Great Plains V300 Assembly Instructions - Manual (Page 18)

Great Plains Mfg., Inc.
18 Opener Down Pressure Kit
148-771M 11/08/2006
Calibrate Bypass Valve (CC only)
Refer to Figure 26
If your tractor has Open Center hydraulics, refer to
“Open Center Operation” on page 21. If you are
unsure what type of hydraulic system is on your tractor,
contact your tractor manufacturer.
Note: Refer to “Post-Installation Lift Cycle” on
page 17 to know what to expect the drill to do as
hydraulics are cycled.
Tractors with Pressure Compensating Closed Cen-
ter Hydraulics (PC Closed)
133. Release locking disk
➀
. Close bypass valve (48)
for no oil flow by turning knob on valve clockwise
completely. Tighten locking disk
➀
. Always oper-
ate the drill with the bypass valve closed.
Tractors with Load Sensing Closed Center Hydrau-
lics (LS Closed) or Pressure Flow Compensating
(PFC) Systems
IMPORTANT !
Failure to use the bypass valve on load-sensing
tractors may cause major tractor damage.
134. Release locking disk
➀
. Close bypass valve (48) for
no oil flow by turning knob on valve clockwise com-
pletely. Tighten locking disk
➀
.
135. With tractor at half throttle, adjust flow-control valve
on tractor so openers raise and lower at a reason-
able speed. Keep tractor at one-half throttle for
remaining steps.
Note: Faster opener raise/lower increases potential for
oil over-heating, excess wear and tractor damage.
136. Engage tractor hydraulics and lower openers. Lock
hydraulic lever on tractor for continuous operation.
137. Release locking disks
➀
and
➁
. Adjust pressure-
control valve (44) for opener down pressure so
gauge (43) is at 1800 psi.
138. While watching gauge (43), slowly turn knob on
bypass valve (48) counterclockwise. Adjust bypass
valve (48) just until needle on gauge (43) begins to
move down from 1800 psi. Use locking disk
➀
to
lock bypass valve at this setting. (See also note
below.)
139. Adjust pressure-control valve (44) to desired opener
down pressure per “Closed Center Field Opera-
tion” on page 19. Tighten locking disk
➁
.
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 1800 psi is a good starting point for setting the
bypass valve, if you consistently operate the drill with low
opener down pressure you can set the bypass valve
below 1800 psi. If you consistently operate the drill with
very high opener down pressure, you may need a
bypass-valve setting above 1800 psi.
Figure 26
Closed Center Valves
25185
48
43
44
➀
➁