Koken Barber Chair Hydraulic Question

[Stretch607]

I have a late 20 to late 30 chair that I am trying to rebuild the hydraulics. Everything is in good shape and cleaned up well.
My question has to do with the ram itself, towards the bottom of the ram there are two rings cut in the ram approximately .050" wide and about .012" deep, I think they are o'ring grooves but not 100 % sure. If they are then they would have to be a very narrow o'rings.
I was not aware of these chairs using o'rings, does anyone out there have any information on this?

Thank you in advance,

 

[Helohoss]

How did your chair work out? I just got a chair of the same vintage. It had been left out under a tree for years and a guy picked it up. He had no time to work on it and sold it to me. The seat and back were rotted right out and most of the oil had been spilled out of it or dried up. It took me two days to get it all the sand and old greased cleaned out of it.
I also noticed the rings with no seals or leather in sight. I have added oil and it is fully functional. I'm not sure of the purpose but a lack of seals (if there were ever any) don't seem to matter.

 

[Stretch607]

Worked out like a champ. I cleaned it up real well, I made a new filter screen for the piston, and I did a lot of measuring and decided that those two grooves weren't for any kind of seal. I assembled everything with assembly lube and filled the reservoir with Non Detergent SAE 30 oil.
I don't believe there ever was seals, the measurements I took around the piston and bore were very concentric (pretty impressive machine work if you ask me) I believe it used the surface tension of the oil as the seal.
I have another chair now that I am rebuilding.

 

[Helohoss]

I have to make a new filter screen as well. How did you go about doing that?


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[Stretch607]

I got mesh 100X100 from McMaster Carr and used a mandrel and die for the size I needed to stamp a piece out.

 

[Helohoss]

That would work well. I don’t have a mandrel and die so I’ll have to figure something else out


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[Stretch607]

If I remember right I used what I had laying around the shop. I believe I cut a piece of material square for what I needed. I think I used a piece of 2" pipe as the die and used a piece of steel that would go inside the pipe.
Once formed, I didn't even trim, I just worked it into the piston. Now, with that being said, I have a machine shop, so I may have had a piece of steel laying around with the diameter I needed.

 

[Helohoss]

I’m a hobbyist woodworker so I’ll probably make my forms from some scraps as well. Should be able to do the same thing, hopefully


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