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