330D System Operation Hydraulic RENR9584

RENR 9584 SYSTEMS OPERATION – HYDRAULIC 330D General Information 01/01/2006 General Information 01/01/2006 Main Hydraulic System 01/01/2006 Main Hydraulic Schematic 01/01/2006 Hydraulic Pump Flow and Pressure Control System 01/01/2006 Electronic Control System 01/01/2006 Pilot System 01/01/2006 Pilot Hydraulic System 01/01/2006 Pilot Oil Circuit 01/01/2006 Power Shift Pressure System 01/01/2006 Pilot Control Valve Circuits 01/01/2006 Pressure Switch Circuits 01/01/2006 Straight Travel Valve Circuit 01/01/2006 Swing Brake 01/01/2006 Boom Priority 01/01/2006 Swing Priority 01/01/2006 Automatic Travel Speed Change Valve 01/01/2006 Gear Pump (Pilot) 01/01/2006 Hydraulic Filter (Pilot) 01/01/2006 Relief Valve (Pilot) 01/01/2006 Accumulator (Pilot) 01/01/2006 Solenoid Valve (Hydraulic Lockout) 01/01/2006 Pilot Valve (Joystick) 01/01/2006 Solenoid Valve (Proportional Reducing) - Power Shift System 01/01/2006 Main Pump System 01/01/2006 Main Hydraulic Pump 01/01/2006 Construction 01/01/2006 Operation 01/01/2006 Pump Control (Main Hydraulic) - Main Pump Regulator 01/01/2006 Operation 01/01/2006 Pump Regulator 01/01/2006 Regulator Operation (full stroke position) 01/01/2006 Regulator Operation (minimum stroke position) 01/01/2006 Regulator Operation (standby position) 01/01/2006 Main Control Valve 01/01/2006 Main Control Valve 01/01/2006 Introduction 01/01/2006 Main Control Valve Operation in NEUTRAL Position 01/01/2006 Individual Valve Operation 01/01/2006 Negative Flow Control System 01/01/2006 Introduction 01/01/2006 Fine Control Operation 01/01/2006 Relief Valve (Negative Flow Control) 01/01/2006 Relief Valve (Main) - Heavy Lift 01/01/2006 Limitation Of Pressure In Circuit 01/01/2006 Main Relief Valve 01/01/2006 CLOSED Position (Heavy Lift OFF) 01/01/2006 OPEN Position (Heavy Lift OFF) 01/01/2006 Heavy Lift Operation 01/01/2006 Relief Valve (Line) 01/01/2006 Check Valve (Load) 01/01/2006 Boom System 01/01/2006 Boom Hydraulic System 01/01/2006 Boom Raise (High Speed) 01/01/2006 Boom Raise (Low Speed) 01/01/2006 Boom Priority 01/01/2006 Boom Lower 01/01/2006 Boom Regeneration Valve 01/01/2006 Boom Drift Reduction Valve 01/01/2006 Boom Raise 01/01/2006 Boom Lower 01/01/2006 Stick System 01/01/2006 Stick Hydraulic System 01/01/2006 Stick Out 01/01/2006 Stick In (Fast) 01/01/2006 Stick In (Slow) 01/01/2006 Stick Regeneration Valve 01/01/2006 Stick Unloading Valve 01/01/2006 Stick Drift Reduction Valve 01/01/2006 Stick Out 01/01/2006 Stick In 01/01/2006

Bucket System 01/01/2006 Bucket Hydraulic System 01/01/2006 Cylinders 01/01/2006 Cylinders (Boom, Stick and Bucket) 01/01/2006 Swing System 01/01/2006 Swing Hydraulic System 01/01/2006 Swing Priority 01/01/2006 Swing Motor 01/01/2006 Pilot Valve (Swing Parking Brake) 01/01/2006 Relief Valve (Swing) 01/01/2006 Oil Makeup (Swing System) 01/01/2006 Relief Valve (Cushion Crossover) - Anti-Reaction Valves 01/01/2006 Solenoid Valve (Fine Swing) 01/01/2006 Swing Drive 01/01/2006 Travel System 01/01/2006 Travel Hydraulic System 01/01/2006 Travel Control 01/01/2006 Forward Travel 01/01/2006 LOW SPEED 01/01/2006 HIGH SPEED 01/01/2006 Automatic Travel Speed Change 01/01/2006 Pilot Valve (Travel) 01/01/2006 Travel Motor 01/01/2006 Travel Parking Brake 01/01/2006 Displacement Change Valve 01/01/2006 Small Displacement Change Operation 01/01/2006 Large Displacement Change Operation 01/01/2006 Travel Counterbalance Valve 01/01/2006 Counterbalance Valve Operation During Level Travel 01/01/2006 Counterbalance Valve Operation During Slope Travel 01/01/2006 Operation Of Travel Crossover Relief Valves During Machine Stop 01/01/2006 Travel Parking Brake Operation 01/01/2006 Oil Makeup (Travel System) 01/01/2006 Control Valve (Straight Travel) 01/01/2006 Final Drive 01/01/2006 Operation 01/01/2006 Swivel 01/01/2006 Return System 01/01/2006 Return Hydraulic System 01/01/2006 Check Valve (Return Makeup) - Slow Return Check Valve 01/01/2006 Bypass Valve (Return) - Bypass Check Valve 01/01/2006 Hydraulic Tank and Filter 01/01/2006 Oil Filter (Return) - Case Drain Filter 01/01/2006 Hydraulic Oil Cooler 01/01/2006 Reference 01/01/2006 Graphic Color Codes 01/01/2006

Systems Operation 330D Excavator Hydraulic System

General Information SMCS - 4000; 4250; 4265; 4284; 4300; 4801; 5050

Reference: For testing and adjusting of the hydraulic system, refer to Testing and Adjusting, "Excavator Hydraulic System" for your machine.

Reference: For systems operation of the electronic control unit and electronic system, refer to Systems Operation/Testing and Adjusting, "Excavator Engine and Pump Control" for your machine.

Reference: For more information on specifications with illustrations, refer to Specifications, "Excavator Machine System Specifications" for your machine.

Reference: For more information on the hydraulic schematics, refer to Schematic, "Excavator Hydraulic System" for your machine.

Reference: For more information on electrical schematics, refer to Schematic, "Excavator Electrical System" for your machine.

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Product: EXCAVATOR Model: 330D L EXCAVATOR B6H Configuration: 330D L Excavator B6H00001-UP (MACHINE) POWERED BY C9 Engine

Media Number -RENR9584-00 Publication Date -01/01/2006 Date Updated -01/02/2006

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Copyright 1993 - 2007 Caterpillar Inc. All Rights Reserved. Private Network For SIS Licensees.

Fri Feb 23 20:17:20 EST 2007


Main Hydraulic System SMCS - 5050; 5051; 5069; 5117; 5472

Main Hydraulic Schematic

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Illustration 1 g01227433

(1) Swing motor

(2) Left travel motor

Hydraulic Pump Flow and Pressure Control System

(32) Idler pump (view from shaft end)

(33) Pilot pump

(34) Slow return check valve

(35) Bypass check valve

(36) Pressure sensor (idler pump)

(37) Proportional reducing valve (power shift pressure)

(38) Oil cooler

(39) Return filter

(40) Hydraulic tank

(41) Gear pump (fan motor)

(42) Relief valve (fan pump)

(43) Fan motor (hydraulic oil cooler)

Illustration 2 g01228123Pump compartment

(26) Drive pump

(32) Idler pump


(44) Delivery line (idler pump)

(45) Delivery line (drive pump)

(3) Right travel motor

(4) Stick cylinder

(5) Travel brake valve (left)

(6) Travel brake valve (right)

(7) Bucket cylinder

(8) Boom cylinder

(9) Swivel

(10) Pilot control valve (travel)

(11) Stick drift reduction valve

(12) Main control valve

(13) Boom drift reduction valve

(14) Pressure switch


(16) Pilot control valve (swing and stick)

(17) Pilot control valve (boom and bucket)

(18) Main relief valve


(20) Accumulator

(21) Reducing valve (boom priority mode or swing priority mode)

(22) Pressure sensor (drive pump)

(23) Swing brake solenoid valve

(24) Valve

(25) Solenoid valve (hydraulic lockout)

(26) Drive pump (view from shaft end)

(27) Travel speed solenoid valve

(28) Pilot oil manifold

(29) Drain filter

(30) Pilot relief valve

(31) Pilot filter

This machine is driven and controlled by the following systems.

The main hydraulic system controls the cylinders, the travel motors and the swing motor.

The pilot hydraulic system supplies oil to the main pumps, the main control valve, the swing brake and the travel motors.

The electronic control system controls the outputs of the engine and pump.

The hydraulic oil cooling system provides oil to the fan motor in order to cool the hydraulic oil.

The main hydraulic system delivers oil flow from idler pump (32) and drive pump (26) in order to control the following components: bucket cylinder (7), stick cylinder (4), boom cylinders (8), right travel motor (3), left travel motor (2) and swing motor (1).

Idler pump (32) and drive pump (26) are bent axial piston type pumps. The performance of both pumps is equal.

Drive pump (26) is directly connected to the engine by a flexible coupling. The drive pump delivers oil to the left control valve body (46) of the main control valve. Idler pump (32) is mechanically connected to the drive pump through gears. The idler pump delivers oil to the right control valve body (45) of the main control valve. Gear type pilot pump (33) supplies oil to the pilot hydraulic system. Gear type pilot pump (33) is mechanically connected to idler pump (32) through gears. Gear pump (41) supplies oil to the oil cooling system. Gear pump (41) is mechanically connected to the engine through gears. All engine output is used to drive these four pumps.

As the load pressure increases during working conditions, the main pumps increase the delivery pressure and the pumps decrease the flow rate. The hydraulic horsepower remains constant even though the delivery pressure and the flow rates change. The hydraulic horsepower is approximately

Illustration 3 g01228403Main control valve


(45) Right control valve body

(46) Left control valve body

identical to the engine horsepower.

When no work is being performed, pump oil flows through main control valve (12) and into hydraulic tank (40). The main control valve sends a negative flow control signal to each main pump regulator in order to destroke the pump to the minimum output flow.

If an operation is being performed, main control valve (12) directs pump oil to the respective cylinders (boom, bucket, and stick) and/or motors (swing and travel). Main control valve (12) contains numerous valve stems, passages, check valves, and orifices in order to carry out a single operation or a combined operation. The working pressure of the main hydraulic system is regulated by main relief valve (18).

The pilot hydraulic system receives oil flow from pilot pump (33). The pilot hydraulic system controls the following functions.

1. The pilot hydraulic system controls the operation of the implement control valves.

Pilot oil flows from pilot pump (33) through pilot manifold (28). The pilot oil then flows to the pilot control valves for machine operation (implement operations, swing operations and travel operation). These pilot control valves are activated by the joysticks and the travel levers/pedals.

When joystick (48), joystick (49), left travel lever/pedal (50) and/or right travel lever/pedal

Illustration 4 g01173678Cab

(47) Monitor panel

(48) Joystick (stick and swing)

(49) Joystick (boom and bucket)

(50) Left travel lever/pedal

(51) Right travel lever/pedal

(52) Straight travel pedal

(53) Engine speed dial

(51) are moved from the NEUTRAL position, the pilot oil flows through the pilot control valves to the corresponding spools at the main control valve (12) .

The pilot pressure oil at that end of the valve spool forces the valve spool to shift. The pilot oil on the other end of the valve spool drains to the hydraulic tank. When the valve spool shifts, oil is then delivered from idler pump (32) or drive pump (26) to the cylinders and motors.

Thus, pilot oil drives each system of the main control valve.

2. The pilot hydraulic system controls the output flow of the main pumps.

During machine operation, pilot pressure is sent to the main pump regulators as a signal pressure. This signal pressure is called power shift pressure. The engine and pump controller receives input signals from various components on the machine. The engine and pump controller processes the input signals. The engine and pump controller then sends an electrical signal to proportional reducing valve (37) at the idler pump regulator in order to regulate the power shift pressure. The power shift pressure controls the output flow of idler pump (32) and drive pump (26). Power shift pressure adjusts the output flow of the main pumps in accordance with the engine speed. For more information concerning power shift pressure, refer to Systems Operation, "Pilot Hydraulic System".

3. The pilot hydraulic system generates signal pressure in order to perform the following operations.

a. Pilot signal pressure activates the Automatic Engine Speed Control (AEC) system. This causes functions to automatically reduce the engine speed when no hydraulic operation is called for.

b. Pilot signal pressure releases the swing parking brake.

c. Pilot signal pressure will automatically change the travel speed to either HIGH or LOW in accordance with the hydraulic system load.

d. Pilot signal pressure operates the straight travel control valve. This maintains straight travel during the operation of an implement.

e. Pilot signal pressure controls the operation of the valves that can be used during a loading operation or a trenching operation.

For more information concerning the pilot hydraulic system, refer to Systems Operation, "Pilot Hydraulic System".


Fri Feb 23 20:20:11 EST 2007


Electronic Control System SMCS - 1900

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(1) Machine ECM


(3) Switch panel

(4) Clench pressure sensor (attachment)

(5) Manual low idle switch

(6) Implement pressure switch

(7) Swing pressure switch

(8) Right travel pressure switch

(9) Left travel pressure switch

(10) Straight travel pressure switch

(11) Right pump pressure sensor

(12) Left pump pressure sensor

(13) Fuse panel

(14) viscous clutch

(15) Fan speed sensor

(16) Engine

(17) Main pumps

(18) Engine speed pickup

(19) Battery

(20) Engine start switch

(21) Backup switch

(22) Monitor

(23) Heavy lift solenoid valve

(24) Straight travel solenoid valve



(27) Hydraulic lockout solenoid

(28) Flow limiter valve (attachment pump)

(29) Pressure switch (attachment pump)

(30) Attachment pedal pressure switch (Left)

(31) Attachment pedal pressure switch (Right)

The electronic control system consists of monitor (12) in the cab and the machine ECM (1) that is located in the compartment behind the cab. The electronic control system controls the engine speed

(32) Proportional reducing valve for auxiliary hydraulics

(33) Power shift solenoid valve

Illustration 2 g01173858(1) Machine ECM

Illustration 3 g01173869(12) Monitor

and the pumps through the machine ECM.

Machine ECM (1) receives input signals from various components on the machine. The machine ECM continuously monitors the input signals in order to control the output flow rate of the main pumps, engine speed and various components of the machine hydraulic systems.

The machine ECM has the following three major functions.

The electronic control system controls the output flow rate of the main pumps. The machine ECM sends an electrical signal to the power shift solenoid that is based on engine speed and the position of the engine speed dial. This allows the main pumps to supply the optimum output that matches the hydraulic load to the machine and the engine speed. When a large load is placed on the machine, the system allows the pumps to destroke. The system utilizes the available maximum engine horsepower.

The electronic control system controls the engine speed. This is called Automatic Engine Speed Control (AEC). When there is a very small load condition or no load condition, the system automatically decreases the engine speed. The AEC system is designed to reduce fuel consumption and noise.

The electronic control system controls various components of the machine hydraulic systems. The machine ECM sends output signals to the swing brake solenoid valve, the travel speed solenoid valve and the straight travel solenoid.

Note: If a problem occurs in the electronic control system, temporary operation of the machine is possible by use of the backup switches that are located in the cab. For more information concerning the backup system, refer to Operation and Maintenance Manual, "Backup Controls".

Reference: For more information concerning the operation of the electronic control system, refer to Systems Operation/Testing and Adjusting, "Engine and Pump Electronic Control System".


Fri Feb 23 20:21:32 EST 2007


Pilot Hydraulic System SMCS - 5050-PS

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i02462061


(1) Swing brake

(2) Displacement change valve (left travel motor)

(3) Displacement change valve (right travel motor)

(4) Line (pilot oil from swing brake solenoid valve)

(5) Travel pilot control valve

(6) Pilot line (BOOM LOWER)

(7) Pilot line (boom drift reduction valve)

(8) Pilot line (STICK IN)

(9) Pilot line (stick drift reduction valve)




(13) Solenoid valve (straight travel)

(14) Pilot line (pilot pressure to left travel pressure switch)

(15) Pilot line (pilot oil to travel pilot control valve)

(16) Right travel control valve

(17) Boom I control valve

(18) Straight travel control valve

(19) Travel pressure switch (left)

(20) Pilot line (pilot pressure to right travel pressure switch)

(21) Travel pressure switch (right)

(22) Pilot line (pilot oil to pilot control valve for the stick and swing)

(23) Pilot line (pilot oil to pilot control valve for the boom and bucket)

(24) Left travel control valve

(25) Pilot control valve for stick and swing

(26) Pilot control valve for boom and bucket

(27) Variable swing priority valve

(28) Pilot line (STICK OUT)

(29) Pilot line (STICK IN)

(30) Pilot line (SWING RIGHT)

(31) Pilot line (SWING LEFT)

(32) Pilot line (BUCKET CLOSE)

(33) Pilot line (BOOM RAISE)

(34) Pilot line (BOOM LOWER)

(35) Pilot line (BUCKET OPEN)

(36) Pilot line (pilot oil from boom pilot control valve)

(37) Pilot line (BOOM RAISE)

(38) Pilot line (pilot oil to the pressure reducing valve for boom priority)

(39) Pilot line (pilot pressure to implement/swing pressure switch)

(40) Implement/swing pressure switch

(41) Pilot line (pilot pressure to displacement change valves)

(42) Pilot line (pilot oil to pressure reducing valve for swing priority)

(43) Pilot line (pilot oil to pilot control valves)

(44) Pilot line (pilot oil to straight travel control valve)


(46) Valve (hydraulic lockout)

(47) Pressure reducing valve for swing priority

(48) Pressure reducing valve for boom priority

(49) Drive pump

(50) Passage (power shift pressure)

(51) Pilot manifold


(53) Passage

(54) hydraulic lockout valve

(55) Passage

(56) Passage

(57) Passage

(58) Idler pump

(59) Pilot pump

(60) Pilot line (pilot oil flow to pilot oil manifold)

(61) Pilot filter

Pilot Oil Circuit The pilot circuit pressure is limited by pilot relief valve (64) .

The oil delivery from pilot pump (59) performs the following main functions.

Create pilot oil pressure in order to control the output flows of the main pumps.




(65) Passage

(66) Pilot line (pilot oil flow from pilot pump to pilot oil filter)

(67) Pilot line (pilot oil flow to pump regulators)

Illustration 2 g01229667Ports and solenoids at the pilot manifold




(54) hydraulic lockout valve

Provide pilot oil pressure to the pilot control valves for implements, swing and travel in order to perform machine operations.

Create pilot oil pressure in order to automatically operate the control devices.

The pilot circuit is classified into the following circuits and each circuit performs one of the above functions.

Power shift pressure system

Pilot control valve circuit

Pressure switch circuits

Straight travel valve circuit

Swing brake

Boom priority

Swing priority

Automatic travel speed change

Power Shift Pressure System

During machine operation, machine ECM (68) receives input signals from the following components:

Engine speed dial (70)

Illustration 3 g01229671(49) Drive pump

(58) Idler pump

(63) Proportional reducing valve (PS pressure)

(59) Pilot pump

(68) Machine ECM

(69) Monitor


(71) Drive pump pressure sensor

(72) Idler pump pressure sensor

(73) Engine speed pickup (flywheel housing)

(74) Pump (fan motor)

Engine speed pickup (73) that is located on the flywheel housing

Idler pump pressure sensor (71)

Drive pump pressure sensor (72)

Monitor in the cab (69)

The machine ECM (68) continually monitors all of the input signals. The input signals are processed by the machine ECM and an output signal is sent to proportional reducing valve (63) at the pump regulator. The proportional reducing valve assists in controlling the output flow of idler pump (58) and drive pump (49) .

The oil delivery from pilot pump (59) flows through the pilot filter to proportional reducing valve (63) at the pump regulator. The electrical signal that is sent from machine ECM (68) causes proportional reducing valve (63) to regulate the pilot pressure to a reduced pressure. This reduced pressure is called power shift pressure (PS). The proportional reducing valve sends the reduced pilot oil pressure through the idler pump regulator and through the drive pump regulator. The output flow of idler pump (58) and drive pump (49) is controlled in accordance with the power shift pressure. The power shift pressure is used to regulate the maximum allowable hydraulic pump output.

The output signal that is sent from the machine ECM to the proportional reducing valve will change when the machine ECM detects a change in any of the input signals. The power shift pressure that is sent to the regulators at the idler pump and the drive pump will change in order to regulate the maximum allowable hydraulic pump output. The desired engine speed is maintained.

A decrease in engine speed increases the power shift pressure. An increase in power shift pressure causes destroke condition of the idler pump and the drive pump. The maximum allowable hydraulic power output is decreased.

An increase in engine speed decreases the power shift pressure. A decrease in power shift pressure causes an upstroke condition of the idler pump and the drive pump. The maximum allowable hydraulic power output is increased.

Note: For more information concerning the operation of the machine ECM, refer to Systems Operation/Testing and Adjusting, "Electronic Control System".

Pilot Control Valve Circuits Oil from pilot pump (59) flows through pilot line (66), pilot filter (61) and pilot line (60) to pilot manifold (51). When the control lever for the hydraulic lockout is shifted to the UNLOCKED position, the machine ECM energizes the hydraulic lockout valve (54). The pilot oil then shifts valve (46). The pilot oil now flows through valve (46) and pilot line (43). The pilot oil now flows to pilot control valves (5), (25) and (26) for implements, swing and travel in order to perform machine operations. When the joysticks and/or travel levers/pedals are moved, the pilot oil flows to main control valve (11) in order to control the machine functions.

When joystick (25) and/or joystick (26) are operated, the pilot control valves send pilot pump oil through the pilot lines to pilot ports at the main control valve in order to shift the spools in the main control valve. Refer to Illustration 4 and Table 1 for the location of the pilot lines and machine operations.

Pilot oil from the pilot control valves flows through pilot lines to the ports on the bottom of the main control valve in order to perform the opposite operation.

The following example is given for the BOOM LOWER operation and the BOOM RAISE operation. Machine operations for a stick operation, bucket operation, travel operation and swing operation are accomplished in the same manner as the boom operation.

When the joystick for the boom is moved to the BOOM RAISE position, pilot oil from pilot control valve (26) flows through pilot line (37) to boom I control valve (17). The pilot pressure shifts the boom I control valve. The oil delivery from the idler pump flows to the head end of the boom cylinders in order to perform the BOOM RAISE operation.

When the joystick for the boom is moved to the BOOM LOWER position, pilot oil from pilot

Illustration 4 g00932058Pilot lines at the main control valve (top view)

Table 1

Pilot line Control Valve Machine Operation

(76) Boom I control valve BOOM LOWER

(77) Bucket control valve BUCKET CLOSE

(78) Swing control valve SWING LEFT

(79) Boom II control valve BOOM RAISE

(80) Stick II control valve STICK IN

(81) Right travel control valve REVERSE RIGHT TRAVEL

(82) Left travel control valve REVERSE LEFT TRAVEL

(83) Stick I control valve STICK IN

control valve (26) flows through pilot line (6) to boom I control valve (17). The pilot pressure shifts the boom I control valve. The pilot oil also flows through pilot line (7) in order to open boom drift reduction valve (12). The return oil from the head end of the boom cylinders flows through the boom drift reduction valve and the boom I control valve to the hydraulic tank. The BOOM LOWER operation is now performed.

Pressure Switch Circuits Pressure switches (19) and (21) are connected to travel pilot control valve (5). Pressure switch (40) is connected to pilot control valve (25) and pilot control valve (26). When all of the joysticks and/or travel levers/pedals are in the NEUTRAL position, the pilot oil pressure to the pressure switches is low. Pressure switches (19), (21) and (40) are OFF. The machine ECM recognizes the OFF condition of all of the pressure switches. The AEC system is activated in order to lower the engine rpm.

If any of the joysticks and/or travel levers/pedals are moved from the NEUTRAL position, the increased pilot oil pressure is sent to the pressure switches. If pressure switch (19), (21) and/or (40) is ON, the machine ECM activates the AEC system in order to increase the engine rpm.

Straight Travel Valve Circuit When a swing operation and/or implement operation is performed during a travel operation, the increase of pilot pressure in pilot line (39) activates implement/swing pressure switch (40). The implement/swing pressure switch sends an electrical signal to the machine ECM. The machine ECM energizes straight travel solenoid (13). Pilot pressure now activates straight travel control valve (18). The straight travel control valve maintains straight travel even though there is a swing operation or an implement operation during travel. For more information concerning the operation of the straight travel control valve, refer to Systems Operation, "Control Valve (Straight Travel)".

Swing Brake When the control lever for the hydraulic lockout is placed in the UNLOCKED position, pilot oil in passage (57) flows through valve (46) and passage (53) to swing brake solenoid valve (45). When any of the joysticks are moved from the NEUTRAL position, the increase of pilot pressure in pilot line (39) activates implement/swing pressure switch (40). The implement/swing pressure switch sends an electrical signal to the machine ECM. An electrical signal from the machine ECM energizes the swing brake solenoid valve (45). Pilot oil in line (4) flows to swing brake (1). This oil releases the swing brake. For more information concerning the operation of the swing brake, refer to Systems Operation, "Pilot Valve (Swing Brake)".

Boom Priority During combined operations of BOOM RAISE and STICK IN, the pilot oil pressure in pilot line (36) and pilot line (38) activates the pressure reducing valve for boom priority. The pressure reducing valve for boom priority allows priority flow to the head end of the boom cylinders during these combined hydraulic operations by disabling the stick II control valve. For more information concerning the pressure reducing valve for boom priority, refer to Systems Operation, "Boom Hydraulic System".

Swing Priority During a swing operation, pilot oil flows from pilot control valve (25) to the pressure reducing valve

for swing priority (47). The pressure reducing valve for swing priority shifts. The pilot oil flow in pilot line (42) from pilot oil manifold (51) is blocked by the pressure reducing valve for swing priority. Most of the drive pump delivery flow goes to the swing motor. For more information concerning the pressure reducing valve for swing priority, refer to Systems Operation, "Swing Hydraulic System".

Automatic Travel Speed Change Valve Pilot oil in passage (56) flows to travel speed solenoid valve (52). When the travel speed switch on the right console is set at the HIGH SPEED position, the travel speed solenoid valve opens. This allows pilot oil to flow through travel speed solenoid valve (52) and through line (41). The oil then flows to the displacement change valve for the left travel motor (2) and the displacement change valve for the right travel motor (3). As the displacement change valve operates, the travel speed is maintained at the HIGH SPEED position.

When the travel speed switch on the right console is set at the HIGH SPEED position, the pressure sensors for the pump delivery pressure control the travel speed in accordance with the travel load. For example, low speed during a high load condition and high speed during a low load condition.

For more information concerning the operation of the displacement change valves, refer to Systems Operation, "Displacement Change Valve".


Fri Feb 23 20:22:34 EST 2007


Gear Pump (Pilot) SMCS - 5073; 5085

The pilot pump is a gear type pump that supplies oil flow to the pilot system. The pilot pump is located inside the main pump compartment and mounted externally to the main pump. The pilot pump shaft is mechanically connected to the idle pump shaft. The pump delivery rate with load is approximately 34 L/min (9.0 US gpm).

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Illustration 1 g01230561Pilot pump


Fri Feb 23 20:23:23 EST 2007


Hydraulic Filter (Pilot) SMCS - 5068; 5092

The oil delivery from the pilot pump flows through pilot oil filter (1) and into the components in the pilot system.

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Illustration 1 g00847833(1) Pilot oil filter


Relief Valve (Pilot) SMCS - 5072

Pilot relief valve (2) is located on the mounting base for the pilot oil filter. The pilot relief valve limits the pressure in the pilot system. The pilot relief valve setting is adjustable.

The pilot oil flows from the pilot pump to inlet port (1). When the pressure in the pilot oil system reaches the pressure setting of pilot relief valve (2), part of the pilot oil flow is returned to the hydraulic tank through port (3). The pressure of the pilot system oil in outlet lines (4) is equal to the pressure setting of the pilot relief valve.

Reference: For more information concerning the pilot relief valve setting, refer to Testing and Adjusting, "Relief Valve (Pilot) - Test and Adjust".

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Illustration 1 g00847828(1) Inlet port (oil flow from pilot pump)


(3) Port (oil flow to hydraulic tank)

(4) Outlet lines (regulated pilot oil pressure)


Fri Feb 23 20:24:31 EST 2007


Accumulator (Pilot) SMCS - 5077

The accumulator stores pilot pressure oil for use at the main control valves. During some operations, the pilot system needs more oil because there is insufficient flow from the pilot pump. Accumulator (5) will provide pilot pressure oil to the pilot system when the pilot pump flow is inadequate. Insufficient supply of pilot oil flow to the pilot system may be caused by the following two reasons:

Implements are lowered while the engine is stopped and oil supply to the main control valves is stopped.

Combined operations

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Illustration 1 g00681745(5) Accumulator

(16) Line (pilot oil from pilot oil manifold)

(17) Mounting block

Filter element (2) in pilot oil filter (1) removes contaminants from the pilot oil.

If the pilot oil is extremely cold or if the flow of pilot oil through filter element (2) becomes restricted by contaminants, the oil bypasses filter element (2) through bypass relief valve (3). Bypass relief valve (3) is built into the base for the pilot oil filter.

Illustration 2 g01230619(1) Pilot oil filter

(2) Filter element

(3) Bypass relief valve


Fri Feb 23 20:23:54 EST 2007


Accumulator

(5) Accumulator

(16) Line (pilot oil flow from pilot oil manifold to the mounting block for the accumulator)

(17) Mounting block

(18) Passage

(19) Inlet port

(20) Pressure oil chamber

(21) Vessel

(22) Bladder

(23) Gas chamber

(24) Passage

(25) Passage

(26) Passage

Pilot oil from the pilot filter enters inlet port (27) of the pilot oil manifold. Pilot oil flows through passage (28) and opens check valve (29). Pilot oil now flows through passages (24) and (26) to the pilot control valves (joysticks and travel levers/pedals).

The pilot oil also flows through passage (25) and line (16) to the mounting block for the accumulator. The pilot oil now flows through passage (18) and inlet port (19) into pressure oil chamber (20). The pilot oil acts against bladder (22) and the nitrogen gas in gas chamber (23) is compressed. Check valve (29) prevents a backflow of the stored oil in the accumulator. The stored oil is used for solely operating the stems of the main control valve.

(27) Inlet port (pilot oil manifold)

(28) Passage

(29) Check valve


Fri Feb 23 20:25:15 EST 2007


Solenoid Valve (Hydraulic Lockout) SMCS - 5479

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Pilot oil manifold


(2) Solenoid valve for hydraulic lockout


(3) Hydraulic lockout lever (LOCKED position)


(3) Hydraulic lockout lever (UNLOCKED position)

Limit switch (6) and plunger (4) are located on a bracket with hydraulic lockout lever (3). The limit switch is activated by hydraulic lockout lever (3) .

When hydraulic lockout lever (3) is shifted to the LOCKED position, solenoid valve (2) of pilot oil manifold (1) is not energized. Pilot oil is not supplied to the pilot control valves. Thus when the joysticks and/or the travel levers/pedals are operated, the cylinders or the motors are not activated also.

The engine will not start unless hydraulic lockout lever (3) is in the LOCKED position. If some one unexpectedly operates the machine, the machine will not operate.

When hydraulic lockout lever (3) is placed in the UNLOCKED position, solenoid valve (2) is energized and pilot oil passes through the solenoid valve. Pilot oil now flows to the pilot control valves.

Illustration 4 g01113912(3) Hydraulic lockout lever

(4) Plunger

(5) Bar

(6) Limit switch

When hydraulic lockout lever (3) is placed in the UNLOCKED position, plunger (4) of limit switch (6) is depressed by control lever (3). Limit switch (6) is in the ON state.

The hydraulic lockout valve (2) consists of solenoid (7) and control valve (10). When hydraulic lockout lever (3) is in the UNLOCKED position, solenoid (7) controls valve (10). When solenoid (7) is energized, spool (9) moves in a downward direction against the force of spring (8). Passage (12)

Illustration 5 g01218100Partial diagram of solenoid valve (hydraulic lockout) (UNLOCKED circuit)


(7) Solenoid

(8) Spring

(9) Spool

(10) Control valve

(11) Passage

(12) Passage

(13) Passage

(14) Passage (return oil)

(15) Passage (pilot oil to swing brake solenoid valve)


(17) Pilot oil flow to pilot valves (joysticks)


(19) Passage

opens. Pilot pressure oil from passage (13) flows through passage (11) to valve (18). The spool in valve (18) moves in a downward direction. Pilot pressure oil in passage (19) flows through valve (18). Pilot oil is now delivered through passage (15) to swing brake solenoid valve (16). Pilot pressure oil in passage (19) is also delivered to the pilot control valves (joysticks and travel levers/pedals) through line (17).

Illustration 6 g01218083Partial drawing of solenoid valve (hydraulic lockout) (LOCKED position)


(7) Solenoid

(8) Spring

(9) Spool

(11) Passage

(12) Passage

(13) Passage


(20) Passage

When hydraulic lockout lever (3) is moved to the LOCKED position, plunger (4) of limit switch (6) is not depressed by control lever (3). Limit switch (6) is in the OFF state.

When hydraulic lockout lever (3) is in the LOCKED position, solenoid (7) is not energized. Spool (9) is forced upward by spring (8). Passage (20) opens and passage (12) closes. Passage (13) is not open to passage (11). Pilot oil supply to line (17) is stopped. Pilot oil supply to the pilot control valves (joysticks and travel levers/pedals) is blocked. The cylinders and the motors can not be activated.


Fri Feb 23 20:26:13 EST 2007


Pilot Valve (Joystick) SMCS - 5705-V4

When joystick (1) and/or joystick (2) are operated, the pilot control valves send pilot pump oil through the pilot lines to pilot ports at the main control valve in order to shift the spools in the main control valve.

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(1) Joystick (left)

(2) Joystick (right)


Pilot control valve

(1) Joystick

(2) Rod

(3) Return passage

(4) Passage

(5) Spool

(6) Plate

(7) Rod

(8) Spring

(9) Seat

(10) Seat

(11) Spring

(12) Spring

When joystick (1) is moved to the right, plate (6) tilts to the right. Plate (6) pushes down on rod (7). Seat (10) moves down against the force of metering spring (11) and spring (12). The force of metering spring (11) shifts spool (16) downward. Passage (15) opens. The pilot oil flows through passage (20), passage (18), passage (15), and port (19) to the main control valve. The pilot oil pressure shifts the spool of the main control valve. This enables the implement operation or swing operation.

The return pilot oil at the opposite end of the spool in the main control valve returns to the pilot control valve through port (17). Since rod (2) is not pushed down by plate (6), return passage (3) is open and passage (4) is closed. The return pilot oil flows through return passage (3), return chamber (13), and port (21) to the hydraulic tank.

The force of metering spring (11) varies with the position of the joystick. Since spool (16) is moved by the force of metering spring (11), the pilot oil pressure that flows through passage (15) to the main control valve directly corresponds with the position of the joystick. Spool modulation in the main control valve directly corresponds with the amount of movement of the joystick.

When the joystick is moved slightly from the NEUTRAL position, metering spring (11) moves spool (16) slightly. Low pilot oil pressure is sent to the spool of the main control valve. The main control valve spool shifts a slight amount. The volume of oil delivery to the cylinders and/or motors is small. The speed of the cylinders and/or motors is slow. As the joystick is moved farther from the NEUTRAL position, the force of metering spring (11) on spool (16) increases. The pilot oil pressure that is sent to the main control valve increases. The spool in the main control valve shifts farther and the speed of the cylinders and/or motors increases. Thus, cylinder speed and motor speed is controlled by the amount of movement and the position of the joystick.

When the joystick is moved slightly from the NEUTRAL position, only metering spring (11) acts on spool (16). Fine control of the cylinders and/or motors is accomplished since the pilot oil pressure that is sent to the main control valve is decreased. As the joystick is moved farther from the NEUTRAL position, the bottom of rod (7) comes in contact with spring (8). Now, the combined force of metering spring (11) and spring (8) act on spool (16). The pilot oil pressure increases rapidly. The cylinders and/or motors respond more rapidly.

When the joystick is released, the joystick will return to the NEUTRAL position due to the force of spring (12).

(13) Return chamber

(14) Return passage

(15) Passage

(16) Spool

(17) Port (return pressure to valve)

(18) Passage (pilot supply pressure)

(19) Port (reduced pressure to valve)

(20) Port (pilot supply)

(21) Port (tank)


Fri Feb 23 20:26:55 EST 2007


Solenoid Valve (Proportional Reducing) - Power Shift System SMCS - 5479

The proportional reducing valve for the power shift pressure is located on the main pump housing. The proportional reducing valve is a solenoid operated control valve. The proportional reducing valve receives supply oil from the pilot pump. The solenoid receives a pulse width modulated signal (PWM signal) from the machine ECM. The PWM signal that is sent from the machine ECM causes the proportional reducing valve to regulate the pilot pressure to a reduced pressure. This reduced pressure is called power shift pressure (PS). The proportional reducing valve sends the reduced pilot oil pressure to the regulators at the idler pump and the drive pump. The output flow of the idler pump and the drive pump is controlled in accordance with the power shift pressure. The power shift pressure is used to control the maximum allowable hydraulic pump output.

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Illustration 1 g01237694Proportional reducing valve (power shift solenoid)

(1) Solenoid

(3) Valve body

(9) Line (pilot oil flow)

Illustration 2 g01237695Proportional reducing valve (increase in PWM signal)

(1) Solenoid

(2) Spring

(3) Valve body

(4) Spool

(5) Passage (return oil flow)

(6) Passage (power shift pressure to pump regulators)

(7) Spool chamber

(8) Passage (pilot oil flow)

A decrease in engine speed causes an increase in power shift pressure and a decrease in pump flow.

While the engine is operating, the machine ECM senses a decrease in engine speed. A decrease in engine speed causes the machine ECM to increase the PWM signal that is sent to solenoid (1). The magnetic force of the solenoid increases. As the magnetic force of the solenoid becomes greater than the force of spring (2), spool (3) moves in a downward direction against the force of the spring. The downward movement of spool (3) blocks the flow of oil from passage (6) to passage (5). Pilot oil in line (9) now flows through passage (8), into spool chamber (7) and into passage (6) at a reduced pressure (power shift pressure). The increased power shift pressure in passage (6) acts on the idler pump regulator and the drive pump regulator. The idler pump and the drive pump destroke as a result of an increase in power shift pressure.


Proportional reducing valve (decrease in PWM signal)

(1) Solenoid

An increase in engine speed causes a decrease in power shift pressure and an increase in pump flow.

While the engine is operating, the machine ECM senses an increase in engine speed. An increase in engine speed causes the machine ECM to decrease the PWM signal that is sent to solenoid (1). The magnetic force of the solenoid decreases. As the force of spring (2) becomes greater than the magnetic force of the solenoid, spool (3) moves in an upward direction. The upward movement of spool (3) blocks the flow of pilot oil from passage (8). Power shift pressure oil in passage (6) now drains into spool chamber (7) and into passage (5). The decreased power shift pressure in passage (6) that is acting on the idler pump regulator and the drive pump regulator causes the idler pump and the drive pump to move to an upstroke position. The idler pump and the drive pump upstroke as a result of a decrease in power shift pressure.

ReferenceFor more information concerning power shift pressure (PS), refer to Systems Operation, "Pilot Hydraulic System".

(2) Spring

(3) Valve body

(4) Spool

(5) Passage (return oil flow)

(6) Passage (power shift pressure to pump regulators)

(7) Spool chamber

(8) Passage (pilot oil flow)


Fri Feb 23 20:27:27 EST 2007


Main Hydraulic Pump SMCS - 5070-MV

Construction

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Main pumps

(1) Port (negative flow control pressure for drive pump)

(2) Outlet port (pilot pressure)

(3) Idler pump

(4) Outlet port (idler pump)

(5) Inlet port (supply oil from the hydraulic tank)


(7) Port (negative flow control pressure for idler pump)

The main pump consists of drive pump (8) and idler pump (3). The drive pump and the idler pump are contained in an integral housing. Both pumps are variable displacement piston pumps. The drive pump and the idler pump are identical in construction and operation.

Supply oil from the hydraulic tank enters inlet port (5). The single inlet port is common to main pumps (8) and (3) as well as pilot pump (11). The drive pump delivers oil through outlet port (9). The idler pump delivers oil through outlet port (4). The pilot pump delivers oil through outlet port (2) .

Both the drive pump and the idler pump have a regulator as part of the pump control system. The flow control of the pumps is performed by the operation of the regulators. The control system is identical for both pumps.

Proportional reducing valve (6) for the power shift pressure is located on the head of the main pump. The proportional reducing valve is controlled by the machine ECM. The proportional reducing valve controls the signal from the power shift pressure for both the drive pump and the idler pump.

Negative flow control pressure from the main control valve enters the drive pump regulator at port (1). Negative flow control pressure from the main control valve enters the idler pump regulator at port (7) .

Case drain oil from the pump housing flows from port (15) to the case drain filter.

Operation

(8) Drive pump

(9) Outlet port (drive pump)

(10) Housing

(11) Pilot pump

(14) Port (power shift pressure)

(15) Case drain port

Illustration 2 g01238115Main pumps (sectional view)

(3) Idler pump

(8) Drive pump

(11) Pilot pump

(16) Gear

(17) Drive shaft

(18) Drive shaft

(19) Gear

(20) Swashplate

(21) Plate

(22) Retainer

(23) Piston slipper

(24) Piston

(25) Barrel

(26) Port plate

(27) Passage

Gear (19) of drive shaft (18) meshes with gear (16) of drive shaft (17). Gear (16) and gear (17) have the same number of teeth. Drive shaft (18) of drive pump (8) is connected to the engine by a coupling. When the engine is running, drive shaft (17) and drive shaft (18) rotate at the same speed. Therefore, drive pump (8) and idler pump (3) rotate at the same speed.

Pilot pump (11) is directly connected with drive shaft (17) .

Barrel (25) contains nine pistons (24). Piston slippers (23) are connected to pistons (24) by retainers (22). The piston slippers are pressed against plate (21). Plate (21) lies on swashplate (20). Barrel (25) is splined to drive shaft (18). As drive shaft (18) rotates, the barrel, the pistons and the piston slippers rotate around swashplate (20) .

The angle of swashplate (20) determines the length of stroke of piston (24). As the angle of the swashplate increases, the length of stroke of the pistons increases and the output flow of the pump increases. As piston slipper (23) rotates around the swashplate, the piston moves out of barrel (25). The piston draws oil from passage (27) of port plate (26) during this movement. As the piston slipper continues to rotate around the swashplate, the piston moves into the barrel. The piston delivers oil to outlet port (13) during this movement. The oil delivery from ports (4) and (9) flows to the main control valve.


Fri Feb 23 20:28:19 EST 2007


Pump Control (Main Hydraulic) - Main Pump Regulator SMCS - 3222; 5070; 5086

Operation The regulators for the drive pump and the idler pump are identical in construction and operation. The following description is given for the drive pump regulator.

The main pump regulators are controlled in the following manner.

Power Shift System - The pump regulators are controlled by the electronic control system. The engine and pump controller continually monitors the engine speed and the load on the engine. The engine and pump controller sends an electrical signal to the proportional reducing valve for power shift pressure. The proportional reducing valve assists in controlling the output flow of the pumps by changing the hydraulic signal pressure (power shift pressure) that flows to the pump regulators.

Cross sensing control - The pump regulators are controlled by cross sensing control. In order to maintain the engine horsepower to the pumps at a constant rate, the pump regulators receive average delivery pressure of the drive pump and the idler pump through the cross sensing control. This is called constant horsepower control.

Negative Flow Control - When the joysticks and/or the travel levers/pedals are in the NEUTRAL position or when the joysticks and/or the travel levers/pedals are partially moved from the NEUTRAL position, the pump regulators receive negative flow control pressure from the main control valve. The main pumps are controlled by negative flow control pressure at this time.

Reference: For more information concerning the power shift system, refer to Systems Operation, "Pilot Hydraulic System".

Reference: For more information concerning the negative flow control operation at the main control valve, refer to Systems Operation, "Negative Flow Control".

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The output characteristics of each pump depends on the following pressures.

Pump output circuit pressure

Power shift pressure

Negative flow control pressure

The flow rate of each pump is represented on P-Q characteristic curve (B) from pressure/flow point (A). Each point on the P-Q characteristic curve represents the flow rate and pressure when pump output horsepower is maintained at a constant rate.

Pump Regulator

Illustration 1 g00687567P-Q characteristic curve

(A) Pressure/flow point (destroke point)

(B) P-Q characteristic curve


Idler pump regulator

(1) Spool

(2) Shoulder

(3) Piston

(4) Passage

(5) Plate

(6) Feedback lever

Pump delivery pressure (PD) acts on pilot piston (3) and spool (1) of regulator (16). Power shift pressure (PS) enters regulator (16) through a passage through the main pump housing. The oil then goes through passage (10) to piston (9) .

During constant horsepower flow control, pump delivery pressure (PD) is acting on the right shoulder of pilot piston (3). Also during constant horsepower flow control, power shift pressure (PS) and cross sensing control pressure (CP) from the idler pump is acting on the left end of piston (3). When the total force of the three pressures is less than the force of spring (7) and spring (8), pilot piston (3) remains stationary. Swashplate (13) maintains the maximum angle for maximum pump flow. When the total force of the three pressures is greater than the force of spring (7) and spring (8), pilot piston (3) is shifted in order to decrease the swashplate angle which will destroke the pump.

During negative flow control, negative flow control pressure (PN) from line (17) acts on the left end surface of pilot piston (18). Pilot piston (18) shifts in order to move feedback lever (5), spool (1) and related components. Negative flow control is maximum when all the control levers are in the NEUTRAL position which requires no pump flow.

Regulator Operation (full stroke position)

(7) Spring

(8) Spring


(PS) Power shift pressure

(CF) Cross sensing control pressure

(PD) Delivery pressure (drive pump)

(11) Chamber

(12) Piston

(13) Swashplate

(14) Chamber

(15) Rod

(16) Regulator

(17) Negative flow control line

(18) Rod


Drive pump regulator

(1) Spool

(2) Shoulder

(3) Piston

(4) Passage

(5) Plate

(6) Feedback lever

(7) Spring

(8) Spring

(9) Piston




Main pump delivery pressure (PD) acts on shoulder (2) of pilot piston (5). Power shift pressure (PS) from passage (10) acts on piston (9) and on the left end of pilot piston (3). When the total force of main pump delivery pressure (PD), power shift pressure (PS), and cross sensing control pressure (CF) is less than the total force of spring (7) and spring (8) pilot piston (3) remains stationary. Plate (5), feedback lever (6), and spool (1) remain stationary. Passage (4) remains blocked. Main pump delivery pressure (PD) cannot enter piston chamber (11) while there is main pump delivery pressure (PD) in piston chamber (14). Piston (12) is shifted all the way to the left. Swashplate (13) is held at a maximum angle which allows the pump to maintain maximum output flow. Main pump delivery pressure (PD), power shift pressure (PS), and cross sensing control pressure (CF) flow to the regulator from passages within the main pump housing.

Regulator Operation (minimum stroke position)


(11) Chamber

(12) Piston

(13) Swashplate

(14) Chamber

When all of the controls are in the NEUTRAL position, no load is present to the drive pump which causes a increase in power shift pressure (PS) and a increase in drive pump delivery pressure (PD) inside the pump. The larger pressures from power shift pressure (PS), delivery pressure (PD), and cross sensing control pressure (CF) combine in order to overcome the forces of spring (7) and spring (8) which shifts piston (3).

Piston (3) shifts rod (15) to the right, rotating lever (6), which rotates lever (5). Lever (5) is connected to spool (1). When lever (5) is rotated spool (1) shifts to the right. This opens passage (4). Delivery pressure (PD) now flows to chamber (11). Lever (5) is also connected to piston (12). When lever (5) is rotated a force is placed against piston (12). The combined force of delivery pressure (PD) and force from lever (5) causes piston (12) to shift to the right. Piston (12) then rotates swashplate (13) to zero angle. The pump displacement is now minimal.

Regulator Operation (standby position)

Illustration 4 g01129935Pump regulator (machine at idle condition)

(1) Spool

(2) Shoulder

(3) Piston

(4) Passage

(5) Plate

(6) Feedback lever

(7) Spring

(8) Spring

(9) Piston





(11) Chamber

(12) Piston

(13) Swashplate

(14) Chamber

(15) Rod


Drive pump regulator

(1) Spool

(2) Shoulder

(3) Piston

(4) Passage

(5) Plate

(6) Feedback lever

(7) Spring

(8) Spring

(9) Piston




The regulator is in the standby mode when all the controls are in the NEUTRAL position and the engine and pump controller raises the power shift pressure to a level that is dependent on the engine speed. Power shift pressure (PS) acts on piston (9). Cross sensing control pressure from the idler pump acts on piston (3) as well as delivery pressure (PD). Negative flow control pressure is at maximum pressure, which acts against piston (18). The engine speed keeps delivery pressure (PD) higher than the negative flow control pressure, power shift pressure (PS), and cross sensing flow pressure (CF). Spring (7) and spring (8) also act with delivery pressure to keep piston (12) from shifting to the right. The swashplate is at a maximum angle. Standby keeps the pump at a maximum angle, although little pressure is needed to destroke the pump.


(11) Chamber

(12) Piston

(13) Swashplate

(14) Chamber


Fri Feb 23 20:29:05 EST 2007


Main Control Valve SMCS - 5051

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Hydraulic schematic


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


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

(5) Return port


(7) Stick regeneration valve

(8) Load check valve

(9) Parallel feeder passage



(12) Attachment control valve

(13) Bucket control valve

(14) Center bypass passage


(16) Stick II control valve

(17) Relief valve (negative flow)


(19) Relief valve (negative flow)

(20) Negative flow control orifice

(21) Boom II control valve

(22) Stick I control valve


(24) Swing control valve



(27) Boom regeneration valve

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


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



(33) Stick unloading valve

(34) Line relief valve (bucket cylinder rod end)

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


(37) Pressure port (left pump)

(38) Negative flow control line (left pump)

(39) Pressure port (right pump)

(40) Negative flow control line (right pump)

(41) Left pump

(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)

(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)

Introduction

(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













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

Main control valve (6) is located in the hydraulic system between the main pumps and actuators

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



(45) Right body

(46) Left body

Illustration 4 g00689579Main control valve (bottom view)


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

Illustration 5 g00689582Bottom view of main control valve


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

(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 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). The right pump oil is delivered through pressure 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). The left pump oil is delivered through pressure port (37), center bypass passage (23) and return port (5) to hydraulic tank (44).

Note: 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.

Main Control Valve Operation in NEUTRAL Position

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 oil flows through center bypass passage (20), negative flow control orifice (18), return passage (19),

Illustration 6 g01239950Main control valve (neutral position)







(7) Inlet port







(14) Right body

(15) Left body


(17) Return port


(19) Return passage


(21) Inlet port


(23) Return passage

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) back to the hydraulic tank. Oil in parallel feeder passages (6) and (10) remains blocked by each control valve spool.

Activation of any joystick and/or travel levers/pedals provides two paths for right pump oil. One path flows 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 control valve (2). Activation of any joystick and/or travel levers/pedals also provides two paths for left pump oil. One path flows through center bypass passage (22) to left travel control valve (9) and stick I control valve (12). The other path flows through parallel feeder passage (10) to swing control valve (11) .

Individual Valve Operation

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

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

Illustration 7 g00747317Bucket 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

When the joystick for the bucket is moved to the BUCKET CLOSE position, pilot oil is supplied to pilot port (8). Spool (11) moves to the left. Center bypass passage (12) is closed and passage (15)

Illustration 8 g00747318Bucket control valve BUCKET CLOSE

(2) Port



(5) Passage

(6) Port

(8) Pilot port

(10) Return passage

(11) Spool


(14) Passage

(15) Passage

becomes opened. Port (14) is now connected to return passage (10) .

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 rod extends, 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.


Fri Feb 23 20:30:22 EST 2007


Negative Flow Control System SMCS - 5050-NE

Introduction The right pump and the left pump receive signal oil pressure from the center bypass passages of the main control valve. This signal oil pressure that is created in the center bypass passages of the main control valve is called negative flow control pressure. Negative flow control pressure flows to the regulators at the right pump and the left pump in order to control the output flow of the pumps. Negative flow control pressure is created during the following machine operating conditions.

All of the joysticks and travel levers/pedals are in the NEUTRAL position.

Any of the joysticks and/or travel levers/pedals are partially moved from the NEUTRAL position in order to perform a fine control operation.

A boom lower operation is performed alone.

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Main control valve (top view)

The right body of the control valve receives supply oil from the right pump. Negative flow control pressure from the right body of the main control valve flows through negative flow control line (13) to the right pump. The left body of the control valve receives supply oil from the left pump. Negative flow control pressure from the left body of the main control valve flows through negative flow control line (12) to the left pump. The negative flow control operation of the right pump and the left pump is identical.

(12) Negative flow control line to left pump

(13) Negative flow control line to right pump


Negative flow control operation (control valves in the NEUTRAL position)


(2) Return line


(4) Passage

(5) relief valve (negative flow control)



Illustration 3 shows the negative flow control operation at the main control valve when all of the control valves are in the NEUTRAL position. When all of the joysticks and the travel levers/pedals are in the NEUTRAL position, the spools of the individual control valves are in the NEUTRAL position. Oil flow to the cylinders and motors is blocked. Center bypass passages (1) and (3) are open.

All of the oil delivery from right pump (15) flows through center bypass passage (3), passage (4) and negative flow control orifice (9) to return line (2). Negative flow control orifice (9) restricts the oil flow. The pressure in passage (4) increases. Increased negative flow control pressure now flows through passage (10) and negative flow control line (13) to the pump regulator. The negative flow control operation of the right pump regulator causes the swashplate of the right pump to move to the

(8) Port


(10) Passage

(11) Return passage



(14) Left pump

(15) Right pump

(16) Pilot pump

Illustration 3 g01210684Bucket control valve (NEUTRAL position)


minimum angle position. The output flow of the right pump is decreased due to the increased negative flow control pressure that is created in center bypass passage (3) .

Since center bypass passage (1) is also open, the negative flow control operation of the left pump regulator is identical to the negative flow control operation of the right pump regulator.

ReferenceFor more information concerning the negative flow control operation of the main pump regulators, refer to Systems Operation, "Pump Control (Main Hydraulic)".


Negative flow control operation (bucket control valve in the BUCKET CLOSE position)


(2) Return line


(4) Passage




(8) Port

Illustration 5 shows the negative flow control operation at the main control valve when only the bucket control valve is in the BUCKET CLOSE position.

All of the control valves in the left body of the main control valve are in the NEUTRAL position. Center bypass passage (1) is open. All of the oil delivery from the left pump flows through center


(10) Passage

(11) Return passage



(14) Left pump

(15) Right pump

(16) Pilot pump

Illustration 5 g01210689Bucket control valve (BUCKET CLOSE position)


bypass passage (1) to negative flow control orifice (7). Since all of the oil delivery from left pump (14) is restricted by negative flow control orifice (7), negative flow control pressure (PN) in center bypass passage (1) is at maximum pressure. The negative flow control pressure flows through negative flow control line (12) to the left pump regulator. The negative flow control operation of the left pump regulator causes the swashplate of the left pump to move to the minimum angle position. The output flow of the left pump is decreased due to the increased negative flow control pressure that is created in center bypass passage (1) .

The joystick for the bucket has been moved fully to the BUCKET CLOSE position. Pilot oil has fully shifted the bucket control valve. The oil delivery from right pump (15) flows into the right body of the main control valve. The oil delivery flows through center bypass passage (3) to the bucket control valve. Since the spool in the bucket control valve is fully shifted, center bypass passage (3) is blocked. All of the oil delivery from the right pump flows to the head end of the bucket cylinder. No oil flows to negative flow control orifice (9) and no negative flow control pressure is created in center bypass passage (3). Since no negative flow control pressure is sent to the right pump regulator, the right pump regulator moves the swashplate of the right pump toward the maximum angle position. The output flow of the right pump is increased since no negative flow control pressure is created in center bypass passage (3) .

Fine Control Operation


Bucket control valve (fine control)

When the joystick for the bucket is in the NEUTRAL position, spool (23) is in the NEUTRAL position. The oil delivery from the right pump flows through center bypass passage (3) to negative flow control orifice (9). When the joystick for the bucket is partially moved from the NEUTRAL position in order to perform a fine control operation, pilot pressure (P) enters the control valve at the pilot port. Pilot pressure shifts spool (23) slightly to the left. The movement of spool (23) partially opens passage (24). Center bypass passage (3) is partially blocked.

The oil delivery from the right pump is now divided into two flow paths. A portion of the oil delivery from the right pump flows through center bypass passage (3) to negative flow control orifice (9). The remainder of the oil delivery from the right pump flows through parallel feeder passage (21) and passage (24) to port (22). The oil flow from center bypass passage (3) to negative flow control orifice (9) decreases. The flow resistance through the negative flow control orifice decreases and the negative flow control pressure (PN) in passage (4) decreases. The negative flow control pressure that is sent to the regulator at the right pump decreases. The pump regulator causes the swashplate of the right pump to move toward the maximum angle position. The output flow of the pump is increased due to the decrease in negative flow control pressure (PN) .

When the joystick for the bucket is moved to the full stroke position, spool (23) shifts fully to the left. Center bypass passage (3) is now blocked by spool (23). Since there is no oil flow through center bypass passage (24), no negative flow control pressure is created. The swashplate of the right pump is moved to the maximum angle position. The output flow of the right pump is maximum. The output flow of the right pump is now controlled by the constant horsepower flow control.

The ability to modulate the negative flow control pressure by partial movement of the joystick enables fine control of the implements.

Relief Valve (Negative Flow Control)



(22) Port

(23) Spool

(24) Passage

(P) Pilot pressure

The following description is given for the operation of the relief valve that is located in the right body of the main control valve. The operation of the relief valve for the negative flow control that is located in the left body of the main control valve is identical.

Illustration 7 g01210695(2) Return line


(4) Passage

(5) Relief valve for negative flow control


(11) Return passage

(17) Plug

(18) Spring

(19) Relief valve body

(20) Valve

(PN) Negative flow control pressure

Relief valve (5) for the negative flow control consists of plug (17), spring (18), relief valve body (19) and valve (20). When any one of the joysticks and/or travel levers/pedals is at the full stroke position, the oil flow through center bypass passage (3) is blocked. No oil flows to the relief valve for the negative flow control.

When all of the joysticks and/or travel levers/pedals are suddenly returned to the NEUTRAL position, all of the output flow from the right pump flows through center bypass passage (3). The negative flow control pressure in center bypass passage (3) and passage (4) suddenly increases. When the negative flow control pressure becomes higher than the pressure setting of relief valve (5) for the negative flow control, valve (20) shifts to the left against the force of spring (18). Oil in center bypass passage (3) is now allowed to flow past valve (20) into return passage (11) to the hydraulic tank. This prevents the hydraulic shock that occurs due to sudden changes in negative flow control pressure.

After the hydraulic shock is relieved by the relief valve for the negative flow control, the force of spring (18) shifts valve (20) to the right. All of the output flow from the right pump flows through center bypass passage (3), negative flow control orifice (9) and return line (2) to the hydraulic tank.

Negative flow control pressure (PN), that is created in center bypass passage (3), reaches maximum pressure since all of the oil flow is restricted by negative flow control orifice (9). The negative flow control pressure flows to the right pump regulator. The regulator at the right pump causes the swashplate of the right pump to move to the minimum angle position. The output flow of the right pump is decreased due to the increase in negative flow control pressure (PN) .


Wed Feb 28 19:33:25 EST 2007


Relief Valve (Main) - Heavy Lift SMCS - 5069

Limitation Of Pressure In Circuit Two types of relief valves are installed on the main control valves in order to limit the pressure in the hydraulic circuit.

The main relief valve limits the pressure in the main hydraulic system.

The line relief valve limits the pressure which is built into the cylinder circuits.

Main Relief Valve

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Straight travel control valve and main relief valve (sectional view)




(4) Check valve

(5) Check valve

(6) Passage

(7) Pilot pump

(8) Right pump

(9) Heavy lift solenoid valve


(11) Passage

(12) Line

(13) Left pump

(14) Line

(15) Line

Oil from right pump (8) and left pump (13) enters main control valve (1) through lines (15) and (14). Right pump oil and left pump oil goes through check valves (5) and (4) to passage (6). The higher oil pressure from the right pump or the left pump goes through passage (6) to main relief valve (10).

CLOSED Position (Heavy Lift OFF)

When main pump oil pressure in passage (6) is less than the main relief pressure setting, valve (18) and valve (21) is closed by the force of spring (20) and spring (22). The oil in passage (6) goes through orifice (24). Oil enters spring chamber (19). The pressure in passage (6) and the pressure in spring chamber (19) are equal. Valve (18) shifts left by the force of spring (20). Valve (18) closes passage (23). There is no oil flow from passage (6) to return passage (25).

(16) Pilot manifold

(17) Line

Illustration 2 g01196496Main relief valve (CLOSED)

(6) Passage

(18) Valve

(19) Spring chamber

(20) Spring

(21) Valve

(22) Spring

(23) Passage

(24) Orifice

OPEN Position (Heavy Lift OFF)

Oil pressure in passage (6) nears the relief pressure setting. Oil pressure in passage (6) overcomes the force of spring (22). The oil pressure opens valve (21). The oil in valve chamber (27) goes through passage (26) to return passage (25). The oil is called low pressure oil. The oil pressure from passage (6) decreases at orifice (24). The oil then goes through spring chamber (19) to valve chamber (27). Because of the decreased oil pressure in spring chamber (19), the oil pressure from passage (6) pushes valve (18) to the right against the force of spring (20). Passage (23) now opens allowing the high pressure oil flow from passage (6) to return passage (25) .

Illustration 3 g01196500Main relief valve (OPEN)

(6) Passage

(18) Valve

(19) Spring chamber

(20) Spring

(21) Valve

(22) Spring

(23) Passage

(24) Orifice

(25) Return passage

(26) Passage

(27) Chamber

Heavy Lift Operation

Illustration 4 g01196503(6) Passage

(18) Valve

(19) Spring chamber

(20) Spring

(21) Valve

(22) Spring

(23) Passage

(24) Orifice

(25) Return passage

(26) Passage

(27) Chamber

(28) Port

(29) Passage

(30) Piston

When the heavy lift switch (31) is placed in the ON position, heavy lift solenoid (9) shifts. Pilot oil now flows from pilot manifold (16) through solenoid (9), line (11), and port (28). Pilot oil enters passage (29) which forces piston (30) to shift to the left which causes a higher force on valve (21). A higher pressure is now needed to open main relief valve (10). The larger pressure results in a greater overall system pressure. The greater system pressure allows more pressure in the boom and stick cylinders which increases the lifting capacity.

Illustration 5 g01184035Switch Panel (right console)

(31) Heavy lift switch


Wed Feb 28 19:34:49 EST 2007


Relief Valve (Line) SMCS - 5117

Each line relief valve contains a makeup valve. The line relief valves are located between each cylinder and the respective control valve.

When the control valves for the cylinders are in the NEUTRAL position and an external force acts on one end of the cylinder, the oil pressure increases on the opposite end of the cylinder. The oil pressure also increases in the passage of the line relief valve that is connected to the cylinder. The line relief valve relieves the high pressure. The line relief valves limit the circuit pressure to the specified pressure settings.

Reference: Refer to Testing and Adjusting, "Pressure Specifications" for the line relief valve pressure settings.

Shutdown

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Line relief valve (CLOSED position)

The high pressure between the cylinder and the control valve is transmitted to passage (1). This pressurizes the line relief valve. The pressure oil flows from passage (1) through passage (9) of piston (7). The oil then flows into spring chamber (4). When the oil pressure is lower than the line relief valve pressure setting, valve (5) remains in the CLOSED position by the force of spring (6). The oil pressure in passage (1) and the oil pressure in spring chamber (4) are equal. The surface area of the right side of valves (2) and (3) is larger than the surface area of the left side. The force on the right side of valves (2) and (3) is greater than the force on the left side. Valves (2) and (3) are forced to the left. The pressure oil does not flow from passage (1) to passage (8).

(1) Passage

(2) Valve

(3) Valve

(4) Spring chamber

(5) Valve

(6) Spring

(7) Piston

(8) Return passage

(9) Passage


Line relief valve (OPEN position)

(1) Passage

(3) Valve

(4) Spring chamber

When the high pressure oil in passage (1) reaches the line relief valve pressure setting, valve (5) overcomes the force of spring (6) and opens. The high pressure oil flows from valve chamber (10) through passage (12) to return passage (8). The pressure now becomes low pressure. The pressure in passage (1) pushes piston (7) to the right until the piston comes in contact with the left end of valve (5). The oil in passage (1) flows around the end of piston (7) and the oil enters spring chamber (4). Since the flow around the outside of piston (7) is restricted, the oil in spring chamber (4) becomes low pressure oil. As a result, valve (3) is pushed to the right. Passage (11) opens. the oil flows from passage (1) to passage (8).

(5) Valve

(6) Spring

(7) Piston

(8) Return passage

(9) Passage

(10) Valve chamber

(11) Passage

(12) Passage


Line relief valve (makeup operation)

(1) Passage

(2) Valve

(3) Valve

(4) Spring chamber

The line relief valve functions as a makeup valve in the following manner.

When oil from one end of the cylinder is discharged through the line relief valve, a vacuum condition is created on the opposite end of the cylinder. Makeup oil is needed to prevent the vacuum condition in the cylinder.

When the vacuum condition occurs on the end of the cylinder that is connected to passage (1), a vacuum condition also occurs in spring chamber (4). The pressure of the oil in passage (8) acts on shoulder (13) of valve (2). Since a vacuum condition is present in spring chamber (4), the pressure in spring chamber (4) is lower than the pressure of the return oil in passage (8). Valves (2) and (3) are pushed to the right by the pressure of the return oil in passage (8). Return oil flows from passage (8) to passage (1) as makeup oil in order to remove the vacuum condition in the cylinder.

(8) Return passage

(9) Passage

(13) Shoulder


Wed Feb 28 19:37:15 EST 2007


Check Valve (Load) SMCS - 5472

The load check valve performs the following two functions.

The load check valve prevents unexpected movement of an implement when a joystick is initially activated at a low pump delivery pressure.

The load check valve prevents oil loss from a high pressure circuit to a lower pressure circuit.

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When the joystick for the boom is in the NEUTRAL position, spring (8) positions spool (10) in the center position. The right pump is at a destroked position. The right pump is delivering standby

Illustration 1 g01181191Boom I control valve (partial shift)

(1) Port (boom cylinder head end)

(2) Passage

(3) Spring


(5) Port (boom cylinder rod end)

(6) Return passage


(8) Spring

(9) Pilot port

(10) Spool


pressure to the boom I control valve. The pump delivery pressure in center bypass passage (11) and parallel feeder passage (7) is lower than the pressure in the boom cylinder head end at port (1). Load check valve (4) is in the CLOSED position.

Slight movement of the joystick for the boom toward the BOOM RAISE position causes low pilot oil pressure to enter port (9). Spool (10) shifts slightly to the right. The right pump begins to move to an upstroke position. A passage partially opens allowing the oil from the rod end of the boom cylinders in port (5) to flow to return passage (6). A passage partially opens allowing the oil from the head end of the boom cylinders in port (1) to flow through passage (2). The work load pressure from the head end of the boom cylinders and the force of spring (3) now acts on load check valve (4). Since the pump delivery pressure is lower than the work load pressure in passage (2), load check valve (4) remains in the closed position. The oil in the boom cylinder head end is blocked.


Boom I control valve (full shift)

(1) Port (boom cylinder head end)

(2) Passage

(3) Spring


(5) Port (boom cylinder rod end)

As the joystick for the boom is moved farther from the NEUTRAL position, the pilot oil pressure at pilot port (9) increases. Spool (10) shifts farther to the right. The right pump upstrokes farther. The pump delivery pressure in center bypass passage (11) and parallel feeder passage (7) increases. Load check valve (4) will not open until the pump delivery pressure becomes greater than the combined force of the work load pressure in passage (2) and the force of spring (8). Unexpected downward movement of the boom during a BOOM RAISE operation is prevented.

Load check valve (4) also prevents oil loss from a high pressure circuit to a lower pressure circuit. For example, the work tool is moved under a light load, and the boom cylinders are raised at the same time. The high pressure oil of the boom cylinders wants to flow toward the low pressure side of the work tool. The load check valve prevents the boom from lowering.

(6) Return passage


(8) Spring

(9) Pilot port

(10) Spool



Wed Feb 28 19:37:52 EST 2007


Boom Hydraulic System SMCS - 5050-BM

Boom Raise (High Speed)

Shutdown

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Hydraulic schematic for BOOM RAISE (high speed)

(1) Boom cylinders

(2) Line (oil flow from boom cylinder rod end)

(3) Line (oil flow to boom cylinder head end)

(4) Valve


(6) Return line

(7) Port


(9) Return passage

(10) Line


(12) Passage

(13) Check valve


(15) Port



(18) Return passage


(20) Port

(21) Pilot line


(23) Pilot line

(24) Pilot line

(25) Pilot line


(27) Left pump

(28) Right pump

(29) Pilot pump

(33) Spring

A BOOM RAISE operation at high speed is accomplished when the oil delivery from both left pump (27) and right pump (28) is supplied to the head end of boom cylinders (1). Boom I control valve (19) and boom II control valve (16) operate during the high speed operation. A BOOM RAISE operation at low speed is accomplished when the oil delivery from only right pump (28) is supplied to the head end of boom cylinders (1). During the low speed operation, boom I control valve (19) operates alone.

The oil delivery from right pump (28) flows through parallel feeder passage (17) in main control valve (11) to boom I control valve (19). The oil delivery from left pump (27) flows through parallel feeder passage (8) in main control valve (11) to boom II control valve (16) .

(37) Spring

Illustration 2 g00747466Main control valve compartment



Illustration 3 g00694273Boom drift reduction valve (bottom view)


When the joystick for the boom is moved to the full BOOM RAISE position, the pilot oil flows from pilot control valve (22) through pilot line (24). The pilot oil flow then divides into two flow paths. Part of the pilot oil flows through pilot line (21) to port (7) of main control valve (11). The remainder of the pilot oil flows through pilot line (23) to port (20) of the main control valve.

A portion of the oil in pilot line (23) also flows through pilot line (25) to the pressure reducing valve for boom priority (26). During a combined operation of BOOM RAISE and STICK IN, BOOM RAISE and STICK OUT, or BOOM RAISE and BUCKET CLOSE, the pilot oil flow to the pressure reducing valve for boom priority (26) causes the boom circuit to receive oil flow priority. This allows the boom to raise at a high speed.


Boom I control valve (BOOM RAISE position)



(18) Return passage

(20) Port

(30) Port

(31) Passage

The pilot oil flow from port (20) shifts spool (35) of boom I control valve (19) against the force of spring (33). The oil delivery from the right pump in parallel feeder passage (17) flows through load check valve (14), passage (31), passage (34) and port (30) to boom drift reduction valve (5). The oil delivery from the right pump shifts valve (4) in boom drift reduction valve (5) to the right. The oil delivery from the right pump then flows through line (3) to the head end of boom cylinders (1) .

Note: For more information on the boom drift reduction valve, refer to Systems Operation, "Boom Drift Reduction Valve".

(32) Passage

(33) Spring

(34) Passage

(35) Spool


Boom II control valve (BOOM RAISE position)

(7) Port


(13) Check valve

The pilot oil flow in port (7) of boom II control valve (16) shifts spool (38) against the force of spring (37). The oil delivery from the left pump in parallel feeder passage (8) now flows through passage (36), passage (39), check valve (13) and flows out of port (15) to line (10). The oil delivery from the left pump combines with the oil delivery from the right pump at boom drift reduction valve (5). The combined pump oil flows through passage (12) and line (3) to the head end of boom cylinders (1) .

Note: The swing priority valve does not affect the boom II control valve.

Return oil from the rod end of boom cylinders (1) flows through line (2) to boom I control valve (19). The oil then flows through passage (32), return passage (18), return passage (9) and return line (6) to the hydraulic tank.

Boom Raise (Low Speed) When the joystick for the boom is moved less than half of the travel distance for BOOM RAISE, low pilot oil pressure is supplied to boom I control valve (19) and boom II control valve (16) .

When the boom is raised at a low speed, boom I control valve (19) opens and boom II control valve (16) remains closed. The force of spring (33) in boom I control valve (19) is less than the force of spring (37) in boom II control valve (16). Because of the low pilot oil pressure, boom I control valve (19) will open and boom II control valve (16) will remain closed.

The oil delivery from right pump (28) now flows to the head end of boom cylinders (1). Without the oil delivery from left pump (27), the cylinder rod movement slows down when the boom is raised. The low speed operation of the boom is performed.

Boom Priority

(15) Port

(36) Passage

(37) Spring

(38) Spool

(39) Passage

During combined operations of BOOM RAISE and STICK IN, the pilot oil pressure from the pilot control valve for the boom (22) activates the pressure reducing valve for boom priority (26). The pressure reducing valve for boom priority (26) causes oil flow priority to the head end of the boom cylinders (1) during this combined hydraulic operation.

When the joystick for the stick is moved to the STICK IN position, a portion of the pilot oil from the pilot control valve for the stick (41) flows through the pressure reducing valve for the boom priority (26) to the stick II control valve (40). As the joystick for the boom is moved farther from the NEUTRAL position during a BOOM RAISE operation, pilot oil pressure from the pilot control valve for the boom (22) increases. This gradual increase in pilot oil pressure causes the spool in the pressure reducing valve for the boom priority (26) to gradually shift.

A portion of the pilot oil that flows to stick II control valve (40) from the pilot control valve for the stick (41) is routed to the hydraulic tank. The pilot oil pressure that acts on stick II control valve (40) decreases. Stick II control valve (40) shifts toward the NEUTRAL position. The amount of oil flow from the main pumps to the stick hydraulic circuit decreases. This causes a greater portion of the oil

Illustration 6 g01240675Hydraulic schematic for BOOM RAISE and STICK IN

(1) Boom cylinders




(41) Pilot control valve (stick and swing)

flow from the main pumps to flow to the head end of the boom cylinders (1) .

Since the pilot oil pressure from the pilot control valve for the boom (22) directly corresponds to the amount of movement or position of the joystick a gradual change to boom priority occurs. Thus, boom priority is controlled by the position of the joystick for the boom and boom priority automatically activates when the joystick reaches a certain position during a BOOM RAISE operation.

The above information describes the condition of BOOM RAISE and STICK IN. During any combined function of BOOM RAISE and STICK IN, BOOM RAISE and STICK OUT, or BOOM RAISE and BUCKET CLOSE, the pressure reducing valve for boom priority allows priority flow to the head end of the boom cylinders by reducing pilot pressure to the stick I, stick II, or bucket control valves.

ReferenceFor more information concerning boom priority, refer to Systems Operation, "Pilot Hydraulic System".

Boom Lower


Hydraulic schematic for BOOM LOWER

(1) Boom cylinders

(2) Line (oil flow to boom cylinder rod end)

During a BOOM LOWER operation, the oil delivery from only right pump (28) is supplied to boom cylinders (1) through boom I control valve (19). Boom I control valve (19) operates alone. Boom II control valve (16) is not operational in the BOOM LOWER operation.

The BOOM LOWER operation contains a regeneration circuit. When the joystick for the boom is

(3) Line (oil flow from boom cylinder head end)

(4) Valve





(18) Return passage



(27) Left pump

(28) Right pump

(29) Pilot pump

(33) Spring

(40) Orifice

(41) Boom regeneration valve

(42) Port

(43) Orifice



(46) Port

(48) Valve

(49) Passage

(50) Drain line

(51) Passage

(52) Pilot line

(53) Pilot line

moved to the BOOM LOWER position, orifice (43) in boom I control valve (19) and boom regeneration valve (41) are operational in the boom hydraulic circuit. The return oil flow from the head end of boom cylinders (1) flows through boom regeneration valve (41) to the rod end of the boom cylinders. The boom regeneration valve is described later in this section.

When the joystick for the boom is moved to the BOOM LOWER position, pilot oil from pilot control valve (22) flows through pilot line (52). The pilot oil flow then divides into three flow paths. Part of the pilot oil flows through port (46) to boom I control valve (19). Part of the pilot oil flows through port (42) to boom regeneration valve (41). The remainder of the pilot oil flows through pilot line (53) of boom drift reduction valve (5) .

Since the pilot oil pressure has caused the spool in boom I control valve (19) to shift against the force of spring (33), the oil delivery from the right pump that flows through center bypass passage (45) is restricted by orifice (43). The negative flow control pressure in negative flow control line (44) decreases. The right pump upstrokes because of the negative flow control operation.

ReferenceFor more information concerning the negative flow control operation, refer to Systems Operation, "Negative Flow Control".


Boom I control valve (BOOM LOWER position)



The pilot oil flow from port (46) shifts spool (35) in boom I control valve (19) against the force of spring (33). The oil delivery from the right pump in parallel feeder passage (17) flows through load check valve (14), passage (49) and port (32). The oil delivery from the right pump then flows through line (2) to the rod end of boom cylinders (1) .

The return oil from the head end of boom cylinders (1) flows through line (3) into boom drift reduction valve (5). Since valve (48) is shifted by the pilot pressure from pilot line (53), passage (49) is open to drain line (50). The return oil pressure shifts valve (4) to the right. The return oil in line (3) enters passage (51) .

A portion of the return oil flows into port (30) of boom I control valve (19). The return oil flow is restricted by orifice (40). The return oil pressure in passage (51) increases. Most of the return oil flows through boom regeneration valve (41). The return oil is now supplied to the rod end of the boom cylinders through line (2) .

Boom Regeneration Valve

(18) Return passage

(30) Port

(32) Port

(33) Spring

(35) Spool

(42) Orifice

(45) Orifice

(46) Port

(49) Passage

Illustration 9 g01211092Boom regeneration valve (slow boom down)


(42) Pilot port

(56) Passage

(57) Check valve

(58) Spool (boom regeneration valve)

(59) Passage

The boom hydraulic circuit contains a regeneration circuit. This regeneration circuit allows the return oil from the head end of the boom cylinders to be supplied to the rod end of the boom cylinders during the BOOM LOWER operation.

When the joystick for the boom is moved to the BOOM LOWER position, pilot oil flow from the pilot control valve (boom and bucket) enters pilot port (42). Spool (58) in the boom regeneration valve shifts downward. The return oil from the head end of the boom cylinders flows through passage (59) and through the throttling slots on the spool for the boom regeneration valve to check valve (57). Check valve (57) opens and the return oil flows through passage (56). The return oil from the head end of the boom cylinders in passage (56) combines with the oil delivery from the right pump. This combined oil now flows to the rod end of the boom cylinders.

The oil delivery from only the right pump is used for the BOOM LOWER operation. Since the boom regeneration valve supplies return oil from the head end to the rod end of the boom cylinders, more efficient use of the oil delivery from the right pump is achieved during a BOOM LOWER operation.

Illustration 10 g01211096Boom regeneration valve (fast boom down)


(42) Pilot port

(56) Passage

(57) Check valve

(58) Spool (boom regeneration valve)

(59) Passage


Wed Feb 28 19:40:40 EST 2007


Boom Drift Reduction Valve SMCS - 5143-BM

The boom drift reduction valve is placed in the boom circuit between the main control valve and the boom cylinders. When the joystick for the boom is in the NEUTRAL position, the boom drift reduction valve stops oil leakage from the head end of the boom cylinders. Stopping oil leakage prevents boom drift.

Boom Raise

Shutdown

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i02429879

Illustration 1 g01214091Boom drift reduction valve (BOOM RAISE)

(1) Passage

(2) Valve

(3) Spring

(4) Spring chamber

(5) Passage

(6) Port

(7) Port

(8) Port

(9) Passage

(11) Spool

(15) Port


When the joystick is moved to perform a BOOM RAISE operation, pilot oil is not sent from the pilot control valve to port (15) of boom drift reduction valve (16). Spool (11) does not shift.

The oil flow from the boom II control valve enters port (6) of the boom drift reduction valve. The oil flow from the boom I control valve enters port (7) of the boom drift reduction valve. The combined oil flow from ports (6) and (7) flows into passage (1). As the oil pressure in passage (1) increases, valve (2) shifts against the force of spring (3). The oil in spring chamber (4) flows through passages (5) and (9) to port (8). The oil delivery in passage (1) now flows through port (8) to the head end of the boom cylinders.

Boom Lower


Boom drift reduction valve (BOOM LOWER)

(1) Passage

(2) Valve

(3) Spring

(4) Spring chamber

(5) Passage

(6) Passage

(7) Port

When the joystick is moved to perform a BOOM LOWER operation, pilot oil is sent from the pilot control valve to port (15) of boom drift reduction valve (16). Spool (11) shifts downward until the spool contacts plug (21). The oil in spring chamber (4) flows through passage (5), the passage in spool (11), spring chamber (20), passage (6), port (18) and drain line (13) to the hydraulic tank.

The return oil from the boom cylinder head end enters port (8). Since the pressure in spring chamber (4) is low, the oil in port (8) shifts valve (2) against the force of spring (3). The oil from the head end of the boom cylinders flows through port (8), passage (1) and passage (7) to the boom I control valve.

(8) Port

(11) Spool

(13) Drain line

(15) Port


(18) Port

(20) Spring chamber

(21) Plug


Wed Feb 28 19:41:35 EST 2007


Stick Hydraulic System SMCS - 5050

Stick Out

Shutdown

Previous Screen



i02485801


Hydraulic schematic for STICK OUT

(1) Stick cylinder

(2) Line (oil flow from stick cylinder rod end)

(3) Line (oil flow to stick cylinder head end)

(4) Valve



(7) Line

(8) Passage

(9) Return passage

(10) Return passage

(11) Return passage





(16) Check valve

(17) Passage


(19) Check valve




(23) Return line

(24) Pilot line

(25) Pilot line

(26) Pilot line


(28) Drive pump

(29) Idler pump

(30) Pilot pump

When the stick hydraulic circuit is operated independently of other hydraulic circuits, stick I control valve (21) and stick II control valve (13) are operational for both the STICK IN operation and the STICK OUT operation. When the stick I control valve and the stick II control valve are operated, the oil delivery from idler pump (29) and drive pump (28 ) is combined. The oil delivery from both pumps flows to stick cylinder (1) in order to perform a stick operation.

The oil delivery from drive pump (28) flows through parallel feeder passage (22) in main control valve (6) to stick II control valve (13). The oil delivery from idler pump (29) flows through center bypass passage (18) in main control valve (6) to stick II control valve (21) .

When the joystick for the stick is moved to the STICK OUT position, the pilot oil flows from pilot

Illustration 2 g00695552Main control valve



Illustration 3 g00695556Main control valve (bottom view)


control valve (27) through pilot line (26). The pilot oil flow then divides into two flow paths. Part of the pilot oil flows through pilot line (24) to stick I control valve (21) in main control valve (6). The remainder of the pilot oil flows through pilot line (25) to stick II control valve (13) in the main control valve.

The pilot oil in pilot line (24) shifts the spool of stick I control valve (21). The oil delivery from idler pump (29) that is in center bypass passage (18) flows through load check valve (15), passage (17) and passage (8). The oil delivery from the idler pump then enters stick drift reduction valve (5). Valve (4) shifts to the left and the oil delivery flows through line (3) to the rod end of stick cylinder (1) .

The pilot oil in pilot line (25) shifts the spool of stick II control valve (13). The oil delivery from drive pump (28) in center bypass passage (12) cannot flow through the stick II control valve to center bypass passage (14) and return passage (11). Part of the oil delivery from the drive pump now flows through check valve (16) and the stick II control valve to line (7). The remainder of the oil delivery from the drive pump flows through parallel feeder passage (22), check valve (19) and the stick II control valve to line (7). All of the oil delivery from the drive pump in line (7) flows to stick drift reduction valve (5) and combines with the oil delivery from the drive pump. The combined pump oil flows to the rod end of stick cylinder (1). This combined pump oil causes the cylinder to retract at an increased rate of speed.

Return oil from the head end of the stick cylinder flows through line (2) and return passage (9) to stick I control valve (21). The return oil then flows through return passage (10) and return line (23) to the hydraulic tank.

Stick In (Fast)


Hydraulic schematic for STICK IN (fast with regeneration)

(1) Stick cylinder

(2) Line (oil flow to stick cylinder rod end)

(3) Line (oil flow from stick cylinder head end)

(4) Valve



(9) Passage

(10) Return passage

(11) Return passage




(16) Check valve


(19) Check valve



(23) Return line


(28) Drive pump

(29) Idler pump

(30) Pilot pump



(33) Pilot line

(34) Pilot line

(35) Pilot line

The STICK IN operation contains a regeneration circuit. When the joystick for the stick is moved to the STICK IN position, stick regeneration valve (31) and stick unloading valve (32) are operational in the stick hydraulic circuit. The return oil from the rod end of stick cylinder (1) is supplied to the head end of the stick cylinder. The regeneration circuit makes more effective use of the return oil from the stick cylinder. This allows the oil delivery from the idler pump and the drive pump to perform other implement functions during a STICK IN operation.

When the joystick for the stick is moved to the STICK IN position, pilot oil from pilot control valve (27) flows through pilot line (33). The pilot oil flow then divides into several flow paths. Part of the pilot oil flows through pilot line (34), pilot line (35) and pilot line (36) to stick I control valve (21). The pilot oil in pilot line (36) also flows through passage (37) in stick drift reduction valve (5). Part of the pilot oil flows through pilot line (38) to stick regeneration valve (31). The remainder of the pilot oil flows through pilot line (39), the pressure reducing valve for boom priority (40) and pilot line (41) to stick II control valve (13) .

Since the pilot oil pressure has caused the spool in stick I control valve (21) to shift downward, the oil delivery from the idler pump flows through center bypass passage (18), load check valve (15), stick I control valve (21) and passage (9) to line (2) .

The pilot oil pressure in pilot line (41) has caused the spool in stick II control valve (13) to shift downward. Part of the oil delivery from the drive pump that is in center bypass passage (12) flows through check valve (16) and stick II control valve (13) to line (42). The remainder of the oil delivery from the drive pump flows through parallel feeder passage (22), check valve (19) and stick II control valve (13) to line (42). All of the oil delivery from the drive pump in line (42) flows to line (2) and combines with the oil delivery from the idler pump. The combined pump oil flows to the head end of stick cylinder (1) .

The return oil from the rod end of the stick cylinder flows through line (3) to stick drift reduction valve (5). Valve (4) in the stick drift reduction valve shifts to the left and the return oil enters passage

(36) Pilot line

(37) Passage

(38) Pilot line

(39) Pilot line


(41) Pilot line

(42) Line

(43) Passage

(44) Passage

(45) Passage

(46) Passage

(47) Passage

(48) Check valve

(43). Part of the return oil in passage (43) flows through stick I control valve (21), return passage (10) and return line (23) to the hydraulic tank. The remainder of the return oil flows through the regeneration circuit to the head end of the stick cylinders.

Stick In (Slow)


Hydraulic schematic for STICK IN (slow without regeneration)

(1) Stick cylinder

(2) Line (oil flow to stick cylinder rod end)

(3) Line (oil flow from stick cylinder head end)

(4) Valve



(9) Passage

(10) Return passage

(11) Return passage




(16) Check valve


(19) Check valve



(23) Return line


(28) Drive pump

(29) Idler pump

(30) Pilot pump



(33) Pilot line

(34) Pilot line

(35) Pilot line

(36) Pilot line

(37) Passage

(38) Pilot line

(39) Pilot line


(41) Pilot line

(42) Line

(43) Passage

(44) Passage

(45) Passage

(46) Passage

As the joystick for stick in is moved slowly, the pilot pressure will not shift stick II control valve (13) or stick regeneration valve (31) .

Stick Regeneration Valve

(47) Passage

(48) Check valve

Illustration 6 g01243867Stick regeneration valve


(9) Passage


(38) Pilot line

(43) Passage

(48) Check valve

The stick hydraulic circuit contains a regeneration circuit. This regeneration circuit allows the return oil from the rod end of the stick cylinder to be supplied to the head end of the stick cylinder during the STICK IN operation.

When the joystick for the stick is moved to the STICK IN position, pilot oil flow from the pilot control valve (stick and swing) flows through pilot line (38). Stick regeneration valve (31) shifts downward. The return oil from the rod end of the stick cylinder flows through passage (43) and through the throttling slots on valve (31) to check valve (48). Check valve (48) opens and the return oil flows through passage (9). The return oil from the rod end of the stick cylinder in passage (9) combines with the oil delivery from the idler pump and the drive pump. This combined oil flow now flows into the head end of the stick cylinder.

Stick Unloading Valve


Stick unloading valve


(9) Passage


Stick unloading valve (32) works in conjunction with stick regeneration valve (31) in order to relieve high pressure in the head end of the stick cylinder during a STICK IN operation.

When the joystick for the stick is moved to the STICK IN position, pilot oil flow from the pilot control valve (stick and swing) flows through pilot line (38). Stick regeneration valve (31) shifts downward. The return oil from the rod end of the stick cylinder flows through passage (43) and through the throttling slots on valve (31) to check valve (48). Check valve (48) opens and the return oil flows through passage (9). The return oil from the rod end of the stick cylinder in passage (9) combines with the oil delivery from the idler pump and the drive pump. This combined oil flow now flows into the head end of the stick cylinder.

Because of the volume of oil that is forced into the head end of the stick cylinder during the regeneration cycle of the STICK IN operation, the pressure of the oil in the head end of the stick cylinder increases. The high pressure oil flows through passage (9) and passage (44). The high pressure oil now acts on the end of stick unloading valve (32). When the force of the high pressure oil becomes greater than the force of spring (50), the stick unloading valve shifts downward. The return oil from the rod end of the stick cylinder in passage (43) flows past the throttling slots on stick regeneration valve (31), through passage (49), through stick unloading valve (32) and passage (47) and into the return circuit to the hydraulic tank. The return oil from the rod end of the stick cylinder is quickly unloaded. At this time, the regeneration circuit for the stick cylinder is inoperable.

When the oil pressure at the head end of the stick cylinder decreases, the oil pressure that acts on the end of stick unloading valve (32) also decreases. The force of spring (50) shifts the stick unloading valve upward. The return oil from the rod end of the stick cylinder is supplied to the head end of the stick cylinder. The regeneration circuit is again operable.


(38) Pilot line

(43) Passage

(44) Passage

(46) Passage

(47) Passage

(49) Passage

(50) Spring


Wed Feb 28 19:42:32 EST 2007


Stick Drift Reduction Valve SMCS - 5143-JJ

The stick drift reduction valve is placed in the stick circuit between the main control valve and the stick cylinder. When the joystick for the stick is in the NEUTRAL position, the stick drift reduction valve stops oil leakage from the rod end of the stick cylinder. Stopping oil leakage prevents stick drift.

Stick Out

Shutdown

Previous Screen



i01310189

Illustration 1 g00694228Stick drift reduction valve (STICK OUT)

(1) Passage

(2) Valve

(3) Spring

(4) Spring chamber

(5) Passage

(6) Port

(7) Port

(8) Port

(9) Passage

(11) Spool

(15) Port


When the joystick is moved to perform a STICK OUT operation, pilot oil is not sent from the pilot control valve to port (15) of stick drift reduction valve (16). Spool (11) does not shift.

The oil flow from the stick II control valve enters port (6) of the stick drift reduction valve. The oil flow from the stick I control valve enters port (7) of the stick drift reduction valve. The combined oil flow from ports (6) and (7) flows into passage (1). As the oil pressure in passage (1) increases, valve (2) shifts against the force of spring (3). The oil in spring chamber (4) flows through passages (5) and (9) to port (8). The oil delivery in passage (1) now flows through port (8) to the rod end of the stick cylinder.

Stick In


Stick drift reduction valve (STICK IN)

(1) Passage

(2) Valve

(3) Spring

(4) Spring chamber

When the joystick is moved to perform a STICK IN operation, pilot oil is sent from the pilot control valve to port (15) of stick drift reduction valve (16). Spool (11) shifts downward until the spool contacts plug (22). The oil in spring chamber (4) flows through passage (5), the orifice in spool (11), spring chamber (20), passage (21), port (18) and drain line (13) to the hydraulic tank.

The return oil from the stick cylinder rod end enters port (8). Since the pressure in spring chamber (4) is low, the oil in port (8) shifts valve (2) against the force of spring (3). The oil from the rod end of the stick cylinder flows through port (8), passage (1) and passage (7) to the stick I control valve.

(5) Passage

(6) Port

(7) Port

(8) Port

(11) Spool

(13) Drain line

(15) Port


(18) Port

(20) Spring chamber

(21) Passage

(22) Plug


Wed Feb 28 19:43:16 EST 2007


Bucket Hydraulic System SMCS - 5050-YB

Shutdown

Previous Screen



i02485472


(1) Pilot line

(2) Line

(3) Line

The oil delivery for the bucket hydraulic circuit is supplied by idler pump (22) only.

(4) Bucket cylinder


(6) Return line




(10) Spring

(11) Orifice


(13) Spring




(17) Return passage

(18) Pilot line



(21) Drive pump

(22) Idler pump

(23) Pilot pump

The oil delivery from idler pump (22) flows through center bypass passage (8) in main control valve (5) to bucket control valve (9). The oil delivery from drive pump (21) flows through center bypass passage (7) in main control valve (5). Illustration 1 shows the main control valve when only the bucket hydraulic circuit is activated.

When the hydraulic activation control lever is in the UNLOCKED position, the oil delivery from pilot pump (23) flows through pilot oil manifold (20) to pilot control valve (15). When the joystick for the bucket is moved to the BUCKET CLOSE position, pilot oil flows through pilot control valve (15) and pilot line (1) to bucket control valve (9). The pilot oil pressure shifts the spool in the bucket control valve against spring (13). The pilot oil on the other end of the spool in the bucket control valve flows through pilot line (18) and pilot control valve (15) to the hydraulic tank.

Since the spool in the bucket control valve is fully shifted, center bypass passage (8) is blocked. None of the oil delivery from the idler pump flows to negative flow control orifice (14) and no negative flow control pressure is created in center bypass passage (8). Since no negative flow control pressure is sent through negative flow control line (19) to the idler pump regulator, the idler pump regulator moves the swashplate of the idler pump toward the maximum angle position. The output flow rate of the idler pump is increased and flows through parallel feeder passage (16), load check valve (12), bucket control valve (9) and line (3) to the head end of bucket cylinder (4) .

Since the oil delivery for the bucket hydraulic circuit is supplied by the idler pump only, the negative control pressure in center bypass passage (7) is high. Drive pump (21) remains at the destroked position.


The return oil from the rod end of the bucket cylinder flows through line (2), orifice (11) in bucket control valve (9), return passage (17) and return line (6) to the hydraulic tank. Orifice (11) restricts the return oil from the rod end of the bucket cylinder.

The BUCKET OPEN operation is similar to the BUCKET CLOSE operation.

When the joystick for the bucket is moved to the BUCKET OPEN position, pilot oil flow from pilot control valve (15) flows through pilot line (18) to the bucket control valve. The spool in the bucket control valve shifts against the force of spring (10). The oil delivery from the idler pump now flows to the rod end of the bucket cylinder.

When the joystick for the bucket is in the NEUTRAL position, springs (10) and (13) maintain the spool in the bucket control valve in the NEUTRAL position. The oil flow from the head end and the rod end of the bucket cylinder is blocked.

Illustration 2 g00697166(9) Bucket control valve


Wed Feb 28 19:43:56 EST 2007


Cylinders (Boom, Stick and Bucket) SMCS - 7562

Shutdown

Previous Screen



i01468748


(1) Rod end port

(2) Head end port

(3) Boom cylinder

(4) Tube

When boom cylinders (3) or stick cylinder (8) moves close to the end of the extension stroke, passage (11) is restricted by snubber (6). The movement of the piston rod slows down before the piston rod stops.

(5) Rod

(6) Snubber

(7) Piston

(8) Stick cylinder

(9) Snubber

(10) Bucket cylinder

Illustration 2 g00766296Snubber operation

(6) Snubber

(11) Passage

When stick cylinder (8) moves close to the end of the retraction stroke, passage (12) is restricted by snubber (9). The movement of the piston rod slows down before the piston rod stops. The shock load is absorbed when the piston is slowed down.

Illustration 3 g00766297Snubber operation (retracting rod)

(9) Snubber

(12) Passage


Wed Feb 28 19:44:37 EST 2007


Swing Hydraulic System SMCS - 5050

Shutdown

Previous Screen



i02485778


Hydraulic schematic for SWING RIGHT

(1) Pilot line

(2) Passage

(3) Swing parking brake

(4) Swing motor

(5) Motor rotary group

(6) Relief valve

(7) Anti-reaction valve

(8) Return line

(9) Line

(10) Line

(11) Passage





(16) Passage

(17) Passage




(21) Passage

(22) Passage


(24) Pilot line

(25) Implement/swing pressure switch

(26) Line


(28) Drive pump

(29) Idler pump

(30) Pilot pump


The oil delivery for the swing hydraulic circuit is supplied by idler pump (28) only. When either one of the joysticks is moved from the NEUTRAL position, swing parking brake (3) is released. Motor rotary group (5) starts to rotate. The swing motor is mounted on top of the swing drive. The swing drive is installed on the upper structure. The swing drive reduces the motor speed by two stages. The swing drive rotates the upper structure.

ReferenceFor more information concerning the operation of the swing motor, refer to Systems Operation, "Swing Motor".

ReferenceFor more information concerning the operation of the swing drive, refer to Systems Operation, "Swing Drive".

ReferenceFor more information concerning the operation of the swing parking brake and the swing brake solenoid valve, refer to Systems Operation, "Pilot Valve (Swing Parking Brake)".

(32) Line


(34) Hydraulic tank


(36) Drain line

(37) Pilot line

(38) Pilot line

(47) Line

(48) Passage

(49) Line





The oil delivery from idler pump (28) flows through center bypass passage (52) in main control valve (14) to swing control valve (18). The oil delivery from idler pump (29) flows through center bypass passage (53) in main control valve (14). Illustration 1 shows the main control valve when only the swing hydraulic circuit is activated.

When the hydraulic lockout lever is in the UNLOCKED position, the oil delivery from pilot pump (30) flows to pilot oil manifold (35) and swing brake solenoid valve (31). The oil delivery from the pilot pump also flows to pilot control valve (23) .

When the swing joystick is moved to the SWING RIGHT position, the implement/swing pressure switch senses the increase in pilot oil pressure. The implement/swing pressure switch changes to the ON position. The implement/swing pressure switch sends an input signal to the machine ECM. The machine ECM then energizes swing brake solenoid valve (31). The swing brake solenoid valve shifts. Pilot oil flows through pilot line (1) to swing parking brake (3). The swing parking brake releases in order to enable a swing operation.

The oil delivery from pilot pump (30) flows from pilot control valve (23) through pilot line (26) and into swing control valve (18). The spool in swing control valve (18) shifts upward. The pilot oil on the other end of the spool in the swing control valve flows through pilot line (37) and pilot control


(4) Swing motor

(8) Return line

(9) Line

(10) Line


Illustration 3 g00697650(31) Swing brake solenoid valve


valve (23) to hydraulic tank (34) .

Since the spool in swing control valve (18) is fully shifted, center bypass passage (52) is blocked. None of the oil delivery from the idler pump flows to negative flow control orifice (54) and no negative flow control pressure is created in center bypass passage (52). Since no negative flow control pressure is sent through negative flow control line (55) to the idler pump regulator, the idler pump regulator moves the swashplate of the idler pump toward the maximum angle position. The output flow rate of the idler pump increases. The oil delivery from the idler pump flows through parallel feeder passage (13), load check valve (12), passage (17), swing control valve (18), passage (16) and line (9) to the swing motor. The oil enters the swing motor and flows to motor rotary group (5). The motor rotary group rotates.

The oil delivery for the swing hydraulic circuit is supplied by the idler pump only. Since only a swing operation is being performed, the control valves that receive the oil delivery from idler pump (29) are in the NEUTRAL position. The negative flow control pressure in center bypass passage (53) is not blocked by any of the control valves. Idler pump (29) remains at the destroked position.


Return oil from motor rotary group (5) flows through line (10) to the main control valve. The return oil flows through swing control valve (18), return passage (11), return line (8) and slow return check valve (33) to hydraulic tank (34). The upper structure swings to the right (clockwise direction).

The SWING LEFT operation is similar to the SWING RIGHT operation.

When the swing joystick is moved to the SWING LEFT position, pilot oil from pilot control valve (23) flows through pilot line (37) and into swing control valve (18). The spool in the swing control valve shifts downward. The oil delivery from the idler pump in parallel feeder passage (13) flows through passage (17) and line (10). The oil delivery enters motor rotary group (5). For a swing left operation, the supply ports and return ports are reverse of the swing right operation. This causes the upper structure to swing to the left (counterclockwise direction).

When the swing joystick is returned to the NEUTRAL position, the springs on each end of the swing control valve maintain the spool in the swing control valve in the NEUTRAL position. The oil flow to the swing motor and the oil flow from the swing motor is blocked by the swing control valve.

Swing Priority The pilot oil pressure from the pilot control valve directly corresponds to the amount of movement or position of the joystick. The pilot oil pressure from the pilot control valve acts on the pressure reducing valve for swing priority and the variable swing priority valve. As the swing joystick is moved farther from the NEUTRAL position, the pilot oil pressure increases. This gradual increase in pilot oil pressure causes a gradual change to swing priority. Thus, swing priority is controlled by the position of the swing joystick and swing priority automatically activates when the joystick reaches a certain position.

When swing priority is activated, the output flow from the idler pump supplies hydraulic oil to the swing hydraulic circuit. Since swing priority increases the swing acceleration, swing priority is useful for loading operations. Swing priority is also useful for leveling operations and trenching operations when higher swing force is required.


Stick I control valve (swing priority OFF)



(22) Passage

(24) Pilot line (swing pilot pressure)


(38) Pilot line (pilot system pressure)

(39) Pin hole

(40) Spool

(41) Spring

(42) Passage (stick I)

(43) Spool

(44) Drain line

(45) Check valve

(46) Orifice

(47) Line

(48) Passage

(50) Spring

(51) Passage

(56) Drain Line


SWING RIGHT operation (swing priority OFF)

(4) Swing motor





When the swing joystick is in the NEUTRAL position, no pilot oil pressure acts on spool (40) of pressure reducing valve for swing priority (27). Full pilot oil pressure flows through pilot line (38), the pressure reducing valve for swing priority (27), line (47) and passage (22) to variable swing priority valve (20). Spool (43) in the variable swing priority valve is shifted upward against the force of spring (41). The oil delivery from idler pump (29) in parallel feeder passage (13) flows through parallel feeder passage (15) and variable swing priority valve (20). The oil delivery enters stick I control valve (19) .

When the swing joystick is moved slightly from the NEUTRAL position in order to perform a SWING RIGHT operation, reduced pilot oil pressure from pilot control valve (23) flows through pilot line (26). The pilot oil then divides into two flow paths. Part of the pilot oil flows through passage (21) to swing control valve (18). The spool in the swing control valve shifts a slight amount that corresponds to the amount of movement of the swing joystick. The remainder of the pilot oil flows through pilot line (24) and passage (48). The pilot oil pressure acts on the shoulder of spool (40) in the pressure reducing valve for swing priority (27). Spool (40) shifts against the force of spring (50) .

Since the reduced pilot oil pressure in passage (22) is still higher than the force of spring (41), spool (43) in variable swing priority valve (20) remains shifted upward. The oil delivery from idler pump (29) to stick I control valve (19) is not restricted. Swing priority is not activated.


(21) Passage

(22) Passage


(24) Pilot line

(26) Pilot line


(28) Drive pump

(29) Idler pump

(30) Pilot pump

(38) Pilot line

(41) Spring

(47) Line

(48) Passage

(50) Spring


Stick I control valve (swing priority ON)



(22) Passage

(24) Pilot line (swing pilot pressure)


(38) Pilot line (pilot system pressure)

(39) Pin hole

(40) Spool

(41) Spring

(42) Passage (stick I)

(43) Spool

(44) Drain line

(45) Check valve

(46) Orifice

(47) Line

(48) Passage

(50) Spring

(51) Passage

(56) Drain line


SWING RIGHT operation (swing priority ON)

(4) Swing motor





As the swing joystick is moved to the FULL STROKE position during a SWING RIGHT operation, the pilot oil pressure in passage (21) increases. The spool in swing control valve (18) shifts fully upward. The pilot oil pressure in pilot line (24) and passage (48) also increases. Spool (40) in the pressure reducing valve for swing priority (27) shifts fully against the force of spring (50) .

Passage (51) restricts the pilot oil flow from pilot line (38) through the pressure reducing valve for swing priority (27). The pilot oil pressure in line (47) and passage (22) also decreases. Spool (43) in variable swing priority valve (20) is pushed downward by the force of spring (41) .

The oil delivery from idler pump (29) in parallel feeder passage (15) is restricted by orifice (46) in check valve (45). A portion of the oil delivery from the idler pump flows into passage (42). Swing priority is now activated. Most of the oil delivery from the idler pump is dedicated to the swing system and flows through the swing control valve to the swing motor. As a result, swing priority and higher swing force can be achieved with the swing joystick.

A portion of the pilot oil at passage (51) flows through passage (39) to spool (40). Pilot oil pressure that flows from passage (22) into variable swing priority valve (20) corresponds to the position of the swing joystick.


(21) Passage

(22) Passage


(24) Pilot line

(26) Pilot line


(28) Drive pump

(29) Idler pump

(30) Pilot pump

(38) Pilot line

(41) Spring

(45) Check valve

(46) Orifice

(47) Line

(48) Passage

(50) Spring


Wed Feb 28 19:45:37 EST 2007


Swing Motor SMCS - 5058-ZW

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i01638171

The swing motor may be divided into the following three groups :

Illustration 1 g00773430Swing motor

(1) Relief valve

(2) Relief valve

(3) Motor head

(4) Port (pilot system oil)

(5) Separator plate

(6) Friction plate

(7) Plate

(8) Body

(9) Drive shaft

(10) Check valve

(11) Makeup port

(12) Drain port

(13) Passage (supply oil or return oil)

(14) Check valve


(16) Port (supply oil or return oil)



(19) Valve plate


(21) Brake spring

(22) Brake piston

(23) Piston

(24) Cylinder barrel

(25) Retainer plate

(26) Shoe

The rotary group consists of the following components : cylinder barrel (24), pistons (23), shoes (26), retainer plate (25) and drive shaft (9) .

The parking brake consists of the following components : brake spring (21), brake piston (22), separator plate (5) and friction plate (6) .

The relief valves and the makeup valves consists of the following components : relief valve (1), relief valve (2), check valve (10) and check valve (14) .

Supply oil from the drive pump is delivered to port (16) or port (17). During a SWING RIGHT operation, the oil delivery enters motor head (3) at port (17) and flows through passage (18). The oil then flows through passage (13) in valve plate (19) and passes through passage (20) in cylinder barrel (24). This oil pressurizes piston (23) in motor head (3).


Motor passages

Shoe (26) is pressed against the upper surface of plate (7) by the force of piston (23). The shoe and the piston slide along the slope of plate (7) in a counterclockwise direction. This sliding force causes cylinder barrel (24) to rotate in a counterclockwise direction (28). As each piston reaches the bottom center position (A), oil flows through passage (27) in valve plate (19). This oil then flows through passage (15) of motor head (3) to the hydraulic tank. As cylinder barrel (27) continues to rotate counterclockwise, the piston and the shoe continue to move up the inclined surface of plate (28). Since cylinder barrel (24) is splined to drive shaft (9), the drive shaft rotates in the same direction as the cylinder barrel.

For a SWING LEFT operation, swing pump supply oil is delivered to port (16). The supply ports and the return ports are reversed. Cylinder barrel (24) turns clockwise.

The case drain oil from the swing motors returns through drain port (12) of motor head (3) to the hydraulic tank.

Reference: For more information concerning the swing parking brake, refer to Systems Operation, "Pilot Valve (Swing Parking Brake)".

Reference: For more information concerning the swing relief valves, refer to Systems Operation, "Relief Valve (Swing)".

(A) Bottom center position

(B) Inlet side (high pressure)

(C) Top center position

(D) Outlet side (low pressure)

(13) Passage (valve plate)

(15) Return passage

(16) Port

(17) Port

(18) Supply passage

(20) Passage (cylinder barrel)


(28) Direction of motor rotation (counterclockwise rotation)


Wed Feb 28 19:46:28 EST 2007


Pilot Valve (Swing Parking Brake) SMCS - 5059; 5483

Swing brake solenoid valve (2) is located on the pilot oil manifold. When any one of the joysticks is moved from the NEUTRAL position, the swing brake solenoid valve is energized in order to release the swing brake. When the swing brake solenoid valve is energized, pilot oil flows to the swing motor in order to release the swing brake.

Note: Operation of the travel levers/pedals will not release the swing brake.

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i02467880

Illustration 1 g00682419(2) Swing brake solenoid valve


Swing brake (disengaged position)


(3) Spool

(4) Spring

(5) Passage

(6) Passage



(9) Spool chamber

(10) Line

(11) Body (swing motor)

(12) Friction plate

(13) Separator plate

(14) Piston chamber

(15) Port (swing motor)


The swing brake is located between motor head (19) of swing motor and body (11). The swing brake consists of the following components : brake spring (18), brake piston (17), separator plate (13) and friction plate (12). Friction plate (12) is splined to cylinder barrel (16). Separator plate (13) is splined to body (11). Separator plate (13) and friction plate (12) move in an axial direction.

When the joysticks are moved from the NEUTRAL position, the implement/swing pressure switch senses the increase in pilot oil pressure at the pilot control valves. The implement/swing pressure switch changes to the ON position. The implement/swing pressure switch sends an input signal to the machine ECM. The machine ECM energizes swing brake solenoid valve (2) .

When swing brake solenoid valve (2) is energized, spool (3) moves in a downward direction against the force of spring (4). Pilot oil in passage (7) flows through spool chamber (6) and line (10) to port (15) of the swing motor. The pilot oil now enters piston chamber (14). The pilot pressure causes brake piston (17) to move upward against the force of brake spring (18). The force that holds separator plate (13) and friction plate (12) together is released. When the swing brake is released, the swing operation of the upper structure is enabled.

Note: If the swing brake becomes inoperable due to failure of swing brake solenoid valve (2), the swing brake can be released by turning the temporary brake release screw in a clockwise direction until the temporary brake release screw stops.

(17) Brake piston

(18) Brake spring

(19) Motor head


Swing brake (engaged position)

When the joysticks are returned to the NEUTRAL position, supply oil from the drive pump to the swing motor is stopped. The implement/swing pressure switch senses the decrease in pilot oil pressure at the pilot control valves. The implement/swing pressure switch changes to the OFF position. The machine ECM senses the change of signal at the implement/swing pressure switch. The machine ECM de-energizes swing brake solenoid valve (2) .

Spool (3) is moved upward by the force of spring (4). Spool (3) blocks pilot oil flow from port (7) to piston chamber (14). Brake spring (18) forces brake piston (17) downward. The oil in piston chamber (14) flows through port (15) and line (10) to pilot oil manifold (8). The oil then flows into spool chamber (6) and passage (9) of spool (3). The oil then flows through passage (5) to the hydraulic tank. As brake piston (17) moves downward, separator plate (13) and friction plate (12) are forced together. Since separator plates (13) are splined to body (11), the rotation of cylinder barrel (16) in the swing motor is stopped. Rotation of the upper structure is prevented.

Since the machine ECM does not de-energize the swing brake solenoid valve until approximately 6.5 seconds after the swing joystick is returned to the NEUTRAL position, the rotation of the swing motors stops before the swing brake is engaged. If the solenoid is de-energized before the rotation of the swing motors stops, damage and wear to the swing brakes would result.


(3) Spool

(4) Spring

(5) Passage

(6) Passage



(9) Spool chamber

(10) Line

(11) Body (swing motor)

(12) Friction plate


(14) Piston chamber

(15) Port (swing motor)


(17) Brake piston

(18) Brake spring

(19) Motor head


Wed Feb 28 19:47:01 EST 2007


Relief Valve (Swing) SMCS - 5454

Shutdown

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i02468619


Pressure circuit for SWING RIGHT operation (partial schematic)

(1) Passage (supply oil)

(2) Makeup port

(3) Relief valve

(4) Passage


(6) Swing motor


(8) Relief valve

(9) Passage

(10) Makeup line

(11) Check valve

(12) Port (supply oil)

(13) Port (return oil)

(14) Check valve

(15) Check valve

(16) Return line



(19) Return line


(2) Makeup port

(3) Relief valve

(6) Swing motor

(8) Relief valve

(10) Makeup line

Relief valves (3) and (8) are located in the head of swing motor (6). These relief valves limit the pressure in the left and right swing circuits to the swing relief valve setting. This provides a cushion effect at a start or stop of the swing operation.

When the swing joystick is returned to the NEUTRAL position during the swing right operation, the swing control valve shifts to the NEUTRAL position. Since the swing control valve is in the NEUTRAL position, the oil delivery through port (12) to the motor rotary group (5) is now blocked

Illustration 3 g01231050Swing relief valve

(4) Return passage

(7) Passage

(20) Orifice

(21) Spring

(22) Stem

(23) Piston chamber

(24) Passage

(25) Piston

(26) Passage

(27) Piston chamber

(28) Orifice

(29) Passage

(30) Adjustment plug

at the swing control valve. The return oil from the motor rotary group through port (13) is also blocked at the swing control valve.

The mass (weight and size) of the upper structure causes the upper structure to attempt to continue to rotate after the swing joystick is returned to the NEUTRAL position. The motor rotary group is also attempting to continue to rotate. The motor rotary group attempts to draw oil through port (12) and attempts to displace the oil through port (13) .

The oil supply to motor rotary group (5) is insufficient. A vacuum condition occurs in passage (1). Return oil is supplied to the motor rotary group as makeup oil in order to prevent the vacuum condition. For more information concerning the makeup operation, refer to Systems Operation, "Oil Makeup (Swing System)".

Since the flow of return oil from the motor rotary group through port (13) is blocked at the swing control valve, the pressure of the blocked oil in passage (7) increases. The increased oil pressure in passage (7) acts on swing relief valve (8). The increased pressure oil forces stem (22) of relief valve (8) to the right (open position) against the force of spring (21). When stem (22) shifts, oil flows through passage (9), check valve (11) and passage (1) to motor rotary group (5). The shock load is absorbed at the stop of a swing movement.

At swing relief valve (8), the increased oil pressure in passage (7) flows through orifice (20) in stem (22) and passage (26) to piston chamber (27). The force of spring (21) is less than the relief valve pressure setting. This causes stem (22) to move to the right (open position) before the oil pressure in passage (7) reaches the relief valve pressure setting. At the same time, the pressure oil in piston chamber (27) flows through passages (24) and (29). Piston (25) moves to the left against the force of spring (21). The oil in piston chamber (23) flows through orifice (28) and into piston chamber (27). Orifice (28) restricts the oil flow into piston chamber (27) .

The swing relief valve maintains the operating pressure of the swing hydraulic circuit at a lower pressure than the swing relief valve setting until the pressure in the swing hydraulic circuit forces piston (25) to the right against adjustment plug (30). When piston (25) contacts adjustment plug (30), the pressure in piston chamber (27) increases. The oil pressure in passage (7) reaches the swing relief valve setting. The oil in passage (7) flows around stem (22) and into return passage (4) .

After stem (22) begins to open and before piston (25) completes the movement to the left, the pressure in the swing hydraulic circuit increases gradually. The pressure in the swing hydraulic circuit does not reach a peak pressure. This is called a two-stage relief operation. The two-stage relief operation absorbs the shock load at the stop of a swing operation.

After the start of a swing right operation, the oil delivery from the drive pump flows through port (12) and passage (1) to motor rotary group (5). The mass (weight and size) of the upper structure causes an increase of oil pressure in passage (1). Stem (22) of swing relief valve (3) opens slightly. A portion of the high pressure oil in passage (1) flows through makeup port (2) to return line (19). This gives a smoother acceleration at the start of a swing operation.


Wed Feb 28 19:47:35 EST 2007


Oil Makeup (Swing System) SMCS - 5080-ZW

Shutdown

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i02469129


Pressure circuit for SWING RIGHT (partial schematic)


(2) Makeup port

(3) Relief valve

(4) Passage


(6) Swing motor


(8) Relief valve

When the swing joystick is moved to the NEUTRAL position during the swing right operation, the swing control valve shifts to the NEUTRAL position. Since the swing control valve is in the NEUTRAL position, the oil delivery through port (12) to motor rotary group (5) is blocked at the swing control valve. The return oil from the motor rotary group through port (13) is also blocked at the swing control valve. The upper structure will attempt to continue to rotate after the swing joystick is returned to the NEUTRAL position. This causes an internal leak of oil in the swing motor. As a result, a vacuum condition occurs at passage (1). In order to prevent this vacuum condition, makeup oil is delivered from the return hydraulic system to the swing motor.

(9) Passage

(10) Makeup line

(11) Check valve

(12) Port (supply oil)

(13) Port (return oil)

(14) Check valve

(15) Check valve

(16) Return line



(19) Return line

Illustration 2 g00850298(10) Makeup line


(19) Return line

When all of the control valves for implements, swing and travel are in the NEUTRAL position, the oil delivery from the idler pump and the drive pump flows through return line (16) to the hydraulic tank. Slow return check valve (18) is located between return line (16) and the hydraulic tank. Slow return check valve (18) maintains the return oil pressure at 290 kPa (42 psi) in return line (16). If a vacuum condition occurs at the swing motor during the stop of a swing operation, the slow return check valve causes return oil from return line (16) to flow to motor rotary group (5) as makeup oil. The slow return check valve eliminates the vacuum condition in the swing motor due to internal leakage.

If the swing joystick is moved suddenly toward the NEUTRAL position from the FULL STROKE position, the swing control valve partially closes. Until the swing control valve reaches the NEUTRAL position, the return oil from the swing motor continues to flow through passage (7) and port (13) to return line (16). The return oil pressure in passage (7) increases but the return oil pressure in passage (7) remains lower than the pressure setting of swing relief valve (8). Swing relief valve (8) remains in the CLOSED position.

A vacuum condition occurs at port (12) and passage (1) due to the insufficient oil delivery from the drive pump and due to the tendency of the motor rotary group to continue to rotate. Since relief valve (8) remains in the CLOSED position, makeup oil does not flow through relief valve (8), passage (9) and check valve (11) to passage (1) to motor rotary group (5) .

Makeup oil is supplied to motor rotary group (5) from return line (16). Return oil flows from return line (16) through makeup line (10), port (2), passage (9), check valve (11) and passage (1) to motor rotary group (5). The vacuum condition in passage (1) is eliminated by the makeup oil from the

Illustration 3 g01231308Slow return check valve

(10) Makeup line

(16) Return line


(19) Return line

return hydraulic system.

During a left swing operation, the return ports and the supply ports of the swing motor are reversed. Makeup oil flows through check valve (14) if a vacuum condition occurs in passage (7) during a swing left operation.


Wed Feb 28 19:48:12 EST 2007


Relief Valve (Cushion Crossover) - Anti-Reaction Valves SMCS - 5111; 5454

At the stop of a swing operation, it is difficult to smoothly stop the upper structure and implements at the desired position. This is due to the mass (weight and size) of the upper structure. The outlet port of the swing motor is blocked. This causes an oscillation or a rocking motion in the swing motor. Anti-reaction valves (3) and (4) provide a more exact swing movement. The anti-reaction valves also prevent shock load at the stop of a swing operation. Anti-reaction valves (3) and (4) are located in block (1). Block (1) is mounted on swing motor (2).

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i02363790


(1) Block

(2) Swing motor

(3) Anti-reaction valve (left swing)

(4) Anti-reaction valve (right swing)

(5) Fine swing solenoid valve


Anti-reaction valve (neutral position)

(1) Block



(5) Fine swing solenoid

(6) Passage

(7) Port

(8) Passage

(9) Passage

During a swing operation of the upper structure, the oil delivery from the left pump flows through passage (8) or passage (10) in block (1) to motor rotary group (36). When the swing joystick is in the NEUTRAL position, the swing control valve is in the NEUTRAL position. The oil delivery from the left pump is blocked at the swing control valve. No oil delivery flows to the motor rotary group. The return oil from the swing motor is also blocked at the swing control valve.

Plunger (24) in anti-reaction valve (3) shifts downward by the force of spring (25) until the plunger is stopped by piston (26). Valve seat (23) shifts downward by the force of spring (22) until the valve seat comes in contact with plunger (24). Plunger (16) and valve seat (14) in anti-reaction valve (4) are shifted downward in the same manner as anti-reaction valve (3).

(10) Passage

(11) Port

(12) Passage

(13) Spring

(14) Valve seat

(15) Passage

(16) Plunger

(17) Passage

(18) Spring

(19) Piston chamber

(20) Passage

(21) Spring chamber

(22) Spring

(23) Valve seat

(24) Plunger

(25) Spring

(26) Piston

(31) Passage



Anti-reaction valve (swing operation)

(1) Block




(6) Passage

(7) Port

(8) Passage

(9) Passage

(10) Passage

When the swing joystick is moved from the NEUTRAL position in order to perform a swing operation, the swing control valve shifts. The oil delivery from the left pump flows through the swing control valve and port (11) in block (1). The oil delivery then flows through passage (10), passage (12) and motor rotary group (36). Return oil from the motor rotary group flows through passage (6), passage (8), port (7) and the swing control valve to the hydraulic tank. The motor rotary group rotates.

A portion of the pressure oil from the left pump at port (11) also flows to anti-reaction valves (3) and (4) .

At anti-reaction valve (3), pressure oil from the left pump and the force of spring (22) shifts valve seat (23) downward against plunger (24). Plunger (24) shifts downward against piston (26) .

Pressure oil from the left pump also flows through passage (9). The pressure oil enters spring chamber (34) of anti-reaction valve (4). Plunger (16) shifts upward against the force of spring (18). Valve seat (14) is moved upward against the force of spring (13) by plunger (16).

(11) Port

(12) Passage

(13) Spring

(14) Valve seat

(15) Passage

(16) Plunger

(17) Passage

(18) Spring

(19) Piston chamber

(20) Passage

(21) Spring chamber

(22) Spring

(23) Valve seat

(24) Plunger

(25) Spring

(26) Piston

(31) Passage

(34) Spring chamber



Anti-reaction valve (swing stop)




(7) Port

(8) Passage

(9) Passage

(10) Passage

(11) Port

(13) Spring

When the swing joystick is returned to the NEUTRAL position, the oil delivery from the left pump to motor rotary group (36) is blocked at the swing control valve. The motor rotary group continues to rotate due to the mass (weight and size) of the upper structure. Since the return oil flow from the motor rotary group is also blocked at the swing control valve, the oil pressure in passage (8) increases. The oil pressure in passage (10) decreases. The increased oil pressure in passage (8) then enters anti-reaction valve (4). The oil flows through passage (15) and passage (17). The oil then enters piston chamber (19). The oil pressure in piston chamber (19) forces plunger (16) upward against the force of spring (18). Valve seat (14) shifts upward against the force of spring (13) .

A portion of the increased oil pressure in passage (8) flows through passage (31) and passage (20). The oil then enters spring chamber (21) in anti-reaction valve (3). The oil pressure in spring chamber (21) forces plunger (24) and valve seat (23) upward against the force of springs (22) and (25) .

(14) Valve seat

(15) Passage

(16) Plunger

(17) Passage

(18) Spring

(19) Piston chamber

(20) Passage

(21) Spring chamber

(22) Spring

(23) Valve seat

(24) Plunger

(25) Spring

(27) Orifice

(26) Piston

(28) Valve chamber

(29) Passage

(30) Ball

(31) Passage

(32) Orifice

(33) Ball

(35) Valve chamber


As the motor rotary group of the swing motor continues to attempt to stop, the oil pressure in passage (8) gradually decreases. The oil pressure in piston chamber (19) decreases. The force of spring (18) causes plunger (16) to shift downward at a rapid rate. Valve seat (14) shifts downward by the force of spring (13). Since orifice (27) restricts the flow of oil from valve chamber (28), valve seat (14) moves in a downward direction more slowly than plunger (16) .

The contact between plunger (16) and valve seat (14) is no longer maintained. The oil pressure in passage (15) forces ball (30) against the top end of plunger (16). The oil in passage (8) now flows through passages (29) and (9) to passage (10) .

During the separation of plunger (16) and valve seat (14) in anti-reaction valve (4), anti-reaction valve (3) activates also. In anti-reaction valve (3), The pressure of the oil that flows from spring chamber (21) to passage (8) decreases. The force of spring (25) causes plunger (24) to shift downward. The force of spring (22) causes valve seat (23) to shift downward. Since orifice (32) restricts the flow of oil from valve chamber (35), valve seat (23) shifts more slowly than plunger (24). The contact between plunger (24) and valve seat (23) is no longer maintained. The oil pressure in passage (20) forces ball (33) against the valve seat (23). Now, the oil flow from passage (8) through passage (31) to passage (10) is blocked by ball (33) .

Since passages (8) and (10) are connected by activation of anti-reaction valve (4), the swing movement of the upper structure stops with a minimal shock load at a desired position. A more exact swing movement is possible. A slight shock load may occur due to the gear backlash of the swing drive.


Anti-reaction valve (reverse rotation)




(7) Port

(8) Passage

(9) Passage

(10) Passage

(11) Port

(13) Spring

When motor rotary group (36) is slightly rotated in the reverse direction due to the gear backlash, oil pressure in passage (10) increases and oil pressure in passage (8) decreases. Anti-reaction valves (3) and (4) function in order to stop the swing movement of the upper structure with a slight reversed motion. The increased oil pressure in passage (10) causes a shock load. The absorption of the shock load is described in the following manner.

In anti-reaction valve (3), plunger (24) and valve seat (23) separate from each other. Ball (33) is forced against plunger (24) by the pressure oil in passage (10). Oil can now flow from passage (10) through passages (20) and (31) to passage (8) .

In anti-reaction valve (4), plunger (16) and valve seat (14) separate from each other. Ball (30) is forced against valve seat (14) by the pressure oil in passage (29). The flow of oil from passage (10)

(14) Valve seat

(15) Passage

(16) Plunger

(17) Passage

(18) Spring

(19) Piston chamber

(20) Passage

(21) Spring chamber

(22) Spring

(23) Valve seat

(24) Plunger

(25) Spring

(27) Orifice

(26) Piston

(28) Valve chamber

(29) Passage

(30) Ball

(31) Passage

(32) Orifice

(33) Ball

(35) Valve chamber


through passage (9) to passage (8) is blocked.

The oil pressure in passage (10) decreases and the rotation of motor rotary group (36) is prevented. The swing movement is gradually stopped.


Wed Feb 28 19:48:51 EST 2007


Solenoid Valve (Fine Swing) SMCS - 5479

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i02373421


Side of swing motor

(1) Block

(2) Swing motor



(35) Fine swing solenoid valve


Fine swing solenoid valve

(1) Block

(8) Passage

(9) Passage

(10) Passage

(31) Passage

(35) Solenoid

(36) Fine swing valve

The fine swing control is installed in order to ensure an exact movement of the swing with minimal shock load. This is done by equalizing the oil pressure in passage (8) and (10) .

When fine swing solenoid (35) is de-energized, spool (39) is in the NEUTRAL position. Spool (39) is located in valve (36). The NEUTRAL position creates a closed connection between passages (37) and (38). In this position, the swing circuit operates in the normal manner.

When the fine swing control switch is ON, solenoid (35) is energized. Spool (39) shifts downward against the force of spring (40). With the spool in this position, passage (8) is open to passage (10) through passages (37) and (38). Orifices (41) and (42) control the flow rate. Orifices (41) and (42) are located in block (1) .

Because the right and the left swing circuits are now connected to each other, some of the outlet oil is allowed to flow to the inlet side. The operation of the swing circuit is more precise with this connection.

Note: When the fine swing control switch is ON, the swing brake is OFF.

(37) Passage

(38) Passage

(39) Spool

(40) Spring

(41) Orifice

(42) Orifice

Illustration 3 g01130114The fine swing control switch is on the right side instrument panel.


Wed Feb 28 19:49:33 EST 2007


Swing Drive SMCS - 5459

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i02469579


Swing drive

(1) First stage planetary carrier

(2) First stage planetary gear

(3) Second stage planetary carrier

(4) Ring gear

(5) Second stage planetary gear

(6) Roller bearing

(7) Roller bearing

(8) Pinion shaft

The swing drive consists of a series of planetary gears. The planetary gears reduce the rotational speed of the swing motor. The swing motor is bolted to the top of the swing drive. The swing drive is bolted to the upper structure. The teeth of the swing drive output pinion shaft (8) engage with bearing gear (15) of the swing bearing. The pinion shaft (8) rotates around bearing gear (15). This causes the machine to swing. Bearing gear (15) is attached to the lower structure.

The swing drive is divided into the following two groups :

The first group is a double reducer of motor speed. The components of the first stage reduction are first stage sun gear (11), first stage planetary gears (2), ring gear (4) and first stage planetary carrier (1). The components of the second stage reduction are second stage sun gear (12), second stage planetary gear (5), ring gear (4) and second stage planetary carrier (3) .

The second group is the group for reduced output speed of the motor. The components of the second group are roller bearing (6), roller bearing (7) and pinion shaft (8). The roller bearings are installed in housing (14) and the roller bearings support pinion shaft (8) .

The swing speed is reduced by a ratio of teeth on the sun gear to ring gear teeth by planetary reduction. Since the sun gear is inside of the ring gear, the swing drive is more compact than reduction units with external teeth.

(10) Shaft (swing motor)

(11) First stage sun gear

(12) Second stage sun gear

(14) Housing

(15) Bearing gear (swing gear)

Swing motor output shaft (10) is splined to first stage sun gear (11). First stage planetary gears (2) of first stage planetary carrier (1) mesh with first stage sun gear (11). When first stage sun gear (11) rotates counterclockwise, first stage planetary gears (2) rotate in a clockwise direction on shafts (16). First stage planetary gears (2) move counterclockwise around ring gear (4). Ring gear (4) is bolted to housing (14). First stage planetary carrier (1) rotates counterclockwise.

Illustration 2 g01231623Operation of the first stage planetary assembly



(4) Ring gear


(16) Shaft (first stage planetary gear)

Splines on inner circumference (17) of first stage planetary carrier (1) engage with the splines on second stage sun gear (12). This causes second stage sun gear (12) to rotate counterclockwise when

Illustration 3 g01231625Swing drive



(3) Second stage planetary carrier

(4) Ring gear

(5) Second stage planetary gear

(6) Roller bearing

(7) Roller bearing

(8) Pinion shaft


(12) Second stage sun gear

(17) Inner circumference of carrier

the first stage planetary carrier rotates. Second stage planetary gears (5) turn clockwise on the shafts and second stage planetary gears (5) move in a counterclockwise direction around ring gear (4). Second stage planetary carrier (3) turns counterclockwise around ring gear (4). The splines on the inner circumference of second stage planetary carrier (3) engage with the splines of pinion shaft (8). When the second stage planetary carrier turns clockwise, pinion shaft (8) rotates counterclockwise.

Pinion shaft (8) engages with bearing gear (15) on the inner circumference of the swing bearing. Bearing gear (15) is bolted to the lower structure. As pinion shaft (8) rotates counterclockwise, pinion shaft (8) moves in a clockwise direction around bearing gear (15). The upper structure also rotates in a clockwise direction around bearing gear (15). This causes the upper structure to swing to the right (clockwise rotation).

Illustration 4 g01231628Rotation of pinion shaft

(8) Pinion shaft

(15) Bearing gear (swing bearing)

(18) Position of moving pinion shaft


Wed Feb 28 19:50:08 EST 2007


Travel Hydraulic System SMCS - 5050

Travel Control

Shutdown

Previous Screen



i02485785

Illustration 1 g00699122(1) Left travel motor

(52) Travel brake valve

The output flow from the drive pump flows through the swivel to the right travel motor. The output flow from the idler pump flows through the swivel to the left travel motor. The pump delivery flow causes rotation of the travel motors. The torque of the travel motors is transmitted to the final drives. The rotational speed of the travel motors is reduced by gear reduction in the final drive. The final drive (55) increases the torque and the rotational force drives track (53) via sprocket (54).

The travel speed can be adjusted by the slight operation of the travel levers/pedals. The travel speed can also be controlled by travel speed control switch (56). This changes the travel speed when the travel levers/pedals are moved to the maximum position. The travel speed control switch can be set at the LOW SPEED position or the HIGH SPEED position. When the travel speed control switch is set at the LOW SPEED position, the tortoise appears on the default message display of the monitor. When the travel speed control switch is set at the HIGH SPEED position, the rabbit appears on the

Illustration 2 g00699126Final drive

(53) Track

(54) Sprocket

(55) Final drive

Illustration 3 g00699127Keypad (right console)

(56) Travel speed control switch

default message display of the monitor. During travel on a flat surface or during gradual downhill travel, the travel speed is set at the HIGH SPEED position in order to realize increased mobility.

When travel speed control switch (56) is set at the HIGH SPEED position, the pressure sensors for pump delivery pressure detect the change in pump load. If the pressure sensors detect a high load, the travel speed is automatically adjusted to LOW SPEED. If the pressure sensors detect a small load, the travel speed is automatically adjusted to HIGH SPEED.

The direction of travel is relative to the position of the lower structure. For normal travel, idler (59) is positioned in front of cab (61) and travel motors (1) and (15) to the rear of the cab. With the machine in the normal position of travel, move the travel levers/pedals (58) and (60) forward. The machine will travel in forward direction (57). This movement is called forward travel. When the travel levers/pedals (58) and (60) are moved toward the operator, the machine travels in reverse direction (62). This direction is called reverse travel.

When cab (61) is rotated by 180 degrees, travel motors (1) and (15) are positioned in front of the cab. The direction of travel and the operation of the travel levers/pedals (58) and (60) are reversed

Illustration 4 g01212769Operation of travel



(57) Forward travel


(59) Idler

(60) Right travel lever/pedal

(61) Cab

(62) Reverse travel

from the normal travel direction.

When the machine is in the normal position of travel and when one of the travel levers/pedals (58) or (60) is moved forward, the respective track travels forward. The machine turns because the stationary track acts as the pivot point. This is called a pivot turn.

This machine will spot turn in order to change the travel direction of the machine in a narrow space. To complete a spot turn operation, move one travel lever/pedal to the rear and move the other travel lever/pedal forward at the same time. One track will travel to the rear and the other track will travel forward. The machine will spot turn around the center axis of the machine.

Forward Travel


Hydraulic schematic for FORWARD TRAVEL


(2) Swashplate


(4) Swashplate control piston (HIGH SPEED)


(6) Brake pilot valve

(7) Passage

(8) Counterbalance valve

(9) Swashplate control piston (LOW SPEED)

(10) Parking brake


(12) Displacement change valve

(13) Passage

(14) Line (pilot system oil pressure)


(16) Swashplate

(17) Swashplate control piston (LOW SPEED)


(19) Passage



(22) Swashplate control piston (HIGH SPEED)

(23) Passage

(24) Passage

(25) Passage

(26) Passage

(27) Line (pilot system oil pressure)

(28) Line (return oil)

(29) Line (supply oil)

(30) Swivel







(37) Return passage


(39) Passage



(42) Pilot line (forward left travel)

(43) Pilot line (forward right travel)

(44) Travel pilot control valve

(45) Return line

(46) Pressure sensor for drive pump

(47) Pressure sensor for idler pump


(49) Idler pump

(50) Drive pump

(51) Pilot pump

(63) Pilot line


Main control valve


When both of the travel levers/pedals are operated, pilot system oil pressure flows from travel pilot control valve (44) through pilot lines (42) and (43) to left travel control valve (38) and right travel control valve (41). The pilot system oil pressure shifts the spools in both of the travel control valves in an upward direction. The travel control valves allow the oil delivery from the drive pump and the idler pump to flow to swivel (30). The swivel transfers the oil delivery from the rotating upper structure to the lines in the lower structure. The oil delivery flows to left travel motor (1) and right travel motor (15) .

Note: The right and left travel controls function in the same manner. The explanation for the left travel control will be used to explain both the right and left travel controls.

When the left travel lever/pedal is moved to the FORWARD TRAVEL position, pilot system oil pressure from travel pilot control valve (44) flows through pilot line (42) to left travel control valve (38). The spool in the left travel control valve shifts in an upward direction. The oil delivery from the idler pump in center bypass passage (40) flows through passage (39), left travel control valve (38), passage (35), line (33), swivel (30) and line (29) to left travel motor (1) .

The oil delivery from the idler pump enters left travel motor (1) and flows through counterbalance valve (8) and passage (5) to motor rotary group (3). At the same time, a portion of the oil delivery from the idler pump flows through passage (7) and brake pilot valve (6) to parking brake (10). The parking brake is released and the oil delivery from the idler pump causes the motor to rotate.

LOW SPEED



Left travel motor (LOW SPEED)


(2) Swashplate


(4) Swashplate control piston






(13) Passage

(27) Pilot line


When travel speed control switch (56) is set at the LOW SPEED position, an electrical signal is sent to machine ECM (C). The machine ECM does not energize travel speed solenoid valve (48) and pilot system oil pressure does not flow through pilot line (27) to displacement change valve (12). The spool in the displacement change valve does not shift. A portion of the oil flow from the idler pump in passage (5) flows through passage (13) and displacement change valve (12) to swashplate control piston (9). As a result, swashplate control piston (9) moves swashplate (2) to the maximum displacement position. At the same time, the oil that acts on swashplate control piston (4) flows into the case drain of the travel motor. One rotation of motor rotary group (3) displaces a larger amount of oil flow. The rotational speed of the left travel motor decreases. The left track moves slowly and better traction is achieved.

The return oil from motor rotary group (3) flows through passage (11), counterbalance valve (8), line (28) and swivel (30). The return oil then flows through line (34), left travel control valve (38), return passage (37) and return line (45) to the hydraulic tank.

Right travel motor (15) receives the oil delivery from the drive pump. The right travel motor functions in the same manner as the left travel motor in the LOW SPEED position.

HIGH SPEED


(49) Idler pump

(51) Pilot pump



(A) Indicator for HIGH SPEED

(B) Indicator for LOW SPEED

(C) Machine ECM


Pilot manifold



Left travel motor (HIGH SPEED)


(2) Swashplate








(13) Passage

When travel speed control switch (56) is set at the HIGH SPEED position, an electrical signal is sent to machine ECM (D). Pressure sensors (46) and (47) also send an electrical signal to the machine ECM. If the travel load is light and when the pump delivery pressure is below a certain pressure, the machine ECM energizes travel speed solenoid valve (48). Pilot system oil pressure flows through travel speed solenoid valve (48) and line (27) to displacement change valve (12). The spool in the displacement change valve shifts. A portion of the oil delivery from the idler pump flows through the displacement change valve to swashplate control piston (4). Swashplate control piston (4) moves swashplate (2) to the minimum displacement position. At the same time, the oil that acts on swashplate control piston (9) flows into the case drain of the travel motor. One rotation of motor rotary group (3) displaces a smaller amount of oil flow. The rotational speed of the left travel motor increases. The left track moves at a faster speed.

The return oil from motor rotary group (3) flows through passage (11), counterbalance valve (8), line (28) and swivel (30). The return oil then flows through line (34), left travel control valve (38), return passage (37) and return line (45) to the hydraulic tank.

Right travel motor (15) receives the oil delivery from the drive pump. The right travel motor functions in the same manner as the left travel motor in HIGH SPEED position.

Automatic Travel Speed Change

(27) Pilot line



(49) Idler pump

(51) Pilot pump



(A) Indicator for HIGH SPEED

(B) Indicator for LOW SPEED

(C) Machine ECM

Pressure sensor (46) monitors the delivery pressure of the drive pump. Pressure sensor (47) monitors the delivery pressure of the idler pump. The motor displacement is low when the travel speed control switch is set at the HIGH SPEED position and the travel load is light. As the pump load increases, the delivery pressure of the pumps increases. When the delivery pressure of the pumps reaches a certain pressure, the pressure sensor sends an electrical signal to the machine ECM. The machine ECM de-energizes travel speed solenoid valve (48). Travel speed solenoid valve (48) blocks the flow of pilot system supply oil to displacement change valves (14) and (20). The oil in swashplate control

Illustration 10 g01242228Main pump compartment

(46) Pressure sensor for drive pump

(47) Pressure sensor for idler pump

pistons (4) and (22) now flows into the case drain of the travel motors. Swashplates (2) and (16) move to the maximum displacement position. One rotation of the motor rotary groups in the travel motors displaces a larger amount of oil flow. The rotational speed of the travel motors decreases. The travel speed is automatically changed to LOW SPEED.

When the pump load decreases and the travel speed control switch is set at the HIGH SPEED position, pressure sensors (46) and (47) will now cause the machine ECM to energize travel speed solenoid valve (48). Displacement change valves (12) and (20) will be shifted by pilot pressure so that the motor rotary groups will change to the minimum displacement position. One rotation of the motor rotary groups displaces a small amount of oil flow. The travel speed will automatically change to HIGH SPEED.

The ability of the machine to automatically change the travel speed allows good performance at high speed and better traction control.


Wed Feb 28 19:50:38 EST 2007


Pilot Valve (Travel) SMCS - 5059-PQ

Shutdown

Previous Screen



i02470842


Travel pilot control valve

(1) Travel lever/pedal

(2) Pedal

(3) Rod

(4) Seat

(5) Spring

(6) Spring

(7) Spool

(8) Passage

(9) Passage

(10) Spring

(11) Spool

(12) Return port

(13) Return chamber

(14) Passage

(15) Passage

(16) Pilot port

(17) Passage

(18) Port

(19) Passage

(20) Passage

(21) Passage

(22) Port

(23) Piston chamber

(24) Orifice

(25) Piston

(26) Spring

(27) Spring

When travel lever/pedal (1) is moved to the FORWARD TRAVEL position, rod (3) moves downward. As rod (3) moves downward, seat (4) moves downward against the force of springs (5) and (6). Passage (19) opens.

As passage (19) opens, the pilot oil from pilot port (16) flows through passages (21), (19), (20), and (9) to port (18). The pilot oil flows through port (18) to the travel control valve. The pilot oil pressure shifts the spool of travel control valve. The oil delivery from the pump now flows through the travel control valve to the travel motor. The travel motor rotates. The machine travels forward.

The return pilot oil at the opposite end of the spool in the travel control valve returns to the travel pilot control valve through port (22). Since spool (11) is pushed upward by the force of spring (10), the return pilot oil flows through passage (17), passage (15), passage (14), return chamber (13) and port (12) to the hydraulic tank.

When travel lever/pedal (1) is moved slightly from the NEUTRAL position for fine travel, rod (3) moves downward and seat (4) moves downward. Spring (6) forces spool (7) downward. Passage (19) opens slightly and the pilot oil pressure increases in port (18). When this pilot oil pressure becomes higher than the force of spring (6), spool (7) moves upward opening passage (8). The pilot pressure oil from port (18) flows through passages (9), (20) and (8) into return chamber (13). The pilot oil pressure decreases slightly. Spool (7) is held in a pressure modulating position. Spool (7) establishes a balance between the pressure in port (18) and the force of spring (6) .

When travel lever/pedal (1) is released, spring (5) forces seat (4) and rod (3) in an upward direction. The force of spring (6) decreases. Spool (7) moves upward. The pilot oil pressure at port (18) flows through passage (9), passage (20), passage (8) and return chamber (13) to the hydraulic tank.

A dampening function is built into the travel pilot control valve which allows the operational speed of the travel lever/pedal to correspond to the movement of the operator's foot. The dampening function also prevents the vibration that occurs when the travel lever/pedal is released.

When travel lever/pedal (1) is moved suddenly from the NEUTRAL position, rod (3) is pushed downward. Rod (3) moves piston (25), spring (26) and spring (27) downward. The hydraulic oil in spring chamber (28) is pressurized. Ball (29) closes the opening. Orifice (24) allows the confined hydraulic oil in spring chamber (28) to gradually flow into piston chamber (23). The gradual flow of oil through orifice (24) causes the dampening function.

Rod (30) is forced upward by springs (31) and (32). The oil pressure in spring chamber (33) decreases. The return oil pressure in return chamber (13) forces ball (34) upward. The return oil in return chamber (13) now flows from return chamber (13) into spring chamber (33). As a result, rod (30) follows the movement of pedal (2) .

(28) Spring chamber

(29) Ball

(30) Rod

(31) Spring

(32) Spring

(33) Spring chamber

(34) Ball

When travel lever/pedal (1) is moved slightly from the NEUTRAL position for fine control, rod (3) is pushed down slowly. As a result, the oil pressure in spring chamber (28) becomes equal to the oil pressure in piston chamber (23). At this point, the dampening function is weak.

Travel lever/pedal (1) operates the same way in the REVERSE TRAVEL position.


Wed Feb 28 19:51:18 EST 2007


Travel Motor SMCS - 79PC-QP

Shutdown

Previous Screen



i02471406


Travel motor

(1) Drive shaft

(4) Swashplate

(5) Slipper

(6) Retainer

(7) Barrel

(8) Passage

(9) Check valve

(10) Check valve

(11) Passage


(13) Port

(14) Valve plate

(15) Head

(16) Stopper

(17) Piston

(18) Guide

(19) Spacer

(20) Spring

(21) Piston

(22) Friction plate


(24) Passage

(25) Passage

(26) Brake spring

(27) Brake piston

(28) Pilot Port

(29) Drain port

(30) Port

(31) Port

(32) Spool

(33) Spring


The travel motor can be divided into the following three groups:

The rotary group consists of the following components: drive shaft (1), slippers (5), retainer (6), barrel (7), guide (18), spacer (19), spring (20) and piston (21) .

Illustration 2 g01232390Travel motor (partial schematic)

(4) Swashplate

(9) Check valve

(10) Check valve


(17) Piston

(28) Pilot Port

(29) Drain port

(30) Port

(31) Port


The parking brake consists of the following components: brake pilot valve (12), friction plates (22), separator plates (23), brake spring (26) and brake piston (27) .

The displacement change valve consists of the following components: check valve (9), check valve (10), piston (17) and displacement change valve (34) .

The flow of the oil delivery from the pump depends on the direction of travel. The oil delivery from the pump flows into the travel motor through port (30) or port (31). Pump oil is forced out of the travel motor through port (31) or (30) .

The case drain oil returns to the hydraulic tank through drain port (29) of head (15) .

The oil delivery from the drive pump flows into the left travel motor through port (30) during forward travel. The oil from port (30) flows through passage (11) in head (15) and through passage (25) in valve plate (14). The oil then flows through passage (24) of barrel (7) and the oil forces pistons (21) to move to the left.

Illustration 3 g01232395Motor passage (side view from head)

(A) Top center

(B) Outlet side (low pressure)

(C) Bottom center

(D) Inlet side (high pressure)

(24) Passage (barrel)



Slipper (5) is coupled to the piston. Slipper (5) and the piston slide on the surface of swashplate (4) from the top center to the bottom center. Slipper (5) and the piston rotate with barrel (7). Supply oil from the drive pump flows through passage (25) of valve plate (14) into pistons (21). The oil then flows through passage (35) of valve plate (14). Oil is discharged from piston (21) through passage (8). The oil then flows through port (31). The barrel turns counterclockwise.

Drive shaft (1) is splined to barrel (7). The shaft and barrel of the left travel motor rotate counterclockwise for forward travel.

In reverse travel, port (30) functions as an oil return port. Port (31) functions as a supply port. The left travel motor rotates clockwise.

When the right travel motor receives the oil delivery from the idler pump through port (30), the right travel motor turns clockwise for forward travel. When the oil delivery from the idler pump flows through port (31), the right travel motor turns counterclockwise for reverse travel.


Wed Feb 28 19:51:49 EST 2007


Travel Parking Brake SMCS - 4267

The travel parking brake is built into the travel motor. When the oil delivery from the pump flows to the travel motor, the parking brake releases and the travel motor starts rotating. When no oil delivery flows to the travel motor, the rotation of the travel motor stops and the travel parking brake engages. For more information concerning the operation of the travel motor, refer to Systems Operation, "Travel Motor ".

Shutdown

Previous Screen



i02471838


Parking brake (parking brake engaged)


In the parking brake section of the travel motor, separator plates (10) are splined to housing (7). Friction plates (9) are splined to barrel (8) .

When the travel lever/pedal is returned to the NEUTRAL position, the oil delivery from the pump is blocked at the travel control valve in the main control valve. Valve (16) moves to the right by the force of spring (15). The oil delivery from the pump does not flow through valve (16). The force of the oil pressure on the left side of brake piston (13) now becomes lower than the force of brake spring (6). The brake piston is pushed slowly to the left by the force of the brake spring. The oil in piston chamber (12) now flows through passage (14) and passage (5). The oil flows through orifice (18) and into the valve of the motor case drain line. Friction plates (9) and separator plates (10) are forced together by the force of brake spring (6). Friction plates (9) are splined to barrel (8). Separator plates (10) are splined to housing (7). When the separator plates and the friction plates are forced together, the rotation of drive shaft (3) in the travel motor gradually slows to a stop as the parking brake engages.

Orifice (18) restricts return oil flow from piston chamber (12). The restriction of the return oil flow delays the application of the parking brake. The parking brake is delayed in order to give the machine time to stop. Earlier wear and/or damage to the machine could result if the machine stayed in motion.

(2) Port

(3) Drive shaft

(4) Head

(5) Passage

(6) Brake spring

(7) Housing

(8) Barrel

(9) Friction plate


(12) Piston chamber

(13) Brake piston

(14) Passage

(15) Spring

(16) Valve

(17) Retainer

(18) Orifice


Parking brake (brake released)


(2) Port

(3) Drive shaft

(4) Head

(5) Passage

(6) Brake spring

(7) Housing

(8) Barrel

(9) Friction plate


(12) Piston chamber

(13) Brake piston

(14) Passage

(15) Spring

(16) Valve

When a travel lever/pedal is moved from the NEUTRAL position, the oil delivery from the pump flows to the inlet port of the travel motor from the travel control valve in the main control valve. A portion of the oil delivery from the pump flows through port (2). Valve (16) moves to the left against the force of spring (15). The oil then flows through passages (5) and (14) to piston chamber (12). Brake piston (13) moves to the right against the force of brake spring (6). The spring force that is holding friction plates (9) and separator plates (10) together is released. Barrel (8) and drive shaft (3) start to rotate.

(17) Retainer

(18) Orifice


Wed Feb 28 19:52:21 EST 2007


Displacement Change Valve SMCS - 3220

Small Displacement Change Operation

Shutdown

Previous Screen



i02471997


Travel motor (partial diagram)

(1) Check valve

(2) Check valve

(3) Pilot port


(5) Passage

(6) Piston chamber


(8) Piston

(9) Swashplate


(11) Drain port


Small displacement change operation

(1) Check valve

(2) Check valve

(3) Pilot port


(6) Piston chamber

When the travel speed control switch on the control panel is pushed and the rabbit appears on the display, the machine is in HIGH SPEED MODE. In this condition, an input signal from the travel speed control switch is sent to the engine and pump controller. The pressure sensor for the pump delivery also provides an input signal to the engine and pump controller. When the travel load is light and when the pump delivery pressure is below a certain level, the output signal from the pressure sensor for the pump delivery is below a certain level. When the pump delivery pressure is below a certain level, the engine and pump controller energizes the travel speed solenoid. When the travel speed solenoid is energized, pilot system oil flows into pilot port (3) of displacement change valve (4). Spool (16) moves to the left against the force of spring (17) until the spool contacts body (18). Main pump oil flows from port (10) of the travel motor through check valve (2). The main pump oil then flows through spool chamber (15) and passage (12) to piston chamber (6). The oil in piston chamber (6) moves piston (8) against swashplate (9). As a result, the angle of swashplate (9) is decreased and the motor displacement is decreased. The travel speed is maximum in this condition.

Large Displacement Change Operation


(8) Piston

(9) Swashplate


(12) Passage

(13) Passage (return)

(14) Hydraulic tank

(15) Spool chamber

(16) Spool

(17) Spring

(18) Body


Large displacement change operation

(1) Check valve

(2) Check valve

(3) Pilot port


(6) Piston chamber


(8) Piston

(9) Swashplate


(12) Passage

(13) Passage (return)

(14) Hydraulic tank

(15) Spool chamber

(16) Spool

(17) Spring

When the angle of swashplate (9) in the travel motor increases, the displacement of the travel motor increases. The angle of swashplate (9) in the travel motor will increase and the travel speed will decrease during the following two conditions.

1. The angle of swashplate (9) in the travel motor will increase and the travel speed will decrease when an increase in pump pressure occurs.

When the machine is in HIGH SPEED MODE and the pump delivery pressure increases above a certain level, the engine and pump controller de-energizes the travel speed solenoid. When the travel speed solenoid is de-energized, pilot system oil stops flowing into pilot port (3) of displacement change valve (4). Spool (16) moves to the right by the force of spring (17) until the spool contacts the stopper. Oil from port (10) of the travel motor is blocked from passage (12). The oil is forced from piston chamber (6) through passage (12) and return passage (13) to hydraulic tank (14). As the angle of swashplate (9) increases, the displacement of the travel motor increases and the travel speed decreases.

2. The angle of swashplate (9) in the travel motor will increase and the travel speed will decrease when the travel speed control switch is pushed in order to obtain LOW SPEED MODE.

When the travel speed control switch on the control panel is pushed and the tortoise appears on the display, the machine is in LOW SPEED MODE. In this condition, an input signal from the travel speed control switch is sent to the engine and pump controller. The engine and pump controller de-energizes the travel speed solenoid. The angle of swashplate (9) increases and the displacement of the travel motor increases. The travel speed decreases.

(18) Body


Wed Feb 28 19:53:06 EST 2007


Travel Counterbalance Valve SMCS - 5051-KV

Shutdown

Previous Screen



i02472619

Illustration 1 g00821157Left travel motor and travel counterbalance valve

(1) Crossover relief valve (reverse travel)

(16) Crossover relief valve (forward travel)

(24) Port (supply port for forward travel)

(27) Port (supply port for reverse travel)


(35) Travel counterbalance valve

Travel counterbalance valve (35) consists of counterbalance valve (33), crossover relief valve (1) and crossover relief valve (16). The travel counterbalance valve is bolted to the travel motor. The travel counterbalance valve has the following four functions.

The travel counterbalance valve prevents a shock load when travel is stopped.

The travel counterbalance valve prevents overspeed while the machine is travelling down a slope.

The travel counterbalance valve prevents cavitation.

The travel counterbalance valve routes a portion of the oil to the travel parking brake in order to release the brake.

Counterbalance Valve Operation During Level Travel



Travel counterbalance valve (level travel)


(2) Passage

(3) Valve

(4) Passage

(5) Passage

(6) Passage

(7) Passage

(8) Valve

(9) Spool

(10) Spring

(11) Passage

(12) Spring

(13) Spring

(14) Damper Spool

(15) Ball


(17) Passage

(18) Spring chamber

(19) Passage

(20) Damper Chamber

(21) Orifice

(22) Passage

(23) Check valve


(25) Passage

(26) Passage


Counterbalance valve (33) consists of spool (9), check valve (23), check valve (28), spring (13) and spring (30). During forward travel on level ground, pump oil is supplied to port (24). The oil flows through port (24), passage (25), and check valve (23). The oil flow forces check valve (23) to open. This allows oil to flow through port (24), passage (25), check valve (23), passage (2), and the port to the rotary group of the travel motor.

A portion of the oil delivery from the drive pump in port (24) flows through passage (22) and passage (17) against ball (15). Ball (15) moves to the right against the force of spring (12) in damper spool (14). The oil delivery then flows through passage (19) into spring chamber (18). The oil pressure in damper chamber (20) acts on the end of spool (9). Spool (9) shifts to the right against the force of spring (30). Passage (7) opens.

As spool (9) shifts to the right, return oil from the travel motor flows through the port, passage (7), passage (26), and port (27) to the hydraulic tank.

When the oil flow from port (24) is blocked, the pressure in damper chamber (20) decreases. The force of spring (30) shifts spool (9) to the left. Passage (7) closes. Return oil from the travel motor is blocked and the rotation of the travel motor stops.

When the direction of travel is reversed, pump oil flows to spool (9) through port (27). Spool (9) shifts to the left. The return oil flows through port (24). During reverse travel, the travel counterbalance valve operates in the same manner as the forward travel operation.

Counterbalance Valve Operation During Slope Travel

(28) Check valve

(29) Passage

(30) Spring

(32) Passage




Travel counterbalance valve (slope travel)


(2) Passage

(3) Valve

(4) Passage

(5) Passage

(6) Passage

(7) Passage

(8) Valve

(9) Spool

When the machine travels down a slope, the travel motors rotate at a higher speed. The higher speed is due to the mass (weight and size) of the machine. When this condition occurs, the pumps cannot maintain the oil supply to the travel motors. The lack of oil supply will cause cavitation in the travel motor. A pressure decrease occurs at port (24). A pressure decrease occurs in spring chamber (18) as well.

The force of spring (30) moves spool (9) to the left. Passage (7) begins to close. This blocks oil flow between passage (7) and passage (26). The return oil from the travel motor and the oil flow to the suction port of the travel motor are restricted. The rotation of the travel motor slows down.

(10) Spring

(11) Passage

(12) Spring

(13) Spring

(14) Damper Spool

(15) Ball


(17) Passage

(18) Spring chamber

(19) Passage

(20) Damper Chamber

(21) Orifice

(22) Passage

(23) Check valve


(25) Passage

(26) Passage


(28) Check valve

(29) Passage

(30) Spring

(32) Passage



The pressure of the oil delivery from the drive pump at port (24) increases. Part of the oil flows through passage (17). Spool (9) shifts to the right. Passage (7) opens. Return oil from the travel motor flows through port (27). The modulation of spool (9) maintains the proper opening of passage (7) when the machine travels down a slope. The travel motor begins to rotate in accordance with the amount of pump oil supply. This prevents cavitation in the travel motors.

When the machine is travelling down a slope, or the machine is suddenly stopped, spool (9) suddenly closes passage (7). This causes a hydraulic pressure spike to occur. A damper is provided at both ends of spool (9) in order to prevent hydraulic pressure spikes. As spool (9) shifts to the left, the oil in damper chamber (20) is pressurized. Ball (15) moves to the left. The oil in spring chamber (18) flows through orifice (21) and into passage (22). Spool (9) slowly moves to the left. Passage (7) slowly closes. The size and the position of orifice (21) maintains the proper shock damper.

Operation Of Travel Crossover Relief Valves During Machine Stop


Travel counterbalance valve (travel stop)


(2) Passage

(3) Valve

(4) Passage

(5) Passage

(6) Passage

(7) Passage

(8) Valve

(9) Spool

(10) Spring

(11) Passage

(12) Spring

(13) Spring

(14) Damper Spool

(15) Ball


(17) Passage

(18) Spring chamber

(19) Passage

(20) Damper Chamber

(21) Orifice

(22) Passage

(23) Check valve


(25) Passage

(26) Passage


(28) Check valve

If the travel levers/pedals are returned to the NEUTRAL position during machine movement, the oil delivery from the pumps is blocked from the travel motors. The pressure at port (24) of the travel counterbalance valve decreases. The force of spring (30) moves spool (9) to the left to the neutral position. The mass (weight and size) of the machine causes the travel motor to continue to rotate. Passage (7) is closed and the flow of return oil is blocked. A sudden pressure increase occurs in passage (11). The return oil in passage (11) flows through passage (6) to crossover relief valve (1). Valve (3) shifts to the left. The return oil in passage (6) flows past the open valve (3) into suction passage (2) of the travel motor.

(29) Passage

(30) Spring

(32) Passage




Travel crossover relief valve

(3) Valve

(2) Passage

(6) Passage

(39) Body

(40) Orifice

(41) Orifice

(42) Orifice

The return oil pressure in passage (6) flows through orifice (41) in valve (3). The oil then flows through orifices (40) and (42) in stem (43). The return oil now flows through passage (44). Shock reducing piston (45) shifts to the right. The travel crossover relief valve maintains the circuit pressure at a lower pressure until the right end of shock reducing piston (45) contacts stem (43). When the shock reducing piston is fully shifted to the right, the oil pressure in passage (6) increases to the pressure setting of the crossover relief valve. All of the oil flow in passage (6) now flows past valve (3) into return passage (2) .

The oil pressure gradually increases until the shock reducing piston shifts fully to the right. Pressure spikes in the travel circuit are eliminated. This is called a two-stage relief operation. The two-stage relief operation absorbs the shock load at the stop of a travel operation.

During forward travel of the left travel motor, oil flow opens crossover relief valve (1) when the machine is stopping. During reverse travel of the left travel motor, crossover relief valve (16) is activated when the machine is stopping.

Crossover relief valves (1) and (16) protect the travel motor by releasing the high pressure oil.

Crossover relief valves (1) and (16) also provide makeup oil from the outlet side of the travel motor to the inlet side of the travel motor. This makeup oil prevents a vacuum condition in the travel motor.

In order to adjust the pressure setting of the crossover relief valves, refer to the crossover relief valves by the functions of the travel control levers. Refer to crossover relief valve (16) as left travel (forward). Refer to crossover relief valve (1) as left travel (reverse).

ReferenceFor more information concerning the pressure settings of the travel crossover relief valves, refer to Testing and Adjusting, "Relief Valve (Crossover) - Test and Adjust".

Travel Parking Brake Operation When the oil delivery from the drive pump at port (24) of the travel counterbalance valve is blocked, spool (9) moves to the right. Passage (4) opens. A portion of the oil delivery in passage (25) flows through passage (4) and passage (32) in order to release the travel parking brake. Since passage (4) opens before passage (7), the rotation of the motor rotary group does not start until the travel parking brake is released.

When the oil delivery to port (24) is blocked in order to stop the rotation of the travel motor, spool (9) returns to the NEUTRAL position. Passage (4) closes after passage (7) closes. This allows the movement of the machine to stop before the travel parking brake is engaged.

ReferenceFor more information concerning the operation of the travel parking brake, refer toSystems Operation, "Travel Parking Brake".

(43) Stem

(44) Passage

(45) Shock reducing piston


Wed Feb 28 19:53:48 EST 2007


Oil Makeup (Travel System) SMCS - 5080

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Oil makeup operation



(3) Passage

(4) Check valve

(5) Line

(6) Swivel

In order to prevent cavitation in the travel motor during travel stop, makeup oil is supplied to the travel motor.

The following description is given for travel stop of the left travel motor. The right travel motor functions in the same manner as the left travel motor.

During travel stop, the travel levers/pedals are moved to the NEUTRAL position. The oil delivery from the drive pump through passage (8) is blocked at travel control valve (9). The oil delivery from the drive pump is not supplied to the left travel motor.

Since no oil delivery is supplied to left travel motor (2), the travel motor will attempt to stop. However, the travel motor will continue to rotate because of the inertia (weight and size) of the machine. This causes a vacuum condition in passage (3) of the travel motor.

When travel control valve (9) is in the NEUTRAL position, return oil flows from return passage (11) through passage (8). The return oil then flows through line (7), swivel (6), line (5), check valve (4) and passage (3) to motor rotary group (1) as makeup oil. This makeup oil prevents cavitation in the travel motor during travel stop.

Makeup oil is supplied for forward travel in the same manner as reverse travel.

(7) Line

(8) Passage


(10) Passage

(11) Return passage


Wed Feb 28 19:54:58 EST 2007


Control Valve (Straight Travel) SMCS - 5462

Straight travel (tracking) can be maintained even though there is a swing operation or implement operation during travel.

Straight travel control valve (2) maintains straight travel even though there is a swing operation or implement operation during travel. The straight travel control valve also improves pipelayer control or placement of timbers.

When the machine travels without swing operation or implement operation, the pressure switch for left travel and the pressure switch for right travel are ON. The implement/swing pressure switch is OFF. The oil delivery from the idler pump flows through right travel control valve (1) to the right travel motor. The oil delivery from the drive pump flows through straight travel control valve (2) and

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left travel control valve (3) to the left travel motor. Because both travel circuits are separated, the machine continues to travel straight, unless a difference in travel resistance occurs between the right and left tracks.

The straight travel system ensures the straight travel of the machine when other circuits are operated during travel. The idler pump and the drive pump supply oil to the travel motors. The idler pump and the drive pump also supply oil for a swing or implement operation. During travel, if an implement operation or a swing operation occurs the oil supply to each travel motor will differ. This would cause the right travel motor and the left travel motor to rotate at different speeds. The different speeds will cause the machine to turn.

The following actions occur when the straight travel control valve is activated.

The pressure switch for left travel and the pressure switch for right travel are ON.

The implement/swing pressure switch is ON.

The idler pump supplies oil to the left travel circuit and to the right travel circuit in order to drive both motors in parallel.

The swing circuit and implement circuits receive oil from the drive pump. When the machine is travelling, the swing circuit and implement circuits do not require a large amount of oil flow. The swing circuit and implement circuits are operated at speeds that are low enough for stable machine operation. The remainder of the oil is shared by the right travel circuit and the left travel circuit.


Straight travel control valve (NEUTRAL position)

Pilot oil pressure is sent from the pilot oil manifold to straight travel solenoid (14). When only the travel levers/pedals are activated, straight travel solenoid (14) is not energized. Pilot oil flow to pilot passage (5) and straight travel control valve (13) is blocked at the straight travel solenoid. The oil pressure in piston chamber (6) is low and spool (12) is shifted to the right by the force of spring (7). The oil delivery from the idler pump and the drive pump flows in the following manner.

The oil delivery from the idler pump flows through line (10) to passage (11) in the straight travel control valve. The oil delivery from the idler pump separates into two flow paths. One path flows through center bypass passage (3) and into the right travel control valve. The other path flows through parallel feeder passage (4) .

The oil delivery from the drive pump flows through line (9) to passage (8) in the straight travel control valve. The oil delivery from the drive pump separates into two flow paths. One path flows through parallel feeder passage (1). The other path flows through center bypass passage (2) and into the left travel control valve.





(5) Pilot passage

(6) Piston chamber

(7) Spring

(8) Passage

(9) Line (oil delivery from the drive pump)

(10) Line (oil delivery from the idler pump)

(11) Passage

(12) Spool


(14) Straight travel solenoid


Straight travel control valve (activated position)





(5) Pilot passage

(6) Piston chamber

(7) Spring

(8) Passage

(9) Line (oil delivery from the drive pump)

(10) Line (oil delivery from the idler pump)

(11) Passage

(12) Spool


(14) Straight travel solenoid

(15) Check valve

When the travel levers/pedals are activated at the same time as either one of the joysticks, straight travel solenoid (14) is energized. The pilot oil flows through the straight travel solenoid to straight travel control valve (13). The pilot oil enters piston chamber (6). The pilot oil pressure in piston chamber (6) increases. Spool (12) shifts to the left against the force of spring (7). The oil delivery from the idler pump and the drive pump flows in the following manner.

The oil delivery from the idler pump flows through line (10) and passage (11) in the straight travel control valve. The oil delivery from the idler pump separates into two flow paths. One path flows through center bypass passage (2) and into the left travel control valve. The other path flows through center bypass passage (3) and into the right travel control valve.

The oil delivery from the drive pump flows through line (9) and passage (8) in the straight travel control valve. The oil delivery from the drive pump separates into two flow paths. One path flows through parallel feeder passage (1). The other path flows through passage (16) and into parallel feeder passage (4). Part of the oil delivery from the drive pump in passage (16) flows through orifice (18) in spool (12) and opens check valve (15). The oil now flows through passage (17) to center bypass passage (2). The oil delivery from the drive pump combines in center bypass passage (2) with the oil delivery from the idler pump. This increases the drive speed of the right travel motor and the left travel motor.

(16) Passage

(17) Passage

(18) Orifice


Wed Feb 28 19:55:39 EST 2007


Final Drive SMCS - 4050

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Final Drive

(1) Roller bearing

The final drive reduces the rotational speed of travel motor (11). Output shaft (23) of travel motor (11) is splined to sun gear (first stage) (15) .

The final drive consists of two groups. The first group consists of the three stages of the planetary gear reduction. The second group is the output group.

The first stage reduction group consists of the following components: sun gear (15), planetary gear (12), planetary carrier (16) and ring gear (17). The group for second stage reduction consists of the following components: sun gear (19), planetary gear (4), planetary carrier (18) and ring gear (20). The third stage reduction group consists of the following components: sun

(2) Planetary shaft (second stage)

(3) Bolt

(4) Planetary gear (second stage)

(5) Roller bearing

(6) Planetary gear (third stage)

(7) Roller bearing

(8) Planetary shaft (third stage)

(9) Drive sprocket housing

(10) Motor housing

(11) Travel motor

(12) Planetary gear (first stage)

(13) Planetary shaft (first stage)

(14) Cover

(15) Sun gear (first stage)

(16) Planetary carrier (first stage)

(17) Ring gear (first stage)

(18) Planetary carrier (second stage)

(19) Sun gear (second stage)

(20) Ring gear (second stage and third stage)

(21) Planetary carrier (third stage)

(22) Sun gear (third stage)

(23) Output shaft (travel motor)

(26) Roller bearing

gear (22), planetary gear (6), planetary carrier (21) and ring gear (20) .

The output group is described in the following manner. The rotation of drive sprocket housing (9) drives the track. Drive sprocket housing (9), ring gear (20) and cover (14) are connected by bolts (3). The drive sprocket housing, the ring gear and the cover are supported by roller bearing (26). This planetary assembly rotates with ring gear (20) .

The planetary gears reduce the travel speed. The travel speed is reduced by the ratio of teeth of the sun gear and the ring gear. The compact final drive offers a greater reduction ratio when the sun gear is incorporated inside the ring gear.

Operation Sun gear (15) is splined to the output shaft of travel motor (23). The rotation of the output shaft is transmitted to the sun gear. When sun gear rotates clockwise, the final drive operates in the following manner.


First stage reduction group

(1) Roller bearing (first stage)



In the first stage reduction group, sun gear (15) causes planetary gears (12) to rotate counterclockwise. Planetary gears (12) mesh with sun gear (15) and ring gear (17). Planetary gears (12) rotate around sun gear (15) and the internal teeth of ring gear (17). Each planetary gear (12) is mounted to planetary carrier (16) by shafts (13) and by roller bearings (1) in order to form a planetary assembly. Planetary carrier (16) rotates in a clockwise direction (27).

(15) Sun gear (first stage)


(17) Ring gear (first stage)

(27) Rotational direction (first stage reduction group)


Engagement of splines




(19) Sun gear (second stage)

The spline of planetary carrier (first stage) (16) meshes with sun gear (second stage) (19). The rotation of planetary carrier (16) is transmitted to sun gear (19). Sun gear (19) rotates clockwise.

In the group for second stage reduction, sun gear (19) causes planetary gears (4) to rotate counterclockwise. Planetary gears (4) mesh with sun gear (19) and ring gear (20). Planetary gears (4) rotate around sun gear (9) and the internal teeth of ring gear (20). Each planetary gear (4) is mounted to planetary carrier (18) by shafts (2) and by roller bearings (5) in order to form a planetary assembly. Planetary carrier (18) rotates clockwise.

The spline of planetary carrier (second stage) (18) meshes with sun gear (third stage) (22). The rotation of planetary carrier (18) is transmitted to sun gear (22). Sun gear (22) rotates clockwise.

In the third stage reduction group, the spline teeth of planetary carrier (21) mesh with teeth on the outer circumference of motor housing (10). Since motor housing (10) is fixed to the track frame, planetary carrier (21) does not rotate.

Planetary shaft (8) is stationary. The planetary gear (third stage) (6) rotates around planetary shaft (8). Since planetary carrier (21 ) is attached to the track frame and the planetary carrier does not move, ring gear (20) rotates counterclockwise. Since ring gear (20) and drive sprocket housing (9) are held together with bolts (3), drive sprocket housing (9) rotates counterclockwise. This causes the right track to move in a forward direction.

(28) Engagement of splines

Illustration 4 g00581172Engagement of splines

(18) Planetary carrier (second stage)

(22) Sun gear (third stage)

(27) Engagement of splines


Wed Feb 28 19:56:17 EST 2007


Swivel SMCS - 5060

Shutdown

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i02345594

Illustration 1 g01171766Swivel

(1) Retainer

(2) Cover

(3) Drain port

(4) Drain hole

(5) Port

(6) Seal

(7) Port

(8) Port

(9) Housing

(10) Port

(11) Port

(12) Flange

(13) Seal

(14) Rotor

(15) Port

(16) Port

(17) Port

(18) Port

(19) Port

(20) Port

(21) Swivel

Table 1

Identification Of Port And Circuit

Ports (Housing) Ports (Rotor) Circuit

7 17 Right travel (reverse)

10 20 Right travel (forward)

The swivel accomplishes two functions. The swivel supplies pump oil from the upper structure to the travel motors of the lower structure. The upper structure swings. The lower structure does not swing. Swivel (22) returns oil from the travel motors to the hydraulic tank.

Housing (9) is bolted to the upper structure at flange (12). Rotor (14) rotates within housing (9). A support arm is bolted to rotor (14) in order to prevent rotation. The ports of housing (9) are open to the ports of rotor (14). The passages in housing (9) and the passages in rotor (14) connect the ports.

Seal (6) for high pressure and seal (13) for low pressure are provided between the sliding surfaces of housing (9) and rotor (14). Seals (6) and (13) prevent oil leakage between the passages.

8 19 Left travel (forward)

5 16 Left travel (reverse)

3 18 Drain

11 15 Change of Travel speed


Wed Feb 28 19:56:57 EST 2007


Return Hydraulic System SMCS - 5050-RJ

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(1) Swing motor

(2) Travel motors

(3) Case drain line

(4) Case drain line

(5) Makeup line (makeup oil to swing motor)

(6) Return line

(7) Return passage

(8) Return line

(9) Return passage






(15) Case drain line

(16) Return line

(17) Fan pump

(18) Pilot pump

(19) Drive pump

(20) Idler pump



(23) Return filter

(24) Hydraulic oil cooler

(25) Fan motor

(26) Hydraulic tank

(27) Case drain filter

(28) Case drain line

The oil delivery from idler pump (20) and drive pump (19) enters main control valve (10). The oil then flows to return line (8) and return line (6) in one of the following manners.

When all joysticks and/or travel levers/pedals are in the NEUTRAL position, pump low pressure standby oil from idler pump (20) flows through center bypass passage (11) and negative flow control orifice (13) to return line (6). Pump low pressure standby oil from drive pump (19) flows through center bypass passage (14) and negative flow control orifice (12) to return line (8) .

When any one of the joysticks and/or travel levers/pedals is shifted from the NEUTRAL position, center bypass passages (11) and/or (14) are blocked. The return oil from the cylinders and/or motors now flows through return passage (9) to return line (8) .

The return oil from return line (6) and return line (8) flows through return lines (16) and slow return check valve (21) .

When the oil temperature is very low, most of the oil is returned through bypass check valve (22) to hydraulic tank (26). The remainder of the oil flows into oil cooler (24) and return filter (23) to hydraulic tank (26) .

When the oil temperature increases, the rate of oil flow through bypass check valve (22) decreases. This causes the rate of oil flow through oil cooler (24) to increase.

ReferenceFor more information concerning the bypass check valve, refer to Systems Operation, "Bypass Valve (Return)".

Case drain oil from idler pump (20), drive pump (19), pilot pump (18), and fan pump (17) flows into case drain line (29). Case drain oil from swing motor (1) and travel motors (2) flows into respective case drain lines (3) and (4). The case drain oil from the motors flows through case drain line (15) and combines with the case drain oil from the pumps at case drain line (28). All of the case drain oil from the pumps and the motors now flows through case drain filter (27) to hydraulic tank (26) .

Makeup line (5) will route return oil to the inlet port of the swing motor if a vacuum condition occurs at the swing motor during swing stop.

For more information concerning the makeup operation of the return hydraulic system at the swing motor, refer to the following sections in this manual.

Systems Operation, "Check Valve (Return Makeup)"

Systems Operation, "Oil Makeup (Swing System)"

Systems Operation, "Relief Valve (Swing)"

(29) Suction line


Wed Feb 28 19:57:44 EST 2007


Check Valve (Return Makeup) - Slow Return Check Valve SMCS - 5067; 5080

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Illustration 1 g00847520Main control valve compartment (return circuit)




(29) Inlet line to oil cooler (18)

Slow return check valve (17) is contained in check valve (28). Slow return check valve (17) is located between the main control valves and the hydraulic tank in the return circuit. The slow return check valve restricts the return oil flow. This restriction causes a pressure increase in return line (16) and makeup line (5) .

If cavitation occurs in the swing motor, oil from return line (16) flows into makeup line (5). This makeup oil is supplied to the inlet port of the swing motor in order to prevent cavitation in the swing motor.

Note: For more information on the makeup operation, refer to System Operation, "Oil Makeup (Swing System)".

Illustration 2 g01234594Slow return check valve and bypass check valve


(16) Return line



(28) Check valve

(29) Inlet line to oil cooler (18)

(30) Return line to bypass check valve

(33) Return line (return flow to return filter)

The return oil flow through slow return check valve (17) is divided into two flow paths. A portion of the oil flows through inlet line (29) to the hydraulic oil cooler. The cooled oil from the hydraulic oil cooler flows through return line (30) and the return filter to the hydraulic tank. The remainder of the oil flow from slow return check valve (17 ) flows through bypass check valve (24) and the return filter to the hydraulic tank. Bypass check valve (24) is contained in check valve (28).


Wed Feb 28 19:58:17 EST 2007


Bypass Valve (Return) - Bypass Check Valve SMCS - 5071

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Illustration 1 g00847520Main control valve compartment (return circuit)




(29) Inlet line to hydraulic oil cooler (18)

The return oil flow through slow return check valve (17) is divided into two flow paths. A portion of the oil flows through inlet line (29) to the hydraulic oil cooler and the remainder of the return oil flows through bypass check valve (24) .

When the temperature of the return oil in inlet line (29) is very low, the viscosity of the oil is high. The flow resistance of the return oil in inlet line (29) is high. Thus, the pressure of the return oil is high.

Illustration 2 g01234594Slow return check valve and bypass check valve


(16) Return line



(28) Check valve

(29) Inlet line to hydraulic oil cooler (18)


(33) Return line (return flow to return filter)

As a result of the high pressure of the return oil, bypass check valve (24) opens. Most of the return oil flows through bypass check valve (24), return line (33) and return filter (19) to hydraulic tank (25). The remainder of the oil flows through inlet line (29) to the hydraulic oil cooler. Since a small amount of the return oil flows to the oil cooler, the temperature of the oil increases.

As the oil temperature increases, the return oil pressure decreases. Bypass check valve (24) begins to close. A greater portion of the return oil flows to the hydraulic oil cooler. Bypass check valve (24) maintains the hydraulic oil at the optimum operating temperature.

Illustration 3 g00849905(19) Return filter

(25) Hydraulic tank

(33) Return line


Wed Feb 28 19:58:59 EST 2007


Hydraulic Tank and Filter SMCS - 5056; 5068

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(19) Return filter

(25) Hydraulic tank

(34) Element

(35) Return chamber

The return oil from the hydraulic oil cooler flows through port (40) and passage (42) to return chamber (35) .

Return filter (19) consists of element (34) and relief valve (41). The return filter is mounted on the rear surface of the hydraulic tank.

The return oil passes through element (34) of return filter (19). The return oil then flows through line (38) to hydraulic tank (25). Thereafter, the oil passes through suction filter (37) and the oil is delivered to the pumps through suction line (39).

Air breather (43) is located on the upper surface of the hydraulic tank. The air breather prevents an increase or a decrease of air pressure in the hydraulic tank regardless of the following circumstances :

Change of air pressure in the hydraulic tank due to cylinder movement.

Change of air pressure in the hydraulic tank capacity due to a temperature change.

(36) Tank chamber

(37) Suction filter

(38) Line

(39) Suction line

(40) Port

(41) Relief valve

(42) Passage

Illustration 2 g01234777(43) Air breather


Wed Feb 28 19:59:52 EST 2007


Oil Filter (Return) - Case Drain Filter SMCS - 5068-RJ

The case drain filter receives case drain oil from the following components.

Right travel motor

Left travel motor

Swing motor

Main hydraulic pump (idler pump and drive pump)

Fan motor

Case drain oil flow from the right travel motor, the left travel motor and the swing motor are combined at the swivel. The case drain oil flow from these components then flows to the case drain filter. The case drain oil from the main hydraulic pump and the fan motor also flows to the case drain

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Illustration 1 g00846942Case drain filter

filter. Return oil then flows from the case drain filter to the hydraulic tank.


Wed Feb 28 20:00:27 EST 2007


Hydraulic Oil Cooler SMCS - 1374

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(18) Hydraulic oil cooler

(19) Fan shroud

(28) Inlet line to hydraulic oil cooler

(29) Hydraulic oil cooler inlet

The hydraulic oil cooler is mounted in front of the engine. Hydraulic oil cooler (18) is integrated with the engine coolant radiator. The hydraulic oil cooler is mounted in the inboard side of the radiator.

The hydraulic oil flows through the hydraulic oil cooler in order to maintain the operating temperature of the oil. A fan that is driven by the engine pulls air through the radiator. A portion of the return oil from the main control valves flows through the bypass check valve and flows through line (28), and inlet (29) to hydraulic oil cooler (18). The hydraulic oil that is cooled by the hydraulic oil cooler flows through outlet (31), return line (30) and the return filter to the hydraulic tank.


(31) Hydraulic oil cooler outlet


Wed Feb 28 20:00:58 EST 2007


Graphic Color Codes SMCS - 5050

Shutdown

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Wed Feb 28 20:01:43 EST 2007

Documents

330D System Operation Hydraulic RENR9584