| |
| Illustration 1 | g01210313 |
|
261-3683 Main Control Valve (3-Function, With Ride Control) Schematic for 950H and 962H 256-6936 Main Control Valve (3-Function, With Ride Control) Schematic for IT62H (1) 261-0018 Control Valve (Tilt) for 950H and 962H (1) 256-8660 Control Valve (Tilt) for IT62H (2) 261-0019 Control Valve (Lift) (3) 253-4026 Ride Control Valve (4) 261-0017 Control Valve (Auxiliary) (5) 271-9248 Valve Manifold (Inlet) (6) 269-9398 Valve Manifold (End Cover) (7) 262-5265 Solenoid Valve (Drift Reduction) (Ride Control Accumulator) (8) 332-1987 Relief Valve (Line, Tilt) (9) 313-7668 Solenoid Valve (Pilot Proportioning) (10) 252-0737 Solenoid Valve (Ride Control, Lift Cylinder) (11) Ride Control Accumulator (12) 272-2334 Relief Valve (Line) (13) 225-0300 Solenoid Valve (Hydraulic Lockout) (14) 245-2975 Pilot Oil Accumulator (Dead Engine Lower) (15) 112-1817 Manual Valve (Dead Engine Lower) (16) Compensation and Load Check Valve (17) 4T-7581 Relief Valve (Ride Control) (18) 282-4349 Pressure Reducing Valve (19) 193-1665 Pressure Reducing Valve (Signal Duplication) (20) 247-8632 Relief Valve (Load Sensing Signal) (21) 260-6737 Valve Stem (Tilt) for 950H and 962H (21) 256-8660 Valve Stem (Tilt) for IT62H (22) 260-8590 Shuttle Valve Load Signal Resolver (23) 260-6738 Valve Stem (Lift) (24) 235-6157 Shuttle Valve (25) 194-1723 Check Valve (26) 252-0737 Solenoid Valve (Ride Control On, Off) (27) 260-6736 Valve Stem (Auxiliary) (28) 254-5789 Relief Valve (Pump Margin Pressure) (A) Hydraulic Tank (B) Pump Port (C) Tank Port (D) Tank Port (E) Signal oil to pump (F) Drain for load sensing relief | |
| |
| Illustration 2 | g01192607 |
|
261-3683 Main Control Valve (3-Function, With Ride Control) for 950H and 962H 256-6936 Main Control Valve (3-Function, With Ride Control) for IT62H (1) 261-0018 Control Valve (Tilt) for 950H and 962H (1) 256-8660 Control Valve (Tilt) for IT62H (2) 261-0019 Control Valve (Lift) (3) 253-4026 Ride Control Valve (4) 261-0017 Control Valve (Auxiliary) (5) 271-9248 Valve Manifold (Inlet) (6) 269-9398 Valve Manifold (End Cover) | |
| |
| Illustration 3 | g01210843 |
|
261-4172 Main Control Valve (3-Function) Schematic for 950H and 962H 256-6935 Main Control Valve (3-Function) Schematic for IT62H | |
| |
| Illustration 4 | g01210844 |
|
261-4172 Main Control Valve (3-Function) for 950H and 962H 256-6935 Main Control Valve (3-Function) for IT62H (1) 261-0018 Control Valve (Tilt) for 950H and 962H (1) 256-8660 Control Valve (Tilt) for IT62H (2) 261-0019 Control Valve (Lift) (4) 261-0017 Control Valve (Auxiliary) (5) 271-9248 Valve Manifold (Inlet) (6) 269-9398 Valve Manifold (End Cover) (39) 247-7601 Control Valve (Hydraulic Block) | |
| |
| Illustration 5 | g01210846 |
|
261-3682 Main Control Valve (2-Function, With Ride Control) Schematic for 950H and 962H 256-6934 Main Control Valve (2-Function, With Ride Control) Schematic for IT62H | |
| |
| Illustration 6 | g01192610 |
|
261-3682 Main Control Valve (2-Function, With Ride Control) for 950H and 962H 256-6934 Main Control Valve (2-Function, With Ride Control) for IT62H (1) 261-0018 Control Valve (Tilt) for 950H and 962H (1) 256-8660 Control Valve (Tilt) for IT62H (2) 261-0019 Control Valve (Lift) (3) 253-4026 Ride Control Valve (5) 271-9248 Valve Manifold (Inlet) (6) 269-9398 Valve Manifold (End Cover) | |
| |
| Illustration 7 | g01210847 |
|
261-4171 Main Control Valve (2-Function) Schematic for 950H and 962H 256-6933 Main Control Valve (2-Function) Schematic for IT62H | |
| |
| Illustration 8 | g01210848 |
|
261-4171 Main Control Valve (2-Function) for 950H and 962H 256-6933 Main Control Valve (2-Function) for IT62H (1) 261-0018 Control Valve (Tilt) for 950H and 962H (1) 256-8660 Control Valve (Tilt) for IT62H (2) 261-0019 Control Valve (Lift) (5) 271-9248 Valve Manifold (Inlet) (6) 269-9398 Valve Manifold (End Cover) (39) 247-7601 Control Valve (Hydraulic Block) | |
Note: The following description of the main control valve references Illustrations 1 through 8.
The supply oil flows from the implement piston pump to the main control valve at point (B). The main control valve controls the flow of hydraulic oil to the cylinders and to the ride control system.
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 (A).
The supply oil flows to the following components: tilt control valve (1), lift control valve (2), ride control valve (3) and auxiliary valve (4).
The supply oil flows to pressure reducing valve (18). Pressure reducing valve (18) 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 allows the bucket 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. Manual valve (15) can be used to lower the bucket if no power can be supplied to the solenoids.
The oil that flows to the load sensing circuit enters signal duplicating reducing valve (19). Normally, the oil flows through the signal duplicating reducing valve.
Signal duplicating reducing valve (19) and load sensing relief valve (20) operate for all of the control valves in the main control valve. Load sensing relief valve (20) limits the maximum signal pressure to the pump at point (E) by draining excess signal oil to the tank at point (F). Signal duplicating reducing valve (19) sends signal oil back to the implement piston pump at point (E).
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 (19) 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.
Both tilt control valve (1) and auxiliary control valve (4) have two line relief valves. One relief valve is for each end of the cylinders. Also, the tilt control valve, the lift control valve, and the ride control valve have an identical solenoid valve. The solenoids for the tilt control valve and the lift control valve are for drift reduction (7).
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 or the solenoid valves, refer to Systems Operation, "Solenoid Valve (Implement)".
Reference: For more information on the operation of the Relief Valve (Load Sensing Signal), refer to Systems Operation, "Relief Valve (Load Sensing Signal)".
Reference: The operation of the ride control valve is explained in Systems Operation, "Ride Control System".
| |
| Illustration 9 | g01195417 |
|
Tilt Control Valve (1) in the HOLD position with the tilt valve stem centered. (7) 262-5265 Solenoid Valve (Drift Reduction) (8A) 332-1987 Relief Valve (Line) Rod End (8B) 332-1987 Relief Valve (Line) Head End (9) 257-0267 Solenoid Valve (Pilot Proportioning) (16) Compensation and Load Check Valve (21) 260-6737 Valve Stem (Tilt) for 950H and 962H (21) 256-8661 Valve Stem (Tilt) for IT62H (22) 260-8590 Shuttle Valve Load Signal Resolver (29A) Work Port to Head End of lift cylinder for Tilt Back position (29B) Work Port for Rod End of lift cylinder for Dump Function (36) Bridge Passage (B) Pump Port (C) Tank Port (D) Tank Port | |
Oil from the implement piston pump flows to tilt control valve (1) at port (B). Tilt valve stem (21) is controlled by solenoids (9). Implement pump oil flows through tilt control valve (1) to lift control valve (2) at pump port (B). Tilt valve stem (21) is spring centered with a closed center. Tilt valve stem (21) has three positions: TILT BACK, HOLD and DUMP.
Springs keep tilt valve stem (21) in the HOLD position when solenoids (9) have not been actuated. Stem movement is controlled by actuation of pilot proportioning solenoids (9) that allow oil to flow to either end of tilt valve stem (21).
Tilt valve stem (21) in the hold position blocks the oil in both ends of the tilt cylinder. This keeps the tilt cylinder from moving. Solenoid valve (7) for drift reduction in tilt control valve (1) further limits cylinder movement toward the DUMP position if leakage occurs between valve stem (21) and the valve body.
When the tilt control lever or the joystick control is moved to the TILT BACK position, pilot oil is sent to the left end of tilt valve stem (21) and tilt valve stem (21) moves to the right. Implement pump oil is sent through the tilt control valve from pump port (B) around tilt valve stem (21) to the bottom of compensation and load check valve (16). Compensation and load check valve (16) is pushed up and flow goes through the openings in the load check valve to bridge passage (36). Oil flows around tilt valve stem (21) and through solenoid valve (7) for drift reduction to work port (29A).
Oil flows to work port (29A) to the head end of the tilt cylinder. This causes the bucket to tilt back. Solenoid valves (9) and tilt valve stem (21) respond in proportion to the signal that is received from the operator controls.
Oil from the rod end of the tilt cylinder enters through work port (29B) and exits to the hydraulic tank through passage (C).
When the tilt control lever or the joystick control is moved to the DUMP position, pilot oil is sent to the right end of tilt valve stem (21) and tilt valve stem (21) moves to the left. Implement oil is sent from pump port (B) around tilt valve stem (21) to the bottom of compensation and check valve (16). Compensation and check valve (16) is pushed up and flow goes through the openings in load check valve (16) to bridge passage (36). Oil flows around tilt valve stem (21) to work port (29B).
Oil flows through work port (29B) to the rod end of the tilt cylinder. This causes the bucket to dump. Solenoid valves (9) and tilt valve stem (21) respond in proportion to the movement of the operator controls.
Oil from the head end of the tilt cylinder comes through work port (29A), flows through energized solenoid valve (7) for drift reduction and exits through tank port (D) to the hydraulic tank.
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 or the solenoid valves, refer to Systems Operation, "Solenoid Valve (Implement)".
| |
| Illustration 10 | g01195418 |
|
Lift Control Valve in HOLD position (7) 262-5265 Solenoid Valve (Drift Reduction) (9) 257-0267 Solenoid Valve (Pilot Proportioning) (16) Compensation and Load Check Valve (22) 260-8590 Shuttle Valve Load Signal Resolver (23) 260-6738 Valve Stem (Lift) (30) 234-4869 Makeup Valve (31A) Work Port for lower function to rod end of lift cylinder (31B) Work Port for lift function to head end of lift cylinder (32) 234-4870 Plug (37) Bridge Passage (B) Pump Port (C) Tank Port (D) Tank Port | |
Oil from the implement piston pump flows to lift control valve (2) at pump port (B). Pump oil flows from pump port (B) through lift control valve (2) to ride control valve (3) and auxiliary control valve (4). Lift valve stem (23) is controlled by solenoids (9). The lift valve stem is spring centered with a closed center. The lift valve stem has four positions: RAISE, HOLD, LOWER and FLOAT.
Springs keep lift valve stem (23) in the HOLD position when solenoid valves (9) have not been actuated. Llift valve stem (23) in the HOLD position blocks the oil in both ends of the lift cylinders. This keeps the lift cylinders from moving.
Solenoid valve (7) for drift reduction in lift control valve (2) further limits lift cylinder drift toward the lower position if leakage occurs between lift valve stem (23) and the valve body.
Stem movement is controlled by actuation of pilot proportioning solenoids (9) that allow oil to flow to either end of lift valve stem (23).
When the lift control lever or the joystick control is moved to the RAISE position, pilot oil is sent to the right end of lift valve stem (23) and lift valve stem (23) moves to the left. Implement pump oil is sent from pump port (B) around lift valve stem (23) to the bottom of compensation and check valve (16). Compensation and check valve (16) is pushed up and flow goes through the openings in load check valve (16) to bridge passage (37). Oil flows around lift valve stem (23) and through solenoid valve (7) for drift reduction to work port (31B).
Oil is allowed to flow to the head end of the lift cylinders. This causes the bucket to rise. Solenoid valves (9) and lift valve stem (23) respond in proportion to the movement of the operator controls.
Oil from the rod end of the lift cylinders enters through work port (31A) and exits through tank port (D) to the hydraulic tank.
When the lift control lever or the joystick control is moved to the LOWER position, pilot oil is sent to the left end of lift valve stem (23) and lift valve stem (23) moves partially to the right. Implement oil is sent from pump port (B) around lift valve stem (23) to the bottom of compensation and load check valve (16). Compensation and load check valve (16) is pushed up and flow goes through the openings in load check valve (16) to bridge passage (37). Oil flows around lift valve stem (23) to work port (31A).
Oil is allowed to flow to the rod end of the lift cylinders. This causes the bucket to lower. Solenoid valves (9) and lift valve stem (23) respond in proportion to the movement of the operator controls.
Oil from the head end of the lift cylinders enters through work port (31B), flows through energized solenoid valve (7) for drift reduction and exits at tank port (C) to the hydraulic tank.
When the lift control lever or the joystick control is moved to the FLOAT position, pilot oil is sent to the left end of lift valve stem (23) and lift valve stem (23) moves completely to the right. The lift control lever is held in the FLOAT position by a soft detent. The lift valve stem remains in the float position until the bucket reaches the preset kickout position. The lift control valve will then return to the HOLD position.
When the operator moves the pilot valve to the FLOAT position, work port (31A) is connected to the tank at tank port (D) through completely shifted lift valve stem (23). Complete movement of lift valve stem (23) to the right closes off the flow of implement pump oil from pump port (B) to bridge passage (37). Work port (31B) continues to be connected to the tank through energized solenoid valve (7) for drift reduction and lift valve stem (23) at port (C).
Oil from the rod end of the lift cylinder and the oil from the head end of the lift cylinder drains to the tank. This allows the weight of the lift arm assembly to lower the lift arm assembly to the ground. The lift arm assembly will follow the contour of the ground. Neither the rod end of the lift cylinder or the head end of the lift cylinder are under hydraulic pressure. The lift cylinders can move freely in either direction according to the force on the bucket.
Reference: For more information on the operation or the solenoid valves, refer to Systems Operation, "Solenoid Valve (Implement)".
| |
| Illustration 11 | g01195423 |
|
Ride control valve (7) 262-5265 Solenoid Valve (Ride Control Accumulator) (10) 252-0737 Solenoid Valve (Ride Control, Lift Cylinder) (17) 4T-7581 Relief Valve (Ride Control) (22) 260-8590 Shuttle Valve Load Signal Resolver (24) 235-6157 Shuttle Valve (25) 194-1723 Check Valve (26) 252-0737 Solenoid Valve (Ride Control On, Off) (32A) Work Port to rod end of lift cylinder (32B) Work Port to head end of lift cylinder (33) 270-1768 Check Valve (Ride Control) (34) 148-8335 Connector to Ride Control Accumulator (B) Pump Port (C) Tank Port (D) Tank Port | |
Ride control valve (3) is an optional control valve. This function provides dampening for the forces that are produced by the bucket as the machine travels over rough terrain. Ride control valve (3) has three positions: AUTO, OFF and SERVICE. Details about the three positions of the ride control valve can be found in Systems Operation, "Ride Control System".
Ride control valve (3) contains solenoid valve (26) which is an On, Off switch. Solenoid valve (26) works with shuttle valve (24) in order to charge ride control accumulator (14). When accumulator (14) is being charged, check valve (25) allows pump oil to enter ride control valve (3) through shuttle valve (24). Oil exits the ride control valve through connector (34) in order to charge ride control accumulator (14).
When ride control accumulator (14) is not being charged, check valve (25) keeps oil from the ride control circuit from returning to the main hydraulic system. If oil pressure rises above the setting of ride control relief valve (17), the relief valve opens in order to allow excess pressure to drain to the hydraulic tank through tank port (C).
Ride control valve (3) also contains solenoid valves (7) and (10). When the ride control system is activated, solenoid valve (7) allows oil to enter the ride control valve from the rod end of the tilt cylinder at port (32A). Oil exits the ride control valve at tank port (D). Solenoid valve (10) works with check valve (33) in order to allow oil from the head end of the lift cylinder to mix with oil from ride control accumulator (14) at port (32B). Nitrogen gas in ride control accumulator (14) acts as a shock absorber for the lift circuit.
Reference: The operation of ride control valve (3) is explained in Systems Operation, "Ride Control System".
Reference: For more information on the operation or the solenoid valves, refer to Systems Operation, "Solenoid Valve (Implement)".
| |
| Illustration 12 | g01195420 |
|
Auxiliary Control Valve in the OPEN position (9) 257-0267 Solenoid Valve (Pilot Proportioning) (12A) 272-2334 Relief Valve (Line) Head end (12B) 272-2334 Relief Valve (Line) Rod end (16) Compensation and Load Check Valve (22) 260-8590 Shuttle Valve Load Signal Resolver (27) 260-6736 Valve Stem (Auxiliary) (35A) Work port to head end of auxiliary cylinder (35B) Work port to rod end of auxiliary cylinder (38) Bridge Passage (B) Pump Port (C) Tank Port (D) Tank Port | |
Auxiliary control valve (4) is an optional control valve. The auxiliary control valve has all of the components that are in the tilt control valve minus the solenoid valve for drift reduction (7). The auxiliary valve controls auxiliary implements such as a logging fork, a side dump bucket, or a multipurpose bucket.
Oil from the implement piston pump flows to the auxiliary control valve at port (B). Auxiliary valve stem (27) is controlled by solenoids (9). Auxiliary valve stem (27) is spring centered with an closed center. Auxiliary valve stem (27) has three positions: CLOSE, HOLD and OPEN.
Springs keep auxiliary valve stem (27) in the HOLD position when solenoids (9) have not been actuated. Implement pump oil flows to auxiliary control valve (4) at port (B). Stem movement is controlled by actuation of pilot proportioning solenoids (9) that allow oil to flow to either end of auxiliary valve stem (27).
The position of auxiliary valve stem (27) blocks the oil in both ends of the auxiliary cylinder. This keeps the auxiliary cylinder from moving.
When the auxiliary control lever or the thumb lever on the joystick control is moved to the CLOSE position, pilot oil is sent to the left end of auxiliary valve stem (27) and auxiliary valve stem (27) moves to the right. Implement oil is sent from pump port (B) around auxiliary valve stem (27) to the bottom of compensation and load check valve (16). Compensation and load check valve (16) is pushed up and flow goes through the openings in the load check valve to bridge passage (38). Oil flows around auxiliary valve stem (27) to work port (35A).
Oil is allowed to flow to the head end of the auxiliary cylinder. This causes the auxiliary cylinder to extend. Solenoid valves (9) and auxiliary valve stem (27) respond in proportion to the signal that is received from the operator controls.
Oil from the rod end of the auxiliary cylinder enters through work port (35B) and exits through tank port (C) to the hydraulic tank.
When the auxiliary control lever or the thumb lever on the joystick control is moved to the OPEN position, pilot oil is sent to the right end of auxiliary valve stem (27) and auxiliary valve stem (27) moves to the left. Implement oil is sent from pump port (B) around auxiliary valve stem (27) to the bottom of compensation and load check valve (16). Compensation and load check valve (16) is pushed up and flow goes through the openings in the load check valve to bridge passage (38). Oil flows around auxiliary valve stem (27) to work port (35B).
Oil flows to the rod end of the auxiliary cylinder. This causes the cylinder to retract. Solenoid valves (9) and auxiliary valve stem (27) respond in proportion to the movement of the operator controls.
Oil from the head end of the auxiliary cylinder enters through work port (35A) and exits through tank port (D) to the hydraulic tank.
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 or the solenoid valves, refer to Systems Operation, "Solenoid Valve (Implement)".
Valve manifold (5) contains signal duplicating reducing valve (19) and relief valve (20) for load sensing. Signal duplicating reducing valve (19) reduces supply oil to signal pressure.
When a circuit is active, signal duplicating reducing valve (19) duplicates the pressure that is received from load signal resolvers (22) of the active circuit with the highest pressure. This signal pressure is then sent to the implement piston pump at point (E). The implement piston pump is upstroked in proportion to the signal pressure that is received.
Relief valve (20) for load sensing limits the maximum signal pressure by draining oil that is above maximum signal pressure back to the hydraulic tank at point (F).
Reference: For more information on the operation or the relief valve for load sensing, refer to Systems Operation, "Relief Valve (Load Sensing Signal)".
Valve manifold (6) contains solenoid valve (13) for hydraulic lockout, pressure reducing valve (18) for pilot pressure and relief valve (28) for margin pressure.
Pressure reducing valve (18) for pilot pressure receives oil from the implement piston pump through pump port (B). The valve reduces the pressure of the system oil to pilot pressure. Pilot pressure oil is sent to the pilot circuit.
Relief valve (28) for margin pressure receives pump oil from pump port (B) and load sensing oil from signal duplicating reducing valve (19). Relief valve (28) allows pump oil from pump port (B) to drain to the hydraulic tank through tank port (C) when no load sensing oil is flowing to relief valve (28). When control levers are in the HOLD position, relief valve (28) remains open in order to relieve pressure in the system. When relief valve (28) receives oil from signal duplicating reducing valve (19), relief valve (28) closes.
Solenoid valve (13) for hydraulic lockout is controlled by an output of the implement ECM. The hydraulic lockout switch in the cab provides input to the implement ECM regarding the desired status of the pilot hydraulic system. When the solenoid valve is energized, the pilot hydraulics are enabled. The pilot hydraulics are disabled when the solenoid is de-energized.
Reference: For more information on the solenoid valve for hydraulic lockout, refer to Systems Operation, "Solenoid Valves (Implement)".
Reference: For more information on the switch for hydraulic lockout, refer to Systems Operation, "Switches".