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Hydraulic cylinder repair for a Cincinnati press brake

Bondo

Hot Rolled
Joined
May 14, 2011
Location
Bridgeton NJ
I'm in south NJ and I am in need of a quality company to repair my leaking cylinders on my 230 ton press brake. The person who was going to do it, which has experience doing the same cylinders got hurt and can't do it now. The company they use to use screwed up at rebuilding them so that's why my buddy did it who is their main mechanic. I'm not looking for the cheapest, looking for quality and still buy lunch.

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Don't know anyone in your area but if I were you I would call around to a couple construction companies (excavating, heavy equipment etc.) and see who they use.
 
Everyone around here uses the same place. But the 3 places I have talked to said they screwed up the cylinders worse then they were.

They brought in "old" workers to re-rebuild them but I can'y get one of them to come help me as they are out of the work force now

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Couple of things.
These aren't just like a log splitter or excavator cylinder, look at the accuracy (stroke length) involved
to hold bend angle.
Both should probably be banded to a good skid, and then they can be shipped pretty much anywhere for a proper
re-build, I would seek out a specialist rebuilder that has done these cylinders before.
 
Couple of things.
These aren't just like a log splitter or excavator cylinder, look at the accuracy (stroke length) involved
to hold bend angle.
[/QUOTE

Elaborate on this, please. I've not noticed any great differences in these cylinders compared to regular ones other than better piston seals.
 
Couple of things.
These aren't just like a log splitter or excavator cylinder, look at the accuracy (stroke length) involved
to hold bend angle.
[/QUOTE

Elaborate on this, please. I've not noticed any great differences in these cylinders compared to regular ones other than better piston seals.
I'm thinking they are balanced for size, so the control doesn't have to compensate as much
when holding parallelism of the ram.

Either way, if the OP's only local shop can't do these competently, it isn't too hard to ship them
somewhere that handles them on a daily basis.
 
Where are the cylinders leaking? Bypassing the piston seals or leaking at the rod seal?

Are these tie rod cylinders or welded cylinders. The Cinci press brake cylinders I've seen are tie rod type.

How old is the brake? Or do you know how long since the cylinders were last rebuilt? Its rare to find a 20 yr old cylinder where the original seals are fully intact. They deteriorate and eventually develop cracks in the seal material. I've disassembled cylinders on many occasions where the rod seal in particular had to be dug out as a bunch of crumbs.

You said the people who worked on them "screwed up the cylinders worse than they were". Does this mean they rebuilt them and they still leaked? or ? ? ?

And said you can't get any of the old hands to come help you. Are you saying you want someone to come to your site and rebuild them? If so, the only thing they can do is change the seals and hope that works. If there's something else wrong with them then they can't do anything without sending or taking them somewhere to a shop with the equipment to handle the repairs.

I'd agree with Alphonso that there's nothing unusual about press brake cylinders. The stroke control on older brakes is handled by flow control and balancing valves while the latest ones control synchronization via servo valves, but the cylinders aren't anything out of the ordinary.
 
If you are really up against it, Bos Machine in Hillsdale, IL can fix them for you. They specialize in press repairs.
 
about 14 years ago we rebuilt both of the hydraulic cylinders on our 500 ton Chicago press brake, large yes but not much different then a standard precession hydraulic cylinder. The rods were in excellent condition as were the cylinder barrels although we did hone them.
Leaky rod seals and piston seals replaced sealing parts and put them back into operation, Been leak free ever since.
 

Considering these people are factory authorized for repairing cylinders from Manitowoc, Grove, Liebherr, Krupp, and Tadano cranes, they've got to be good at it. There's no application where a cylinder failure is a bigger liability than in a hydraulic crane. When the OEM gives them its official blessing for doing repairs, they don't do that lightly as making the recommendation carries liability for the OEM as well.
 
It is just the seal that's leaking. As the ram moves, oil leaks out. I already have the new seal kits from Cincinnati. I was told that if I can find a local guy, it is way easier to replace the seals without removing the cylinder.

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It is just the seal that's leaking. As the ram moves, oil leaks out. I already have the new seal kits from Cincinnati. I was told that if I can find a local guy, it is way easier to replace the seals without removing the cylinder.

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What do the rod ends look like? Big welded eye or clevis? Screw on eye, clevis or other connection device? If screw on, just unscrew the end piece, unscrew the gland nut from the cylinder and replace the rod seal, dust wiper and "o" rings on the bench.
 








 
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