New single acting hydraulic cylinder ram leaks.

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Flynth

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Some time ago I bought few parts for my press build. It took me a while to make the chassis. I did a quick test of the cylinder and pump on the bench when I bought it. I didn't notice any issues back then so I drained it and I put it away for 2 years.

However, this time preparing to install it in a press I put the whole system together, I did some basic testing and after I was done I left the cylinder standing on the ground with the rest of the system on a bench.

Imagine my surprise when I found a puddle of oil under the cylinder few hours later :-( I thought it is one of the fittings, but the body of the cylinder was dry(all of the fittings are on the top) and oil was only below where ram emerges from it. Clearly the leak is the ram :(

Now it is far too late to get any warranty. I'm pretty disappointed I didn't notice it before and I haven't tested it properly when I got it.

So, before I start ripping it apart let me ask this. Is it possible the new seals have to align under pressure and can leak a little before it is used the first time?

Also, why would a new built cylinder leak? Is it fairly easy to mess up manufacturing of those cylinders to the point of leaking with no pressure?

Finally, is there a point trying heavier weight hydraulic oil? I guess if it leaks with no pressure on it it will probably pour under pressure... If anyone has any advice please let me know.

It is the cylinder that is used in Grizzly T27978 press and other "50 ton" presses.
 
Yes, I would test it under pressure, to make sure the seals are set properly, before tearing it apart.
 
Ulma Doctor said:
I’ll bet you a donut that the ram only has a wiper and the seals are on the piston.
Wipers are more effective on dust and dirt than sealing oil
Click to expand...
Sorry no bet :) I think you're correct.

This is a single acting cylinder with external spring return. I've been looking for more information about this kind of cylinders and it appears there are two kinds. A ram type: basically the rod is the piston and the ram seal is effectively fulfilling the role of a piston seal too, and a normal type where you have a piston that does all the sealing and as you said there is only a wiper rather than a rod seal.

I'm pretty sure this is the normal type despite it is being named "a hydraulic ram". This is because the specs mention "ram diameter" 90mm, and rod 53mm. So there has to be a 90mm piston.

Eddyde said:
Yes, I would test it under pressure, to make sure the seals are set properly, before tearing it apart.
Click to expand...

Yes, I'll do that.

Also I wonder those cylinder seals are probably not great at sealing very low flows. I found an article online (by a seal manufacturer that recommends their own seals, what a surprise) that claims typical cylinder seals leak a little and one needs special "zero leak" cylinder seals to prevent it. Unfortunately those "zero leak" seals are available only up to 8300psi. While this system is supposed to get to 10000psi.

So I might need to live with it. Good news is that if true it shouldn't leak more during use. We'll see.
 
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