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| Illustration 1 | g03496470 |
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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 | |
The control manifold controls the brake and the hydraulic fan system. The brake system has priority over the hydraulic fan system. The fan system is only used on demand.
Operation Below Brake Cut-In Pressure
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| Illustration 2 | g03498741 |
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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 (Brake 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 cut-of adjustment (A) Load sense port (B) Load sense test port (C) Pump discharge test port (D) Pump entry port (E) Tank return port (F) Accumulator port (G) Accumulator port (H) Pressure sensor port (J) Pressure sensor port | |
At machine startup when the accumulators are empty or when pressure sensor (6) and pressure sensor (7) sense that the brake system pressure has reached the pre-determined cut-in, brake charge solenoid (9G) will be in the yellow position shown. This high-pressure signal is sent to pump (15) causing the pump to upstroke in displacement to meet the demand of the brake charge system. The high-pressure signal from brake charge solenoid (9G) is also sent to the spring side of priority valve (9F). Priority valve (9F) will continuously meter between the yellow and gray position to ensure that brake charge gets priority.
Excess flow not needed by the brake charge system will be sent to the fan system. Inverse shuttle valve (9H) senses the accumulator port (F) or brake accumulator port (G) that has the lowest pressure. Inverse shuttle valve (9H) will continuously be metering between the three positions shown. The metering ensures that the brake accumulator with the lowest pressure gets charged first. In the event of a failure, the accumulator with the highest pressure will be protected.
Operation at Brake Cut-Out Pressure
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| Illustration 3 | g03498742 |
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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 (Brake charge) (9H) Shuttle valve (9J) Inverse shuttle valve (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 adjustments (A) Load sense port (B) Load sense test port (C) Pump discharge port (D) Pump entry port (E) Tank return port (F) Accumulator port (G) Accumulator port (H) Pressure sensor port (J) Pressure sensor port | |
When pressure sensor (6) and sensor (7) sense that the brake system pressure has reached the pre-determined cut-out pressure, a signal will be sent to brake charge solenoid (9G). Brake charge solenoid (9G) will shift to the yellow position. High pressure acting on the spring side of priority valve (9D) and shuttle valve (9F) will then be drained to tank. Priority valve (9D) will then shift to the yellow position, blocking flow to the brake charge circuit and directing the flow to the fan circuit. Check valve (9B) will close, maintaining high pressure in the brake charge circuit. Pump (15) will destroke in displacement to meet the demand of the fan.
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| Illustration 4 | g03495601 |
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(1) Passage
(2) Passage (3) Check ball | |
The shuttle valve sends pressure in order 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 | g03517517 |
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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 | |