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| Illustration 1 | g06126958 |
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Schematic for the hydraulic fan system (1) Screen Group (if equipped) (2) Hydraulic Fan Motor (3) Makeup Valve (Hydraulic Fan) (4) Check Valve (Hydraulic Oil Cooler Bypass) (5) Hydraulic Oil Cooler (6) High-Pressure Screen Group (if equipped) (7) Solenoid Valve (hydraulic fan) (8) Pressure Switch (filter bypass) (9) Pressure Sensor (if equipped) (10) Oil Filter (case drain) (11) Orifice (12) Pressure Switch (filter bypass) (13) Hydraulic Fan Pump (14) Pump Control Valve (15) Hydraulic Oil Tank (16) Relief Valve (Pilot) (17) Filter (Pilot) (18) Pressure Switch (19) Autolube Supply | |
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| Illustration 2 | g06132692 |
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Pump compartment (7) Solenoid Valve (hydraulic fan) (13) Hydraulic Fan Pump | |
The hydraulic fan pump controls oil flow for the fan system and the pilot system. The hydraulic fan system pressure must maintain high enough pressure in order to maintain proper pilot pressure. In the event pilot pressure is not to specification, fan system calibration is required.
The hydraulic fan system consists of the following components: hydraulic fan pump (13), the solenoid valve (hydraulic fan) (7), hydraulic fan motor (2) and hydraulic oil cooler (5)
Hydraulic fan pump (13) is a variable displacement piston pump. In the hydraulic fan system, the demand for more fan speed through an increase of oil flow is supplied by the hydraulic fan pump (13). The discharge pressure of the hydraulic fan pump is controlled by solenoid valve (7) (Hydraulic fan). When solenoid valve receives a change in current from the engine electronic control module (ECM), signal pressure to the fan pump will change accordingly. As signal pressure changes, the displacement will change in order to maintain the pump pressure above the signal pressure. Also, the flow of pressure will change in order to maintain the pump pressure above the signal pressure. The engine ECM receives information from temperature sensors for the engine coolant and for the implement hydraulic tank (implement, hydraulic fan, and engine intake manifold).
When the current to solenoid valve (7) is at the maximum, the fan pump is at minimum output. If the fan speed solenoid fails or there is another problem in the electrical circuit for the hydraulic fan system, the fan pump will go to high-pressure cutoff. Then, the pump will produce maximum output. The maximum output that is provided by fan pump (13) is controlled by the adjustment of the high-pressure cutoff in the pump control valve (14).
The hydraulic fan motor (13) is a fixed displacement motor that is equipped with makeup valve (3). The makeup valve allows the hydraulic oil to flow from the fan motor outlet through the makeup valve back to the fan motor inlet. This flow will prevent cavitation in the motor.
When the engine is first started and the hydraulic oil is cold, the oil from the piston motor cannot easily flow through the hydraulic oil cooler. Oil pressure will increase in the hydraulic oil cooler. The check valve for the hydraulic oil cooler bypass will open. Check valve (4) limits the maximum oil pressure drop through the oil cooler to
When the engine is started and if all temperatures for the three sensors are below the key target temperatures the engine ECM will send the maximum current to solenoid valve (7). Signal oil to the flow control spool is open to the hydraulic oil tank (15) through the solenoid valve (7). Supply oil is directed to the actuator piston in order to destroke the pump (13). The angle of the pump swashplate is at a minimum. The hydraulic fan pump will produce a minimum flow.
As one of the temperatures of the three sensors increases above the key target temperature, the engine ECM sends a proportional reduction in current to solenoid valve (7). Solenoid valve will start to shift. This action will allow some of the supply oil to flow to the flow control spool. The flow control spool starts to shift. A proportional amount of oil will flow back to the hydraulic oil tank (15). As the pressure behind the actuator piston begins to decrease, the actuator spring will increase the swashplate angle . The pump output flow will increase. The fan speed will increase.
As the temperatures of the machine continue to increase, the engine ECM will continue to reduce the current that is sent to solenoid valve (7). Solenoid valve will continue to shift in the downward direction. This action will increase the hydraulic signal to the flow control spool. The control spool will continue to drain oil that is behind the actuator piston. The swashplate moves more toward a maximum angle and the pump flow continues to increase. The fan speed continues to increase.
As the pressure to the pump compensator increases, the output flow of the fan pump increases. This pressure increases the rpm of hydraulic fan motor (2). The increase in pressure of the pump output oil will work on the right side of both flow control spool and pressure compensator spool. The spool for the flow control will move to the left. The pressure on the right side of compensator spool will overcome the spring. The compensator spool will start to shift to the left. This action will allow some of the pump output oil to flow to the piston of the actuator. This flow will slightly destroke the pump in order to reduce pump flow.
Once the cutoff pressure is reached, resulting in maximum output flow and maximum fan speed, the pressure cutoff spool will meter the flow of supply oil to the actuator piston and from the actuator piston. The adjustment of the cutoff spool can be adjusted for any maximum pressure.
The cutoff spool is similar to a relief valve. If the motor would lock up, the cutoff spool would destroke the pump to a minimum angle. Then, the pump would produce minimum flow.
Piston Pump (Hydraulic Fan) (Implement Pilot)
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| Illustration 3 | g02698756 |
| (13) Fan pump | |
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| Illustration 4 | g01456682 |
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Hydraulic Fan pump (16) Housing of The Pump (17) Actuator Piston (18) Piston (19) Cylinder Barrel (20) Port Plate (21) Outlet Passage to The Fan Motor (22) Drive Shaft (23) Swashplate (24) Piston Shoe (25) Shoe Plate (26) Spring (27) Actuator Piston (28) Inlet Passage From the Hydraulic Tank (29) Head | |
Hydraulic Fan pump (13) is a variable displacement piston pump. The hydraulic fan pump is controlled by a load sensing line that is connected to pump control valve (14). The movement of pistons (18) in the pump draws oil from hydraulic tank (15). Then, hydraulic fan pump (13) provides oil flow to hydraulic fan motor (2).
When the engine is running and drive shaft (22) is rotating, the components that rotate are cylinder barrel (19), pistons (18), piston shoes (24), and shoe plates (25). Within barrel (19), there are nine piston assemblies (18). The components of the pump that remain are fastened to pump housing (16).
Oil from hydraulic oil tank (15) flows into pump head (29) at inlet passage (28). Then, the oil flows from inlet passage into port plate (20). When drive shaft (22) rotates, the openings in cylinder barrel (19) move toward the passages in port plate (20).
Each piston (18) inside cylinder barrel (19) is held against swashplate (23) by shoe plate (25). Swashplate can be at any angle between the maximum angle and the minimum angle. The angle of swashplate determines the displacement of oil that is pushed out of each cylinder barrel (19).
As pistons (18) follow the angle of swashplate (23), the pistons move in and out of cylinder barrel (19). When pistons move out of cylinder barrel, oil is pulled into cylinder barrel.
As cylinder barrel (19) rotates, the angle of swashplate (23) pushes pistons (18) into cylinder barrel. Then, pistons push oil out of cylinder barrel and oil flows through the outlet passages of port plate (20).
The minimum angle is perpendicular with drive shaft (22). The discharge of oil is greater when the angle of swashplate (23) is greater. Oil is discharged through port plate (20) to outlet passage (21).
When swashplate (23) is at the maximum angle, the pump is at the maximum displacement.
The swashplate angle is controlled by spring (26) and actuator piston (27). Actuator piston is activated by oil pressure from solenoid valve (7).
Pressure Control Valve (Hydraulic Fan Pump)
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| Illustration 5 | g06132706 |
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Hydraulic fan pump (14) Pump Control Valves | |
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| Illustration 6 | g01462910 |
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| Illustration 7 | g02698778 |
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Components of pressure and flow compensator valve (30) Housing (31) Spring (32) Port (load sensing signal) (33) Actuator Piston (34) Port (load sensing signal) (35) Port Passage For Case Drain (36) Actuator Pressure (37) Discharge Pressure (38) Cavity (flow compensator) | |
The flow of oil for the hydraulic fan system is regulated by pump control valve (14). Pump control valve maintains the correct oil flow that is provided by the fan pump. Pump flow and pump pressure cutoff are maintained by either sending or draining actuator piston (33).
Actuator piston (33) and spring (31) work against each other in order to determine the angle of swashplate (23). The discharge pressure of the pump is
Pump control valve (14) is able to limit pressure. Pump control valve prevents overloading the hydraulic fan system. When pump outlet pressure exceeds
Pressure at the signal port flows into port (32). Then, the spool is shifted to the left. Then, the oil fills the cavity behind actuator piston (33). As the pressure behind piston increases, actuator piston begins to move. Then, swashplate (23) rotates in the clockwise direction. The pump destrokes and maintains an output pressure of
When one of the sensors register a temperature that is above the key target temperature the engine ECM sends a proportional reduction in current to solenoid valve (7). Solenoid valve shifts.
Upstroking increases the pump displacement. Upstroking occurs when one or more of the temperature sensors sense a higher temperature. When a higher temperature is sensed the ECM determines the proper amount of current in order to be sent to the solenoid valve (hydraulic fan). Solenoid valve (7) increases the signal pressure or the solenoid valve decreases the signal pressure that is sent to pump control valve (14) through the load sensing line.
The load sensing signal pressure enters through port (32) which fills the pressure cavity. The signal pressure and the force of spring (31) shifts the compensator spool to the right. The oil behind actuator piston (33) flows to the passage (case drain) (35). The force of spring overrides the force of the oil pressure behind actuator piston. Then, the angle of swashplate (23) proportionally increases. When the angle of swashplate increases, the pump upstrokes and the displacement of the pump increases.
As the pressure to the hydraulic fan pump increases, the output flow increases and the speed of hydraulic fan motor (2) increases. The flow is then maintained in order to keep pressure to the hydraulic fan motor rotating at that speed. When the hydraulic pump supply pressure reaches the spring setting of the pressure cutoff spool, the oil pressure behind the pressure cutoff spool will override the cutoff spring (31). The pressure cutoffspool shifts to the left. When the pressure cutoff spool moves to the left, the land on the cutoff spool will block the oil flow from actuator piston (33) to hydraulic oil tank (15). At the same time, pump supply oil is metered around the cutoff spool by the land on the spool. The metered oil supply flows behind actuator piston (33). The oil pressure behind the actuator piston and spring are equalized. The swashplate is at the angle in order to produce flow for the adjusted maximum pressure. The pump will provide the fan system with the maximum flow in order to maintain the maximum pressure and resulting fan speed. The maximum fan speed can be changed by adjusting force on spring for the cutoff spool .
If the temperature of the sensors is dropping toward the key target temperatures, the engine ECM sends an increase in current to solenoid valve (7). Solenoid valve shifts. The solenoid valve opens a path for oil that is above the flow control spool in order to be metered out to the hydraulic tank. Solenoid valve decreases the signal pressure to pump control valves (14) through the load sensing line.
The force that is behind the right end of flow control spool will override spring (31). As signal oil from cavity flow compensator (38) is released, the further flow control spool will move to the left. As the spool begins to move to the left, pump supply oil will flow around the land on the spool for flow control. The oil flows through pump control valve (14), through passage port (load sensing signal) (34) and to actuator piston (33). The oil pressure increases at the actuator. The actuator moves to the left against the swashplate (23). The swashplate will override spring and the swashplate moves to a reduced angle. The output of the pump will decrease.
If the signal pressure does not change, the flow compensator spool will remain in the metering position. When the flow compensator spool is in the metering position, the fan circuit is equalized.
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| Illustration 8 | g01456686 |
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Hydraulic fan motor (39) Shaft (40) Case (41) Retainer Plate (42) Pistons (seven) (43) Pin (pivot) (44) Barrel (45) Port Plate (46) Head | |
Hydraulic fan motor (2) is a bent axis type motor. The motor is also a piston-type motor. The motor has a fixed displacement of oil per revolution. The fan drive motor is mounted on a frame in front of the radiator.
The following rotating components of the motor are: shaft (39), retainer plate (41), pistons (42), pin (pivot) (43) and barrel (44). The parts that do not turn are the following: case (40), port plate (45) and head (46).
When shaft (39) turns, the fan blade at the same speed.
Any internal leakage drains back to the hydraulic oil tank through the drain passage.
The hydraulic fan motor turns the fan at a speed in order to match the cooling system requirements. When the requirements of the cooling system are met, the power demand on the engine is decreased.
Solenoid Valve (Hydraulic Fan)
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| Illustration 9 | g02698781 |
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Pump compartment (7) Solenoid Valve (Hydraulic Fan) | |
The solenoid valve (7) (hydraulic fan) is located behind the operator compartment.
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| Illustration 10 | g01456685 |
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Components of the solenoid valve (hydraulic fan) (7) Solenoid Valve (hydraulic fan) (47) Manifold (48) Passage to The Hydraulic Tank (49) Poppet (variable orifice) (50) Passage (signal pressure) (51) Orifice (52) Passage (hydraulic pump pressure) | |
Solenoid valve (7) (hydraulic fan) that controls signal pressure to the pump compensator is located in the pump compartment behind the cab. Solenoid valve (hydraulic fan) consists of solenoid valve (7) and manifold (47).
When solenoid valve (7) is de-energized, the discharge pressure from the hydraulic fan pump flows into passage to the hydraulic oil tank (48), through orifice (51), and into passage (52) (hydraulic pump pressure). The oil then flows from passage to the pump control valve (14). The flow of oil is the signal pressure.
The engine ECM receives a signal from the hydraulic oil temperature sensor and the engine coolant temperature sensor. The engine ECM also receives a signal from the intake manifold temperature sensor. The engine ECM will then send a current to solenoid valve (7). As the temperature decreases, the current to solenoid valve is increased. When solenoid valve is energized, poppet (49) is allowed to raise. Then, oil from the passage (signal pressure) (50) is allowed to flow to the passage (hydraulic oil tank) (48). This flow causes the signal pressure in passage (50) to decrease. As the signal pressure decreases, the fan speed decreases and the pump destrokes. In the hydraulic fan system, the amount of oil that is allowed to flow from the signal line to the hydraulic tank is proportional to the amount of current change that is sent by the engine electronic control module (ECM).
The engine ECM receives a signal from the hydraulic oil temperature sensor, the engine coolant temperature sensor, and the intake manifold temperature sensor. The engine ECM will then send a current to proportional solenoid valve (7). As the temperature increases, the amount of current going to the proportional solenoid valve decreases. Poppet (49) is seated and the signal pressure in passage (50) increases. As the signal pressure increases, the pump upstrokes and the fan speed increases.
In the demand fan system, the speed of the fan and the output of the hydraulic fan pump is directly controlled by the engine ECM through solenoid valve (7). The engine ECM interprets signals from three sensors on the machine. Then, the engine ECM sends a proportional amount of current to solenoid valve.
The sensor for the intake manifold temperature sends a signal to contact J2-56 through the C967-BU(Blue)wire on the engine ECM.
The oil temperature sensor (implement) is used for the measurement of liquid temperatures. The duty cycle will change as the temperature of the oil increases. The hydraulic oil temperature is read directly by the Implement ECM. From the Implement ECM, data is sent to the engine ECM through the Cat Data Link.
The engine coolant temperature sensor is a sensor that sends a signal to contact J2-13 on the engine ECM through wire 995-BU(Blue).
The following conditions must be met, in order to run the fan system at minimum fan speed.
- The intake manifold temperature is below
59 °C (138 °F) . - The implement oil temperature is below
87 °C (189 °F) . - The engine coolant temperature is below
92 °C (198 °F) .
As one of the sensors reads a temperature that is above the key target temperature, the engine ECM interprets a demand for more cooling. The engine ECM starts sending a reduced amount of current from J1-43 on the engine ECM through wire H746-YL(Yellow)to solenoid valve (7). The solenoid valve will move proportionally, toward the de-energized direction.
Note: The fan may run at max speed if any of the sensors are faulted or if the engine ECM is not receiving implement oil temperature over the Cat Data Link.