my latest project tractor: a 2003 McCormick GX50H

[Kyle_in_Tex]

My 4310 uses cruise along with the system that keeps it from bogging the engine to relegate the speed. But instead of adding more power, it just reduces speed to allow the engine to catch up (unless you have it at full power already). I rarely use this feature combination.

Your system looks complicated, at least until you figure out mentally what it is supposed to do.

 

[dfkrug]

My 4310 uses cruise along with the system that keeps it from bogging the engine to
relegate the speed. But instead of adding more power, it just reduces speed to allow the engine to catch up (unless
you have it at full power already). I rarely use this feature combination.

Your system looks complicated, at least until you figure out mentally what it is supposed to do.

You have the "eHydro", correct? I really want to get a look at that system. Not so much the "speed match",
or whatever that feature is called. I want to see how the connection between the pedals and the swash plate
work. It is electrically-controlled, that's all I know (from TBN posts).

 

[dfkrug]

G'day I'm guessing the accumulator is to provide brake pressure in case of engine failure, good
luck with it all I look forward to seeing what you find, it is never much fun putting back together what others have pulled
apart.

The lines are connected to the PTO brake, not the wheel brakes. The McCormick uses pretty conventional internal
wet brakes to stop the wheels, lever-actuated.

The PTO brake seems to use a big shoe, internal to the gearbox. This is in contrast to the PTO brakes I had
to repair twice on JDs: multiple clutch plates.

 

[dfkrug]

...and here is the smoking gun:

I got then engine started, and it runs great. I traced the hyd lines and determined that no fluid
was getting to the PS pump or any of the servos. At this point, my first suspicion was that the
fluid was too low. ATF is used and the level is hard to detect. It calls for 40 liters, and since the
tractor was recently split and reassembled, I suspected empty inlet lines to the pumps.

Checking that (by cracking open, then removing hoses), I determined the inlet to the PS pump
had air in it. These pumps do not suck well, and (if worn) really need the inlet manifolds to
be full of fluid. So I added a couple of gallons of ATF. Still, no dice.

PS pump shaft is sheared off (photo). The power steering pump also powers the servos
for HST, PTO, and diff locks. It also acts as HST charge pump.

 

[dfkrug]

So why did the pump fail?

First, I tried turning the shaft manually, grabbing the shaft stup. I could not turn it. Using
a pair of pliers, I got it to turn. As soon as I broke it loose, it turned easily. Not good.

Opening it up, I see many small pieces or aluminum, apparently fragments of the pump
body. The internals of the pump (rotors and end plates) did not come out as easily as
I expect with good pumps. Inside the body is extensive scoring, which you can easily
feel. Definitely fails the fingernail test.

 

[dfkrug]

Now here is the dilemma: if I buy a new pump and install it, debris fragments have already
been pumped to the PS valve and everything else. Have they been damaged? Should
everything be taken apart and cleaned first? The HST seems to have an inlet filter
between the charge pump and the HST, so that is protected.

I suspect the pump was poorly made from the beginning. It was purchased from a dealer
a few years ago, according to the service record, but has prob less than 100 hours on it.
It has no brand name on it, but is made in Slovakia. JD uses units from this maker, too.

Queries to 3 dealers yielded one quotation, nearly $500 and it has to come from out of the
country. I have ordered a Dynamic pump instead, which has the same dimensions and
volume, but no splined shaft.

 

[dfkrug]

So, rather than buy another pump from the dealer, and wait weeks and weeks for the delivery, I did some
research and found that a Dynamic pump with the same flange, but the wrong shaft. These pumps
are only $108 from our pals at SurpCntr, and we can modify the shaft.

This is the pump. I calculated it was about 0.25 cubic inches and it uses a shorter/taller gearset
(photo). The owner has a machine shop and he ground the shaft, drilled out the broken splined
end of the other pump, and glued it on with Locktite 680. I hope it stays attached!

It fits fine.

 

[dfkrug]

Hooked everything back up and started the engine. I now have power steering. Great.

Unfortunately, the HST is still dead. Time for more detective work. Here is the HST schematic.
the service manual is horrible, and the dealer says he can not give me detailed parts diagrams.
What's up with that? I need those to help with identifying parts and functionality.

At this point, I have to conclude that the pump failure (or the attempted fixes) have caused
the HST failure. There is virtually NO chance of two independent catastrophic failures.

Stay tuned.

 

[dfkrug]

Well, to get better access, I need to remove the remaining sheet metal and split the tractor.
The remaining body is all one piece and difficult to remove, requiring the removal of most
of the wiring harness, and the numerous hard-to-access cables. Landini made a very
maintenance-mean unit here.

Time for the forklift.

Pix show the naked tractor. You can see how some previous mechanic left a screwdriver in there
to hold the PTO speed cable on. Other stuff not connected at all. Ain't cleaning up after others
a (female dog)?

 

[dfkrug]

Although Landini did a poor job of documention and ease-of-maintenance engineering, I do
appreciate some innovative systems on this tractor.

This is the electrically-controlled PTO clutch and brake. The clutch is a conventional
multi-plate unit as seen everywhere, but the brake is a brass shoe that is activated
by a hyd cylinder in the PTO cover. No worry about it flying apart when you turn off
the PTO at high RPM with a rotary cutter on the 3-pt. (Attention, John Deere)

(I am off for a couple of weeks to NYC and Quebec, so I may not get back to this thread
before then. I DID find the problem, BTW.)