Great Plains 3P4025AH Operator Manual - Manual (Page 38)

34 3P4025AH Table of Contents Index Great Plains Manufacturing, Inc.
411-099M Table of Contents Index 2014-07-29
Fan Circuit Operation
See also “Fan and Adjustment” on page 42.
Refer to Figure 26
Operating flow
Case Drain and Shut-off flow
Two hydraulic hoses serve the fan, and must be properly
connected for the fan to operate in the correct
direction
, and at recommended speeds. See
“Hydraulic Hose Hookup” on page 16.
1. Connect the case drain line to tractor sump.
2. Connect the motor return line , to remote circuit
return (Extend port) or to sump.
3. Connect the motor inlet (supply, pressure) line to a
tractor remote capable of 20 liters per minute. If a
priority remote is available, use it for the fan.
4. The fan hydraulic circuit includes a check valve ,
which provides a relief path for oil at motor shutoff.
If the fan is connected in reverse, flow through this
valve results in low fan rpm, providing 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 - the seed monitor does report fan rpm).
You may stop the fan by setting the circuit to Neutral or
Float. The check valve slows the blades to a stop by
locally recirculating the oil.
Always start the fan with a low flow setting. Gradually
bring fan up to the recommended initial meter
pressurization.
At excessive rpm, too much air flow can cause:
• oil heating
• slow lift times
If desired pressure cannot be reached, or requires
unusually high oil flow at low butterfly valve settings,
chances are the fan is running backwards. Reverse the
inlet/return lines at the hitch.
Butterfly Valve
Refer to Figure 26
This valve
is used to balance air-flow between planter
sections. It is set and pinned at the factory and requires
no adjustment.
Note: Fan speed can change as oil heats to operating
temperature. Re-check meter pressurization more
often during early operations.
Note: 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 high rpm. A
reversed fan may send some air to the meters, but
is incapable of providing reliable air flow for
planting.
Low Population Risk at Turns:
The fan requires up to 4.5 gpm. This figure does not include oil
for lift/lower or oil for marker operation. Aggressive lift/lower
operations, and simultaneous lift/marker operations, can
reduce fan rpm below that needed to pressurize meter disks.
If seed falls out of pockets, low population bands will occur
shortly after turns.
Unless the tractor has generous oil flow capacity, raise/fold
markers before lift, and lift slowly. Watch meter pressurization
and tune operations to keep it at planting levels in turns.
Figure 26
Fan Hydraulics
36146
5
1
3
4
5
2
6
1
2
3
4
5
1
6