Fitting spacing shims on stub axle of 1702D

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oldbrownhat
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Fitting spacing shims on stub axle of 1702D

Postby oldbrownhat » Tue Sep 01, 2020 8:23 pm

Darn... wretched stub axle on my 1702D broke off the wheel mounting plate. (I think I already replaced this in 2018.) Fortunately, a retired millwright friend up the street cleaned up the break and welded it up solidly for me.

Now a question about the spacing shims (marked in red on the attached pic.) Is there a preferred technique to fitting these and knowing how many are needed? One time I think I "printed" the gears with Prussian Blue to get as good a fit as possible between the horizontal & vertical gears (#10 & 19). I can do this again but is there a simpler rule of thumb for this?

1702D spacing shims.jpg
1702D spacing shims.jpg (51.96 KiB) Viewed 484 times
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winston
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Re: Fitting spacing shims on stub axle of 1702D

Postby winston » Wed Sep 02, 2020 6:30 am

Probably no help but pretty sure you are looking for .004 - .006" backlash at that point.

oldbrownhat
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Re: Fitting spacing shims on stub axle of 1702D

Postby oldbrownhat » Thu Sep 03, 2020 2:33 pm

Despite having had the wheel assemblies off a few times in the last few years, I just realized today that since there are indexing pins in the yoke above, I can attach the stub axle assembly without the lower casting, which makes it possible to see the gear engagement (!)

There is quite a bit of slop in all the gears so it's hard to assess the backlash. I doubt I can get it down to .004-,006" though.(Maybe on a brand new machine.) There's even a little bit of loosenessin the fit of the stub axle crown gear on the spline. Anyway, I added a second 0.26mm (0.010") shim and there doesn't seem to be any binding when I turn the wheel axle, although there is quite a bit of resistance from the rest of the drive mechanism. So I called it good and tightened the lock nut down properly with its toothed washer and some Loctite 277 on the threads. I'll let it cure and reassemble the whole shebang tomorrow. I think it's likely as tight as it ever has been while I've had the machine.
Attachments
Yanmar LH gear in place.JPG
Yanmar LH gear in place.JPG (110.02 KiB) Viewed 462 times
If a politician found he had cannibals among his constituents,
he would promise them missionaries for dinner. (H.L. Mencken)

winston
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Location: North East Texas

Re: Fitting spacing shims on stub axle of 1702D

Postby winston » Thu Sep 03, 2020 5:24 pm

If you add enough shims you can get backlash down to 0, however, with your wear the tooth contact might suffer. One of those times you need to let common sense rule.

oldbrownhat
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Posts: 30
Joined: Wed Jul 14, 2010 6:15 pm
Location: Mission, B.C., Canada

Re: Fitting spacing shims on stub axle of 1702D

Postby oldbrownhat » Thu Sep 03, 2020 6:33 pm

LOL. I looked at my selection of shims and thought about that but deceded it just wasn't worth it, given the wear on a 30-35 yr. old machine. "Close enough for government work" as they say :). The tractor isn't in daily use so it should still last a while... or until something else goes wrong that I've had no experience repairing. I know the front wheel assembly pretty well by now, At least this happened in good weather in an accessible spot and not in the middle of winter at the back of the property :)
If a politician found he had cannibals among his constituents,
he would promise them missionaries for dinner. (H.L. Mencken)


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