Yes, I replace the failed hydro with another working one. I tested it with a drill before I removed it from the rear end it came attached to. It worked fine. I replaced the old manual relief valves with the two new ones from the failed hydro. Guess what? It stopped working. Put the manual valves back in, and it worked. So that's what I installed in the grader.

This test revealed that it's likely that my problem with the "failed" hydro was that BOTH of the new relief valves had failed. How odd.

I reinstalled the loose bearing with bearing set adhesive and reassembled the "failed" hydro. Put a different pair of relief valves in it and it works now.

Apparently the replacement valves I installed were both bad when I originally tested with replacement valves.

Two failed auto relief valves that were less than a year old. I think.

Good to have an answer to the puzzle! And the silver lining is you have a spare hydro for the next project.

I bet you don’t have an excavator or a crane :bigthink:

Ok, now I want to know:
Were did the "new" failed hydro valves come from?
and why they failed? they are simple and visible with just a check ball/spring and plunger, not rocket science.
So glad you found the problem! although it would of been nice that you found it in the beginning, but then again, hands on experience is the best teacher not soon forgotten. :beerchug:

I'm thinking crawler tractor. Hydro axles front and rear, facing each other. One has the swash plate reversed (so "reverse" goes faster than "forward"). One side of each axle disabled, disconnected from the spider assembly (splines ground off?) so only one side works on each axle, right on front axle, left on rear axle for example.

Two operating levers, one for each hydro swash plate. Front axle drives the right track, rear axle drives the left track.

Tell me that's a crazy idea before I get carried away with it. Please.

MachTechDirect. I bought 4 of them last year for the grader build. The two in the front hydro are both working fine. I can't see a problem with them but did not take them apart. I'll probably send them back to Mark and let him figure out what the problem is.

I went through my bag of valves and sorted them by working/not working by testing them each on a hydro/axle on a wood cradle. Found 8 working and 5 or 6 not working or leaking.

Nope. That's a great idea for a project!

Remove the spiders and lock one axle to the carrier and let the other axle idle. Can probably use an old spider for the spline and weld it to a plate that bolts to the carrier.

Something to ponder while you're grading.

Interesting, he has a good reputation, I would think he would want to make it right and find the problem with them.

The spider gears are not splined. Probably remove the spiders and weld the axle grear to the carrier. On the side that is free I suppose the cross pin would hold the axle from moving inward. Without the spiders in place something needs to hold the free axle gear from moving inward too much.

Frank, I have been thinking about your crawler idea. If you have the front rear turned around do you need to turn the charge pump 180 degrees because the drive shaft will be turning the opposite direction? Another thing I was thinking about is you can swap the ring gear to the left side and that will change direction instead of messing with the swash plate. You could change the linkage to move the control the same direction for forward then. The Cub rears can have the ring gear on either side. It makes no difference. In tractor pulling some guys run their tractors off the pto side of the engine instead of off the flywheel. When they to that they change the ring gear to the opposite side.