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Sorry, I forgot to look at my disassembly drawings today. If my fuzzy memory recalls, there is a check valve in the face of the big flange in the piston. Perhaps Nawrocki is referring to that valve. I think there are also check valves in the hydraulics which prevent the collet closer from depressurizing in the event of power off hydraulic failure. The purpose of these check valves is to maintain your collet closer state so you don't throw a workpiece if your hydraulics fail while the spindle is whizzing away. If you kill power, your collet is supposed to stay closed (if your outside fixturing) or open (if you are using an inside jaw chuck).
It is possible that you have a sticky check valve which is not consistently opening. One bad check valve would be consistent with slow actuation in only one direction because the check valve would slow the fluid flow in one direction and block it in the other.
I'm a bit stuck on the quad ring issue. I'm pretty sure that my Hardinge T42 collet actuator did not have quad rings anywhere. Are you sure that you have the right seal on the piston? I distinctly remember changing my piston seal because it looked like it had a bit of a flat spot on it's cross section. Like an "O" ring turning into a "D" ring with the flat at the periphery. Perhaps you have the wrong seal in there altogether. Did your Gosiger rep provide the seal? Are you sure it's the right part?
MadMax, yes I purchased them from Gosiger and used the schematic for the collet closer. I am confident it is correct. They were identical to the ones that came off, square shape instead of round.
Curiously, the new quad ring broke right above the check valve. Not sure were it broke the first time. There is a small hole in the quad ring groove going down to the check valve. ??????
I think I shouldn't dwell on the oring issue. I got my machine used. It's possible that the previous owner put in an oring instead of a quad ring and I just went along and replaced it with the same thing.
It's very strange to have a pinhole in a failed quad ring. I suspect that you got a defective part. My experience with oring and quad ring failures is that you don't get pinholing. The failures I've seen in rubber seals are cracking (most common), abrasion (cross section scrubs down), extrusion where the seal spurts out of the gland and shears (very high pressure applications), blistering (rapid decompression of a gas which the oring is permeable to). I don't think I've ever seen a pinholed oring that wasn't stabbed by a removal tool.
I'm assuming you mean "X" cross section instead of square. A square shape wouldn't be self energizing.
Did you inspect those check valves? I think they're in the piston assembly because the can't be upstream of the labyrinth seal which is relatively leaky. If the check valves were outside of the labyrinth seal, the piston wouldn't lock up in the event of a hydraulic failure.
MadMax, I must have misstated. The quaud rong was never replaced with an O ring. Quad came out and quad went in. The pin hole I was referring to was the one in the piston, from the quad ring groove to the check valve. I checked the schematic and there is suppose to be a lee plug in there. This is where I raised my eyebrows, the ring broke right over that hole.
I think it's a sticky check valve. Machine is working OK now. I am ordering some more rings and a check valve (both are the same) and will pull it apart some Saturday morning in the near future.
Sorry, I mistated. I meant to say that the previous owner of MY machine may have swapped my quad with an "O" ring. My bad. I.e. I should not get too hung up on your machine having a quad ring because I'm not positively sure that mine ever had the right ring.
OK, same thing a couple of months later, collet closer hangs up when actuating and there's a broken quad ring. This time it's in 2 spots, both over the check valves. There is a small holes under the quad ring at these spots. It's to connect a cross hole. No plugs in these spots and according to the schematic there is suppose to be a lee plug. I ordered them and it's actually 2 pieces. One is a small brass plug with a small hole through the center (orafis) and the other appears to be a cap that presses into the hole. I called Gosiger and Hardinge, no one knows anything about this (surprise).
What I think is happening is when the pressure goes through the check valve it's also pushing up the quad ring. Eventually the ring decays. We found small bits of the quad ring in the check valve.
Does anyone know what the installation is on the 2 pieces for the lee plugs? I think a set screw in this hole should work just fine. Or, ignore the brass piece and just press the cap in the hole.
I read your post about diagnosing collet closer issues on Hardinge T42 lathes, specifically when it closes slowly. I have a T42 and the collet closer won't open. I get a blinking red light on the control panel when I push the collet open button. It closes fine. I rebuilt the collet closer (new seals everywhere), and it actually opened a few times after the rebuild (I thought I had fixed it) but now it won't open again. Hoping you can shed some light... thank you in advance...
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