Hydro question for Allan in NE

Dave from MN · Apr 18, 2010

How hard would it be (since you have done it I beleive) for me to attempt to go through my hydro( what I can access easily) and replace orings and what ever else that I could do with out having a major rebuild on my hydro 544. It works good and I can stall the tractor under load and the hydro doesnt seem to have issues, but i do have some issues with the speed control being inconsistant and some times I have it set to a speed, then all of a sudden it will take off like I moved the lever, I am thinking IO have some thing that nees adjustment or have some orings of some thing in the speed control functions. Any advise?

Allan in NE · Apr 18, 2010

Hi Dave,

If it were mine and it works okay, I'd sure leave it alone. They aren't like an automatic transmission; they're a completely different bird and really, really tough.

The keeper has come off the end of the shuttle valve, therefore the poor little guy doesn't know where it's center is and this is causing your "lurching" headache.

This valve can be yanked and repaired in 20 minutes from the outside of the tractor.

I'm on my laptop right now, but if you need the picture on how to access it, hollar and I'll get the picture off my other machine.

Allan

Allan in NE · Apr 19, 2010

Dave,

Pull this plug on the housing. Behind it you will find the center section with the shuttle valve cover plug looking you in the face.

Remove the smaller center section plug and fish that broken snap ring, the valve, 2 flat washers and its spring out of the hole.

If it doesn't come out in pieces, I'm wrong, but sure don't think so. :>)

Anyway, go to the hardware store and get yourself another 3-cent snap ring. You'll see how it should all fit together with a flat washer on each side of the spring.

Allan

pete 23 · Apr 19, 2010

I hope for his sake you are correct on your diagnosis, that being said, I have had several hydros apart, never once did I find that to be the problem. Had stuck shuttle valves, plug fell out on end of shuttle valve causing a lurch problem, several worn lever mechanisms causing drive to stop midway into range and a host of simple to complete trashed units. I would suspect something in the speed ratio cam or orfices or servo cylinders myself and would do a pressure test on the servo circuit but, there are a million things that can and do happen inside these units. For the most part, they are very reliable with good clean fluid and filters changes.

Owen Aaland · Apr 19, 2010

The symptom of a broken snap ring is usually from neutral the tractor will not move when you move the lever into the forward position or the hydro will suddenly engage at the speed position where the lever is set. If you go from neutral into reverse and then into forward the hydro will work as normal.

In my experience of sudden failures the three main causes were, snap ring of shuttle valve, stuck high pressure relief valve, and a crack in the flare of a jumper tube. They seemed to be about evenly divided as to which occurred most often.

Allan in NE · Apr 20, 2010

Dunno fellas,

Betcha I got him in the ballpark. :>)

Allan

Hydro question for Allan in NE

Dave from MN

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Allan in NE

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Allan in NE

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pete 23

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Owen Aaland

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Allan in NE

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