: maximum when the bed is open and horizontal, falling to almost nothing as it stands vertical against the wall. A gas spring runs the opposite way — lowest force when extended (bed open), highest when compressed (bed stowed). Those two curves crossing is what gives you a bed that stays down at the bottom and holds closed at the top. Competitors quote a single force figure and a calculator; the figure that actually matters is the extended force at the open position, because that’s the one deciding whether your bed stays on the floor.

How to Size Gas Springs for Wall Beds

Start from the moment balance about the hinge. It tells you the spring force needed to support the bed at any given arc angle: Worked example, a queen wall bed. Frame plus mattress mass is 50 kg (110 lb), so the weight is W = m × g = 50 × 9.81 = 491 N (110 lbf). Put the centre of gravity 1.0 m (39 in) from the hinge, use two springs (n = 2), and a spring moment arm of 0.18 m (7 in). At the fully open position (φ = 0°, cos φ = 1), the force that would fully balance the bed is: That is the force not to spec. Set the extended force at the open position to about 75–85% of it — roughly 1020–1160 N (229–261 lbf) each — and the bed rests down on its own, while the spring’s rising force as it compresses toward the wall does the lifting. Move to mid-arc (φ = 45°) and the load torque drops to W × L_g × cos 45° = 491 × 0.707 = 347 N·m, which is why a spring that felt fine open can feel heavy halfway up if the force progression is wrong. Confirm the worked figure with a small safety surcharge, F_design = F × SF with SF around 1.1–1.3, and you have a defensible starting force. One more correction matters in cold rooms. Gas spring force falls about 0.3% per °C, so F_T ≈ F₂₀ × [1 + 0.003 × (T − 20)]. A bed in a 10°C (50°F) guest room loses roughly 3% — about 33 N (7 lbf) off an 1100 N spring — which is the sluggish-winter complaint people blame on the bed. The answer is to size at the real operating temperature, not to add raw force. This is exactly where a sanity-check pays for itself. A US wall-bed kit manufacturer once sent us frame dimensions along with a force figure carried over from a heavier oak-framed model. Running the moment balance at the open position showed the number was too high for their new lighter foam-and-ply frame — the bed would have crept up off the floor on its own. We brought the extended force down before they cut tooling; the corrected pair held the bed down when open and still made the lift effortless. The physics catches that in five minutes; a production run does not.

Mounting that protects the spring

Where the lower (body) pivot sits relative to the hinge changes the effective moment arm — and shifting that mount point alters open/close behaviour more than changing the force does. Mount so the rod points down in the bed’s usual resting position to keep the seals lubricated and the action quiet. Use ball-socket or eyelet end fittings that allow slight angular misalignment, and keep both pivots in the same plane of motion: gas springs take axial load only, and side-load shortens life. The right mounting brackets make that alignment repeatable across a production run.

One Spring or Two? Almost Always Two

Above twin size, a wall bed wants a matched pair. A single central spring can handle a narrow twin frame, but full, queen and king frames carry their load across enough width that one spring lets the frame rack and wear unevenly on one side.

Do Wall Bed Gas Springs Need Stainless or Locking?

For most wall beds, no — and this is where the honest answer differs from the upsell. A wall bed lives indoors, so a black nitrided rod (900–1000 HV, 20–30 µm) with HNBR-sealed standard gas springs gives ample corrosion protection at a sensible price. The durability driver indoors is not rust; it’s the static-load seal wear that comes from an over-forced spring, which correct sizing already solves. There are two exceptions worth specifying up front. If the bed goes into a humid or salt-air setting — a coastal apartment, a houseboat, an RV or marine conversion — then a chrome rod pits and seals fail early, and 316L stainless is the right call. And where you want the bed to hold firmly stowed against accidental release, or held open hands-free during servicing, a locking gas spring adds a mechanical hold at the end of stroke. The release method depends on the frame and how the bed is operated, so it’s worth specifying with us rather than assuming a default.

Specification Quick-Reference by Bed Size

Treat these as starting points. Two beds of identical weight can need forces hundreds of newtons apart once hinge offset and the open angle are accounted for — so run the moment balance, or send your frame dimensions and we’ll return a force figure.

Frequently Asked Questions

Conclusion

A wall bed that works for years comes down to one idea competitors skip: the spring is sized to a window, not a number. Low enough at the open position to keep the bed on the floor, with enough rising force through the arc to make the lift effortless, and corrected for the temperature it actually lives in. Get those right and the rest — seal compound, material, mounting — falls into place. Newtone has supplied this kind of precision lift support to manufacturers and distributors for over two decades, OEM and aftermarket from the same platform. Whether you’re designing a new wall-bed line, replacing a spring that won’t hold the bed down, or evaluating a supplier for long-term volume, send us the frame and we’ll do the math. Share your bed size, frame and mattress weight, and hinge geometry. We’ll return a force recommendation, a datasheet, and a quote — typically within five business hours.

Get a Force Calculation or Quote

Tell us your bed size, weight, and hinge geometry. Our engineering team runs the moment balance, recommends a matched force, and quotes — no charge for the calculation.

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Supply: OEM & Aftermarket — Global Export