Great Plains 1625AHL Operator Manual - Manual (Page 55)

Great Plains Manufacturing, Inc. Table of Contents Index Operating Instructions 51
2014-04-21 Table of Contents Index 411-020M
Fan Operation
See also “Air Systems General Operating
Information” on page 52.
Refer to Figure 38
Three hydraulic hoses serve the fan, and must be
properly connected for the fan to operate in the correct
direction
, at recommended speeds, and without
damage. See “Hydraulic Hose Hookup” on page 20.
1. Always connect the case drain line first.
This line protects the outer shaft seal of the hydraulic
motor. The case drain is a small line to the hitch,
provisioned with a specialized low-seep flat-face
case drain Quick Disconnect. Pressure spikes during
motor operation, and pressure cycles due to
temperature change are bled off by the case drain.
Motor Seal Damage Hazard:
Do not apply pressure to the case drain line. Do not change the
special QD connector. A restricted or sealed case drain line
will promptly result in motor seal damage.
2. Connect the motor return line second, to sump.
The planter includes a 1
1 ⁄
16
inch low back-pressure
QD coupler set. Install the receptacle on a tractor
sump port, and not at a normal remote return port.
The unusual size aids in ensuring correct
connection, so that the motor return line handles
high volume at low back-pressure, ensuring full
motor performance.
3. Connect the motor inlet line to a tractor remote
capable of the flow rates shown at “Fan General
Operating Information” on page 53.
4. The fan hydraulic circuit includes a check valve ,
which provides a relief path for oil at motor shutoff.
The resulting low fan rpm provides strong indication
reversed connection.
Correct fan direction is shown at .If reversed fan is
suspected, observe it during shutoff, as the direction
of motion is easier to see at lower rpms as it slows to
a stop (initial startup is virtually instantaneous,
making observation at start difficult).
Fan speed is controlled by the tractor circuit (and not the
seed monitor). Fan rpm is reported by the seed monitor.
Rely on the Magnehelic
®
pressure gauges to optimize
fan rpm.
Figure 38
Hydraulics at Fan
36000
1
2
3
4
5
5
1
2
If the fan is connected in reverse, it may not run at all
(due to no oil source at the return connection). If oil is
present, oil bypass at the check valve
prevents the
fan from reaching operating rpm. A reversed fan is
incapable of providing sufficient air flow for planting.
4
3
4
5