Farm Equipment - Question on D21 pinion / bull gears

Question on D21 pinion / bull gears

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Category: Allis Chalmers
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URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=178432
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Topic: Question on D21 pinion / bull gears

Posted By: tbran
Subject: Question on D21 pinion / bull gears
Date Posted: 18 Feb 2021 at 9:20am

We have a unique opportunity as a customer who had a machine shop and a D21 with bad bull gears/pinion is about to embark on reverse engineering a set of the wider gears but might shave a few thous to make fit EZ.

He will machine the pinion billet - then send to a friend who will hog the gears. A very reputable business with lots of high end military contracts. The Bulls would be from solid cutouts and hogged and then he would machine the rest.

The price - and this is an estimate - would be $1100 for the pinion and about $1900 for the bull gear. He can do extras as the material is not what makes this expensive. We have called around looking for these an the prices are much more than new. We are not looking to profit - just keep the old gals going.

The most important thing is having a few sold will save on the set up per/unit and the gear company will save the program.

If you have a need - let us know. The next batch will be higher - if there is one.

Again, we have done some preliminary serious research = prices might vary but we are serious.

PS this company does reverse engineer haploid spiral bevel ring gear / pinions as well. Now those are expensive ( have seen some huge ones there used in pill press - tablet making machines and some tiny ones)

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When told "it's not the money,it's the principle", remember, it's always the money..

Replies:

Posted By: Hurst
Date Posted: 19 Feb 2021 at 10:11am

Just my engineer side thinking, but would it be possible to make a herringbone (double helical) design for the pinion gear to help spread the stress on the gears? Just an idea that would theoretically give you stronger gears without increasing the size.

Hurst

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1979 Allis Chalmers 7000
5800 Hours

Posted By: wildcat2
Date Posted: 20 Feb 2021 at 9:55am

My brother and I restored a D21 that had a bad pinion gear, we were able to replace the ring and pinion with a good one from a 220. The bull gears where starting to flake so we reversed them from one side to the other side. Don't know if that would be an option for you.

Posted By: SteveM C/IL
Date Posted: 20 Feb 2021 at 11:30pm

I have been inside my 45 and 220. It seems to me the engineers didn't quite have the tooth crown designed right because too many teeth seem to be flaking about half way up the tooth. I am not a metalurgist or engineer so can't speak with authority. Both tractors should out live me sooo..... Didn't notice that in my 5000hr 8070 transmission.