10EE back gear bearing removal - how?

DaveC · Oct 2, 2006

I've discovered that my backgear's outer sheave bearing (PN EE-3715) has a broken keeper and will need to be replace. Does anyone know to get that bearing out? I've got the bearing exposed and the snap ring removed, but it doesn't seem to want to slip apart. Is it a press fit? The manual is unclear on this since this detail was apparently redesigned in 1966 and my (new) 1959 manual doesn't have the correct revision of this print.

Also, I'm concerned that the sheave's shaft (the part with the big spline and gear) may be damaged, since the shaft spins freely while the bearing remains stationary. Is this normal behavior with the bearing apart?

Thanks in advance for any info!

DaveC
10EE SN 41978

rke[pler · Oct 2, 2006

You should be able to pull the whole backgear case off the motor face, then push the through shaft through the bearings. At that point you can see that the snap ring is simply to keep the bearings from going into the backgear housing.

If you have the design with feet I have a drawing for it.

DaveC · Oct 2, 2006

Thanks, Russ. I have the motor out, and the gearbox detached and fully apart. What I did not have was a large enough hammer. After I read your post, I went out to the shop and gave the shaft a firm whack with a deadblow hammer, and it sure enough came apart.

I think I'm off to the races now, pun intended...

Thanks!

DC

DaveC · Oct 2, 2006

One other thing: 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?

Thanks anyone for an explanation!

DC

rke[pler · Oct 2, 2006

The sheave shaft appears to be deliberately undercut as it passes through the outer bearing, allowing the shaft to float.

I don't have the same model backgear, but that doesn't sound right at all. As you say, there's no point to having the bearings there if it's not supporting anything. I'd bet that you have something poorly modified, or the bearing locked up and the shaft spun in some way that it looks clean.

My backgear had an odd modification, a collar that looked to be designed to keep the sliding gear to be fed "too far". It worked a lot better with the collar removed.

[ 10-02-2006, 12:44 PM: Message edited by: rke[pler ]

DaveC · Oct 3, 2006

Russ, I think you're right. Looking at the assembly closer, I can see discoloration in the area as if a bronze or brass sleeve once existed in the space between the bearing and shaft. I can also clearly see where the shaft has been turned down to a smaller diameter under the bearing. I'm not sure if there was a bushing on the original part, or if this was a repair. If anyone has this assembly apart, could you examine it for me and let me know if there is any bronze or brass in this location? Thanks!

So I called Monarch and found that replacement bearings come as a matched pair - for $640! That's not going to happen, so I will see if a standard 209NC bearing will work. I guess I'll have to make a bushing as well, probably using a shrink fit or something.

DC

peterh5322 · Oct 3, 2006

"So I called Monarch and found that replacement bearings come as a matched pair - for $640!"

They're a pair of angular contact bearings according to my assembly drawing, so it would be natural to purchase as a set.

rke[pler · Oct 3, 2006

If anyone has this assembly apart, could you examine it for me and let me know if there is any bronze or brass in this location?

The drawing I have has a very small relief on the shaft going under the bearing maybe 1/8", the rest unrelieved. You should be able to set the old bearings and spacer on the shaft and see how far your relief goes and make sure that it does go under the front bearing. If so I'd try and find a replacement for the shaft, and failing that, build up the shaft with spray or weld and refinish it (it sounds like it's too much for hard chrome, but I'd check anyway as that's likely to be cheapest).

If you do determine that the shaft is messed up check with Monarch on the availability of a used shaft. It's very likely that they have one. Failing that there was a motor/backgear on eBay in the past couple of weeks going for a few bucks. I don't recall if it was the same model as yours but you could put the whole shebang in your lathe if necessary.

That's not going to happen, so I will see if a standard 209NC bearing will work.

I'm not sure that'll work well. The difference is that the outer bearing is flanged, so you need the ND 420209DTL and the inner a 7209WNMRBSU (both from my notes when I bought them from General Bearings Company in LA).

DaveC · Oct 3, 2006

They're a pair of angular contact bearings according to my assembly drawing, so it would be natural to purchase as a set.

The bearings that were installed in my machine certainly don't look like angular contact bearings, but they would make sense in this application.

DC

DaveC · Oct 3, 2006

Here are some pictures of what I found inside my backgear.

Here's the whole bearing assembly as it was removed from the gearbox:

Here's the assembly with the outer bearing removed, but the spacer still in place.

And here's a closeup of the shaft with the spacer removed. Notice that the ground section of the shaft extends only about 0.05" beyond the end of the spacer. Also notice that the area under the outer bearing does not have a machined or scored surface, but rather looks like a casting.

So does anyone know what's up with this thing?

Thanks again for any info!

DC

rke[pler · Oct 4, 2006

Sure doesn't look right, at least according to my memory. What is the flanged bearing number on yours? It might be that it's not a 420209 and the shaft was modified to fit an available bearing. But really, it looks like a bearing spun on that puppy but good.

I took the pulley and caps off mine, but have to break the whole backgear apart to get at that shaft. I don't want to blow the gaskets doing that until we're sure that no one else has a backgear apart.

mccolld · Oct 4, 2006

I rebuilt my backgear box about a year or so ago. I replaced the top shaft bearings and the main shaft bearing on the motor side. I wanted to replace the angular contact bearings on the sheave side but they were too expensive. I attempted to locate alternatives but I was unable to find any with the groove cut into the outer race. The replacements I found were $70, but again, without the groove. (Russ, what did you pay for your bearings and did they have the outer groove? I ended up keeping the originals since they were in passable shape.

The assembly in mine is exactly like yours (except for the splines - mine is keyed) but the shaft is not turned down. Also, best that I remember, the ID of the spacer was larger than the shaft. I found that odd but didn't change it.

Doug

Ed Miles · Oct 4, 2006

What is the catalog numer on the bearing. You will have to have the shaft seat built up again and ground to the correct size. The damage you are looking at is called fretting which is the result of a loose shaft fit that under rotating load the smaller shaft diameter rolls in the inner ring bore and slowly wears the shaft down and the bearing bore larger. You will need two new beaings and the shaft seat rebuilt. If you send the catalog number of the bearing I can give you the dimension for the shaft diameter.
Ed

rke[pler · Oct 4, 2006

Russ, what did you pay for your bearings and did they have the outer groove?

The replacement bearings I got were the original spec for the backgear, the outer a ND 420209DTL and the inner a 7209WNMRBSU. The 3 year old invoice shows $144 total from General Bearings Company in LA.

DaveC · Oct 4, 2006

Thanks everyone for the replies. Fretting damage makes sense - I've just never seen it this close up and personal. Unfortunately the original bearings don't have any numbers on them that I can see. I dug through some bearing catalogs and found what appears to be a replacement for the sheave-side bearing. Its a SKF #209NR. That is not an angular-contact type, though, just a plain 45mm bore with snap ring groove.

So I'll see if I can find a replacement shaft from Monarch. It might cost less than the lathe did, but maybe not. Then I'll see if General Bearings has any of the bearing pairs left. Then I'll hit my boss up for a raise...

Cheers!

DC

Ed Miles · Oct 4, 2006

Dave, When you have an idler spur gear the bearing are always two ball bearings with the spacer to get a bit of seperation. Bases on the numbers you could use a 6209-2RS (2 Seals)and another 6209 2RS NR (Snap ring groove and a snap ring). These are of the shelf bearings. Do not ask for New Departure (ND). This brand is no longer produced but there are still some on distributors shelves and they will gouge you for an arm and a leg for them.

Ed

DaveC · Oct 5, 2006

Thanks, Ed.

Neither of the bearings have seals or shields, since the whole assembly lives in an oil bath. So I will need to modify your part numbers a bit. The data I have so far are:

45 mm ID
85 mm OD
19 mm width
outer bearing has snap ring groove
no seals or shields on either bearing

What I'm not 100% sure about is if they are angular contact or not.

I'm looking online at SKF and Timkin-Torrington-Fafnir catalogs, but I don't have the ABMA numbers yet.

DC

donie · Oct 5, 2006

The snap ring groove is a bummer!

Ed Miles · Oct 5, 2006

Dave, you have the camera to take the photos so it is a simple process to check if these are A/C bearings. You have the worn bearing off the shaft. Take a shot of the side of the bearing and then turn it over and take one of the other side and send me an Email with the two pictures so we can confirm they are only D/G bearings. The assembly you have does not have the parts to be an A/C assembly.

Ed

rimcanyon · Oct 5, 2006

Dave,

I needed bearings with snap ring grooves when I rebuilt my 10EE gearbox a few years ago, and there were some horribly expensive ND OEM bearings available, or a cheap generic equivalent without the snapring groove. I bought the generic bearings and cut the groove using carbide tooling. Worked fine.

-Dave

10EE back gear bearing removal - how?

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