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| Illustration 1 | g06021598 |
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(A) Standard fan
(B) Optional reversing fan (1) Fixed displacement gear pump (2) Oil cooler outlet (3) Hystat charge (4) Flow control valve (5) Makeup valve (6) Fan drive gear motor (7) Relief valve (8) Fan reversing valve (9) Fan reversing control valve (10) Makeup valve (11) Flow control valve | |
The hydraulic fan system contains fixed displacement gear pump (1) and fixed displacement fan drive gear motor (6). The hydraulic fan system also includes either the standard fan (A) or reversing fan (B).
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| Illustration 2 | g03721013 |
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(A) Standard fan
(4) Flow control valve (5) Makeup valve (6) Fan drive gear motor | |
When the engine is started, hydraulic oil is drawn from the tank by fixed displacement gear pump (1). Flow control valve (4) is controlled by the machine ECM. The speed of the fan motor depends on the amount of flow that is allowed through flow control valve (4). The control of the fan speed is based on the value of the following conditions:
- Air inlet temperature
- Hydraulic oil temperature
- Engine coolant temperature
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| Illustration 3 | g03732701 |
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Standard demand fan (12) Hydraulic oil temperature sensor (13) Machine ECM (14) Demand fan solenoid (15) Engine ECM (16) Air inlet temperature sensor (17) Engine coolant temperature sensor | |
Engine ECM (15) controls the command to demand fan solenoid (14). The engine ECM uses input from the three temperature sensors to determine the command. Air inlet temperature (16) and engine coolant temperature (17) are communicated to engine ECM (15) directly. Information from the hydraulic oil temperature sensor (12) is sent through machine ECM (13) to engine ECM (15). Flow control valve (4) closes to restrict the flow of oil through the flow control valve. When the flow of oil through the flow control valve is restricted, oil must flow through fan drive gear motor (6). Thus causing the fan motor to turn faster. The speed of the fan depends on the amount of current that is sent to the demand fan solenoid valve.
When the machine requires less air flow, the machine ECM will increase the amount of electric current to demand fan solenoid (14) to shift the flow control valve more open. When the flow of oil through the control valve is increased, the flow of oil from the hydraulic fan pump will flow through the flow control valve instead of flowing to the fan motor. Thus causing the fan motor to turn more slowly. The speed of the fan depends on the amount of current that is sent to the demand fan solenoid valve.
Makeup valve (5) prevents cavitation of the fan motor during deceleration.
The optional reversing hydraulic fan system has a reversing solenoid (19) which is controlled by engine ECM (15). When the top of reversing fan switch (18) is depressed, the Engine ECM energizes reversing solenoid (19). When the bottom of the reversing fan switch is depressed, the fan reversing solenoid is energized to reverse the fan for 10 seconds. The cycle will repeat every 30 minutes until the reversing fan switch is returned to the center position.
The following features can be configured using AVSpare Electronic Technician (ET):
- "Enable/Disable"
- "Purge cycle duration"
- "Purge cycle interval"
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| Illustration 4 | g03107264 |
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| Illustration 5 | g03831903 |
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(B) Reversing fan (forward)
(C) Reversing fan (reverse) (6) Fan drive gear motor (7) Relief valve (8) Fan reversing valve (9) Flow control valve (10) Makeup valve (11) Flow control valve (12) Hydraulic oil temperature sensor (13) Machine ECM (14) Demand fan solenoid (15) Engine ECM (16) Air inlet temperature sensor (17) Engine coolant temperature sensor (18) Reversing fan switch (19) Reversing fan solenoid | |
The machine can be equipped with a reversing fan. The cooling capacity of the machine is diminished when any of the following components are obstructed with debris:
- The radiator
- The hydraulic oil cooler
- The air-to-air aftercooler (ATAAC)
- The screens in the enclosure doors
Flow control valve (11) and makeup valve (10) operate the same way as flow control valve (4) and makeup valve (5) in the standard fan system. The operation of the reversing fan is identical to the operation of the standard fan except for the fan reversing valve (8). When the flow control valve (9) is shifted by the reversing fan solenoid (19), the flow of the oil through the hydraulic fan motor is reversed. Thus causing the hydraulic fan motor to turn in the opposite direction. Engine ECM (15) will slow the hydraulic fan motor prior to reversing the hydraulic fan motor to prevent mechanical damage.
Note: For additional information on the Engine ECM and connected hardware, refer to Troubleshooting, UENR0662 and System Operation, UENR4515.