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| Illustration 1 | g03497079 |
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(1) Priority valve
(2) Screen (3) Pressure relief valve gp (4) Orifice (5) Solenoid valve group (brake accumulator charge) (6) Solenoid valve group (hydraulic fan) (7) Orifice (8) Pressure sensor (9) Shuttle valve group (10) Pressure sensor (11) Tank port (12) Fan port (13) Brake accumulator (right) (14) Check valve (15) Brake accumulator (left) (16) Shuttle valve (17) Load sense (18) Pump | |
Operation of the hydraulic Fan System
Fan Speed Solenoid Energized (Operation Below Maximum Fan Speed and Brakes Not Charging
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| Illustration 2 | g03498856 |
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(1) Hydraulic tank
(2) Brake control valve group (3) Return filter (3C) Filter bypass (4) Brake accumulator (5) Brake accumulator (6) Pressure sensor one (7) Pressure sensor two (8) Block (9) Control manifold group (9A) Relief valve (9B) Check valve (9C) Screen (9D) Priority valve (9E) Solenoid valve group (hydraulic fan) (9F) Shuttle valve (9G) Solenoid valve group (brake accumulator charge) (9H) Inverse shuttle valve (9J) Orifice (10) Hydraulic oil cooler (11) Cooler bypass valve (12) Temperature sensor (13) Check valve (14) Fan motor (15) Fan and Brake pump (16) Pump control valve (16A) Margin adjustment (16B) High-pressure cutoff adjustment (A) Load sense port (B) Load sense test port (C) Pump discharge test port (D) Pump entry port (E) Tank return port (F) Fan port | |
When the brake system pressure is below cut in pressure, the brake system receives a higher priority than the fan system. Priority valve (9D) is closed. Pump flow to the fan motor is blocked when the priority valve is closed.
When the brake system is not charging, priority valve (9D) is in the yellow position. This position blocks flow to the brake circuit. During a brake charge event, the priority valve (9D) will modulate between the yellow and gray position. This modulation gives the brake charge system priority and any excess flow will go to the fan system. The fan system is a demand fan. The solenoid valve group (hydraulic fan) (9E) controls the load sense pressure being sent to the pump (15).
As the current to solenoid valve group (hydraulic fan) (9E) increases, the fan speed will decrease. The amount of current applied to solenoid valve group (hydraulic fan) (9E) is controlled by the Electronic Control Module (ECM). The ECM receives inputs from the hydraulic oil temperature sensor, inlet air manifold temperature sensor, and engine coolant temperature sensor. The maximum temperature between these signals will drive the appropriate fan speed.
Flow leaves pump (15) and enters the control manifold (9) at port (D). A pilot pressure signal is taken at the inlet of control manifold (9). The pilot pressure signal is sent through solenoid valve group (hydraulic fan) (9E). The pilot pressure signal is controlled based on the current signal from the ECM. This pilot signal leaves load sense port (A) and is sent to pump (15). Pump (15) displacement will adjust to meet the demand. The resulting output flow from pump (15) will travel through solenoid valve group (hydraulic fan) (9E), exit port (F). The outflow will then go through motor (14), oil cooler (10), and back to tank (1).
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| Illustration 3 | g03498861 |
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(1) Hydraulic tank
(2) Brake control valve group (3) Return filter (3C) Filter bypass (4) Brake accumulator (5) Brake accumulator (6) Brake accumulator sensor (primary) (7) Brake accumulator sensor (secondary) (8) Block (9) Control manifold group (9A) Relief valve (9B) Check valve (9C) Screen (9D) Priority valve (9E) Solenoid valve group (hydraulic fan) (9F) Inverse shuttle valve (9G) Solenoid valve Brake) (9H) Shuttle valve (9J) Orifice (10) Hydraulic oil cooler (11) Cooler bypass valve (12) Temperature sensor (13) Check valve (14) Fan motor (15) Fan and Brake pump (16) Pump control valve (16A) Margin adjustment (16B) High pressure cut out adjustment (A) Load sense port (B) Load sense test port (C) Pump discharge test port (D) Pump entry port (E) Tank return port (F) Fan port | |
When the brake system is not charging, priority valve (9D) is in the yellow position. This position blocks flow to the brake circuit. During a brake charge event, the priority valve (9D) will modulate between the yellow and gray position. This modulation will give the brake charge system priority and any excess flow will go to the fan system. The fan system is a demand fan. The proportional solenoid valve (9E) controls the load sense pressure being sent to the pump (15). As the current to the proportional solenoid valve (9E) increases, the fan speed will decrease. The amount of current applied to the proportional solenoid valve (9E) is controlled by the Electronic Control Module (ECM).
The ECM receives inputs from the hydraulic oil temperature sensor, inlet air manifold temperature sensor, and engine coolant temperature sensor. The maximum temperature between these signals will drive the appropriate fan speed. Flow leaves pump (15) and enters the control manifold (9) at port (D). A pilot pressure signal is taken at the inlet of control manifold and sent through the proportional solenoid valve (9E). The pilot pressure signal is controlled based on the current signal from the ECM. This pilot signal leaves the load sense port (A) and is sent to the pump (15). Pump (15) displacement will adjust to meet the demand. The resulting output flow from pump (15) will travel through priority valve (9E), exit port (F). The outflow will then go through motor (14), oil cooler (10), and back to tank (1).
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| Illustration 4 | g03495657 |
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(1) Passage
(2) Passage (3) Check ball | |
The shuttle valve sends pressure to signal the pump to meet the pressure demand of the hydraulic fan and service brakes. When the service brake pressure is below the cut in pressure, the pressure in passage (2) is greater than the pressure in passage (1). The pressure forces check ball (3) to the left and pressurized oil to exit through passage (1). This signals the pump to upstroke. When the brake system reaches the cut out pressure, the signal pressure for the brake becomes zero. The check ball (3) moves to the right. This movement of the ball allows the pump to sense the requirement for the fan system.
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| Illustration 5 | g03504301 |
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(6) Pressure sensor one
(7) Pressure sensor two (9) Control manifold group (9A) Relief valve (9B) Check valve (9C) Screen (9D) Priority valve (9E) Solenoid valve (fan speed) (9F) Shuttle valve (9G) Solenoid valve (brake) (9H) Shuttle valve | |
Optional Hydraulic Fan System (Maximum Fan Speed in the Reverse Direction)
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| Illustration 6 | g06340188 |
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(1) Hydraulic tank
(2) Brake control valve group (9D) Priority valve (9E) Solenoid valve (fan speed) (9F) Shuttle valve (9G) Solenoid valve (brake) (9H) Shuttle valve (11) Cooler bypass valve (14) Fan motor (Reversing Fan) (15) Fan and Brake pump (17) Crossover relief valve (18) Check valve (19) Implement pump (20) Fan reversing valve (21) Reversing actuator piston | |
Fan motor (14) is shown rotating in the reverse direction at maximum speed in Illustration 6. The operation of fan pump (15) for the optional reversing fan is identical to the operation of the standard fan pump.
Engine ECM activates the reversing mode automatically at programmed intervals. The operator may manually override the automatic reversing cycle through the machine display.
Note: For the reversing fan to perform a purge cycle, the machine must be in motion with the parking brake released.
When the engine ECM activates the reversing mode, the fan reversing valve (20) on fan motor (14) is energized. This action will allow reduced high-pressure oil to act as pilot oil on reversing actuator piston (21). This allows the actuator to adjust the swashplate in the fan motor to the reverse position.
High-pressure oil from fan pump (15) flows through reversing actuator piston (21) to reversing fan motor (14), as shown. The fan motor rotates in the reverse direction. The fan pulls air from the rear of the machine. The air is forced through the radiator and the cooling package to the blow debris out.
Return oil flows to hydraulic oil cooler.
Because cooler bypass valve (11) is closed, the oil flows through hydraulic oil cooler.