Main Control Valve

7/30/2019 Main Control Valve

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Operacin de Sistemas320C Excavator Hydraulic System

Main Control Valve

SMCS - 5051

Cerrar SIS

Pantalla anterior

Producto: EXCAVATORModelo: 320C EXCAVATOR PAB

Configuracin: 320C & 320C L Excavators PAB00001-UP (MACHINE)POWERED BY 3066 Engine

Nmero de medio -RENR3816-10 Fecha de publicacin -01/02/2010 Fecha de actualizacin -19/02/2010

i01859537

Illustration 1 g00774017

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

Pgina 1 de 12320C & 320C L Excavators PAB00001-UP (MACHINE) POWERED BY 3066 En...

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(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


(24) Swing control valve

(25) Left travel control valve


(27) Boom regeneration valve

(28) Line relief valve (boom cylinder rod end)


(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)


(37) Inlet port (left pump)

(38) Negative flow control line (left pump)

(39) Inlet port (right pump)

(40) Negative flow control line (right pump)

(41) Left pump




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(42) Pilot pump

(43) Right pump

(44) Hydraulic tank


Main control valve ports

(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)




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(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 (left pump)

(HR) Negative flow signal pressure port (right 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




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Introduction


(10) Straight travel solenoid valve











(28) Line relief valve (boom cylinder rod end)

(30) Line relief valve (stick cylinder head end)

(32) Main relief valve


(45) Right body

(46) Left body




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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 right pump (43), left

pump (41) and pilot pump (42) to the hydraulic circuits are controlled by the operation of eachcomponent in the main control valve. By this control, the speed and direction of the cylinders and themotors 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 coupledtogether 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). The rightpump oil 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 (bucketcylinder 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 thejoysticks 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) decreasethe 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 onthe boom drift reduction valve. The line relief valve (boom cylinder rod end) (28) is alsolocated on the right body.

d. Boom regeneration valve (27) supplies return oil from the head end of the boom cylindersto 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


Main control valve (bottom view)

(3) Boom drift reduction valve

(4) Line relief valve (boom cylinder head end)


Bottom view of main control valve

(1) Stick drift reduction valve

(2) Line relief valve (stick cylinder rod end)




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control valve (22) and boom II control valve (21) are located in left body (45). The left pump oilis delivered through inlet port (37), center bypass passage (23) and return port (5) to hydraulictank (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 theNEUTRAL position. The line relief valve (stick cylinder rod end) (2) is mounted on thestick 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 thejoysticks 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) decreasethe pump flow.

c. Stick regeneration valve (7) supplies return oil from the rod end of the stick cylinder to thehead 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 cylindersand the motors. Main control valve operation in the NEUTRAL position is described later in thissection.

The main control valve controls the negative flow control signal. For more information on thenegative flow control operation, refer to Systems Operation, "Negative Flow Control".

The main control valve prevents cylinder drift with the load check valves. For more informationon the load check valves, refer to Systems Operation, "Check Valve (Load)".

The main control valve limits the circuit pressure with relief valve operation. For moreinformation 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 furtherinformation on the components.

Main Control Valve Operation in NEUTRAL Position




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Main control valve (neutral position)







(7) Inlet port







(14) Right body

(15) Left body


(17) Return port


(19) Return passage





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The right pump supplies oil to right body (14) through inlet port (7). The oil then flows through center

bypass passage (20) and parallel feeder passage (6). The left pump supplies oil to left body (15)through inlet port (21). The oil then flows through center bypass passage (22) and parallel feeder

passage (10) .

When all of the joysticks and/or travel levers/pedals are in the NEUTRAL position, right pump oilflows through center bypass passage (20), negative flow control orifice (18), return passage (19),return passage (23) and return port (17) back to the hydraulic tank. Left pump oil from inlet port (21)flows through center bypass passage (22), negative flow control orifice (16) and return port (17) backto the hydraulic tank. Oil in parallel feeder passages (6) and (10) remains blocked by each controlvalve spool.

Activation of any joystick and/or travel levers/pedals provides two paths for right pump oil. One pathflows through center bypass passage (20) to right travel control valve (5). The other path flows through

parallel feeder passage (6), attachment control valve (4), bucket control valve (3) and boom I controlvalve (2). Activation of any joystick and/or travel levers/pedals also provides two paths for left pumpoil. One path flows through center bypass passage (22) to left travel control valve (9) and stick Icontrol valve (12). The other path flows through parallel feeder passage (10) to swing control valve(11) .

Individual Valve Operation

(21) Inlet port


(23) Return passage




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Bucket control valve (NEUTRAL position)


(2) Port



(5) Passage

(6) Port

(7) Line relief valve (bucket cylinder head end)

(8) Pilot port

(9) Pilot port

(10) Return passage

(11) Spool


(13) Spring

Pgina 10 de 12320C & 320C L Excavators PAB00001-UP (MACHINE) POWERED BY 3066 ...



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The bucket control valve is used as a typical example for describing the operation of individual controlvalves.

When the joysticks and/or travel levers/pedals are in the NEUTRAL position, pilot oil does not flow toport (8) and port (9). Spool (11) is centered in the NEUTRAL position by the force of spring (13). Theright pump oil flows through center bypass passage (12) to the hydraulic tank.

When the joystick for the bucket is moved to the BUCKET CLOSE position, pilot oil is supplied topilot port (8). Spool (11) moves to the left. Center bypass passage (12) is closed and passage (15)becomes opened. Port (14) is now connected to return passage (10) .


Bucket control valve BUCKET CLOSE

(2) Port



(5) Passage

(6) Port

(8) Pilot port

(10) Return passage

(11) Spool


(14) Passage

(15) Passage




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Oil that is in parallel feeder passage (3) flows through load check valve (4), passage (5) and passage(15). The oil then flows to port (6). The bucket cylinder rod extends. When the bucket cylinder rodextends, the displaced oil in the rod end flows to port (2) .

Oil flows through port (2) to return passage (14) and back to the hydraulic tank.

Copyright 1993 - 2013 Caterpillar Inc.Todos los derechos reservados.Red privada para licenciados del SIS.

Tue May 14 05:51:49 UTC+0200 2013


Main Control Valve

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