Guide
Ottoman Bed Gas Struts: Why They Fail, and What the Numbers Mean
An ottoman bed lid that will not stay up is not usually broken. Gas struts are sized for a weight range, and the mattress is part of that weight. Get the mattress wrong and the lid misbehaves in one of two opposite ways, both of which look like a fault.
What the number on the strut means
Gas struts are rated in newtons. An ottoman uses a pair of struts, and each one has its rating in newtons printed on the cylinder. That figure is the force each strut pushes with when compressed, and the pair is chosen by the manufacturer to balance the base plus a mattress within an expected weight band.
That is the part almost nobody explains: the struts are not sized for the bed, they are sized for the bed with a mattress on it. Our own assembly note says it plainly — keep the mattress on the base when you lift it, or the pistons will not work properly. Lifting a bare ottoman base is the single most common way people conclude their struts are faulty.
The two faults, and how to tell them apart
| What it does | What it means | Usual cause |
|---|---|---|
| Lid will not stay up, sinks slowly or drops | Not enough force for the load | Mattress heavier than the struts were specified for, or a strut has lost gas |
| Lid springs up on its own, or fights you closing it | Too much force for the load | Mattress lighter than the struts were specified for, or no mattress fitted |
| One side lifts before the other, base twists | The pair is mismatched | One strut has failed, or they were fitted the wrong way round |
| Held fine when new, sinks now | Gradual gas loss | Normal end of life, or a seal damaged by side loading |
Swipe sideways to see the whole table
Check these five things, in this order
- Is the mattress on the base? Test with the mattress fitted, never bare. This alone explains most reports of a lid that flies up.
- How heavy is the mattress? Ottoman frames state a maximum mattress weight — check the figure the maker gives for your frame. A deep pocket sprung super king mattress can go well past that. Above the limit, no strut will hold it.
- Are both struts the same? Look at the printed rating on each cylinder. A 600 N paired with anything else will lift unevenly and wear both out.
- Is either strut fitted upside down? Most gas struts are designed to sit with the cylinder above the rod so the seal stays oiled. Fitted the other way up they lose gas far sooner.
- Is the base being loaded sideways? A strut takes force along its length only. Pushing the lid sideways as it opens bends the rod and kills the seal.
The frame rating is a different number, and it matters more
People mix up two figures. The strut rating in newtons is about lifting the lid. The frame load rating in kilograms is about holding people, and it is the number that decides whether the bed is right for you.
Check the load rating the maker gives for your frame, mattress included. Where a manufacturer does not state one, we say so rather than inventing a number, because a load rating nobody will put in writing is not a load rating.
Before you replace anything
Replacement struts are sold by newton rating and by fitting length, and both have to match. Measure the existing strut end to end with the lid closed, read the printed rating, and buy the pair rather than one. Replacing a single strut on a two year old bed gives you a matched pair for about a month and then the same uneven lift.
If the frame itself has bent where the strut mounts, a new strut will not help. That bracket is usually the weakest point on a cheap ottoman, and it is worth looking at before you spend anything.
How to avoid the problem when you buy
Three numbers tell you whether an ottoman will work with the mattress you already own: the strut rating, the maximum mattress weight, and the maximum mattress height. Most listings give you none of them.
We publish the assembled outside dimensions of every frame we sell, and the maker's own figures wherever they give them. See king size ottoman beds, and if you are weighing an ottoman against drawers, the storage beds comparison sets out what each needs in floor space.