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Monarch 10EE gearbox excessive endplay

nxd

Plastic
Joined
Jun 2, 2019
Hi all,

We have a Monarch 10EE in our shop that has been "broken" for many years now that I'm trying to give some much-needed TLC to bring back into working order. Everything it needs done is just maintenance type stuff, but I'm not familiar with the 10EE (beyond what I have read on these forums and elsewhere), so I thought I'd ask for some advice here.

Anyway, this unit is one of the early MG units. I noticed that the output shaft on the gearbox on the DC motor has what seems like an awful lot of endplay, about ~0.075". There's about 0.875" of shaft sticking out when the shaft is pushed all the way in, and gently pulling on it yanks it out to ~0.950". I've also observed that the endplay in the shaft is loosely coupled with the gear selection lever position; the gear selection lever moves a tad if pressure is applied to it and the shaft is moved in/out.

The oil fill sight glass is hard to see through, so my thought was that if I'm going to drain, flush, and re-fill the thing, I might as well disassemble the gearbox and see if there's something afoot inside. Does this sound like a reasonable course of action? What might I expect to find inside, and would anyone know what might explain this large amount of endplay?

Thanks.
 
No expert here so hopefully more experienced people will chime in.

I recently acquired a 10ee.

Once powered up to verify it worked I cleaned the machine up and changed all the fluids.

If you have a square deal machine you can remove the faceplate and look at a bunch of the gears and also see the bottom of the oil reservoir. In my case except for a couple small chips the bottom was perfectly clean.

Once cleaned, oiled and running I found the oil seals on the various handles were leaking so I installed new seals.
Next was the sight glasses as they were also leaking and seeing the oil level was difficult due to the very thin gasket. 1st I tried cleaning and adding a thicker gasket which failed. While tightening the sight glasses I also cracked on from the hole to the edge. I then got some .250 thick clear lexan and machined new sight glasses (because hey I have a lathe) and removed the old gaskets and installed the new thicker ones with thicker gaskets. Now the levels are easier to see and there is a very clear level line thanks to the thicker gaskets.

Now I am hearing a bearing nose on start up at the rear of the machine which I am going to look into today.

Good luck and have fun with the machine.

Sent from my SM-G950U using Tapatalk
 
The gearbox pulley shaft is running in an angular contact bearing pair and should have no play. You can easily remove the front plate of the gearbox after draining the oil and inspect the bearings. If they need to be replaced it is quite possible that a replacement pair of the right size is on EBay.
 
Already covered to death.

Just read MORE, "right here on PM".

There are several threads covering rebuilds of that gearbox, plenty of photos, part numbers, proper bearings, proven workable substitutes - even TiG-up and re-shaping of worn clutch dogs and what can be done if a gear is trashed beyond safe use.

No mystery left to cover in the general sense - save that you nor we know not (yet) what shape YOUR one is in beyond guessing the obvious.

Open your one up, take decent photos,

THEN some among us may be able to point you to more specific advice and cost/benefit choices.

Hi thermite,

I did find some threads prior to posting that showed the inside of the gearbox. I did some searching to see if others had observed the same issue that I did, i.e., excessive endplay, and I didn't find anything. That's not to say that perhaps someone else hasn't discussed that issue before; I just didn't find it. So, I wanted to ask about this specific issue just in case someone more knowledgeable than I had something to say like, "Well, obviously, excessive endplay is because your encabulator is worn, which causes..." or in case someone said, "No, don't disassemble the gearbox before you do ____!" or "be careful that you don't wreck the ____ by doing ____!" etc.

Out of respect for the 10EE, my own ignorance and inexperience, and a desire to not make things worse, I'm just trying to be as careful as I can, and I thought that asking for advice from those who do have lots of experience with the 10EE would be a good way of being even more careful. Perhaps I should have linked to the gearbox rebuild threads that I have already read. Also, just to be clear, by opening my thread with "I'm not [that] familiar with..." I meant to just indicate that I'm not knowledgeable and I worry that I might mess something up; I wasn't at all expecting a user to save me the effort of reading by telling me all about the 10EE; sorry if it seemed like I was suggesting that.

I have not yet pulled the gearbox apart (other things to do, though I may attempt this later this evening), but I did remove the oil fill screw and poked inside with a borescope. I was able to see roughly the condition of the shift fork, a gear in the upper half of the gearbox, and a gear in the lower half, and they seemed undamaged.

The gearbox pulley shaft is running in an angular contact bearing pair and should have no play. You can easily remove the front plate of the gearbox after draining the oil and inspect the bearings. If they need to be replaced it is quite possible that a replacement pair of the right size is on EBay.

Thanks for the clarification! I had assumed that it was this straight forward, but was a little nervous to just pull it apart.

Jaymce, good luck with your acquisition!

If you have a square deal machine you can remove the faceplate and look at a bunch of the gears and also see the bottom of the oil reservoir. In my case except for a couple small chips the bottom was perfectly clean.

When you refer to the square dial faceplate, are you referring to the style of 10EE with several gear change levers, as opposed to the round gear selection knob arrangement (which I assume is the "round dial" variant)? In that case, this would be a round dial machine.

This machine came from the Navy and had been painted numerous times, so part of the work that I have done has simply been to remove paint from places that it should not have been. The headstock gearbox, for example, was painted over so much that the top cast piece which seals that gearbox looked like it was part of the headstock and didn't remove. Anyway, I did remove it and look inside and the gears that I can see look fine. The oil is ancient and needs to be flushed/replaced, though. The sight glasses could also use with cleaning; they're hard to see through. Also, it appears that someone lost all of the fill caps for all of the oil reservoirs, so I need to machine a bunch of those...

Also, I'm not sure that I follow what you were saying about the thicker gaskets, though--how did those interfere with seeing through the sight glasses?

Now I am hearing a bearing nose on start up at the rear of the machine which I am going to look into today.

What initially alerted me to even look at the gearbox more closely was that it made a fair amount of noise--that's with the belts off, so the motor was only turning the gearbox. (I don't remember if it made more noise in low or high, though.) I did also find that someone had, in the past, attempted replacing the brushes on the DC motor and put one in backwards, which may have contributed to the sound(?). (I have started to re-seat the brushes with 100 grit garnet paper, but this will take a while.)

Good luck and have fun with the machine.

Thanks!
 
When I added thicker gaskets it gave more room / space between the sight glass and the level line etched in the aluminum. With the thin gasket once the oil entered the sight area it would wick up and give a false reading. Between the new lens, cleaning the aluminum and thicker gasket I now have a very clear level line.

Sent from my SM-G950U using Tapatalk
 
Hi again thermite,

Just looking at the parts diagrams in the manual, reading through those old threads, and looking at the disassembly photos that I could find, it wasn't clear to me quite exactly how the gearbox went together. Despite the large amount of end play, there was no observable radial play. Rotating the shaft felt smooth. The end play that I felt did not feel like it was the result of worn races, and the bearing balls being allowed to move the 0.075" axially.

So, with an incomplete mental picture of the gearbox assembly (having myself never taken one of these gearboxes apart), I did not have a firm understanding of what retained the shaft axially to know (for certain) that (as I now know) the shaft is retained axially purely by the interference fit between it and the bearing, and the bearing and the housing.

Had I known that for absolute certain before I posted originally, I wouldn't have had anything to ask, because any axial motion of the shaft would imply bearing failure so long as those interference fits were still good. But, with the shaft sliding axially so easily, it didn't seem possible to me that the shaft-to-bearing fit was supposed to be an interference fit. (Again, this didn't feel to me like loose ball bearings in worn-out races.)

So, I just finished taking the gearbox off. Once I was able to get it open, the output shaft & gear assembly literally just slid out of the bearing under its own weight. As it turns out, the end play was due to the shaft sliding freely in the bearing, and the only reason that the end-play was only ~0.075" was that the gear would, as it moved backward into the gearbox, hit other parts in the gearbox, preventing it from moving any further back.

I had read this thread prior to my original post. In retrospect, the OP of this thread seems to report the same issue, but phrased differently such that I didn't make the connection that the problem he observed would have resulted in the problem that I saw:

The sheave shaft appears to be deliberately undercut as it passes through the outer bearing, allowing the shaft to float. So what does the outer bearing support, and how?

The consensus in that thread seemed to be that his shaft spun in the bearing, thereby ruining the interference fit. I now believe that that's what happened to mine as well.

Perhaps it was immediately obvious to those more experienced and knowledgeable such as yourself that this was a likely failure mode. This is the first time (in my limited experience) that I have seen this type of failure. I did not previously know that it was possible for a shaft to spin in a bearing such that no axial play would be observable, and that rotation of the shaft could feel smooth, like the bearings were still fine (as they largely are).

By the way, when I did drain the oil, I got maybe a couple of ounces out of the gearbox. There were some tiny specks of metal visible in what little came out. Could an oil leak cause a bearing to seize, the shaft to spin in the bearing, but the bearing ultimately able to be turned by hand...? Or, did the oil leak result from the bearing failure (i.e., other way around)?

Also, I will note that my particular gearbox had a pair of New Departure 3209 (6209 equiv.) deep groove radial ball bearings. These are d=45mm ID (1.7717"); I measured 1.772" with just a pair of calipers. (I will measure these again with a telescoping gauge and mic when I come back to this.) The shaft measured ~1.770 (again, just with calipers; I will re-measure with a mic later). I guess (based on the path of others in previous threads) I may be calling Monarch for a new shaft, and looking to secure new angular contact bearings.

One last thing: the gears and dogs all looked fine. The little replaceable shift fork bits (not sure what to call them) were slightly worn, so I will look into either making new ones myself or buying these from Monarch (if they have these for sale). (Might anyone have a suggestion as to what specific material these should be made out of, or does the material not matter much?)

Here's an animated gif showing the output shaft sliding axially freely in and out of the bearing:

EDIT: looks like that didn't upload correctly. Try this link instead.
 

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From the OP it doesn't sound like trashed bearing(s) or shaft worn loose. I keep thinking, if it's sliding in and out there has to be something missing; a spacer/shim/washer-looking thingy or the big clip that holds the grooved bearing? Your description of both bearings being grooved makes me wonder about it being rebuilt before. Only one of the two is grooved in my limited experience.

I'm all ears to know if I'm way off! I keep thinking of a ring that goes in there...just has to be something physically missing?
 
The gif sure does make it look like it is a proper slip fit. If miraculously the bearings are still good you could loctite the shaft into the bearings. I know rebuilding mine I have come across things that say there is “no way this could be right” many times. As Steve at Monarch told me more than once, you have no idea what previous owners did to the machine. The bearings spacers are so precise they could have held the bearings preloaded even while the shaft was loose.

As a former technical columnist author your posts have impressive clarity.

One last thing, based on your trepidation, do you have the parts diagrams? If not don’t do anything else until you have them. Many different sources for them. Also, based on reading the linked thread, I am questioning my memory whether they were angular contact or normal, and I am not at home right now to check my parts diagrams.

John
 
It has been a long time since I converted my 10EE to VFD, but when I was running the M/G with backgear like yours, my gearbox had bad seals (aka 'automatic belt oiler')...

From what I recall, ;ateral play in that shaft had no significance in operation, performance, or longetivity, and IIRC, my gearbox bearings were slip-fit on the shaft as well.

Realize that any component subject to thermal change, must accomodate expansion... and likewise, in design, it is not wise to try to captivate or otherwise enforce precision upon some component, where captivity or precision is not necessary... you don't want thermal expansion to cause something to interfere or deflect, and cause problems elsewhere.

SO... while slop in that component may be initially discomforting, it may be inconsequential, or even moreso, desireable.

FWIW... last time I checked, you can CALL Monarch, with your machine's serial number, and they can look up the original sale document, pull the appropriate documents, and make you a complete copy of the original manual set... you will find it very useful, as then you'll be able to tell what is original, and what has been changed.

They can also source parts for most Monarch machines... they did for me.
 
I am home now and checked my parts drawing. The bearings are not angular contact. The are normal ballbearings with a spacer on both the inner and out race. Outer spacer so the assembly can be pressed into the casting and inner spacer so they can be pressed off the shaft through the holes in the gear. Again, if they are still serviceable glue the shaft in with loctite and move on. If the fit is very smooth as your gif makes it look, then use Loctite 290 which will wick around the circumference of the assembled parts. 290 will hold forever, but if you are not convinced use 290 with Loctite primer.
 
Thanks all for the suggestions and information. Apologies if this is post is too long as I try to respond to everyone in turn...:

From the OP it doesn't sound like trashed bearing(s) or shaft worn loose. I keep thinking, if it's sliding in and out there has to be something missing; a spacer/shim/washer-looking thingy or the big clip that holds the grooved bearing?

I also wondered if there was something missing, but I don't think that there is. I'm not certain that I totally understand what's supposed to retain everything, but I don't see what could be missing. The circlip was present, as was the spacer/shim/washer-looking thingy, and the cap that screws over that.

Your description of both bearings being grooved makes me wonder about it being rebuilt before. Only one of the two is grooved in my limited experience.

I guess I wasn't clear: while there are two bearings with the same part number (New Departure 3209), only one of the bearings is grooved. At first I thought that it may have been rebuilt before, but based on more recent comments on this thread, now I'm not sure.

The gif sure does make it look like it is a proper slip fit. If miraculously the bearings are still good you could loctite the shaft into the bearings.

Again, if they are still serviceable glue the shaft in with loctite and move on. If the fit is very smooth as your gif makes it look, then use Loctite 290 which will wick around the circumference of the assembled parts.

I had this same thought, though I don't have prior experience with bearing retainer. Thanks for suggesting a particular type. I'm a little hesitant to use bearing retainer to secure the output shaft to the old bearings in case they're no good, as I don't know how I would get the bearings off at that point. If I go this route (to salvage the shaft), I think I will use new 3602 bearings.

The bearings spacers are so precise they could have held the bearings preloaded even while the shaft was loose.

I'm not quite sure that I follow. The bearings that were in there are deep groove, so they shouldn't get an axial preload, right?

As a former technical columnist author your posts have impressive clarity.

Thank you, I appreciate the compliment!

One last thing, based on your trepidation, do you have the parts diagrams?

The only parts diagram that I have is what I could find in this manual:

monarch_10ee_e1b.jpg

I didn't realize that there were drawings available for these lathes until you said this, which explains how I see so many other users posting detailed part numbers (i.e., EExxxx). I have not been able to locate a detailed manual for this lathe in our shop. When I contact Monarch I'll see what they'd charge for this.

I am home now and checked my parts drawing. The bearings are not angular contact. The are normal ballbearings with a spacer on both the inner and out race. Outer spacer so the assembly can be pressed into the casting and inner spacer so they can be pressed off the shaft through the holes in the gear.

Interesting--I guess that makes your and my lathes in the minority? Perhaps Monarch switched to angular contact later. See, for example, this comment from this thread:

The bearings in mine are, in fact, 6209s - standard ball bearings. Talking to Scott at Monarch he says that they should be angular contact bearings - 7209s.

Before I saw your post, I started to wonder if maybe the bearings in my gearbox were original, based on the parts photo I attached above:

monarch_10ee_e1b_bearings.jpg

Before, I had suspected that the reason the shaft measured slightly smaller than the bearing ID was that the shaft spun in an original set of angular contact bearings, and were then replaced with the ND 3602's as a substitute. It was theorized in this thread that the reason for DaveC's shaft coming loose within the bearing was due to fretting, which is something I didn't know about previously. Taking a closer look at my gearbox, the bearing closer to the output side of the gearbox and the shaft at that same point show a surface finish that could be this?

IMG_1414.jpgIMG_1432.jpg

FWIW, the square-dial machines used two slightly different gearboxes, but even so, most internal parts are the same.

Whether your one is round-dial or square, AFAIK, all the MG-era 10EE with "large-frame" Reliance 3 HP-rated DC 690/2400 RPM final-drive motor, (single-keyway motor shaft, not splined), are the same as to which bearings & c. fit and whether the input bearing shares duty with motor output shaft or not.

Do keep in mind in your research and parts sourcing though, that later gearboxes may not be 100% identical as to internal parts to your one.

Thanks for pointing out those differences. I did notice that DaveC's gearbox had a splined output shaft whereas mine has a slot for a key. The output shaft of the motor in my unit is keyed and not splined like you described. I'm not sure what you mean by "whether the input bearing shares duty with motor output shaft or not" though? There was not a bearing in the rear of the housing (at the gearbox input, which is the motor shaft), so the bearing in the motor frame is all there was to support the motor output shaft / gearbox input shaft.

Also, I realized that the plate which seals the end of the output shaft had been removed some years prior. I didn't know until yesterday that there was supposed to be something sealing the end of the output shaft, but it's fairly obvious in retrospect. (The motor output shaft slides inside of the output shaft and fits loosely; oil can leak around the motor output shaft and out of the center of the gearbox output shaft if this plate is not in place.) At first, I suspected that this may have explained why there was no oil in the gearbox, but I no longer suspect that the removal of this plate had anything to do with that: I believe that the bottom of the output shaft ID is above the oil level, and I think that this plate was only removed to facilitate removal of the sheaves. I did find the plate in a box of parts, so I at least don't have to get or make one of these.

One last thing: the taper pins that I found were a little suspicious, suggesting possible prior rebuild. They were of the sort that are threaded on one end, but the threads were quite buggered. The other really odd thing is that they had nuts installed on them--I can't imagine Monarch installing tapered pins with nuts that could vibrate off inside of the gearbox and possibly wreck something. I also am not sure that I've seen photos of any other gearboxes on these forums that have shown threaded tapered pins, and the parts diagram that I have doesn't show threads on these, either.

It has been a long time since I converted my 10EE to VFD, but when I was running the M/G with backgear like yours, my gearbox had bad seals (aka 'automatic belt oiler')...

From what I recall, lateral play in that shaft had no significance in operation, performance, or longetivity, and IIRC, my gearbox bearings were slip-fit on the shaft as well.

Realize that any component subject to thermal change, must accomodate expansion... and likewise, in design, it is not wise to try to captivate or otherwise enforce precision upon some component, where captivity or precision is not necessary... you don't want thermal expansion to cause something to interfere or deflect, and cause problems elsewhere.

SO... while slop in that component may be initially discomforting, it may be inconsequential, or even moreso, desireable.

I'm not entirely certain that I agree with this sentiment, as lateral play of the output shaft means that, when the gearbox is in its "low" range, the output shaft gear might not be meshing fully with the gear from the shaft above. When the gearbox is in "high" (1:1) and the dogs are engaged, the shift fork will apply pressure on the output shaft (by way of the dog gear, I'll call it), limiting the shaft axial travel. But, in any case, the shaft can rotate freely in the bearings, which seem to primarily want to stay stationary and not rotate. If there's not adequate lubrication between the shaft and the bearings (which, as the gearbox is splash lubricated, seems likely), I would expect the shaft OD and bearing ID to wear where they rub, which seems undesirable. At this point, the 3602s would seem better replaced with bronze bushings?

FWIW... last time I checked, you can CALL Monarch, with your machine's serial number, and they can look up the original sale document, pull the appropriate documents, and make you a complete copy of the original manual set... you will find it very useful, as then you'll be able to tell what is original, and what has been changed.

They can also source parts for most Monarch machines... they did for me.

Thanks for the suggestion. I intend on reaching out to them some time this week.
 
...
The only parts diagram that I have is what I could find in this manual:

View attachment 259156

I didn't realize that there were drawings available for these lathes until you said this, which explains how I see so many other users posting detailed part numbers (i.e., EExxxx). I have not been able to locate a detailed manual for this lathe in our shop. When I contact Monarch I'll see what they'd charge for this.
...
Unfortunately, drawings for round-dial 10EEs ARE NOT available from Monarch. The round-dial documentation is officially "OBSOLETE-DISCARDED" (this is per Terrie at Monarch). At my request, she was kind enough to go on an extensive search of "the catacombs" for round-dial 10EE assembly drawings, like the ones that they provide for square-dials, and came up virtually empty. In the past, someone here managed to get a round-dial gearbox drawing (IIRC), but Terrie could not lay hands on it again. About the only thing she found was an older version of the round-dial headstock drawing, EE-99. Unless things have improved dramatically, you won't be getting any assembly drawings when you buy the documentation package for a round-dial 10EE.

The manual for square-dial 10EEs includes "parts sheets" for each assembly that call out the EExxxx numbers for each part. For example, parts sheet 101 covers the back-gear unit. The square dial documentation package includes a generic set of assembly drawings. Here's a link to a 1965 square-dial manual (link) which includes both the parts sheets and the generic assembly drawings. Fortunately, many of the EExxxx parts from the round-dial found their way into the square-dial and you can get a pretty good idea what's what from the square-dial drawings.

One very useful thing that you do get from Monarch is the build sheet for the machine, including the name of the original buyer.

Cal
 
Threaded taper pins that hold the shift forks to the shaft allow you to remove the pins, since there isn't much (or any, really) room to tap them up and out. You'll realize it quick when you actually need to remove the pins. If I remember correctly, nut is rolled on and pin tapped into place, allowing for tapping to distort the end so nut can't roll off. At least that's what I did when installing them.
 








 
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