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| Illustration 1 | g03424732 |
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Control Valve Stack (1) Inlet Manifold (2) Bowl Control Valve (3) Ejector Control Valve (4) Apron Control Valve (5) Outlet Manifold (6) Solenoid Valve | |
Three implement control valves are mounted together in the valve stack: bowl control valve (2), ejector control valve (3), and apron control valve (4).
Inlet manifold (1) is mounted to the rear of the valve stack. The inlet manifold contains the implement lockout solenoid valve, load sense duplicating valve, and load sense relief valve.
Outlet manifold (5) is mounted to the front of the valve stack. the outlet manifold contains the margin pressure relief valve.
The implement control valves are activated by proportional solenoids (6). A solenoid is located at both ends of each control valve. The solenoids control the pilot oil that shifts the valve spools. The solenoids are activated by electrical signals from the implement ECM. The electrical signals are proportional to the direction and the amount of movement of the implement control levers.
The apron control valve in the stack does not have a shuttle valve, all other control valves have a shuttle valve. The shuttle valves work together in order to ensure that the highest pressure that is commanded by a single control valve is sent as the signal to the pump compensator valve.
The spools of the implement control valves are shifted by pilot oil. The flow of pilot oil to the end of the control valve spools is controlled by a proportional solenoid. Every control valve has a solenoid on each end of the spool.
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| Illustration 2 | g03339665 |
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Solenoid valve (de-energized solenoid) (1) Spring (2) Valve spool (3) Passage to hydraulic oil tank (4) Passage from pilot supply oil (5) Passage from pilot chamber (BB) Cutaway section (CC) Component surface (FF) Activated component (GG) Tank pressure (RR) First pilot pressure reduction | |
When an implement is in the HOLD position, both solenoids on the implement control valve are de-energized. When the solenoid is de-energized, spring (1) forces valve spool (2) upward. In this position, pilot supply oil in passage (4) is blocked. The oil that is from the end of the control valve spool drains through passage (5). The oil flows around valve spool (2) and the oil returns to the hydraulic tank through passage (3).
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| Illustration 3 | g03339667 |
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Solenoid valve (energized solenoid) (1) Spring (2) Valve spool (3) Passage to hydraulic oil tank (4) Passage from pilot supply oil (5) Passage to pilot chamber (BB) Cutaway section (CC) Component surface (FF) Activated component (GG) Tank pressure (RR) First pilot pressure reduction | |
When an implement is activated, the solenoid on one end of the implement control valve is energized. The solenoid forces valve spool (2) downward. In this position, passage (3) to passage (5) is blocked.
Passage (4) is open and pilot supply oil flows around valve spool (2) to passage (5). Pilot oil from passage (5) exerts pressure on the end of the control valve spool and the spool shifts.
The solenoid is a proportional solenoid. The solenoid moves valve spool (2) downward by an amount that is proportional to the amount of movement of the implement control lever. When valve spool (2) is pushed down further, passage (4) is opened more. More pilot oil is allowed into passage (5). The implement control spool shifts proportionally to the pilot oil pressure.
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| Illustration 4 | g03430215 |
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(4) Line Relief Valve
(5A) Bowl Lower Solenoid Valve (5B) Bowl Raise Solenoid Valve (7 ) Tank (9) Valve Spool (10) Compensation and Load Check Valve (11) Shuttle Valve (13) Pump Supply Port (15) Drift Reduction Valve (A) Work port (B) Work port (C) Bridge passage | |
Oil from the implement piston pump flows to the bowl control valve at pump supply port (13). Bowl valve spool (9) is controlled by solenoids (5A) and (5B). The bowl valve spool is spring centered with a closed center. The bowl valve spool has three positions: HOLD, RAISE and LOWER.
The bowl of the Wheel Tractor-Scraper is controlled by the forward and rearward movement of the joystick.
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| Illustration 5 | g03649643 |
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(1) Implement ECM
(2) Bowl Cylinders (3) Bowl Control Valve (4) Line Relief Valve (5A) Bowl Lower Solenoid Valve (5B) Bowl Raise Solenoid Valve (6) Pilot Supply Oil (7 ) Tank (8) Pilot Drain (9) Valve Spool (10) Compensation and Load Check Valve (11) Shuttle Valve (12) Load Sense (13) Pump Supply Port (14) Margin Pressure (15) Drift Reduction Valve (16) Joystick | |
Springs keep bowl valve spool (9) in the HOLD position when solenoid valves (5A) and (5B) have not been actuated. Bowl valve spool (9) in the HOLD position blocks the oil in both ends of the lift cylinders. This blockage of oil keeps the bowl cylinders from moving.
Drift reduction valve (15) for drift reduction in the bowl control valve further limits bowl cylinders drift toward the lower position if leakage occurs between lift valve spool (9) and the valve body.
Spool movement is controlled by actuation of pilot proportioning solenoids (5A) and (5B) that allow oil to flow to either end of bowl valve spool (9).
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| Illustration 6 | g03649711 |
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(1) Implement ECM
(2) Bowl Cylinders (3) Bowl Control Valve (4) Line Relief Valve (5A) Bowl Raise Solenoid Valve (5B) Bowl Lower Solenoid Valve (6) Pilot Supply Oil (7) Tank Port (8) Pilot Drain (9) Valve Spool (10) Compensation and Load Check Valve (11) Shuttle Valve (12) Load Sense (13) Pump Supply Port (14) Margin Pressure (15) Drift Reduction Valve (16) Joystick | |
When the operator pulls the joystick rearward, to the Raise position, the bowl will travel upward. The joystick sends a 500 Hz PWM signal to Implement ECM connector contact J2-24. The ECM sends a signal to the Bowl Raise Solenoid through connector contact J1-48. Then, pilot oil is sent to the left end of bowl valve spool (9) and bowl valve spool (9) moves partially to the right. Implement oil is sent from pump supply port (13) around bowl valve spool (9) to the bottom of compensation and load check valve (10). Compensation and load check valve (10) is pushed up and flow goes through the openings in load check valve (10) to bridge passage (C). Oil flows around bowl valve spool (9) to work port (A).
Oil is allowed to flow to the rod end of the bowl cylinders. This flow of oil causes the bowl to raise. Solenoid valve (5A) and bowl valve spool (9) respond in proportion to the movement of the operator controls.
Oil from the head end of the lift cylinders enters through work port (B), flows around bowl valve spools (9) and exits at tank port (7) to the hydraulic tank.
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| Illustration 7 | g03649718 |
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(1) Implement ECM
(2) Bowl Cylinders (3) Bowl Control Valve (4) Line Relief Valve (5A) Bowl Raise Solenoid Valve (5B) Bowl Lower Solenoid Valve (6) Pilot Supply Oil (7 ) Tank (8) Pilot Drain (9) Valve Spool (10) Compensation and Load Check Valve (11) Shuttle Valve (12) Load Sense (13) Pump Supply Port (14) Margin Pressure (15) Drift Reduction Valve (16) Joystick | |
When the operator pushes the joystick forward, to the LOWER position, the bowl will travel downward. The joystick sends a 500 Hz PWM signal to Implement ECM connector contact J2-24. The ECM sends a signal to the Bowl Lower Solenoid through connector contact J1-49. Then, pilot oil is sent to the right end of bowl valve spool (9) and bowl valve spool (9) moves to the left. Implement pump oil is sent from pump port (7) around bowl valve spool (9) to the bottom of compensation and check valve (10). Compensation and check valve (10) is pushed up and flow goes through the openings in load check valve (10) to bridge passage (C). Oil flows around lift valve spool (9) to work port (B).
Oil is allowed to flow to the head end of the bowl cylinders. This flow of oil causes the bowl to lower. Solenoid valve (5B) and bowl valve spool (9) respond in proportion to the movement of the operator controls.
Oil from the rod end of the lift cylinders enters through work port (A) and exits through tank port (7) to the hydraulic tank.
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| Illustration 8 | g03426971 |
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(4A) Solenoid valve group (ejector forward)
(4B) Solenoid valve group (ejector return) (7) Tank port (8) Ejector valve spool (9) Compensation and load check valve (10) Shuttle valve (12) Pump supply port (14) Ejector forward kickout pressure sensor (15) Ejector return kickout pressure sensor (A) Work port (B) Work port (C) Bridge passage | |
The ejector of the Wheel Tractor-Scraper is controlled by the left and right movement of the joystick.
The ejector control valve has all of the components that are in the apron control valve minus the work port relief valves. Instead of work port relief valves the ejector section has ejector forward and return kick-out valves.
Oil from the implement piston pump flows to the ejector control valve at port (7). The ejector valve spool (8) is controlled by solenoids (4A) and (4B). Ejector valve spool (8) is spring centered with a closed center. Ejector valve spool (8) has three positions: HOLD, EXTEND and RETRACT.
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| Illustration 9 | g03649745 |
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(1) Implement ECM
(2) Ejector Cylinder (3) Ejector Control Valve (4A) Ejector Extend Solenoid Valve (4B) Ejector Retract Solenoid Valve (5) Pilot Supply Oil (6) Tank (7) Pilot Drain (8) Valve Spool (9) Compensation and Load Check Valve (10) Shuttle Valve (11) Load Sense (12) Pump Supply Port (13) Margin Pressure (14) Joystick | |
Springs keep ejector valve spool (8) in the HOLD position when solenoids (4A) or (4B) have not been actuated. Implement pump oil flows to control valve (3) at pump supply port (12). Spool movement is controlled by actuation of pilot proportioning solenoids (4A) or (4B) that allow oil to flow to either end of ejector valve spool (8).
The position of ejector valve spool (8) blocks the oil in both ends of the ejector cylinder. This blockage of oil keeps the ejector cylinder from moving.
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| Illustration 10 | g03649839 |
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(1) Implement ECM
(2) Ejector Cylinder (3) Ejector Control Valve (4A) Ejector Extend Solenoid Valve (4B) Ejector Retract Solenoid Valve (5) Pilot Supply Oil (6) Tank (7) Pilot Drain (8) Valve Spool (9) Compensation and Load Check Valve (10) Shuttle Valve (11) Load Sense (12) Pump Supply Port (13) Margin Pressure (14) Joystick | |
When the operator moves the joystick to the left, to the EXTEND position, the ejector will move forward. The joystick sends a 500 Hz PWM signal to the Implement ECM at connector contact J2-25. The ECM sends a signal to the Ejector Forward Solenoid through connector contact J1-51. Then, pilot oil is sent to the right end of ejector valve spool (8) and ejector valve spool (8) moves to the left. Implement oil is sent from pump supply port (12) around ejector valve spool (8) to the bottom of compensation and load check valve (9). Flow goes through the openings in the compensator to bridge passage (C). Oil flows around ejector valve spool (8) to work port (A).
Oil flows to the head end of the ejector cylinder. This flow of oil causes the ejector cylinder to extend. Solenoid valves (4A) and ejector valve spool (8) respond in proportion to the movement of the operator controls.
Oil from the rod end of the ejector cylinder enters through work port (B) and exits through tank port (7) to the hydraulic tank.
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| Illustration 11 | g03649862 |
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(1) Implement ECM
(2) Ejector Cylinder (3) Ejector Control Valve (4A) Ejector Extend Solenoid Valve (4B) Ejector Retract Solenoid Valve (5) Pilot Supply Oil (6) Tank (7) Pilot Drain (8) Valve Spool (9) Compensation and Load Check Valve (10) Shuttle Valve (11) Load Sense (12) Pump Supply Port (13) Margin Pressure (14) Joystick | |
When the operator moves the joystick to the right, to the RETRACT position, the ejector will return to the rearward position. The joystick sends a 500 Hz PWM signal to the Implement ECM at connector contact J2-25. The ECM sends a signal to the Ejector Reverse Solenoid through connector contact J1-52. The rearward velocity will increase as the angular displacement of the lever increases (up to the detent). Then, pilot oil is sent to the left end of ejector valve spool (8) and ejector valve spool (8) moves to the right. Implement oil is sent from pump port (7) around ejector valve spool (8) to the bottom of compensation and load check valve (9). Compensation and load check valve (9) is pushed up and flow goes through the openings in the compensator to bridge passage (C). Oil flows around ejector valve spool (8) to work port (B).
Oil is allowed to flow to the rod end of the ejector cylinder. This flow of oil causes the ejector cylinder to retract. Solenoid valve (4B) and ejector valve spool (8) respond in proportion to the signal that is received from the operator controls.
Oil from the head end of the ejector cylinder enters through work port (A) and exits through tank port (7) to the hydraulic tank.
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| Illustration 12 | g03431202 |
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(4) Line relief valve
(5A) Solenoid valve group (apron open) (5B) Solenoid valve group (apron close) (8) Tank pressure (9) Apron valve spool (10) Compensation and check valve (12) Pump supply port (A) Work port (B) Work port (C) Bridge passage | |
The apron of the Wheel Tractor-Scraper is controlled by the left and right movement of a thumb roller on the joystick.
Oil from the implement piston pump flows to apron control valve at pump supply port (12). The flow then reaches the apron valve. Apron valve spool (9) is controlled by solenoids (5A) and (5B). The apron valve spool is spring centered with a closed center. The lift valve spool has four positions: HOLD, RAISE, LOWER and FLOAT.
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| Illustration 13 | g03649873 |
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(1) Implement ECM
(2) Apron Cylinder (3) Apron Control Valve (4) Line Relief Valves (5A) Apron Extend Solenoid Valve (5B) Apron Solenoid Valve (6) Pilot Supply Oil (7) Tank (8) Pilot Drain (9) Valve Spool (10) Compensation and Load Check Valve (11) Load Sense (12) Pump Supply Port (13) Margin Pressure (14) Joystick | |
Springs keep apron valve spool (9) in the HOLD position when solenoid valves (5A) and (5B) have not been actuated. Apron valve spool (9) in the HOLD position blocks the oil in both ends of the apron cylinder. This blocking of the oil keeps the apron cylinder from moving.
Spool movement is controlled by actuation of pilot proportioning solenoids (5A) and (5B) that allow oil to flow to either end of apron valve spool (9).
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| Illustration 14 | g03649921 |
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(1) Implement ECM
(2) Apron Cylinder (3) Apron Control Valve (4) Line Relief Valves (5A) Apron Extend Solenoid Valve (5B) Apron Solenoid Valve (6) Pilot Supply Oil (7) Tank (8) Pilot Drain (9) Valve Spool (10) Compensation and Load Check Valve (11) Load Sense (12) Pump Supply Port (13) Margin Pressure (14) Joystick | |
When the operator moves the thumb roller on the joystick to the right, the apron will move upward. The thumb roller on the joystick sends a 500 Hz PWM signal to the Implement Control ECM at connector contact J2-26. The ECM sends a signal to the Solenoid (Apron Raise) through connector contact J1-58.
When the apron control roller or the joystick control is moved to the RAISE position, pilot oil is sent to the right end of apron valve spool (9) and apron valve spool (9) moves to the left. Implement pump oil is sent from pump supply port (12) around apron valve spool (9) to the bottom of compensation and check valve (10). Compensation and check valve (10) is pushed up and flow goes through the openings in load check valve (10) to bridge passage (C). Oil flows around apron valve spool (9) to work port (A).
Oil is allowed to flow to the head end of the apron cylinder. This flow of oil causes the apron to rise. Solenoid valve (5A) and apron valve spool (9) respond in proportion to the movement of the operator controls.
Oil from the rod end of the apron cylinder enters through work port (B) and exits through tank port (8) to the hydraulic tank.
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| Illustration 15 | g03649932 |
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(1) Implement ECM
(2) Apron Cylinder (3) Apron Control Valve (4) Line Relief Valves (5A) Apron Extend Solenoid Valve (5B) Apron Solenoid Valve (6) Pilot Supply Oil (7) Tank (8) Pilot Drain (9) Valve Spool (10) Compensation and Load Check Valve (11) Load Sense (12) Pump Supply Port (13) Margin Pressure (14) Joystick | |
When the operator moves the thumb roller on the joystick to the left, to the LOWER position, the apron will move downward. The thumb roller on the joystick sends a 500 Hz PWM signal to the Implement Control ECM at connector contact J2-26. The ECM sends a signal to the Solenoid (Apron Lower) through connector contact J1-59. Then, pilot oil is sent to the left end of apron valve spool (9) and apron valve spool (9) moves partially to the right. Implement oil is sent from pump supply port (12) around apron valve spool (9) to the bottom of compensation and load check valve (10). Compensation and load check valve (10) is pushed up and flow goes through the openings in load check valve (10) to bridge passage (C). Oil flows around apron valve spool (9) to work port (B).
Oil is allowed to flow to the rod end of the apron cylinder. This flow of oil causes the apron to lower. Solenoid valve (5B) and apron valve spool (9) respond in proportion to the movement of the operator controls.
Oil from the head end of the lift cylinders enters through work port (A) and exits at tank port (8) to the hydraulic tank.
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| Illustration 16 | g03649940 |
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(1) Implement ECM
(2) Apron Cylinder (3) Apron Control Valve (4) Line Relief Valves (5A) Apron Extend Solenoid Valve (5B) Apron Solenoid Valve (6) Pilot Supply Oil (7) Tank (8) Pilot Drain (9) Valve Spool (10) Compensation and Load Check Valve (11) Load Sense (12) Pump Supply Port (13) Margin Pressure (14) Joystick | |
The apron float mode is triggered by moving the thumb roller on the joystick to the full lower position and then allowing the roller to spring back to the neutral position. The time period between the full lower command and the neutral command must be less than 200 milliseconds. Zero current is sent to the Apron Raise Solenoid. A maximum / float command current is sent to the Apron Lower Solenoid. The apron float lamp will illuminate. These commands will remain active until one of the following events occurs:
- Any diagnostic code for the apron is detected.
- A command for changing the elevation of the apron is sent from the joystick to the Machine Control ECM.
When the apron control roller is moved to the FLOAT position, pilot oil is sent to the left end of apron valve spool (9) and apron valve spool (9) moves completely to the right. The apron valve spool remains in the float position until another apron command is given by the operator. The apron control valve will then return to the HOLD position.
When apron valve spool (9) is in the FLOAT position, complete movement of apron valve spool (9) to the right closes off the flow of implement pump oil from pump port (12) to bridge passage (C). Work ports (A) and (B) are connected to the tank by apron valve spool (9) at port (8).
Oil from the rod end of the apron cylinder and the oil from the head end of the apron cylinder drains to the tank. This flow of oil allows the weight of the apron assembly to lower the apron assembly to the closed position. The apron will raise as pressure is exerted against it. Neither the rod end of the apron cylinder or the head end of the apron cylinder are under hydraulic pressure. The apron cylinder can move freely in either direction according to the force on the apron.
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| Illustration 17 | g03649946 |
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(1) Dead engine manual bowl drop
(2) Dead engine lower shuttle valve (3) Left bowl cylinder (4) Right bowl cylinder, Bowl level position cylinder (5) Ejector cylinder (6) Apron cylinder (7) Apron rod line pressure tap (8) Apron rod line pressure sensor (9) Ejector forward kickout pressure sensor (10) Ejector return kickout pressure sensor (11) Bowl head line pressure sensor (12) Bowl rod line pressure sensor (13) Pilot pressure tap (14) Implement pilot accumulator (15) Drift reduction valve (16) Bowl raise relief (17) Apron raise relief (18) Apron lower relief (19) Apron open solenoid (20) Ejector extend solenoid (21) Bowl lower solenoid (22) Implement lockout valve (23) Implement tank return pressure tap (24) Implement pump supply pressure tap (25) Bowl valve spool (26) Apron valve spool (27) Ejector valve spool (28) Compensation and load check valve (29) Compensation and load check valve (30) Compensation and load check valve (31) Load sense duplicating reducing valve (32) Shuttle valve (33) Shuttle valve (34) Margin pressure relief valve (35) Apron close solenoid (36) Ejector retract solenoid (37) Bowl raise solenoid (38) Load sense relief valve (39) Inlet manifold (40) Control valve group (bowl) (41) Control valve group (ejector) (42) Control valve group (apron) (43) Outlet manifold (44) Cushion-Hitch/Pilot oil filter (45) Implement load sense pressure tap (46) Pump control (load sense spool) (47) Cushion-Hitch pump (48) Pilot oil manifold (49) Pilot pressure reducing valve (50) Pump control (high-pressure cut off) (51) Implement pump group (52) Destroke piston (53) Cushion-Hitch enable solenoid (A) Pilot drain (B) Return to tank (C) Pilot drain (D) Implement pump suction (E) Pump case drain to tank (F) Pilot drain (G) Cushion-Hitch pilot supply pressure (H) Cushion-Hitch pump supply pressure | |
The supply oil flows from the implement piston pump to the main control valve. The main control valve controls the flow of hydraulic oil to the cylinders.
Most of the supply oil flows to control valves for the implement circuits. Oil returns from the control valve and flows to the tank at point (B).
The supply oil flows to the following components: bowl control valve (40), ejector control valve (41) and apron control valve (42).
The supply oil flows from the cushion hitch pump to pressure reducing valve (49). Pressure reducing valve (49) reduces the oil pressure to pilot pressure. The pressure reducing valve provides oil to the pilot system.
The oil that flows to pilot oil accumulator (14) charges the pilot oil accumulator. This charging of the pilot accumulator allows the bowl and apron to be lowered if the engine stops. Then, the oil flows through the main control valve as pilot oil. The pilot oil flows through the solenoid valves in order to move the spools to the correct position. The key start switch must be in the ON position for this function to work. Dead engine manual bowl drop valve (1) can be used to lower the bowl and apron if no power can be supplied to the solenoids.
The oil that flows to the load sensing circuit enters signal duplicating reducing valve (31). Normally, the oil flows through the signal duplicating reducing valve.
Signal duplicating reducing valve (31) and load sensing relief valve (38) operate for all of the control valves in the main control valve. Load sensing relief valve (31) limits the maximum signal pressure to the pump at point (45) by draining excess signal oil to the tank at point (C). Signal duplicating reducing valve (31) sends signal oil back to the implement piston pump at point (45).
The control valves are proportional priority and pressure compensated. If a circuit is active, or if more than one circuit is active, signal duplicating reducing valve (31) duplicates the highest signal oil pressure. The highest signal oil pressure is applied to all of the control valves.
Oil flow enters the control valve and flows through a parallel feeder passage to all circuits. All four circuits on the machine can be operated independently.
The apron control valve has two line relief valves (17) and (18). The bowl control valve has a bowl raise relief (16).
Reference: For more information on the operation or the line relief valves, refer to Systems Operation, "Relief Valve (Line)".
Reference: For more information on the operation of the Relief Valve (Load Sensing Signal), refer to Systems Operation, "Relief Valve (Load Sensing Signal)".