i01630775
Main Control Valve
g00847201
Hydraulic schematic (1) Stick drift reduction valve
(2) Line relief valve (stick cylinder rod end) (3) Boom drift reduction valve
(4) Line relief valve (boom cylinder head end) (5) Return port
(6) Main control valve (7) Stick regeneration valve (8) Load check valve (9) Parallel feeder passage (10) Straight travel solenoid valve (11) Right travel control valve (12) Attachment control valve (13) Bucket control valve (14) Center bypass passage (15) Boom I control valve (16) Stick II control valve (17) Relief valve (negative flow) (18) Straight travel control valve (19) Relief valve (negative flow) (20) Negative flow control orifice (21) Boom II control valve (22) Stick I control valve (23) Center bypass passage (24) Swing control valve (25) Left travel control valve (26) Load check valve (27) Boom regeneration valve
(28) Line relief valve (boom cylinder rod end) (29) Negative flow control orifice
(30) Line relief valve (stick cylinder head end) (31) Variable swing priority valve
(32) Main relief valve (33) Stick unloading valve
(34) Line relief valve (bucket cylinder rod end) (35) Line relief valve (bucket cylinder head end) (36) Parallel feeder passage
(37) Inlet port (drive pump)
(38) Negative flow control line (drive pump) (39) Inlet port (Idler pump)
(40) Negative flow control line (idler pump) (41) Drive pump
(42) Pilot pump (43) Idler pump (44) Hydraulic tank
g00689563
Illustration 43
(AR1) Right travel control valve (REVERSE TRAVEL)
(AR2) Attachment control valve (port) (AR3) Bucket control valve (BUCKET
CLOSE)
(AR4) Boom I control valve (BOOM LOWER) (AR5) Stick II control valve (STICK IN) (BR1) Right travel control valve (FORWARD
TRAVEL)
(BR2) Attachment control valve (port) (BR3) Bucket control valve (BUCKET OPEN) (BR4) Boom I control valve (BOOM RAISE) (BR5) Stick II control valve (STICK OUT) (AL1) Left travel control (REVERSE
TRAVEL)
(AL2) Swing control valve (SWING LEFT) (AL3) Stick I control valve (STICK IN) (AL4) Boom II control valve (BOOM RAISE) (BL1) Left travel control valve (FORWARD
TRAVEL)
(BL2) Swing control valve (SWING RIGHT) (BL3) Stick I control valve (STICK OUT) (aR1) Pilot port at right travel control valve
(REVERSE TRAVEL)
(aR2) Pilot port at attachment control valve (aR3) Pilot port at bucket control valve
(BUCKET CLOSE)
(aR4) Pilot port at boom I control valve (BOOM LOWER)
(aR5) Pilot port at stick II control valve (STICK IN)
(aL1) Pilot port at left travel control valve (REVERSE TRAVEL)
(aL2) Pilot port at swing control valve (SWING LEFT)
(aL3) Pilot port at stick I control valve (STICK IN)
(aL4) Pilot port at boom II control valve (BOOM RAISE)
(bR1) Pilot port at right travel control valve (FORWARD TRAVEL)
(bR2) Pilot port at attachment control valve (bR3) Pilot port at bucket control valve
(BUCKET OPEN)
(bR4) Pilot port at boom I control valve (BOOM RAISE)
(bR5) Pilot port at stick II control valve (STICK OUT)
(bL1) Pilot port at left travel control valve (FORWARD TRAVEL)
(bL2) Pilot port at swing control valve (SWING RIGHT)
(bL3) Pilot port at stick I control valve (STICK OUT)
(bL4) Pilot port at boom II control valve (STICK IN)
(DST) Drain port (straight travel control valve)
(HL) Negative flow signal pressure port (drive pump)
(HR) Negative flow signal pressure port (idler pump)
(Pi1) Pilot port (boom regeneration valve) (Pi2) Pilot port (stick regeneration valve) (Pi3) Pilot port (variable swing priority valve) (Pi4) Pilot port (straight travel solenoid valve) (R2) Return port
(R3) Return port
Introduction
g00689566
Illustration 44
(10) Straight travel solenoid valve (11) Right travel control valve (12) Attachment control valve (13) Bucket control valve (15) Boom I control valve (16) Stick II control valve (18) Straight travel control valve (21) Boom II control valve (22) Stick I control valve (24) Swing control valve (25) Left travel control valve
(28) Line relief valve (boom cylinder rod end) (30) Line relief valve (stick cylinder head end) (32) Main relief valve
(34) Line relief valve (bucket cylinder rod end) (45) Right body
(46) Left body
g00689579
Illustration 45
Main control valve (bottom view) (3) Boom drift reduction valve
(4) Line relief valve (boom cylinder head end)
g00689582
Illustration 46
Bottom view of main control valve (1) Stick drift reduction valve
Main control valve (6) is located in the hydraulic system between the main pumps and actuators (cylinders and motors). Depending on the machine operation, the oil flow from idler pump (43), drive pump (41) and pilot pump (42) to the hydraulic circuits are controlled by the operation of each component in the main control valve. By this control, the speed and direction of the cylinders and the motors can be controlled and adjusted. The pump delivery pressure can be controlled and adjusted.
The main control valve includes right body (46) and left body (45). The main control valve is coupled together with bolts in order to make one assembly.
1. The right travel control valve (11), attachment control valve (12), bucket control valve (13), boom I control valve (15) and stick II control valve (16) are located in right body (46). Hydraulic oil from the idler pump is delivered through inlet port (39), center bypass passage (14) and return port (5) to hydraulic tank (44). In addition, the following components are located in right body (46).
a. The line relief valve (bucket cylinder rod end) (34) and the line relief valve (bucket cylinder head end) (35) limit the pressure in the bucket circuit due to external forces.
b. When the joysticks and/or travel levers/pedals are in the NEUTRAL position, or when the joysticks and/or travel levers/pedals are partially moved from the NEUTRAL position, negative flow control relief valve (19) and the negative flow control orifice (29) decrease the pump flow.
c. Boom drift reduction valve (3) prevents boom drift when the joystick for the boom is in the NEUTRAL position. The line relief valve (boom cylinder head end) (4) is mounted on the boom drift reduction valve. The line relief valve (boom cylinder rod end) (28) is also located on the right body.
d. Boom regeneration valve (27) supplies return oil from the head end of the boom cylinders to the rod end of the boom cylinders when the boom is lowered.
e. Load check valves (26) are part of the following control valves: attachment control valve (12), bucket control valve (13), boom I control valve (15), and stick II control valve (16).
1. Straight travel control valve (18), left travel control valve (25), swing control valve (24), stick I control valve (22) and boom II control valve (21) are located in left body (45). Hydraulic oil from the drive pump is delivered through inlet port (37), center bypass passage (23) and return port (5) to hydraulic tank (44). In addition, the following components are located in left body (45).
a. Stick drift reduction valve (1) prevents stick drift when the joystick for the stick is in the NEUTRAL position. The line relief valve (stick cylinder rod end) (2) is mounted on the stick drift reduction valve. The line relief valve (stick cylinder head end) (30) is also located on the left body.
b. When the joysticks and/or travel levers/pedals are in the NEUTRAL position, or when the joysticks and/or travel levers/pedals are partially moved from the NEUTRAL position, negative flow control relief valve (17) and the negative flow control orifice (20) decrease the pump flow.
c. Stick regeneration valve (7) supplies return oil from the rod end of the stick cylinder to the head end of the stick cylinder during the stick in function.
d. Stick unloading valve (33) reduces the back pressure in the rod end of the stick cylinder during the stick in function.
e. Load check valves (8) are part of the following control valves: swing control valve (24) and stick I control valve (22).
f. Main relief valve (32) limits the main hydraulic system pressure.
•
When the main control valve is in the NEUTRAL position, no pump oil flows to the cylinders and the motors. Main control valve operation in the NEUTRAL position is described later in this section.•
The main control valve controls the negative flow control signal. For more information on the negative flow control operation, refer to Systems Operation, “Negative Flow Control”.•
The main control valve prevents cylinder drift with the load check valves. For more information on the load check valves, refer to Systems Operation, “Check Valve (Load)”.•
The main control valve limits the circuit pressure with relief valve operation. For more information on the limitation of circuit pressure, refer to Systems Operation, “Relief Valve (Main)” and Systems Operation, “Relief Valve (Line)”.The description of other components that are installed on the main control valve or in the main control valve will be listed separately. Refer to the appropriate sections that are in this manual for further information on the components.