Great Plains 2525A Operator Manual - Manual (Page 28)

24 2025A/2525A Table of Contents Index Great Plains Manufacturing, Inc.
118-999M Table of Contents Index 2013-06-04
Fan Circuit Operation
See also “Fan and Adjustment” on page 35.
Refer to Figure 13
Three hydraulic hoses serve the fan, and must be prop-
erly connected for the fan to operate in the correct
direction
, at recommended speeds, and without dam-
age. See “Hydraulic Hose Hookup” on page 14.
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, pro-
visioned with a specialized low-seep flat-face case
drain Quick Disconnect. Pressure spikes during
motor operation, and pressure cycles due to temper-
ature 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 drill includes a 11
⁄
tor>16in 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 4.5 gallons/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 provides strong indica-
tion 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, mak-
ing observation at start difficult).
Fan speed is controlled by the tractor circuit and butterfly
valve (and not the seed monitor).
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.
Figure 13
Hydraulics at Fan
29781
1
2
3 4
5
1
2
3
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 reli-
able air flow for planting.
5
4
5
1
Fan speed can change as oil heats to operating temper-
ature. Re-check meter pressure more often during early
operations.