Great Plains Hydraulic Depth Stop - Manual (Page 3)

3
Assembly Instructions
10/19/07 2N-24 & 2N-30 Drills Hydraulic Depth Stop Update 196-188M
Great Plains Mfg., Inc.
Lifting System
Bleeding the Field Lift Hydraulics
This folding drill is equipped with rephasing type hydraulic
lift cylinders that require a special procedure for bleeding
air from the hydraulic system. If your dealer has not al-
ready prepared the cylinders 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.
1. Put the tractor in park and activate its parking brake. If
the tractor does not have these features, block 2 or 3
of its wheels to positively prevent the tractor from roll-
ing during this bleeding operation.
2. Back up and support the main frame and the outboard
ends of both boxes. Raise and support these 3 areas
just high enough to take the weight off of all four lift cyl-
inders. If the gauge wheel cylinders have previously
been engaged, they may be used to assist in raising
the drill.
3. With the drill blocked and supported, unpin both ends
of all four wheel cylinders. Remove and safely position
the cylinders so the base end of the cylinder is lower
than the rod end port. Also, make sure there is enough
room for the rods of each cylinder to fully extend with-
out contacting anything.
NOTE: In order to prevent trapped air pockets, the
port on the rod end must be higher than any other
part of the cylinder during the bleeding operation.
4. With the tractor at idle, hold the remote lever on to put
fluid into the lifting circuit. When the slave cylinders on
both wing drill boxes have completely extended, hold
the remote lever on for one minute.
5. Retract the cylinder rods. Extend the rods again and
hold the remote lever on for one more minute. Repeat
this step two more times to completely bleed the sys-
tem.
6. Retract and reattach the hydraulic cylinders.
7. Add oil to the tractor’s hydraulic reservoir to fill it to the
proper level.
Operation
Coulter Depth Adjustments using the Coulter
Depth Control Valve
The "master-slave" field lift cylinders on your drill control the
depth of the coulters. A depth stop valve on the line which feeds
the base end of the master hydraulic cylinders, regulates the re-
tracted length of these cylinders. One clockwise revolution of the
knob lowers the coulters approximately 3/32". Depth adjust-
ments are best made with the drill slightly raised with the depth
stop engagement arm on the clevis end of the cylinder rod not
touching the valve. After adjusting the valve, raise and lower the
drill a few times and recheck the depth.