Restoring Old Pneumatic Cylinders

[Klirre]

So... I took a good look on my old pneumatic cylinders from the late 90's. They are in dire need of some lubrication, I will buy some silicone oil next time I'm in a hardware store. The biggest issue is that they're only single-acting nowadays, i.e. they extend but refuse to retract no matter how much I pump up the pressure tank. I suppose the top seal between the housing and piston is leaking pretty badly. Is there any way of fixing this? I tried opening one of them but I'm afraid of breaking them. Do i have to take them apart in order to lubricate them? Otherwise I'll try with silicone oil first and see if it helps at all. Is there any point in polishing the pistons with steel wool or does it only make things worse?

Let's assume the worst, if they're shot and there's no way or fixing them, How hard is it to get hold on good large v1 cylinders? I'd prefer the old square bottom ones to match the ones I've already got.

I'm thankful for all types of input, I hope there's some pneumatic guru out there who knows how to save my cylinders.

[JM1971]

You should be able to replace the rubber o-ring that most likely has perished by now, its doubtful that the ring can be restored with some lubricant but you never know.

There is probably someone who knows the o-ring sizes and where to get them, otherwise you could try good old amazon/ebay.

https://www.amazon.co.uk/s/ref=nb_sb_noss_2?url=search-alias%3Daps&field-keywords=rubber+o+ring

[Klirre]

You should be able to replace the rubber o-ring that most likely has perished by now, its doubtful that the ring can be restored with some lubricant but you never know.

There is probably someone who knows the o-ring sizes and where to get them, otherwise you could try good old amazon/ebay.

https://www.amazon.c...s=rubber o ring

Are you sure it's just a regular O-ring? Because I've got loads of them at home in different sizes. The problem of opening the cylinders without ruining them still remains, they're really well built.

[JM1971]

Are you sure it's just a regular O-ring? Because I've got loads of them at home in different sizes. The problem of opening the cylinders without ruining them still remains, they're really well built.

Yeah its designed to unfixable so you have buy a new one, lego motors from the 70's had repairable wires, those days are long gone, now its all cheap plastic that breaks if you so much as think about repairing it.

That don't stop some people, even if you break it then there's apoxy resin. :D

Edited August 21, 2016 by JM1971

[Dafgek81]

They are easy to open IMO, I did it to airbrush the pneumatic cylinders on my Actros white.

Just put a dull knife between the black top, just by the hole and khob on the side and gently push it up slightly, then shift the knife towards the other side and do the same there.

It will come apart, almost without any damage, maybe a little scratch, but nothing more.

Or else, try and contact Lego customer service and try to get some o-rings there.

[RohanBeckett]

need to find a good technique to replace the hose connector (nipple) on some of my cylinders - that's the most common fault I have with mine - about 2-3 broken ones...

[Dafgek81]

need to find a good technique to replace the hose connector (nipple) on some of my cylinders - that's the most common fault I have with mine - about 2-3 broken ones...

Search for a company that repairs or builds hydraulic or pneumatic cylinders.

Or a modelshop that sell petrol driven cars, they use those connectors for hoses and fuellines

[Klirre]

So... I finally got one of mine open. I found some old yellow grease inside and I'm starting to wonder if that has been there all the time or if I've tried to fix them before... It looks and smells like regular grease, is there any specific property (color?) to silicone grease?

Anyhow, the top seal is really dry, I'm amazed it hasn't crumbled to pieces yet. It's no ordinary O-ring, so I'll probably have to contact Lego and see if they are willing to supply a new set of seals for each of my cylinders. I could just as well change all of them while I'm at it, better to be safe than sorry.

[Dafgek81]

So... I finally got one of mine open. I found some old yellow grease inside and I'm starting to wonder if that has been there all the time or if I've tried to fix them before... It looks and smells like regular grease, is there any specific property (color?) to silicone grease?

The grease in there is original, found the same grease in my cylinders.

I've just put some of it on the o-ring with toothpicks.

And sometimes I spray the rams with some silicone spray.

And in the inlets when I don't want to open them up.

[Klirre]

The grease in there is original, found the same grease in my cylinders.

I've just put some of it on the o-ring with toothpicks.

And sometimes I spray the rams with some silicone spray.

And in the inlets when I don't want to open them up.

Good to hear, I emailed customer service at Lego and we'll see if they can help me out.

[Klirre]

So... I've talked to customer service now, the only thing they can source are fully assembeled cylinders, and they are long out of production. They told me to go buy "new" ones from bricklink/brickowl.

Have anyone here at EB ever managed to fix broken seals? Is it possible to replace the original seal with an O-ring? I really don't feel like buying 3 cylinders that might well be broken from some guy through bricklink...

[syclone]

So... I've talked to customer service now, the only thing they can source are fully assembeled cylinders, and they are long out of production. They told me to go buy "new" ones from bricklink/brickowl.

Have anyone here at EB ever managed to fix broken seals? Is it possible to replace the original seal with an O-ring? I really don't feel like buying 3 cylinders that might well be broken from some guy through bricklink...

Normally the seller must write that something is broken , so your chances of getting something ot as described are very low . Never had problems with bricklink Edited August 22, 2016 by LXF

[Kristof]

Agreed. I bought several pneumatic pumps and cylinders branded 'new' and all the parts were clearly new in pristine condition. Just pick the store with 99+% positive feedback and at least few hundreds sales abd you are good :)

[Klirre]

Thanks for the replies, it looks like I'm spending a bunch of money on pneumatics soon... The first purchase is always the hardest, you never know what to expect buying stuff over the internet.