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Hardinge T42 Collet Closer "Leak"

IAmAlex

Aluminum
Joined
Sep 11, 2015
We have two Hardinge Conquest T42 lathes, and I am getting to my wit's end with one of them. It is the model with the hydraulic-driven subspindle and live tooling. The machine is "leaking" out of the back of the collet closer. I say "leaking" because the oil is running out of an area that looks like a relief groove. Below is a picture of that groove from the outside. We have had this closer completely apart so both visually and by the drawing, I know that this groove goes straight through to the hollow trough where the hydraulic oil drains into the drain hose. Another image of the drawing below. Here is everything we have tried to fix this issue:

- Remove and clean collet closer and replace all seals
- This machine has a main pump and a gear pump that draws oil through the collet drain hose and circulates it through a radiator.
- Replaced cooling pump with a brand new unit
- Disassembled and cleaned radiator fins and pipes
- We removed the main pump and swapped it to our other T42 and it worked fine on that machine
- Removed all lines from the hydraulic manifold, cleaned all lines and inside manifold
- Drained and cleaned hydraulic tank
- New hydraulic oil

After doing all of this, the pump is quieter but that's all. Our test is using a program that closes the collet for 10 seconds, opens it, closes it for 10 seconds, on repeat mode. This will run for 1.5 hours before the oil start running out of the collet closer "relief groove". This morning I started the machine, let it sit for 2 hours with the hydraulics on but no collet closing. After 2 hours, these are the temps I measured with a laser thermometer:

- cooling gear pump, 105F
- Hydraulic manifold, 119F
- Main pump, 127F
- Hydraulic motor, 165F
- Tank, 120F (viewed on tank thermometer/sight glass)

Started running our collet program, and within 10 minutes it was leaking again. I also notice small air bubbles in the oil in the drain line. This makes me think the heat is the issue, and our other T42 does not get this hot. But we have replaced/verified everything I can think of so I don't know what would be generating the heat.

I have been trying to fix this on and off for almost a year, so any help would be greatly appreciated. Hardinge has been less than helpful and they take forever to respond.










Capture.JPG1690301977184.png
 
I don't have a 42, but on a 65 I have watched the gear pump suck coolant in from that area. I have had a hydro tank filled with coolant up to the pick-up level. I have added a T in the line with a standpipe to ambient which allows the scavenge pump to draw the fluid back to the pump from that point, but the closer sees no vacuum at all, just gravity drain to the T.

So, it seems that you are having the opposite issue.

Any chance that you are having an issue with the collapsing of the return hose?
You don't mention this in your build sheet.

???


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Think Snow Eh!
Ox
 
I don't have a 42, but on a 65 I have watched the gear pump suck coolant in from that area. I have had a hydro tank filled with coolant up to the pick-up level. I have added a T in the line with a standpipe to ambient which allows the scavenge pump to draw the fluid back to the pump from that point, but the closer sees no vacuum at all, just gravity drain to the T.

So, it seems that you are having the opposite issue.

Any chance that you are having an issue with the collapsing of the return hose?
You don't mention this in your build sheet.

???


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Think Snow Eh!
Ox
I forgot to mention - we replaced the drain hose because we broke the old brittle one fumbling around with the other parts. But the original was never pinched anywhere and the new one isn't either. No coolant in the tank either.

We also always have good oil flow into the drain hose from the collet closer - the oil is never backed up going back up the line into the closer (so I don't understand why it is getting pushed out of that relief slot anyway). The oil does seem to gradually back up in the drain line at the gear pump. By the time the machine starts to leak, that line is completely full. The oil is still moving but it is full. That is even with the new gear pump.

We have another T42 with a nearly identical hydraulic system and it runs perfectly fine, no leaks or overflows, temps are lower.
 
Well it sounds as tho you just mentioned your issue.
Your line is filling up, and even if you still see a bit of air in there, there does NOT seem to be more flow that supply.
Your gear pump must not be drawing much if any volume.
Is there any adjustment screws on the gear pump anywhere?
Are you sure that you are plumbed on the right side of the pump?
Going the right direction?

You have a dual output shaft motor on that?
Or is the gear pump piggy back on the end of the vane (?) pump?
Or both possibly in the case of a sub-spindle?

I take it that this was a problem before you replaced the pump - otherwise you wouldn't have replaced the pump, but ...

A good pump should suck the chrome off a Harley through that cavity that you point to.
(which is why I added the inline T - but not on a 42)


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Think Snow Eh!
Ox
 
Well it sounds as tho you just mentioned your issue.
Your line is filling up, and even if you still see a bit of air in there, there does NOT seem to be more flow that supply.
Your gear pump must not be drawing much if any volume.
We thought this was the issue, so we replaced that pump but no dice. It does draw well for that first 1-1.5 hours but then the line will get full.
Is there any adjustment screws on the gear pump anywhere?
No, it is just a sealed pump. Eaton/Danfoss 26001-RZG
Are you sure that you are plumbed on the right side of the pump?
Yes.
Going the right direction?
Yes, because we put the old pump on backwards once and SHOT oil out of the same "relief groove" we are leaking from.
You have a dual output shaft motor on that?
Yep, motor in the middle with main pump on right, gear pump on left.
Or is the gear pump piggy back on the end of the vane (?) pump?
Or both possibly in the case of a sub-spindle?
Interestingly this machine has the hydraulic sub-spindle, which according to Hardinge's manual should have the motor going into the tank with the pump in the tank. This machine does not have that, it has the dual shaft layout.
I take it that this was a problem before you replaced the pump - otherwise you wouldn't have replaced the pump, but ...
Yep, that's why we replaced the pump.
A good pump should suck the chrome off a Harley through that cavity that you point to.
(which is why I added the inline T - but not on a 42)


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Think Snow Eh!
Ox
 
"- Disassembled and cleaned radiator fins and pipes"


OK, so what does this mean?
Shirley you didn't "clean" the insides of the radiator tubes?

How 'bout you go around the rad and see how it runs?

Your problem does NOT seem to be at the closer.


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Think Snow Eh!
Ox
 
"- Disassembled and cleaned radiator fins and pipes"


OK, so what does this mean?
Shirley you didn't "clean" the insides of the radiator tubes?
Yes, we did. We took the entire radiator unit off, degreased and scrubbed the fins to get the years of dirt and grime off. With the inside of the tubes, we just poured some degreaser into the tubes and let it run out the other side, rinse with hot water and blew out with compressed air (obviously none of this was when it was attached to the machine).
How 'bout you go around the rad and see how it runs?
The fan runs and blows air through the radiator, and it comes out hot on the other side.
Your problem does NOT seem to be at the closer.


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Think Snow Eh!
Ox
 
But apparently not enough volume through it.

Just bypass it for a few hours and see what your result is.



Either you are dumping too much oil at the closer, or you have restricted flow at the rad.
One or the other.


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Think Snow Eh!
Ox
 
Touch the gear pump once it is getting to be a problem.
Is it slightly warm, or quite warm?

If your rad is plugged up, the gear pump will be pushing WAY harder than it should be.
The pump should see virtually no pressure - just a transfer pump is all.

If the rad is plugged (1/2?) then the gear pump is adding heat to the system that it normally would not be.


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Think Snow Eh!
Ox
 
Once the hydraulics run for an hour or so, the gear pump is too hot to touch. The entire system is getting much hotter than our other lathe.
 
In your original post you said that the gear pump was 105*.
Now you say that you can't touch it.

???


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Think Snow Eh!
Ox
 
I like Ox's idea to bypass the radiator.

Have you tried swapping actuator's between the two machines? Swapping radiator's? If it were me, I'd keep swapping parts until I got the problem to move.
 
I had a chuck actuator that leaked like that. The return hose was restricted. I upsized the hose and the problem disappeared.

I have a hardinge 42SP with a similar giant hydraulic pumping cooling monstrosity hanging off the back. Sure seems like a bit of rube Goldberg stuff.
 
In your original post you said that the gear pump was 105*.
Now you say that you can't touch it.

???


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Think Snow Eh!
Ox
I think I mixed up my numbers somewhere. Everything we've done so far definitely made the system take longer to heat up, but by the time the collet closer leaks the whole system is much hotter than our other T42.
Just curious, don’t know the setup.
Is the gear pump drawing through the cooler or pushing oil through the cooler?
Cheers Ross
The gear pump is before the cooler, so it has to be pushing it through the cooler.
I had a chuck actuator that leaked like that. The return hose was restricted. I upsized the hose and the problem disappeared.

I have a hardinge 42SP with a similar giant hydraulic pumping cooling monstrosity hanging off the back. Sure seems like a bit of rube Goldberg stuff.
How big was your original drain hose? This is already a 1'' ID so I don't think upsizing it is going to fix the problem.
I like Ox's idea to bypass the radiator.

Have you tried swapping actuator's between the two machines? Swapping radiator's? If it were me, I'd keep swapping parts until I got the problem to move.
We've swapped a bunch of other parts but not these two. I'm going to bypass the radiator this morning and see where that gets us. If nothing else it rules another thing out. Thanks for the suggestions everyone.
 
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Ran our collet open/close test program with the radiator bypassed. Still leaked after an hour. The oil in the drain hose at the gear pump starts to get frothy after 50 minutes. My laser thermometer is putting the gear pump at 105F, but it's definitely too hot to keep a hand on.

I had our other T42 running the same program at the same time, and that hose has far less oil building up at the gear pump - less oil and the flow is slower. It's hard to tell if there is more flow coming out at the collet closer on one than the other. If there is it is not enough to be obvious to me.

The frothy oil makes me think we have air getting in, but it only happens after 50 min- 1hour and I can't find any leaks.
 
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