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Unimog

Allis Chalmers Big Ten drive gears

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Unimog
I have just aquired an Allis Chalmers Big Ten. It runs good but it needs the drive gears in the primary gear box that is located behind the engine and has the drive shaft going into it. The gears are bevel cut and one is located on the end of the drive shaft and the other on a driven cross shaft that provides power to the mower deck and transmission via v belts. Any help would be appreciated, thank you.

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Dutch
quote:
Originally posted by Unimog
I have just aquired an Allis Chalmers Big Ten. It runs good but it needs the drive gears in the primary gear box that is located behind the engine and has the drive shaft going into it. The gears are bevel cut and one is located on the end of the drive shaft and the other on a driven cross shaft that provides power to the mower deck and transmission via v belts. Any help would be appreciated, thank you.
That "primary gear box" is known as the Bevel Gear Box (BGB). It should be removed and completely rebuilt. Just follow the instructions in the repair manual (free online download). The BGB holds the front and rear of the tractor together. For the first time, plan on the job taking about 6-8 hours. New parts should still be available.

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Mack
B series service - drivetrain section. http://simplicitytechpubs.com/6767PRINT/PDF_files/TP_500_3478_00_LT_A_SecE.pdf Contact the sponsor's on the host page for parts. http://www.simpletractors.com/default.htm

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RayS
There is also a set on ebay forsale by a member of this club. Here is a link http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=66761&item=4340492741&rd=1 .If they are in good shape this would be a good deal.

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Dutch
For all online manuals, refer to the "sticky" at the top of this page titled, "Simplicity Manuals Tech. Publications Doc. Search" All Simplicity/Allis tractors use a MFG# or Product#. That should be a 202xxxx for an Allis, which x-refs to a 99xxxx for a Simplicity. You'll need that number to know what tractor you have. If the decal is missing from your tractor, you'll have to make a guess. Check out > http://www.simpletractors.com/Main/x-ref_table.htm Looks like a Big Ten will be either a 2025060, or 2025061. Use the Simp # (990350 / 990351) for manuals and parts. Use the Simp # for all parts and repair info. Except for color, they are the same tractor. Parts are available from any local Simplicity dealer, or online (for example > http://www.jackssmallengines.com ) or by telephone (for example > http://www.sandylakeimp.com )

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PeppyDan
I have been told not to reuse the bevel gears. They wear into each other and over time, with the bearing getting worn these gears if reused will not mesh properly for quiet operation. I personally tried to reuse a set when rebuilding a BGB. It was very loud after new bearing/seals were installed. Does anyone else have comments on this. Was this a one time fluke or is it typical. Dan

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johnerj
Dan, This is very typical. Most of these are 30 or so years old and the gears do wear acording to the play, and misalignment. I have also read not to reuse the old gears IF you have excess play or slop in them. The machines we build here at work have a bevel gear box in them, and we always use lapping compound on them when running them in. After a period of about 16 hours of running the lapping compound is cleaned off then the backlash is reset, and then they are lubed. If we rebuild an old machine new gears and bearings are installed. John

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clyde
David, welcome to the club. Looks like you got all the right advice already (which is very typical here). If you decide to swap in a used BGB, member Dan (rokon2813) lives pretty close to you and may be able to help you out.

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Unimog
Wow, you people are great. Super fast and accurate advice. It is really nice to see such interest in these machines. Thank you very much. I will keep you posted on my progress. I would like to get the machine together with the snow blower to use just for fun. Then put the mower deck on and send it to it's final resting place, the great lawnmower nursing home and graveyard, where all good mowers go to die, my girlfriends house. Where checking the oil and simple maintenence have no meaning. And, "it was knocking for about an hour then stopped running and started leaking and smoking" is the usually final epitaph. Maybee if I can find another mower this old beauty can live a long retirement next to my 57' Cub, 63' Cub Cadet, and my old Jacobson 10hp.

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PeppyDan
John, can you explain in more detail how to go about running in the gears with lapping compound. Do you mix it with the oil and then clean/change gearbox oil after useing the tractor or do you run the gearbox on a "test bench" with only lapping compound? This could help rejuvinate a few sets of gears I have lying around.I have thought of doing this but wondered how it would react with gears & the bearings! Dan

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johnerj
Dan, we run them on the bench with an electric motor. Use white lithium spray grease on the bearings and then lapping compound just on the gears, no oil. It is mainly to remove any burrs, and smooth the contact points of the gears. I have found that it does not quiet the old gears. If the bearings had slop in them then they will be worn past the point of bringing them back. I have done 3 old gear boxes this way, and the gears in my 7116 are still a bit noisy. If the bearing were not to bad, then the gears will be good to use without lapping them. At work we only do this to new gears, and if the back lash can not be set properly in the old gears then they are replaced. John

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dhardin
If you got it open try to replace as much as you can aford with new, its time and money well spent. From my limited experence the cross shaft bearing stay tight longer than the inside input shaft bearing. If the input shaft inside bearing has a small amount of wear you cant see it, just replace it, its a common bearing at NAPA for about 4 bucks. I did not and trashed a matched set of gears (used) from a fine member. But as luck would have it the brokin tooth in the set was bifferent than the old set. Witch ment i had a good input and output gears but not a match set. I reassembled the bgb on the bench and spun it, as luck would be with me again there was a exeptable lash and grear mess so i instaled it and have used it for the last year. So using a non matched set of gears can be done but it is not recomeded for the time it takes, and if your tractor fund is up, mine was not at the time. As you will find for the cost of a new set of bgb gears i bought a compleate parts tractor. Also check and or replace the keys if they are not tight. Most of the time if the bgb is in need of repair the keys will also take a beating and roll ever so slightly in the keyway adding to the end play/lash problem. Good luck.

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