Lower Main Control Valve
Lower Main Control Valve Schematic
 | |
| Illustration 1 | g03400546 |
(1) Control valve group (left rear stabilizer) (2) Control valve group (right rear stabilizer) (3) Control valve group (right front stabilizer) (4) Control valve group (left front stabilizer) (5) Control valve group (steering) (6) Control valve group (lower main) (7) Control valve group (right front travel motor) (8) Control valve group (left front travel motor) (9) Control valve group (left rear travel motor) (10) Control valve group (right rear travel motor) (11) Pilot relief valve (12) Pilot pressure reducing valve (13) Signal duplication valve (load sense) (14) Load sense relief valve (15) Main hydraulic pumps (16) Lower hydraulic shutoff solenoid valve manifold (17) Swivel (18) Rear back pressure manifold (19) Hydraulic oil cooler (20) Front back pressure manifold (21) Case drain filters (22) Return filters (23) Hydraulic oil tank | |
The lower main control valve is a load sensing bank valve that consists of the nine control valves. The lower main control valve operates the stabilizer cylinders, steering cylinders, and travel motors.
All of the control valves are controlled by proportional solenoid valves. The proportional solenoid valves are activated by the joystick controls inside the cab. All of the control valves are actuated by pilot oil. When the operator moves a function, the pilot oil controls the movement of the closed center valve spools. The valve spools are spring centered.
The pressure settings of the line relief valves and the signal limiter valves are different for of the control valve sections of the main control valve. The line relief valves are not adjustable.
The steering control valve has line relief valves and signal limiter valves. All of the other control valves do not have line relief valves or signal limiter valves. The line relief valves for the travel motors are located on the travel motor.
Lower Main Control Valve Ports
 | |
| Illustration 2 | g03400556 |
(A1) Port (pilot oil to travel displacement valves) (BR1) Port (pilot oil to travel parking brakes) (BRI) Port (pilot oil from manual brake release valve) (BRO) Port (pilot oil to manual brake release valve) (GA) Test port "GA" - pilot oil to travel displacement valves (GBP) Test port "GBP" - pilot oil to travel parking brakes (L1) Port "A" - right rear travel motor (FORWARD TRAVEL) (L2) Port "A" - right rear travel motor (FORWARD TRAVEL) (L3) Port "A" - left front travel motor (FORWARD TRAVEL) (L4) Port "A" - right front travel motor (FORWARD TRAVEL) (L5) Port "B" - steering (left) (L6) Port "B" - left front stabilizer (STABILIZER RAISE) (L7) Port "B" - right front stabilizer (STABILIZER RAISE) (L8) Port "B" - right rear stabilizer (STABILIZER RAISE) (L9) Port "B" - left rear stabilizer (STABILIZER RAISE) (OR2) Adjustable orifice (hydraulic warming) (OR3) Plug - location of orifice "OR3" (P1) Pressure port (supply oil from main pumps) (PM) Pressure port (supply oil from main pumps) (R1) Port "B" - right rear travel motor (REVERSE TRAVEL) (R2) Port "B" - right rear travel motor (REVERSE TRAVEL) (R3) Port "B" - left front travel motor (REVERSE TRAVEL) (R4) Port "B" - right front travel motor (REVERSE TRAVEL) (R5) Port "A" - steering (right) (R6) Port "A" - left front stabilizer (STABILIZER LOWER) (R7) Port "A" - right front stabilizer (STABILIZER LOWER) (R8) Port "A" - right rear stabilizer (STABILIZER LOWER) (R9) Port "A" - left rear stabilizer (STABILIZER LOWER) (SH) Plug - load sense pressure (TP) Return port (from case drains of travel motors) (T1) Return port (to swivel) (T3) Return port (supply oil to left axle oscillating cylinder) (TM) Return port (to swivel) (TR) Travel pressure | |
 | |
| Illustration 3 | g03400560 |
(DLS) Adjustable orifice (duplicate load sense relief) (L1) Port "A" - right rear travel motor (FORWARD TRAVEL) (L2) Port "A" - right rear travel motor (FORWARD TRAVEL) (L3) Port "A" - left front travel motor (FORWARD TRAVEL) (L4) Port "A" - right front travel motor (FORWARD TRAVEL) (L5) Port "B" - steering (left) (L6) Port "B" - left front stabilizer (STABILIZER RAISE) (L7) Port "B" - right front stabilizer (STABILIZER RAISE) (L8) Port "B" - right rear stabilizer (STABILIZER RAISE) (L9) Port "B" - left rear stabilizer (STABILIZER RAISE) (LS) Port - load sense (outlet to swivel) (OR2) Adjustable orifice (hydraulic warming) (OR3) Plug - location of orifice "OR3" (P1) Pressure port (supply oil from main pumps) (PL) Port - load sense (lower main valve) (PL2) Port - load sense (outlet to swivel) (PM) Pressure port (supply oil from main pumps) (PX) Port - main pump pressure (R1) Port "B" - right rear travel motor (REVERSE TRAVEL) (R2) Port "B" - right rear travel motor (REVERSE TRAVEL) (R3) Port "B" - left front travel motor (REVERSE TRAVEL) (R4) Port "B" - right front travel motor (REVERSE TRAVEL) (R5) Port "A" - steering (right) (R6) Port "A" - left front stabilizer (STABILIZER LOWER) (R7) Port "A" - right front stabilizer (STABILIZER LOWER) (R8) Port "A" - right rear stabilizer (STABILIZER LOWER) (R9) Port "A" - left rear stabilizer (STABILIZER LOWER) (T1) Return port (to swivel) (T2) Return port (supply oil to right axle oscillating cylinder) (TM) Return port (to swivel) | |
Upper Main Control Valve
Upper Main Control Valve Schematic
 | |
| Illustration 4 | g03400549 |
(24) Control valve group (grapple open/close) (25) Control valve group (cab up/down) (26) Control valve group (cab for/aft) (27) Control valve group (grapple rotate) (28) Load Sense Pressure Sensor (29) Control valve group (upper main) (30) Control valve group (main boom master) (31) Control valve group (stick master) (32) Control valve group (grapple open/close) (33) Control valve group (stick slave) (34) Control valve group (boom slave) (35) Pilot relief valve (36) Pilot pressure reducing valve (37) Signal duplication valve (load sense) (38) Main relief valve (39) Load sense relief valve (40) Main hydraulic pumps (41) Lower hydraulic shutoff solenoid valve manifold (42) Swivel (43) Rear back pressure manifold (44) Hydraulic oil cooler (45) Front back pressure manifold (46) Case drain filters (47) Return filters (48) Hydraulic oil tank | |
The upper main control valve is a load sensing bank valve. The upper main control valve consists of the eight control valves. The upper main control valve operates the following hydraulic circuits: boom, cab lift (up/down), cab lift (for/aft), grapple (open/close), grapple (rotate) and stick.
All of the control valves are controlled by proportional solenoid valves. The proportional solenoid valves are activated by the joystick controls inside the cab. All of the control valves are actuated by pilot oil. When the operator moves a function, the pilot oil controls the movement of the closed center valve spools. The valve spools are spring centered.
Both of the boom control valves and the main stick control valve contain line relief valves.
All of the control valves contain signal limiter valves.
The pressure settings of the line relief valves and the signal limiter valves are different for of the control valve sections of the upper main control valve. The line relief valves are not adjustable.
Upper Main Control Valve Ports
 | |
| Illustration 5 | g03400563 |
(L1) Port "A" - boom secondary (BOOM RAISE) (L2) Port "A" - stick secondary (STICK OUT) (L3) Port "A" - grapple cylinders (GRAPPLE CLOSE) (L4) Port "A" - stick master (STICK OUT) (L5) Port "A" - boom master (BOOM RAISE) (L6) Port "B" - grapple rotate (ROTATE RIGHT) (L7) Port "B" - cab riser cylinders (RISER AFT) (L8) Port "B" - cab riser cylinders (RISER DOWN ) (L9) Port "B" - auxiliary valve (GRAPPLE OPEN) (LS) Load sense (LSP) Load sense pressure (PL) Load sense port (plugged) (PX) Pressure port (plugged) (P1) Pressure port (supply oil from main pumps) (P2) Pressure port (supply oil from main pumps) (R1) Port "B" - boom secondary (BOOM LOWER) (R2) Port "B" - stick secondary (STICK IN) (R3) Port "B" - grapple cylinders (GRAPPLE OPEN) (R4) Port "B" - stick master (STICK IN) (R5) Port "B" - boom master (BOOM LOWER) (R6) Port "A" - grapple rotate (ROTATE LEFT) (R7) Port "A" - cab riser cylinders (RISER FOR) (R8) Port "A" - cab riser cylinders (RISER UP ) (R9) Port "A" - auxiliary valve (GRAPPLE CLOSE) (T) Return port (plugged) (T1) Return port (to swivel) (T3) Return port (to front back pressure manifold) (TP) Return port | |
 | |
| Illustration 6 | g03400565 |
(L1) Port "A" - boom secondary (BOOM RAISE) (L2) Port "A" - stick secondary (STICK OUT) (L3) Port "A" - grapple cylinders (GRAPPLE CLOSE) (L4) Port "A" - stick master (STICK OUT) (L5) Port "A" - boom master (BOOM RAISE) (L6) Port "B" - grapple rotate (ROTATE RIGHT) (L7) Port "B" - cab riser cylinders (RISER AFT) (L8) Port "B" - cab riser cylinders (RISER DOWN ) (L9) Port "B" - auxiliary valve (GRAPPLE OPEN) (LSP) Load sense pressure (P1) Pressure port (supply oil from main pumps) (P2) Pressure port (supply oil from main pumps) (PS) Port - pilot pressure (R1) Port "B" - boom secondary (BOOM LOWER) (R2) Port "B" - stick secondary (STICK IN) (R3) Port "B" - grapple cylinders (GRAPPLE OPEN) (R4) Port "B" - stick master (STICK IN) (R5) Port "B" - boom master (BOOM LOWER) (R6) Port "A" - grapple rotate (ROTATE LEFT) (R7) Port "A" - cab riser cylinders (RISER FOR) (R8) Port "A" - cab riser cylinders (RISER UP ) (R9) Port "A" - auxiliary valve (GRAPPLE CLOSE) (T) Return port (plugged) (T1) Return port (to swivel) (T2) Port (plugged) (T4) Port - return oil from hydraulic cooling fan motor (TP) Return port | |
Main Control Valve Components
Inlet Section
The following explanations are for the inlet section of the main control valve. The inlet section of the lower main control valve does not have a main relief valve.
Refer to "Lower Main Control Valve Schematic" and "Upper Main Control Valve Schematic" for additional information regarding the inlet section of the main control valve.
 | |
| Illustration 7 | g03591519 |
Upper main control valve center section (typical example) (P1) Pressure port (supply oil from main pumps) (T1) Return port (to swivel) (49) Main relief valve (50) Load sense relief valve (51) Main control valve | |
Main control valve (51) includes the following components:
- Check valve and screen
- Load sense relief valve
- Main relief valve
- Pilot pressure reducing valve
- Pilot relief valve
- Signal duplication valve (load sense)
Pressure oil from the main pumps flows into the main control valve (51) through port (P1) to the inlet section of the main control valve and into the main control valve through port (P2) located on the end section. Refer to "Lower Main Control Valve Ports" and "Upper Main Control Valve Ports" for port locations.
Pilot pressure is generated inside the inlet section of the control valve as oil flows to the pilot pressure reducing valve through an internal orifice. The pilot pressure is reduced from pump pressure. Refer to Testing and Adjusting , UENR3552, "Hydraulic System", "Specifications" for the pilot pressure of the machine.
The pressure oil then flows to the signal duplication valve for load sense pressure. The load sense pressure is reduced from pump pressure.
Pressure oil flows out the main control valve (51) through port (T1) to the hydraulic oil tank.
Control Valve Sections
Refer to "Lower Main Control Valve Schematic" and "Upper Main Control Valve Schematic" for additional information regarding the control valve sections.
The following explanations are for the control valve section of the main control valve. Some control valve sections may not have line relief valves or signal limiter valves.
Control valves (60) includes the following components:
- Compensator valve
- Line relief valves
- Signal limiter relief valves
- Solenoid valves (proportional)
 | |
| Illustration 8 | g03591577 |
Control valve (typical example) (52) Signal limiter valve (extend) (53) Line relief valve (retract) (54) Signal limiter valve (retract) (55) Port "B" (retract) (56) Port "A" (extend) (57) Line relief valve (extend) (58) Solenoid valve (retract) (59) Solenoid valve (extend) (60) Control valve (61) Stroke limiter screw | |
 | |
| Illustration 9 | g03591579 |
Control valve (typical example) (52) Signal limiter valve (extend) (53) Line relief valve (extend) (54) Signal limiter valve (retract) (55) Port "A" (retract) (56) Port "B" (extend) (57) Line relief valve (retract) (58) Solenoid valve (retract) (59) Solenoid valve (extend) (60) Control valve (61) Stroke limiter screw | |
 | |
| Illustration 10 | g03591580 |
Control valve (typical example) (52) Signal limiter valve (extend) (53) Line relief valve (extend) (54) Signal limiter valve (retract) (55) Port "A" (retract) (56) Port "B" (extend) (57) Line relief valve (retract) (58) Solenoid valve (retract) (59) Solenoid valve (extend) (60) Control valve (61) Stroke limiter screw (62) Compensator valve (63) Orifice (64) Spool | |
The major components are shown. The control valves are closed center, pilot operated control valves.
Each control valve has two line relief valves (53) and (57) . The pressure setting of each line relief valve is non-adjustable. The line relief valves protect the cylinders and hydraulic oil lines from damage. When an external load acts on the machine, the oil pressure in the circuit increases. When the pressure in the circuit exceeds the relief valve pressure setting, the line relief valve opens. The oil in the circuit returns to the hydraulic oil tank. The check valves in the line relief valves prevent cavitation in the cylinders.
Each control valve has two signal limiter valves (52) and (54) . The pressure setting is adjustable. The pressure setting of the signal limiter valve controls the signal to the pump. Signal limiter valves limit the pressure in the signal circuit.
Each valve has two proportional solenoid valves (58) and (59) that are pilot operated. When the operator performs a command with the control switch, the IQAN receives a signal from the switch. The IQAN control sends current to the solenoid. The pilot oil flows through solenoid and orifice to the top of valve spool.
The spools have stroke limiter screws (61) that are used to limit the maximum travel of the spools. The stroke limiter screws are also used to limit the maximum flow through the valves.
As spool (64) moves, the pressure oil and the flow that is required from the main pumps changes. A series of ball resolver valves direct the highest work port pressure to the main pumps. The required pressure is sensed in the load sensing system. This signal ensures that the implement with the highest demand determines the stroking of the implement pump.
Pump pressure oil flows through the pressure compensator valve (62) . Regardless of the pump pressure, the pressure compensator valve (62) maintains constant oil flow to the cylinder.
When a circuit is deactivated, the pressure on the load sensing relief valve decreases. When the function is not activated, there is no load sensing pressure that is sent to the main pumps.