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| Illustration 1 | g02715817 |
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(1) Sensor
(2) Test Port (3) Shuttle Valve (4) To Brake System (5) Keypad module (6) CAN data link (7) Engine Control Module (ECM) (8) Accumulator Charge Logic Element (9) Solenoid Valve (10) Priority Valve (11) Flow Control Valve (12) Relief Valve (13) Test Port (14) Pressure Control Valve (15) Flow Control Valve (16) Pump (17) Engine PTO (18) Fan Motor (19) Crossover Relief Valve (20) Reversing Fan Solenoid Valve (if equipped) (21) Check Valve (22) Tank | |
The hydraulic fan system contains variable displacement hydraulic pump (16).
When the engine is started, hydraulic oil is drawn from the tank (22) by the fan drive pump (16). The pump sends oil to the priority valve (10). The oil flows to the brake system and the hydraulic fan system. The pilot oil pressure to the priority valve causes the spool in the priority valve to shift to the right.
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| Illustration 2 | g02717857 |
| (27) Reversing fan switch | |
If the machine is equipped with the optional reversing fan, fan reversing valve (20) is installed. The fan reversing valve (20) controls the direction of the flow of oil to the fan drive motor (18). The direction of the flow of oil determines the direction of rotation of the fan. The reversing fan solenoid (20) is activated by the Engine ECM (7). The reversing fan solenoid can be activated by the button (27) on the keypad module (5) in the cab. The button communicates through the CAN data link (7) to the ECM in order to activate solenoids.
The CAN data link is an input/output of the ECM. The data is bidirectional. The CAN data link allows the ECM to input information and allows the ECM to output information.
The crossover relief valve (19) sends oil to the opposite side of the motor when the pressure exceeds the relief setting.
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| Illustration 3 | g02717651 |
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(1) Sensor
(2) Test Port (3) Shuttle Valve (4) To Brake System (5) Keypad module (6) CAN data link (7) Engine Control Module (ECM) (8) Accumulator Charge Logic Element (9) Solenoid Valve (10) Priority Valve (11) Flow Control Valve (12) Relief Valve (13) Test Port (14) Pressure Control Valve (15) Flow Control Valve (16) Pump (17) Engine PTO (18) Fan Motor (21) Check Valve (22) Tank (23) Fan Solenoid Valve | |
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| Illustration 4 | g02718313 |
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(18) Standard fan motor (if equipped)
(21) Check valve (24) Inlet (25) Outlet (26) Case Drain | |
The speed of the fan is limited by the fan motor (18) and the current signal sent to solenoid valve (23). The speed of the fan motor also depends on the RPMs of the engine. The control of the fan speed is based on the value of the following conditions:
- Inlet manifold temperature
- Transmission oil temperature
- Hydraulic oil temperature
- Engine coolant temperature
- Ambient temperature (only when air conditioning is turned on)
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| Illustration 5 | g02802436 |
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(1) Sensor
(2) Test Port (3) Shuttle Valve (4) To Brake System (5) Keypad module (6) CAN data link (7) Engine Control Module (ECM) (8) Accumulator Charge Logic Element (9) Solenoid Valve (10) Priority Valve (11) Flow Control Valve (12) Relief Valve (13) Test Port (14) Pressure Control Valve (15) Flow Control Valve (16) Pump (17) Motor (18) Fan Motor (19) Crossover Relief Valve (20) Reversing Fan Solenoid Valve (if equipped) (21) Check Valve (22) Tank | |
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| Illustration 6 | g02718298 |
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(18) Fan Motor
(19) Crossover Relief Valve (20) Reversing Fan Solenoid Valve (if equipped) (21) Check Valve (24) Inlet (25) Outlet (26) Case Drain | |
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 transmission oil cooler
- The screens in the enclosure doors
The reversing fan allows the debris to be removed without turning off the machine.
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| Illustration 7 | g02717854 |
| (27) Reversing fan switch | |
The operation of reversing fan (18) is identical to the operation of standard fan except for fan reversing valve (20) and Crossover Relief Valve (19). When Crossover Relief Valve (19) senses high pressure on one side of the hydraulic fan motor, the valve opens. The open valve relieves pressure to the opposite side of the hydraulic fan motor. When fan reversing valve (20) is shifted, the flow of the oil through the hydraulic fan motor is reversed. This action will cause the hydraulic fan motor to turn in the opposite direction. The machine ECM will slow down the hydraulic fan motor prior to reversing the hydraulic fan motor in order to prevent mechanical damage.
The purpose of the Reversing Fan button is to provide the operator a way to clean the debris from the radiator using the cooling fan.
The reversing fan switch (27) sends a signal through the Controller Area Network (CAN) to the fan reversing valve (6).
If the light is ON, Reversing Fan is enabled in automatic mode.
Press and hold the button for 2 seconds to reverse the fan. Three lights by the button will be illuminated. After the manual reversing cycle, the fan will resume the previous setting.
The automatic mode will reverse the fan for 10 seconds after every 30 minutes.
Note: The time can be changed by your Cat dealer.
The system will remember your selection when the machine is powered off and back on again.