my latest project tractor: a 2003 McCormick GX50H

[dfkrug]

Well, it's been a long time since I had a broken tractor to fix, and now I have a
new one.

This is a 50hp hydrostatic tractor, made by Landini in Italy, a GX50H. It uses
a 4-cylinder Yanmar Diesel, and features a compact size (only slightly longer
than my CK30) with 4x4 and lockable front AND rear diffs. The HST unit
is servo-controlled, rather than direct-acting, and there are numerous electric
sub-systems, but no computer.

Unusual for me, this unit belongs to someone else, and he has given up on
fixing its problem: the engine runs, but it does not move. It has been to
a tractor shop and they failed to fix it, too. It's an HST problem, so I am
interested. Sadly, the unit has been worked on first, and is not fully
reassembled.

It has no loader so it is not worth a lot in our local market. Maybe $8-9K fixed.

This has been delivered only a couple of days ago, and I can so far tell that
the manual is lousy, and there is not even a wiring diagram. !

I hope to get this fixed in the next month or so, and will post as I make
progress. There is a budget, however, and it may not get fixed at all. Time
will tell. Anyone knowing about these tractors, feel free to chime in.

 

[George2615]

You might be able to get some help / info from LS Tractor.They have been building tractors for Landini / McCormick since 1995.

LS Tractor info taken from Wikipedia
(The history of LS Tractors goes back to 1975 as a division of Hyundai, and began with cooperation with Yanmar of Japan. In 1983, the former GoldStar Cable Company acquired the company and renamed it GoldStar tractors. The company names were changed to LG in 1995.

Tractors have been sold under GoldStar, Fiat-GoldStar, LG, LG-Fiat, LG-New Holland, LS and LS-New Holland names in South Korea. In North America, they have been sold as LG Montana, Montana, Farmtrac LandTrac, LongAgri LandTrac, McCormick Tractors and Landini.)

 

[dfkrug]

You might be able to get some help / info from LS Tractor.They have been building
tractors for Landini / McCormick since 1995.

It seems this one is also known as a Landini Mistral America.

I visited LG once in Korea, back in 1989. At the time, they were going by the name Lucky-Goldstar. That
was the electronics side of the biz, however. Later became LG-Semicon, IIRC.

 

[Kyle_in_Tex]

Looks like she was rode hard and put away dirty. Seeing the tire wear, I'm wondering what she did for a living?

 

[dfkrug]

Seeing the tire wear, I'm wondering what she did for a living?

Yeah, about 2200 hours and there was some kind of mower/mulcher mounted to the right
front. Hence the RF tire is much more worn than the LF tire.

 

[dfkrug]

...it also had a cab attached.

Anyway, I had a printed copy of the service manual, but the most important parts (hyd and electrical
schematics) were unreadable. So I called a dealer and he was nice enough to send me a PDF by email.
That's great. I wish more dealers were like that. 2 thumbs up, McCormick/Landini.

The manual is very hard to follow, however, and there are major elements missing. Like how to test
and service the HST. Not just take it apart and reinstall it.

First, I pressure-washed everything I could get to. The floor and rear half-fenders will stay attached
since they are integral with the steering column and lots of other stuff. Too hard to remove. I
want things as clean as possible before opening up any hydraulics.

So, I traced what I could, and some things were a bit mistifying. Not even mentioned in the manual.
Like this thing. It is a couple of rusty springs inside a cylinder, which is attached to a fitting
on the hyraulic line that controls the PTO clutch/brake servos. I guess it is a pressure accumulator,
so the PTO brake stays engaged if you shut the engine down?

It does not seem to be working, given all the rust. The closed end has a vent hole, and no way to
keep water out. :-(

 

[dfkrug]

This tractor features 2 hydraulic gear pumps driven off the front of the engine. One
is for the Power Steering and HST "super-charging", along with the servo controls
for HST, PTO, and differential locks. The other pump is bigger, and it supplies
fluid for the AUX valves (2 installed), and the "Power Lift", aka the 3-point cylinder.

Reservoirs for both systems are independent, and the PS pump system uses ATF,
which seems unusual. The other system uses regular hydraulic fluid.

Up to now, all my Kubotas, JDs, and Kioti/Bobcats have used direct-acting HST
controls, where your foot pedals or rocker connects to a linkage that directly
tilts the swash plate inside the HST.

For the McCormick, the pedals act directly on a 2-spool valve that sends fluid
to small hydraulic cylinders inside the HST to do the work of tilting the swash
plate.

The PTO clutch/brake and the diff locks are controlled by electrical switches,
which then open solenoid spool valves to operate servo cylinders inside each
system.

 

[ultrarunner]

You done some complicated repairs... with any luck this will be another success added to the dfkrug saga!

 

[dfkrug]

This tractor uses another, parallel hydraulic servo controller to provide cruise control. It
is a hand-operated lever on a 2-way, single spool valve that stays wherever you put it.
Other HST tractors I have owned either use friction to lock the go-pedals in place (Kioti),
or an electromagnet to do the same (Deere).

Both the foot pedals and the hand lever connect to a hydraulic block on the firewall
that acts as sort of an OR-gate, as we call them in the electronics biz (2nd photo).

 

[banjodunn]

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.

Jon

 

[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.)