Hydraulic Lift Cylinder, Installing new style Piston ring

JBKINWA

Member
Does anyone have a good method for installing the piston into the cylinder when you are using the single land new style piston with the inner O-ring and Teflon outer ring assembly?
This is a 3 3/8" cylinder. It is too tight to use a standard ring compressor. plus you have that nice beveled area toward the hitch cover side that doesn't allow you to engage the ring evenly into the cylinder.
I had heated the ring with very hot water to install on the piston, let it set for quite a few hours to shrink and relax and then put the piston assy in the freezer prior to installing it. I was able to get it in without rolling the ring but it is very tight. Sound familiar to anyone?
 
Yup sounds very familiar. The way i do it is to get the ring hot enough to install on the piston and squeezed it back into shape with ring compressor. Then while it was still hot quickly install into the cylinder and let it cool in the cylinder and take its final shape. Very snug fit and seals nicely.
When i parked it to start the restoration on the front half i left a blade attached and about a foot off the ground to see how well it held. Stayed right where i left it for 3 weeks before it started to settle a little. I accidentally bumped the lever with the tarp and it's sitting on the ground now.
 
The issue I had was the compressor was too thick to engage the cylinder past the bevel. I will have to find a thinner compressor or use shim stock to get the ring past the bevel. Just pulled it back apart and the Teflon ring had thickened up on the bevel side and wasn't moving freely in the groove. seriously thinking of getting new rings for the old piston and reinstalling it.
 
That is the way that I did it. The old piston was removed by compressed air into the standpipe hole. It was 3 1/8" in size. The bore was in perfect shape. The old piston had three rings, and the new type 3 1/8" piston has only one groove for one rubber ring and a sealing teflon ring that sits on top of the rubber ring. I boiled the teflon ring for 2 minutes to soften it, and then used two screwdrivers and both feet to hold the piston and sealing ring partially on the piston and then to pry it on the piston on top of the rubber ring.

A piston compressor was used compress the ring/piston and drive it into the piston bore using a strong wooden dowel. The bore already had a very slight beveled edge to it.
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Hmm.. The one i just replaced did not have that extra bevel like that. The couple i have seen were all straight cut on the end. You are going to have to put it in far as it'll go with the compressor and then work the short side in a little at a time with flat blade screw driver i think.
Unless someone has a better idea.
 
The issue I had was not being able to keep the entire ring compressed all of the way around once I got to the bevel side. I just need something thinner. The compressor I have is about .030 thick
 
I worked it in with a plastic glass tool but ended up with too much ring to that side and no free play in the groove. I thought it would relax after I worked it a few times but I couldn't move the piston by hand. Took 120 P.S.I. to remove the piston. Try to get something figured out by the time the new seal gets here.
 
Maybe call the place you got the cylinder from and have them pull another one off the shelf and see if it has that bevel. Doesn't seem right to have that. If that is correct then you might have to use the 3 ring piston and ring setup instead.
 
New piston is much tighter in the bore than the old 3 ring one. Do you know if this is typical with the new single land piston?
 
Yes the replacement cylinder is a Massey cylinder. same casting number. The original fix was to remill the lower land to accept a 1/4" o-ring in place of the lower cast ring. The only lathe I have access to will not accept that big of stock.
 
I guess I had gotten into a bit of a hurry, I did not check the fit prior to putting it together. 1 edge of the piston skirt was swelled. It must have been dropped or something. Nothing a flat file and some emery cloth won't fix. Looks like I will have to try the beer can method for seal install :)
 
Used to have some similar looking seal arrangements on Green tractors, trick was to warm the ring to fit, then wind electrical insulation tape round and round, fairly thickly, compress the seal with a big worm drive hose clamp, then into the freezer for an hour or so. Then off with the clamp and tape, check you hadn't damaged it, lube and fit.
 
My final solution was to use a Fosters beer can inside the ring compressor to extend down past the bevel and into the cylinder. It was cheaper than buying steel shim stock. Fosters uses a thicker aluminum and the can dia is just a little smaller than the piston. just cut the top and bottom off and split it up the side. worked out very well.
 

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