Great Plains 3P4025AH Operator Manual - Manual (Page 51)

Great Plains Manufacturing, Inc. Table of Contents Index Adjustments 47
2014-07-29 Table of Contents Index 411-099M
Lift-Assist Needle Valve Adjustment
(Option)
If the planter does not have lift-assist
a
, continue with
down-pressure setup on the next page.
Refer to Figure 35
The lift-assist needle valve
assures that the
down-pressure system levels the wings before the
Lift-Assist raises. This prevents lateral dragging of
openers in field lift. Sequencing during lower is controlled
by the PO check valve
and has no adjustment.
The needle valve requires an initial setup, some
re-adjustment after setting field down-pressure,
re-adjustment for different field conditions, and a
seasonal check.
Setup/adjustment requires moving the planter to field
conditions, hitched to a tractor. Empty seed hoppers are
preferred for this adjustment, but not essential.
Initial Needle Valve Setup
Perform step 1-3 and 5 only on first use of the planter, or
if the needle valve itself required maintenance.
You will need a hex key/wrench for the set screw. Hex
key size may vary with valve brand. If the valve has two
set screws, loosen the one closer to the valve body.
1. At the Bypass Valve , release the locking disk
by turning it counter-clockwise.
2. Close the valve by turning knob fully clockwise.
3. Tighten locking disk . When using a tractor with
PC Closed hydraulics, always operate the planter
with the bypass valve closed.
4. At the needle valve , loosen the set screw .
5. Turn the valve knob fully clockwise, then
counter-clockwise one turn.
6. Unfold the planter. Install the Wing Lock pins
(page 22). With the 2-point hitch raised, retract the
down-pressure/lift-assist circuit to lower.
7. Carefully extend the circuit for list-assist, observing
whether wings level occurs prior to lift, and lift occurs
at a reasonable rate.
If lift occurs before wings level, turn the needle valve
knob
1 ⁄
4
turn clockwise to reduce lift flow to the
lift-assist cylinders.
If lift is too slow, turn the needle valve knob
1 ⁄
4
turn
counter-clockwise to increase lift flow to the lift-assist
cylinders. Do not add so much flow that lift occurs
before wings level.
8. When satisfied with lift sequence and rate, secure
the needle valve set screw.
Further Needle Valve Adjustment
9.
Verify field lift sequence and rate again after
adjusting down-pressure.
10. Verify field lift sequence and rate with full hoppers
when afield. Conversely, if the adjustment was
initially made with full hoppers, verify sequence and
rate as they empty.
a. A planter with the hydraulic down-pressure has this valve installed even if lift-assist is not present.
If lift-assist is not present, the line is plugged at the valve and no adjustment is necessary.
Figure 35
Lift-Assist Rate Adjustment
36147
2
3
1
5
6
4
7
1
4
2 5
6
5
1 7