Great Plains 3PYP Operator Manual - Manual (Page 165)

Great Plains Manufacturing, Inc. Table of Contents Index Appendix D: Older Equipment 161
2014-09-09 Table of Contents Index 401-312M
LS Closed/PFC Down Pressure
(S/N A1007S to A1024S) and (S/N A1006S-)
For (S/N A1025S+) see next page
Tractors with Load Sensing Closed Center Hydraulics
(LS Closed) or Pressure Flow Compensating (PFC)
Systems
Refer to Figure 157 and Figure 158
Failure to use the bypass valve on load-sensing tractors may
cause major tractor damage.
1. Release locking disk .
2. Close bypass valve for no oil flow by turning
knob on valve clockwise completely.
3. Tighten locking disk .
4. With tractor at half throttle, adjust flow-control valve
on tractor so openers raise and lower at a
reasonable speed. Keep tractor at one-half throttle
for remaining steps.
Note: Faster opener raise/lower increases potential for oil
over-heating, wear and tractor damage.
5. Engage tractor hydraulics and lower openers. Lock
hydraulic lever on tractor for continuous operation.
6. Release locking disks and . Adjust
pressure-control valve knob for opener down
pressure so gauge is at 600 psi.
7. While watching gauge , slowly turn knob on
bypass valve counterclockwise. Adjust bypass
knob just until needle on gauge begins to move
down from 600 psi. Use locking disk to lock
bypass valve at this setting. (See also note below.)
8. Adjust pressure-control valve to desired opener
down pressure per “Hydraulic Down Pressure” on
page 52. Tighten locking disks
and .
Note: The higher the bypass pressure, the greater the
potential for oil over-heating and tractor damage. At
the same time, for proper opener operation the
bypass valve must be set at least 300 psi above the
opener down-pressure setting when the tractor is
at one-half throttle. Therefore, you should set the
bypass valve as low as possible while staying at
least 300 psi above the opener down pressure
setting.
While 600 psi is a good starting point for setting the
bypass valve, if you consistently operate the planter with
low opener down pressure you can set the bypass valve
below 600 psi. If you consistently operate the planter
with very high opener down pressure, you may need a
bypass-valve setting above 600 psi.
2
2
4
3 1
Figure 157: s/n A1007S to A1024S
Hydraulic Down Pressure Valves
27371
7
5
6
3
1
4
3
Figure 158: s/n A1006S-
Hydraulic Down Pressure Valves
25239
2
2
4
3
1
7
5
6
3 5
2 6
7
7 4
1
4 7
3
3 5