What is this Clutch on my Gornati Leopard 180 ?

[FredCailloux]

That clutch is designed to slip under overload conditions.

That is what I suspect, for I cannot find any command arm to disengage it.

 

[FredCailloux]

It's a fricion clutch, non-resettable and nonadjustable (beyond initial setup), so no problem burying it in the apron. You will need to rely on that part operating as it was meant to, so whatever is binding will need to be remedied.

I'm not sure what I am seeing in pic #1116. Is that supposed to be keyed? The keyway looks "packed" or even soldered, does not compute...

Here is own I understand it works. The Lathe transmission activate the long driving shaft.
That long shaft activate this Apron shaft shown on fig.1111
This shaft as an eccentric section to activate a plunger to the oil pump. See 1171, 1172

The Gear can rotate freely on the Shaft (if the clutch discs are absent). The Shaft has a Keyseat. The ICH as a Keyway.
The Key lock the ICH on the Shaft, activating the clutch discs. The clutch transfer torque to the Gear.
Then the Gear can drive the Apron movement.
If, for some reason, the Apron movement is blocked then the clutch will prevent catastrophic breakdown.
At least, that is how I understand it. Feel free to share any other insight.

My problem is I cannot find a way to dismantle this shaft and its two main parts, the gear and ICH.
They seem to be stuck by the key and a hammer doesn’t give me a good feeling at this point.
Figure 1170 gives another point of view. See other comments on the preceding page.
I want to play it safe. If anyone has an idea how to remove these 3 parts I sure would like to hear it.

Thanks for your help.

 

[FredCailloux]

I am making great progress. I was able to pull the ICH from the Shaft using a puller. Should have though about it sooner.

Now I have another problem. I cannot get the Key out of the Keyseat. This key is stuck in like its unbelievable.
In 1175 you can see the remnants of my attempts.
The Key prevent me from removing the Gear.

Is there a machinist out there who can share his wisdom ?
Thanks

 

[pontiac428]

Is there a machinist out there who can share his wisdom ?
Thanks

If nipping onto the edges with vise grips and pulling the key isn't working, I'd grab a torch and apply a little heat- only enough to start slightly smoking the oil, and pull again. If still stuck, quench that puppy quickly in water. If it doesn't fall out on its own, there is always choice #3- do what the manufacturer should have done in the first place, drill and tap a small (#4 maybe) jacking screw hole in the keyway itself. It's okay if you go into the shaft a little. Thread in a bolt, and it will push the key away from the seat. But start easy and work up to that.

 

[extropic]

Fred,
I agree with John's recommendations for removal of the key.

However, Please don't leave me hanging regarding what "the small metal insert" is/was?
Just a random piece of trash or burr?

 

[FredCailloux]

Fred,
I agree with John's recommendations for removal of the key.

However, Please don't leave me hanging regarding what "the small metal insert" is/was?
Just a random piece of trash or burr?

Ya! a nice little burr, perfectly formed to trick me thinking it was a slice of metal to further squeeze the Key.
I actually laugh when I saw it. I was able to take it out with my finger so much it was feeble.

As far as piercing and tapping a hole in that Key, I hope I wont have to do that. This Key is made of the same metal of the rest and seems to be quite strong alloy. I just cant imagine a #4 drill going in the middle of that Key. #4 OD is about half the Key width (0.23").

I was thinking, maybe I can weld something to the Key and pull it. That would be the death of that Key but I can always replace it.

Let's try heat first.

Hey! Thank you all for your involvement.

 

[FredCailloux]

After lots of heating, banging and destroying two taps I decided that I am not going to get that Gear out of the Shaft. To much trouble for no logical justification. The Gear will stay on the Shaft and the Apron will be rebuilt like that.
The Key is still usable. So I will rebuild the whole clutch as is.

Now my next question would be: How to I adjust the clutch to the correct torque?
Has anyone know what torque range this safety clutch should be adjusted to?
If I know what is the force required at the Apron when machining then I can calculate the max torque to adjust the clutch.

Cheers

 

[pontiac428]

Key stock is typically quite soft (midway through the Rockwell B scale) because it's job is to be tough, not hard. That said, key stock is a higher carbon steel that is hardenable, but I really wouldn't expect it, the key is the sacrificial part of the system.

Welding a stub of something to the key is a good trick. I employ it often when things are stuck, the heat is what makes it work so well.

 

[pontiac428]

After lots of heating, banging and destroying two taps I decided that I am not going to get that Gear out of the Shaft. To much trouble for no logical justification. The Gear will stay on the Shaft and the Apron will be rebuilt like that.
The Key is still usable. So I will rebuild the whole clutch as is.

Now my next question would be: How to I adjust the clutch to the correct torque?
Has anyone know what torque range this safety clutch should be adjusted to?
If I know what is the force required at the Apron when machining then I can calculate the max torque to adjust the clutch.

Cheers

My lathe's manual purposefully does not provide a setup spec for the drive clutch. It is intended to be determined by the setup. I set mine so that it never disengages under normal feed, but still pops with hand pressure (my clutch is based on springs and cams, different mechanism, same purpose). I am not interested in having the clutch disengage while doing earnest work, but I also want the clutch to work before the shear pin in the gearbox does.

If your manual gives you a torque spec, you can set it by putting the clutch in a vise and attaching a moment arm of known radius to the output side. Pull the moment arm with a fish scale and record the reading when the clutch slips. Do your conversions from arm length and tension to lb-ft or NM torque, and you've got it. I would not be surprised if you don't find a figure published, though. In that case, just try to put the set point back were it was by using the wear marks on the assembly to guide you.

 

[FredCailloux]

My lathe's manual purposefully does not provide a setup spec for the drive clutch. It is intended to be determined by the setup. I set mine so that it never disengages under normal feed, but still pops with hand pressure (my clutch is based on springs and cams, different mechanism, same purpose). I am not interested in having the clutch disengage while doing earnest work, but I also want the clutch to work before the shear pin in the gearbox does.

If your manual gives you a torque spec, you can set it by putting the clutch in a vise and attaching a moment arm of known radius to the output side. Pull the moment arm with a fish scale and record the reading when the clutch slips. Do your conversions from arm length and tension to lb-ft or NM torque, and you've got it. I would not be surprised if you don't find a figure published, though. In that case, just try to put the set point back were it was by using the wear marks on the assembly to guide you.

I'm not sure how I can evaluate properly the clutch adjustment. This thing is bathing in oil. Assuredly, if I make an adjustment with the clutch outside the Apron, the slipping torque will certainly be much different. Would it? Should I adjust by bathing the whole thing in oil? That could be a bit complicated.