[AT] It's trying, but... no lift

[Cecil Bearden]

Those systems were a piston pump with an unloader valve and a relief 
valve.  I have seen a few relief valves go bad in my years of working 
with Ferguson systems, but it is rare.  It is possible that sitting out 
in the open over the winter in NY created enough condensation that the 
spring in the relief valve rusted and broke.  The control/relief valves 
were pretty reliable, but they had their issues.  My first guess is that 
the rings in the top deck hydraulic piston have broken and the oil is 
leaking by in the lift piston.   There is also the possibility tht this 
machine has set for so long and then moved around and loosened up the 
crud in the bottom of the sump and the screen has picked it up.

Please note the what I am going to tell  you is from the regular 135 
tractors and the 35 tractors.  The vineyard may be different, 
conceptually they are the same..   A good FACTORY service manual is 
invaluable here.   I got burned by I&T manuals, so I really do not 
recommend them anymore.  The Wisconsin historical society may have a 
reprint of the manual available for you.  They have a lot and their 
charge for reprints is really cheap.

On the lift control quadrant ( right side hyd lift lever )  There should 
be 2 levers.  The long one for lift and the short one for draft.  
Sometimes the draft control will over ride the lift.  The draft control 
lever(short one with the square metal knob) should be between the 2 
arrows that say draft on the quadrant.  It should be stamped into the 
metal.
   That knob should be in the center between the arrows.  Then try to 
raise the lift with the other lever.  if not, leave the lift lever a 
little below the top and then move the draft lever to see if anything 
happens.  This might fix your problem.  If not see below.  If you are 
going to change the fluid, you need to clean the screen.

On the left side of the transmission, under the seat is a round plate 
with the PTO lever.  Remove the plate with the lever. Disconnect the PTO 
shaft and start the tractor with the mower attached.  Raise the lift and 
watch for fluid draining from the top deck lift piston and dripping down 
into the sump.  A drip is OK, we just do not want a gusher..   If it 
just drips, your problem is in the bottom.

inside the transmission about 4 to 6 inches in the bottom is a filter 
screen that looks about the size of a pop can It has a top and bottom 
cup, and is separated about an inch in the middle.  The top half has a 
metal handle piece that you use to unscrew counterclockwise the top is 
attached to a bolt that screws into the intake of the pump.  You take 
the screen with both cups out and wash it out.  This is easiest when the 
oil is drained.  There are 2 drain plugs,  one under the front of the 
transmission behind the clutch housing, and the other under the plate 
you took off. If the screen is full of junk, you have found the problem.

When you replace the round plate with the PTO lever,  make sure the 
inside lever goes in the slot of the PTO shifter.

If you have any problems, take some pictures and post on here. We will 
try to fix it remotely!!

Cecil in oKla


On 9/15/2016 7:38 AM, Bo Hinch wrote:
> Sounds to me like you have a piece of trash in the pressure unloader valve
> .
>
> On Thu, Sep 15, 2016 at 6:28 AM, Stephen Offiler <soffiler at gmail.com> wrote:
>
>> Just a few quick thoughts Scott.
>>
>> 1)  you used the word "suddenly".  Was it literally fine one minute and
>> problematic the next?  Or, did it actually go away sort of gradually?
>>
>> 2)  Have you tried it again since?
>>
>>
>> Steve O.
>> PS:  when I'm faced with draining ~8 gallons (I've got about 7 gallons in
>> my modern-ish Ford 1520 hydrostat)  I drain part of it and stick the drain
>> plug back in, then deal with the amount (2-3 gallons) I've drained, then
>> repeat as required.  OK, yeah, putting the drain plug back into a stream of
>> draining oil is a bit messy admittedly.
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