Gear Mesh between bevel pinion and ring gear

McCormick-Deering 22-36 Project.

Transmission almost put back together after replacing four tapered roller bearings and the spline shaft hub, and making some custom chrome-cobalt castings to take up the wear on the spline shaft, using these 6 shims between the hub and the spline shaft to successfully take up the slack.
Before completing the rebuild, I decided to test the gear mesh, without the entire weight of the tranny to contend with.
I put the tranny back into the frame, fitting the two tapered orientation pins, one on each side, also using the proper thickness gasket material under the tranny where it meets the frame, then bolting the tranny down.

I painted two teeth on the ring gear with marker paste and then ran the gears together, back and forth 30 times or more and all the way around several times.

The following image shows the gear mesh pattern.
Without giving my opinions, which I have, I would like to have your feedback on what conclusions to draw and what to do.

Thanks, Tom


<a href="http://s99.photobucket.com/albums/l281/Tom_084/?action=view&amp;current=Gearmeshpattern1forposting.jpg" target="_blank"> </a>

Hope this helps,looks to me like a toe type is happening,but can't really tell by a few teeth,we usually do atleast a half a dozen or more,but that just us,does a more accurate telling of the meshing of the teeth. Regards,LOU & VICTOR

With respect it is not hypoid style, straight bevel gears adjust differently. there is not much change in in-out movement. Jim

You are (at least) a little confused.

The tractor uses a simple bevel gearset.

The diagram you have posted is for setting up a HYPOID gearset, a TOTALLY different (and a LOT more fussy) animal.

I DO NOT know how IH intended the gears to be set up, but what you are doing, using the hypoid instructions ain't the way!

I would GUESS it would be set up with the rear tips of the pinion teeth more or less even with the inner end of the teeth on the ringgear, then move the ringgear right or left 'til a certain amount of play is achieved.

Not mistaken,just put a picture of what I was talking about being toe close mesh,a gear set is a gear set, regardless of what oil they run in, you have to move the pinion by shims or the ring gear by shims,exceptions are newer designs. older ones are either shimmed,or spaced by shims to get the desired effect of gear mesh.Without bad wear characteristics, howling or annoying whine,although with some older models some whine is unpreventable.The tooth contact should be shaped,for lack of a better description, like a cigar or submarine,with the most contact at the center of the tooth,not at either edge or close to the top only.Not trying to ruffle feathers,but I can remember rear differentials and transmissions ran 40% mineral oil for lubrication,makes no difference what the lubrication is,it is all set the same way,just different angles of the tooth.
Regards,Victor & LOU

Do the gears have any dimensions marked on them? Here is a address of a pdf file that explains it some:

files.engineering.com/download.aspx?file=Bevel_Gear_Backlash.pdf...

Looks to me like, so long as the pinion gear and the ring gear teeth are fully meshed, there is no provision for toe or heel adjustment. But certainly there is for back-lash adjustment. Only way to change toe-heel adjustment would be to change the angle of the gears intersecting.

The world is more complicated than that. Hypoid gears have a different tooth profile and mesh dynamics. It's not just a different lubricating oil requirement.

I can't see the heel of the gears in that picture. If they are indeed flush then how much backlash do you have ? Test in several spots. do you have any info for that model on backlash specs. ????

On a straight bevel set like that, your pinion would need to move back a bit, then the ring gear would need to be shimmed out a bit. If it is a parade tractor you may not want to bother.

Yeah, don't follow the hypoid instructions, the spiral cut and offset from centre line make them different to set up.

"a gear set is a gear set, regardless of what oil they run in,"

Who said ANYTHING about what oil the run in???

Check out the link below to see what HYPOID means.
WIKIPOID

Without actually being there first hand, and just looking at the pics, I'd say personally the contact pattern you've got looks fine to me. I say this because it appears that you've got full contact between the faces of the ring and pinion gear and the teeth aren't bottoming out. Rather they appear to be hitting at what appears like a proper depth with each other. That said given the fact they are straight cut bevel gears don't let the extra little bit on the toe bother you. I've never seen anybody turn the gearset that many times when setting them up. As many times as you say you turned it the 'problem' could be one tooth that isn't exactly right and the number of turns just makes it look like the problem is worse than it actually is. As a part of that train of thinking, just the transfer of the paint from one tooth to another on the first round would make that one tooth be higher than the others. From that point on it will just make the problem look worse every time that high spot goes around and hits and picks up more of the marking compound. Granted the depth they mesh also controls the amount of backlash but as long as it is within spec, or 'feels good' if you have no actual factory spec. All that said, if the gears have been running together for years, and you had them apart you can bet they will never run together again exactly the same as they were origionally. Too if they are new or used gears they will not run together exactly true from the start. Either way, given the pattern that you've got, as long as there isn't an excessive amount of backlash then I'd go with it.

Looks Good Tom. Shim to get backlash and try to keep the outer edges of the gear and pinion even. On a helical bevel gear you move the pinion in or out to make the pattern even on both sides of the tooth and move the gear in or out to set backlash. On a straight cut like yours I would move both to keep the pitch cones together.
Later Bob

Hey Lou -

Thanks for the picture! That is very helpful to see how the adjustment should be made!

Thanks for the comments.

Howard

Bob At age 75 + I can tell ya I do know about Hypoid . I don't need any Smart Azz to try and tell me what I should look at or tell me any thing until they walk a while in my shoes. I've been here a lot longer then most and if the Good Lord is willin, I'll be here a little longer . What we were trying to do was be helpful .but I see there are those who dis agree,and make a reply with malice. Sorry your in that number. LOU

LOU, there was no malice intended.

Straight bevel gears and hypoid gears are like apples and oranges and for reasons known only to you, you insist on tossing them in the same basket, which ain't gonna work.

But that's fine, go on being a legend in your own mind, as will I! (LOL!)