Lather help needed my lathe died.

I have a 12 x 36 Churchhill lathe from England. The clutch has been slipping for a long time after it runs and gets hot it ususlly does fine all day but today it will not run. I took it apart and the clutch has a disc type brake pad covered in oil and black grease. I don't know if it is suppose to be covered in oil or if that is leakage from many years of use. I'm not sure what to do at this point. Should I degrease the clutch disc plate and put it back together and see what happens? It has 3 springs and about 15 balls inside I will have to stick the balls in place with some thick grease to hold them there to get it back together. I don't know any other way to hold the balls in place while I put it back together unless rotate the whole lathe 90 degrees and stand the lathe up on end. Once it is together maybe some degreaser spray can be used to remove the grease. Maybe it needs a little grease I don't???

Anyone here have any ideas???

The clutch plate might need to be replaced, what on earth can I do about that, I bet no such thing is available anymore???

Im not familiar with churchhill lathes, or the clutch that you discribed, but as a rule if there is a clutch plate for foward engagement there is usualy /always? one for reverse, cant you just swap the discs over and live without reverse?

KB

is this it?

http://www.lathes.co.uk/churchill cub/

A friend of mine has a Churchill Cub MkIII.

The clutch design is very strange: it appears to rely on three pairs of rollers springing a clamping 'ring' in an over-centre mechanism. It seems to me that ANY wear will cause it to fail. The clutch on this lathe had been 'shimmed' to lock it up and disable it. I don't know if he's worked out how to fix it yet.

Last ditch effort, you might wipe it clean, then it will probably slip, but let it, then when the rest of the oil burns out, it will grab like the bejesus, or not work at all. Then you could shim it like above, or remove it. If you burn the oil out, it will get very "grabby" if it's supposed to be a dry clutch and it's similar to an automotive clutch. I've never seen or worked on a lathe clutch, so don't look at me if it blows up!

Have you thought about re-lining the clutch. I went on the net and found a
company that sells lining material. They also supplied the rivets. Did a motorcycle
clutch myself. A big sheet cost me $20, 2 feet by 3 feet.

I recommend using brake clearner to clean the disc and cold(as in from the freezer)petroleum jelly to hold the balls in.When you restart the lathe the petroleum jelly will soften and run out,most likely.Be prepared to wipe up the excess using a rag soaked with brake clearner.

http://www.lathes.co.uk/churchill cub/


YES!!!!!! That is it.

My friend has dug out some pictures of the clutch:

He says:

Hi Bill,

These are all the pics I have of the clutch mech. What type (Mk) of Cub is
it BTW?

If it's just a case of wear, to why it's slipping, then probably all it
needs is adjustment of the preload collar on the wavy spring washer? If he
takes it apart, can he note the arrangement and dimensions of the rollers in
the over-centre latching/pressure mechanism?

Cheers,

Chris.

Click to expand...

I think (from a quick look at the real thing a while ago) that the short rod connects the inner shaft to the outer ring, the splined inner ring has a similar slot to match the one on the splined shaft. Thus the clutch lever moves the inner shaft and toggles the outer ring over the four rollers, that make up the over-centre mechanism, pressing the clutch plates to engage the clutch or against the washer to disengage it.

It sounds like you may have a sprague clutch. Research this type of clutch and see if it applies. Springs, ramps and rollers all go together and get stuffed inside an outer drum (or ring). They engage when the innershaft is rotating faster than the outer. I worked with them on old Saab cars with what they called "freewheeling". Just a thought...

Jim Caudill said:

It sounds like you may have a sprague clutch. Research this type of clutch and see if it applies. Springs, ramps and rollers all go together and get stuffed inside an outer drum (or ring). They engage when the innershaft is rotating faster than the outer. I worked with them on old Saab cars with what they called "freewheeling". Just a thought...

Click to expand...

No Jim, it is not a sprague clutch (although I can see how it might sound like one)

Each of the four pairs of rollers are at right angles to the shaft. The pair will roll on top of each other as one ring slides axially over the other, but are constrained by the space between the rings (there is no separate spring, other than the outer ring flexing), so creating a force in one direction or the other (like a typical over-centre mechanism).

My clutch is FIXED and it works better than it has very worked in the past. I soaked the clutch friction disk in Naptha for 3 hours. I cleaned all the parts with Naptha. I put all the parts back on the shaft except for the cup part under the hex nut and the part that fits inside the cup part and the balls.

Holding the cup up I dropped in the other part. I put some thick grease inside around the outside edge and dripped in all the balls. The balls stuck in the grease and would not fall out.

Next pull the handle on the lathe to put it in gear. It won't stay there by itself so I had to hold it there. The part inside the cup and the cup both have threads in them and they are both probably metric. The cup looks like 1/2" fine threads and the part inside the cup looks like it has 7/8" fine thread. With the handle pulled I placed the cup assembly on the shaft. I slowely release the lever until the 1/2" shaft toughes the cup. Keep releasing the lever and at the same time push the pin that sticks out of the hole in the cup down until the pin is flush with the outside surface of the cup. Then I turned the cup and it screwed both the 1/2" and 7/8" threads on the shafts at the same time. I screw down until the 1/2" shaft was sticking out about 3/8" past the outside surface of the cup. Put on the nut and locked it and turned on the lathe. It would not stay in gear. After some experementing I learned how it works. The cup has to be turned about 1/20 th of a turn while pulling the level at the same time. When the correct place if found it stays in gear. Don't ask me why it stays in gear I don't know. If the cup it turned IN or OUT too far it will not stay in gear. If it is screwed in too far it never clicks past the point where it wants to stay in gear and if it is not screwed in enough it never clicks and tries lock in place. It is a very sensitive adjustment. If it is off one way or the other more than about 1/20th of a turn it won't work. The cool thing is it makes no difference how much the friction plate wares out all you do it screw the cup in a little and it fixes it.

Cool. Any idea how it got greased?

Glad you have fixed it Gary, but I'm finding it hard to reconcile your description with the clutch on my friends cub. Do the photos I've posted look like your machine. (do you know which model cub you have?)

Could you post pictures?

Bill

Billtodd said:

Glad you have fixed it Gary, but Iam finding it hard to reconcile your descriptioon with the clutch on my friens cub. Do the photos I've posted look like your machine. (do you know which model cub you have?)

Could you post pictures?

Bill

Click to expand...

The first photo of the double V belt pully looks identical to my machine. In that photo someone has already taken off the hex nut, 1/2" shaft is gone, other parts are not there either.

Billtodd said:

Glad you have fixed it Gary, but Iam finding it hard to reconcile your descriptioon with the clutch on my friens cub. Do the photos I've posted look like your machine. (do you know which model cub you have?)

Could you post pictures?

Bill

Click to expand...

The first photo of the double V belt pully looks identical to my machine. In that photo someone has already taken off the hex nut, 1/2" shaft is gone, other parts are not there either. I see an hole in the end of the large shaft where the smaller shaft should be.

Billtodd said:

Glad you have fixed it Gary, but Iam finding it hard to reconcile your descriptioon with the clutch on my friens cub. Do the photos I've posted look like your machine. (do you know which model cub you have?)

Could you post pictures?

Bill

Click to expand...

The first photo of the double V belt pully looks identical to my machine. In that photo someone has already taken off the hex nut, 1/2" shaft is gone, other parts are not there either. I see an hole in the end of the large shaft where the smaller shaft should be. I see the metal disc and the clutch friction disk is not there either. There should be 2 more metal pieces with a metal cup over them with metal roller bearing balls inside and a hex nut to hold it to the 1/2" shaft. I already have mine back together. Wish I had taken some pics.

Thank for that Gary. I'll pass it on to Chris with your fixing instructions. Hopefully, he has the missing bit somewhere.

Bill

After a long consultation (aka chin-wag) with Chris, this is how I think it is supposed to work:

Billtodd said:

After a long consultation (aka chin-wag) with Chris, this is how I think it is supposed to work:

Click to expand...

I think I'm missing something. How does this mechanism disengage From what I think I'm seeing, the inner most diameter is splined, and it looks like those 4 sets of 3 rollers are captive to both the inner and outer rings.