Great Plains 2SNG30 Operator Manual - Manual (Page 21)

8/17/2006 202-499m
19
Bleeding Hydraulics
!
WARNING
Escaping fluid under pressure can have sufficient pres-
sure to penetrate the skin. Check all hydraulic lines
and fittings before applying pressure. Fluid escaping
from a very small hole can be almost invisible. Use pa-
per or cardboard, not body parts, and wear heavy
gloves to check for suspected leaks. If injured, seek
medical assistance from a doctor that is familiar with
this type of injury. Foreign fluids in the tissue must be
surgically removed within a few hours or gangrene
will result.
NOTE: The SAE O-Ring and JIC 37˚ Flare type
hose connections do not require sealant for re-
connecting. They do not require high torque for a
good seal.
IMPORTANT: When using sealant on pipe
threads the friction between the threads is re-
duced; therefore, be certain not to over tight-
en, causing damage to a valve, cylinder port or
fitting.
!
CAUTION
This drill has a negative tongue weight when unfolded
and raised. Be certain that the drill is hitched securely
to your tractor draw bar and be certain the hitch safety
chain is securely attached to the drill hitch and tractor
before raising or unfolding the drill!
Bleeding the Lifting Hydraulic System
This Folding Drill is equipped with rephasing type
hydraulic lift cylinders that require a special proce-
dure for bleeding air from the hydraulic system. If
your dealer has not already prepared the cylin-
ders for transport use, read the following
information carefully. The rephasing cylinders will
not function properly if this bleeding procedure is
not followed. Do not crack hose fittings in order to
bleed air from this system.
NOTE: Check the hydraulic fluid level in the trac-
tor reservoir and fill to the proper level before
starting this procedure. If the bleeding is per-
formed with a low reservoir supply, there is a
chance of drawing air into the system. System ca-
pacity is approximately 3.3 gallons and requires
one pair of remote outlets.
1. If required, raise your drill 1" in order to extend
your lift cylinders a little. Loosen the jam nuts
on top of the transport vertical tubes and
screw the adjustment screw in until it bottoms.
Lower the drill until the cylinders become
loose.
2. Unpin the cylinders from the mainframe and
turn the cylinders upside down to a position
where the rod end is higher than the base end.
Support the cylinders in a safe location. One
transport tire may have to be removed in order
to unpin the master cylinder.
3. Start the tractor and run the engine at idle.
With the rod end of the cylinders higher than
the base end, hydraulically extend the cylin-
ders and hold the tractor control lever in posi-
tion for sixty seconds after the cylinders have
extended to their maximum stroke.
4. Hydraulically retract the cylinders, then repeat
the extending procedure several more times
until both cylinders are free of air and operate
together.
5. Repin the cylinders to the main frame and axle
with the rod end down. If air is tapped in either
cylinder, the affected cylinder will have a
spongy, erratic movement and the machine
will not raise evenly. Refill the tractor hydraulic
fluid reservoir to its proper level.
NOTE: After drill is raised, a slight settling will oc-
cur due to the action of the rephasing cylinder
NOTE: In order to prevent trapped air pockets,
the port on the rod end must be higher than
any other port of the cylinder during the bleed-
ing operation.
NOTE: The folding and transport wing lift cylinders
are not rephasing type cylinders and do not re-
quire this bleeding procedure.