Great Plains NTA3007 Operator Manual - Manual (Page 109)

Great Plains Manufacturing, Inc. Table of Contents Index Adjustments 105
2012-07-02 Table of Contents Index 166-371M
Bypass with LS or PFC Closed Syste ms
Refer to Figure 103
Turn the adjustment knob counter-clockwise to increase
flow.
Turn the adjustment knob clockwise to decrease flow.
Turning it fully clockwise stops all bypass flow.
7. Adjust down-pressure before adjusting bypass.
8. With tractor at half throttle, adjust tractor flow-control
valve so that openers raise and lower at a
reasonable speed. Keep tractor at one-half throttle
for the remaining step.
Note: The faster openers raise and lower, the greater
potential for oil heating, premature wear or tractor
damage. The higher the bypass pressure, the
greater the potential for oil heating and premature
tractor damage. At the same time, for proper
opener operation the bypass valve must be set at
least 20 bar (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 20 bar (300 psi) above the opener down
pressure setting.
9. Slowly open the bypass valve until the
down-pressure gauges just start to decline.
10. Turn the bypass knob one turn in the closing
direction.
11. Lock the knob at that setting.
While 140 bar (2100 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 140 bar (2100 psi). If you
consistently operate the drill with very high opener down
pressure, you may need a bypass-valve setting above
140 bar (2100 psi).
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 circuit #1 will starve the other circuit, making
one function inoperable.
To operate markers and constant opener down pressure
at the same time, connect the openers to circuit #2 and
the markers to circuit #3.
Machine Damage Risk:
Failure to use the bypass valve
on load-sensing tractors
may cause major tractor damage.
Figure 103
Bypass Adjustment
29422
B
1
2
w
c
t
T
C
W
B