Slow-close Refer Lid Struts?

[jviss]

My Tartan 3800 has top-loading access to the fridge. The two lids have one support strut, each, that do a great job of holding them open. However, when you start to close them, at some point, the struts seem to pull them closed, and they can slam with a lot of force. My wife severely injured a finger last year, when a lid slammed shut on it.

I'd like to find struts that hold the lids open, but that close the lids slowly once they are started down.

Does anyone know of such a thing?

 

[twalker H260]

Do you have photos of your current? If it is the pneumatic style you find on car hatches etc. They can become weak over time and then exhibit the type of behaviour you describe. Likely available from the big box stores, McMaster car etc and likely from the sailboat owners store.

There are many other styles available - generally in cabinet hardware suppliers such as richelieu.com and hafele.com. Sailboat owners would likely be able to point you in the right direction on this as well.

 

[Rick D]

SBO sells some here. Send them the open and close length and any info on them.

 

[DougM]

Those gas struts can be found at most auto parts stores in varying length and weight capacities.
A good way to figure out the weight you would need is to use a luggage scale to lift the lid.
The drawback of the auto store versions is that they are not necessarily stainless steel which might be preferable in a salt water environment. They cost less, just replace them more often.

 

[jviss]

O.K., here's the dope. They are certainly springy, and have damping when recoiling/extending from compression. But, maybe not enough, or maybe the geometry of the mounting is just not right. I don't know. They assist in opening the lids, but when the lids are closed, at a certain point they slam shut. Dangerous.

Here's a pic:

Here's what's printed on them:

Short (port): extended length 7.5", center to enter; travel 2 3/16":

Service Plus Distributors, Inc.
Bristol, PA 19007

GSSX-4900-20 H06/08/27

Mount SPD Gas Springs Rod Down
Do Not Open - High Pressure

Long (starboard): extended length 10", center to enter; travel 3 3/16":

Service Plus Distributors, Inc.
Bristol, PA 19007
www.spdhardware.com

Nitrider
GSSX-5000-20 G10/05 8223

Mount SPD Gas Springs Rod Down
Do Not Open - High Pressure

The url printed on one is dead; the new link is: https://www.asraymond.com/gas-struts.html

The site indicates they should prevent "the snap effect." Maybe mine are worn out or defective?

 

[jviss]

You know, guys, it's the geometry of how these are mounted. I don't think there's anything wrong with the struts.

The geometry of the mount is such that the maximum compression of the strut is with the lid still open about 30º. Once that point is passed, the strut is now pushing the lid shut, extending. There's no dampening in that direction, I don't think, so it's a gas spring slamming the lid shut.

I wonder it this was intentional, to keep the lids closed? If so, I think it's a big mistake.

Opinions, ideas welcome. I will write to the distributor as well, and maybe to Tartan.

Also, those black buttons in the top of the pic are fittings to prevent the ball joint from coming undone; two are missing.

 

[twalker H260]

They may be weak rather than totally failed - average lifespan seems to be in the 3-5yr range but I have used many for far longer but they don’t function as effectively.
As mentioned in a previous post the regular versions are fairly widely available. For a stainless version you might be able to get from the link you supplied.
I would try giving the site store - SBO- sailboat owners a call and see what they might be able to do for you. 877-932-7245 Their service is great, price is reasonable and it supports all these great forums! No connection to sbo - just a happy customer and forum user!

 

[jviss]

Thanks, but I want to figure out if the struts are worn out, or if it's an installation/design error, first. I've written to the distributor explaining the situation.

 

[twalker H260]

How old are your struts? You can try pushing on them (end to end). Do you get increasing resistance as they are shortened through their entire range or is it the same/less resistance as compressed? Is there substantial resistance to compression? If not increasing or little resistance to compression they are shot. From what you describe in your first post it is a fairly typical failure mode for a gas strut.

Replacement struts should run 10-20 dollars and be available locally. Extended length from your part numbers are 7.5” and 10”, both should have 20lb force. If the originals are still good you may just need some with a higher force rating -25 lb would likely do it but 30lb are available.

Does your lid close faster at the end of is movement with the struts in place or the same from the same point with struts removed? If the same or only marginally slower - struts have failed.

By design the struts should be pushing through their entire extension if they have any “pull” nearing complete compression they have again failed.

 

[jviss]

I don't know the age. They could be original, so circa 1996. They present what seems the right force to compress, 20 lb. They have some dampening extending, too. They take more than a second to extend, maybe 1.5 to 2 seconds, with no load.

 

[jviss]

What they are doing: as the lid goes from fully open to fully closed, the strut is first compressed, reaching the installation's maximum compression at about 30º from fully closed, and then the strut is extending, pushing the lid shut. That is, when open, the strut is fully extended. When closed it is partially extended. Make sense?

 

[twalker H260]

should have little to no dampening on extension - with no load should be almost instantaneous.

I’ll have to draw a few diagrams for myself to see if I can get a geometry that would allow full extension-max-compression- followed by some extension.

Does lid currently open past 90°?

Placement of mounting brackets could be incorrect but there is usually a fairly broad range where they are effective.

Are hinges located on top back edge of lid or does the lid utilise a pivot on the side?

I’ll see if I can dig up the mounting info for a back hinge 10” support for you to compare to current.

 

[jviss]

should have little to no dampening on extension - with no load should be almost instantaneous.

They do, indeed, have dampening on extension, which is what one wants, no? Otherwise the lid would spring open violently. I think my issue is that there's not enough dampening (damping?) on extension. Because of that, the lid snaps shut when strut begins to extend again, once the travel goes "over center."

Let me explain. Thinking about this some more, I think the geometry is intentional. Without a latch, if the strut didn't begin to extend again when the lid was near closing, there would be nothing to hold the lid shut against the strut spring.

I’ll have to draw a few diagrams for myself to see if I can get a geometry that would allow full extension-max-compression- followed by some extension.

That's what I have.

Does lid currently open past 90°?

No.

Are hinges located on top back edge of lid or does the lid utilise a pivot on the side?

Back edge.

 

[jviss]

Pic and a diagram:

Note that in the diagram, with the lid open the strut is at maximum extension, "A." At B, it's at maximum compression, and with continued closing of the lid begins to extend again, C. The force of extension keeps the lid closed with this geometry.

 

[twalker H260]

Your drawings and photos help a lot. And could explain part of the issue. The majority of struts are designed for “rod down” installation - you can get ones designed for installation in any orientation but they are substantially more expensive. I haven’t been able as yet to confirm if yours existing are a universal orientation.

From the manufacturers website they state yours have dampening on extension only-not on close.

https://www.asraymond.com/standard-gas-struts.html

You could look for a strut that has dampening on close and allows for horizontal mount, switch to a vertical mounting if possible(would help with the slamming even if it doesn’t have dampening) or switch to a stay without the pneumatic assist.

Something similar to:

https://www.richelieu.com/ca/en/cat...adjustable-soft-down-stay/1061922?s=door+stay

Lid will likely feel heavier to open with the side stay then it does with the gas strut.

I’ll keep looking for additional info for you.

To reduce the “over the center” effect you could move the center line of the cabinet mount ball so it is in plane with the lid mount ball and parallel to the lid when the lid is shut. If you can get it below that point it would likely help even more but you might need to move the mount point closer to the hinge. This would give the effect of trying to push open the lid a bit rather than using the strut to keep closed.

 

[dLj]

One thing that is not clear to me from this discussion. Did these ever work correctly? Is this slamming shut something that has developed over time or always been a problem?

dj

 

[jviss]

It's always been a problem since I've owned the boat, which is about 2 years. It's a 23 year old boat.

 

[dLj]

So seems like the Pistons are the wrong type. Your setup seems good. But you need better buffering. Having the strength to hold the doors closed is one thing, the speed at which it is applied is the problem. So you don't replace those Pistons, but need the same travel on Pistons that have better buffering. Sure doesn't look like you need to redesign anything, just find the right Pistons. Does that seem right to you?

dj