Question on my HD11 series B

I just bought a FA HD11 B at an auction & all seemed to work ok.
Once I got it home & tried to push a little dirt I found out the tractor
Moves fine until you put it under a load then it stalls? It appears the
driveshaft is turning but not quite at engine rpm & I can detect a
load on the engine but the tracks quit moving????? I ordered books
but don't have them yet. Where do I start? The tranny appears to be
full of the correct oil. Any guidance is appreciated!!! gts

With the blade & rippers up the tractors operates fine. It moves forward & backwards & shifts to high range in both.
Under wide open throttle if you lower the blade the tracks will stop moving even though the engine is still running
at high rpm. The driveshaft is still turning just a lot slower than the engine rpm. All the gauges appeared to be in the "green".

what do you mean by the driveshaft is still turning,, did you open up the tranny or some inspection cover to see something turning? I have an 11B on mine there is no where to see a shaft turning other than the front of the crank shaft, or the finals turning. There is a cover on the bell housing you could see the torqe converter/ flywheel. I wonder if your powershift is slipping, did you try changing the filters or look inside of them to see if they are full of metal? My guess is if you just bought this on auction, this is the reason they sold  it, and I would further guess the fix isnt cheap.

The driveshaft I speak of is the one between the converter & transmission. I thought the steering clutches were released by pressure? I will pull the diff cover this weekend & see if I get anything coming out of the tranny.

Don't know if I can help but we have 4 HD 11B series powershift dozers in are AC collection. We've had a couple of them for almost 30 years. They all seem to have there own personality's.We have one scenario that's close to yours. We brought one in that we had very little history on and when we started running it it was very sluggish. Based on some other experiences we had  we decided to run it after we checked the oils and filters. We have to run it for 15-20 minutes minimum before it will work properly,weather temp could be 100 degrees or 25 degrees. Once it's working ok it works fine in very adverse conditions. Are prior experience being an HD11EP powershift that was very sluggish and would creep when it was in neutral. We thought we identified the converter as the problem,so after disassembly and no smoking gun, we replaced some worn parts and still had the same results. At that time the transmission pressures all checked out ok. It has the same symptoms. Won't hardly move when we start it, 15 - 20 minutes it's fine, I can feel it when it's close to normal.   Don't know why there like that and we probably won't know untill were forced to go further. The other fourm posts are all good info also. The only reason I was bringing it up was because your original post doesn't say how long you might have tried to run it. My recommendation would be to check the oils and filters for metal and then run it for at least 20 min. (if you haven't run it that long yet) 

Anyone trying to offer you advise that dont know AC torque converter tractors have a drive shaft between torque converter and trans are the wrong people to be doing so. If your drive shaft is turning and your tracks are not, your transmission clutches are not fully engaging.   Robert McIntosh

You know all later 11s use the right clutch shaft for forward gears, and early tractors used the left one