129 Wont Move
 

I recently picked up a Cub 129. I bought it non running and recently got it going and it runs very well. Now the problem I’m having is that the tractor won’t move. Not forward and not reverse. I ruled out some simple things like check spiral pins in driveshaft, oil level, etc. I even removed and cleaned the two hydro valves on top of the pump. Still nothing. Any ideas? Any help is appreciated!

Did someone change the transmission filter,,
and end up with an air lock in the filter, keeping oil from getting to the pump?? :bigthink:

Does the shaft through the hydro turn when the engine is running? There is a shaft that comes out the back of the hydro? It will turn with the input shaft. Check that.

A broken spirol pin is not obvious as it remains in the hole and may still be sheared off on the shaft inside the coupling.

Lack of fluid in the rear end, plugged filter, charge pump on backwards, pinched o-ring on the charge pump cover, broken swash plate/trunnion arm, no connection between speed lever on dash and the hydro cam plate.

1. Verify output on rear of hydro is turning, if not, you've got a spirol pin sheared
2. Change fluid and filter. Clean out rear end in the process. 7 qts Hytran or other similar hydraulic fluid. Roll the tractor by hand to prime the pump if the filter has been recently changed.
3. Remove the tunnel cover and observe the speed control lever, it should move the cam plate beside the hydro which in turn should move the trunnion arm fore and aft.
4. Possible both relief valves are shot. Usually I find one--so it moves one way but not the other. But both is possible. Make sure the buttons on top of the valves are not stuck down. (assuming they are manual valves)
5. Has anyone recently worked on the charge pump?

The filter is what I’m assuming the original. Yellow in color with IH on it.

I will have to check everything you suggested. I will double check pin in driveshaft. It was hard to tell while running if it was turning the pump but I think it was. Tractor appears to have never really been touched as far as being worked on.

My money is on a sheared pin.

Sometimes after sitting a long time, especially if they are high hours,
they just don't want to prime.
You might try removing the fill plug and wrapping a rag around your air hose, GENTLY give it a little pressure.
A few pounds, not high pressure, you just want to push the oil into the system.
Do check as mentioned, that the pump is turning.
This trick also helps when a filter is changed and it don't want to prime.:beerchug:

I never thought about this trick for priming a hydraulic system, but I've used this trick to prime a few Diesel engines that have run out of fuel by using the same blowgun and rag in the filler up hole trick. It works.

I'm just finishing up a bunch of work on a 129 myself. Mine has the opposite issue. It screams, very fast
Definitely faster than my buddy's 1250 or my cousin's 127. I can run it at a reasonable speed alright but if I hit a bump it goes full tilt. Gonna have to check that bushing at the bottom of the hydro shift rod for starters, I guess.
One thing, I just did swap out the hydro with a ported version from a 1650 which I had never previously been able to run before I pulled the hydro since it came to me without an engine.

Original filter??? 45 years old, at least. If it isn't broken pins or stuck relief valves, yeah....I'd go right to the oil and filter change.