Great Plains 3PYPA Operator Manual - Manual (Page 64)

60 3PYPA Table of Contents Index Great Plains Manufacturing, Inc.
401-647M Table of Contents Index 03/20/2012
Hydraulic Down Pressure
Refer to Figure 70
If desired opener depth cannot be consistently achieved
using cam adjustment (page 69), or gauge wheels are
slipping at the force required, the optional hydraulic down
pressure system may remedy the problem. Cylinders
transfer some center section weight to wings, controlled
by valves at the front of the center section.
Oil Heating / Tractor Wear Risks:
The current hydraulic down pressure option is compatible only
with “closed center” tractor hydraulics.
1. Before making depth adjustments with valve ,
make sure the system (valve ) has been calibrated
(page 165), and review how the system behaves as
hydraulics are cycled.
To adjust hydraulic down pressure:
2. At all rows, set the cam (mechanical spring) down
pressure to notch 3 (page 69).
3. The lever for the down pressure circuit remote must
be LOCKED OPEN to provide constant pressure/
flow to the down-pressure cylinders. See operations
tips in sidebar for specific tractor models.
4. With the tractor hydraulic lever locked forward,
release the lock disk
, turn the knob on the pres-
sure control valve .
5. Watch the pressure gauge and set the desired
pressure. Clockwise increases the pressure and
counterclockwise decreases pressure. The recom-
mended pressure range for planting is between
400 psi and 600 psi.
6. Once the pressure is set, lock the knob with the
lock disk .
The row down-force setting controls the soil firming pres-
sure on the press wheel as well as the disk penetrating
force. DO NOT use more down-force than necessary to
obtain the desired opener penetration and to maintain
the proper firming action over the seed. Excessive
opener force leads to excessive wear and damage of the
opener components.
Priority Flow Hydraulic Systems
On some tractors with load-sensing hydraulics, the circuit
#1 is capable of taking nearly 100 percent of available
hydraulic flow. Operating the openers or markers on cir-
cuit #1 will starve the other circuit, making one function
inoperable.
To operate markers and constant opener down pressure
at the same time, connect the lift assist to circuit #2 and
the markers to circuit #3.
Null4:
Null4:
Null4:
Figure 70
Hydraulic Down Pressure System
29194
John Deere 8000 Series tractors:
Set timer to continuous.
Push lever forward until detent clicks.
Case-IH Magnum tractors:
Lock lever forward in detent position. You may need to
turn up detent pressure to its maximum setting. Do not
tie hydraulic lever past detent position with a strap. See
your tractor dealer for hydraulic-system details.
Other tractors:
Lock lever forward in detent position. You may need to
turn up detent pressure to maximum or use a mechani-
cal detent holder to hold lever forward. See your tractor
dealer for providing constant flow to openers.
On some tractors with very positive remote hydraulic
checks, a slight increase in the reading on the pressure
gauges may occur after the tractor remote lever is
returned to neutral. This is caused by back pressure on
the opener cylinders and may be ignored.
The NET OPERATING PRESSURE on the opener cyl-
inders is maintained at the pressure you selected while
the tractor remote lever was held forward–not at the
“apparently increased” pressure. Reactivating the trac-
tor lever forward confirms this
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