Great Plains 2S-2600F Operator Manual v2 - Manual (Page 18)

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Section 2 Operating Instructions
2S-2600 and 2S-2600F Two-Section Folding Drill 195-200M-A 9/26/13
Great Plains Mfg., Inc.
Setting the Bypass Valve
A bypass valve is plumbed into the opener down pressure
circuit. See Figure 2-8. Tractors with load-sensing, closed-
center hydraulics require this bypass valve to protect the
tractor hydraulic system.
Figure 2-8
Bypass Valve
If you are unsure what type of hydraulic system is on your
tractor, contact your tractor manufacturer.
Tractors with Open Center Hydraulics
Close bypass valve for no oil flow by turning knob on valve
clockwise completely. Always operate the drill with the by-
pass valve closed.
Tractors with Pressure Compensating Closed Center
Hydraulics (PC Closed)
Close bypass valve for no oil flow by turning knob on valve
clockwise completely. Always operate the drill with the by-
pass valve closed.
Tractors with Load Sensing Closed Center Hydraulics
(LS Closed) Pressure Flow Compensating (PFC)
Systems
1. Close bypass valve for no oil flow by turning knob on
valve clockwise completely.
2. 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: The faster openers raise and lower, the greater po-
tential for oil heating, premature wear or tractor damage.
Keep tractor at one-half throttle for remaining steps.
3. Engage tractor hydraulics and lower openers. Lock
hydraulic lever on tractor for continuous operation.
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IMPORTANT: Failure to use the bypass valve on load-
sensing tractors may cause major tractor damage.
4. Adjust pressure-control valves on drill for opener
down pressure so gauges are at 1800 psi. See Figure
2-11.
Figure 2-9
Pressure Control Valves
5. While watching gauges on drill, slowly turn knob on
bypass valve counterclockwise. Adjust bypass valve
just until needles on gauges begin to move down from
1800 psi. Lock bypass valve at this setting. (See also
note below.)
6. Adjust pressure-control valves on drill to desired
opener down pressure as explained under Opener
Down Pressure, beginning on page 33.
NOTE: 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 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 pos-
sible while staying at least 300 psi above the opener down
pressure setting.
While 1800 psi is a good starting point for setting the by-
pass 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 set-
ting above 1800 psi.
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