Left rear shaft turning but not spindle for track

[RHT]

I have a 1950 2 cylinder MC which has 3 rollers. Today while moving dirt the left side track stopped moving . The left rear shaft turns but not there is a gap between the shaft retainer nut and the track wheel,where I can see the shaft and key- something broke or came disconnected. Does anyone have any ideas what part broke or what parts I need so that the rear shaft and track wheel on left side both move ? Thank you. Even a PDF on disassembly and reassembly so that I can get this issue fixed and operational.

[original possum]

If you're lucky you can tighten the nut to about 900 ft lbs and get back to work. But I would break the track, remove the sprocket, and see if the sprocket and/or axle needs to be replaced. Tighten the other side too. You will need to break the track regardless to make sure the sprocket lines up with the splines. Most people cut off the back of the rock guard for clearance to remove the sprocket instead of removing the guard and rollers. Won't look original, though.

[fundytides]

Is the axle shaft turning in the hub? If so, the spline on the axle shaft, in the hub or both must be bad unless the nut has backed off and allowed the hub to become loose on the shaft. If you have to replace either the shaft or the hub, there are two different one used depending on the serial number of your unit. Different splines I think. The ones used on the later MC (serial #15151 and up) are the same as used on early 40c (up to serial 62263). Good luck!

[RHT]

The nut and shaft are turning but not the track sprocket. I'm not sure if the nut is backed off . It looks like the shaft has moved outwards beyond the track sprocket. I believe that something has broke or loose on the inside. I will need to take the inside cover off to see what happened. I do appreciate the insight and all the ideas that will help me get this resolved. I will write down the serial numbers when I return to finish the diagnostics. Thanks for all of the ideas to help me sort this out. RHT

[fundytides]

Do you mean that the shaft has moved outward through the hub that the sprocket is bolted to? If the shaft is turning but the hub is not, there has to be a problem with the axle and/or hub splines. The hub can not turn without turning the sprocket unless all sprocket bolts and guide pins are broken off.

[RHT]

I located the serial number for the 1950 model MC Crawler- Upon closer examination, it appears that the nut that is tightened for the left rear axle has not loosened up. The nut and shaft have moved outside the track sprocket. I can see the key in the shaft in the portion that is protruding. I will disassemble the inside cover of that shaft to see what exactly happened. I probably should purchase a service manual for this crawler and locate a parts supplier who can give me the correct part numbers and corresponding prices so I can assess costs once I know the extent of the damage. Any pointers or insight is appreciated.
RHT

[Lavoy]

I'm a little stumped on what you mean. There are only two possibilities I can think of. The hub is loose on the axle, or the axle has come out of the bull gear. If the nut is turning, and the hub is not, the splines are stripped in the hub and/or on the axle, there is no key, if you can see one, someone else has modified something.
If the axle has spun in the hub, it is extremely likely that one or both pieces are ruined beyond any repair, and tightening the nut will not help.
Lavoy

[original possum]

If you see a key then your axle is busted. Otherwise you would see tapered splines. Go to http://jdpc.deere.com/jdpc/servlet/com.deere.u90490 - type in MC, click exact model search, click FIND, and go eat lunch while the .pdf downloads. Save it to your desktop. then open it, click alphabetical index, F, final drive, scroll down to crawler and voila - there it is.

[RHT]

I am new to this forum and if the tapered splines run the length of the shaft, then possibly, that is what I'm observing. I will look at the link and files provided to me and get a better idea of whats going on. Thanks for everyone's input. I just bought this MC in October and didn't put 8hrs on it when the back sprocket and axle issue emerged. I did purchase a service manual from one of the links provided. I determined to get this crawler back in operation.

[RHT]

I did locate a picture of the bull gear for the 1950 MC and it looks like the splines that I am seeing as the bull gear came unseated inside and moved outward. I am not sure but i think the bull gear must lock into a gear somehow . Before I order parts, I am going to see if I can look at the axle assembly from the inside to see what happened. I believe that there is an access plate .