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Caterpillar hydraulic excavators serie D
SERV1852-02 August 2008 GLOBAL SERVICE LEARNING TECHNICAL PRESENTATION 320D-336D HYDRAULIC EXCAVATORS TIER III ENGINES MAIN HYDRAULIC PUMPS AND PUMP CONTROL VALVE GROUPS Service Training Meeting Guide (STMG) 320D-336D HYDRAULIC EXCAVATORS TIER III ENGINES MAIN HYDRAULIC PUMPS AND PUMP CONTROL VALVE GROUPS AUDIENCE Level II - Service personnel who understand the principles of machine systems operation, diagnostic equipment, and procedures for testing and adjusting CONTENT This presentation provides an introduction and describes the components and systems operation of the 320D-336D main hydraulic pumps and pump control valve groups Additional presentations will cover the machine walkaround, engines, pilot system, main control valve group, implements swing system, travel system, and tool control systems in more detail This presentation may be used for self-paced and self-directed training OBJECTIVES After learning the information in this presentation, the technician will be able to: identify the components and explain the operation of the 320D-336D hydraulic excavators main hydraulic pumps and controls, and diagnose problems in the main hydraulic pumps and controls REFERENCES 320D Hydraulic Excavator Specalog 323D L and 323D LN Hydraulic Excavators 324D Hydraulic Excavator Specalog 325D Hydraulic Excavator Specalog 328D Hydraulic Excavator Specalog 330D Hydraulic Excavator Specalog Machine Monitoring System - Systems Operation Self-study "300D Series Hydraulic Excavators, 345C Hydraulic Excavator, and 365C & 385C Large Hydraulic Excavators iTIM " '300C' Series Hydraulic Excavators-Electronic Control Systems" iTIM "325C Hydraulic Excavators-Hydraulic Systems" 325D Hydraulic Schematic Estimated Time: hour Illustrations: 22 Form: SERV1852-02 Date: August 2008 © 2008 Caterpillar AEHQ5856 HEHH3327 AEHQ5663 AEHQ5665 AEHQ5706 AEHQ5667 RENR8068 SERV7032 SERV2693 SERV2701 KENR6157 SERV1852-02 08/08 -3- Text Reference Main Pumps TABLE OF CONTENTS INTRODUCTION 320D - 329D MAIN HYDRAULIC PUMP GROUP 11 Pump Control Valve Group 16 330D / 336D MAIN HYDRAULIC PUMP GROUP 21 Pump Control Valve Group 27 CONCLUSION 36 SERV1852-02 08/08 -4- Text Reference Main Pumps PREREQUISITES "Fundamentals of Mobile Hydraulics Self Study Course" "Fundamentals of Power Train Self Study Course" "Fundamentals of Electrical Systems Self Study Course" "Fundamentals of Engines Self Study Course" TEMV3002 TEMV3003 TEMV3004 TEMV3001 NOTES Nomenclature Change: During the fourth quarter of 2008, the 325D and 330D nomenclature changed The 325D became the 329D and the 330D became the 336D for most arrangements The exceptions are as follows: - The nomenclature for the 325D MH and 330D MH did not change - The nomenclature for the 325D FM and 330D FM did not change - The 325D HD HW did not change into 329D HD HW This model is being discontinued However, the 330D HD HW changed to the 336D HD HW SERV1852-02 08/08 -5- Text Reference Main Pumps MAIN HYDRAULIC PUMPS AND PUMP CONTROL VALVE GROUPS Stick Cylinder Bucket Cylinder Swing Motor Main Control Valve Group Pilot Control Valves Priority Valves Pilot Manifold Pilot Pump Fan Motor Boom Cylinders Travel Motors Main Hydraulic Pumps M Fan Pump Tank The Fan Motor and Pump are only used on the 330D and 336D INTRODUCTION This section of the presentation will cover the main hydraulic pumps and pump controls for the 300D Hydraulic Excavators The main pump group consists of a variable displacement piston drive pump and a variable displacement piston idler pump The drive pump and the idler pump are part of an integral housing The drive pump and the idler pump are identical in construction and operation The pumps are sometimes referred to as S.B.S (side by side) pumps The main difference between all of the pumps is the maximum pump flow for each model Both the drive pump and the idler pump have individual pump control valve groups to control the pump flow The 320D through the 329D use the same type of pump control valve group The 330D/336D pump control valve group is the same as the pump control valve group used on the 345C pump SERV1852-02 08/08 -6- Text Reference Main Pumps POWER SHIFT PRESSURE SYSTEM Idler Pump Pump Control Valve Power Shift PRV Solenoid Engine Speed Sensor Drive Pump Output Pressure Sensor Engine ECM Machine ECM Pilot Pump Engine Speed Dial Monitor OK Power shift pressure is controlled by the Machine ECM, and assists in pump regulation Power shift pressure is one of three pressures to control the pump The pilot pump supplies the power shift PRV solenoid with pilot oil The Machine ECM monitors the selected engine speed (from the engine speed dial), the actual engine speed (from the engine speed sensor and Engine ECM), and the pump output pressures (from the output pressure sensors) The power shift PRV solenoid valve regulates the pressure of the power shift oil depending upon the signal from the Machine ECM to the pump control valve groups When the engine speed dial is in position 10, the Machine ECM varies the power shift pressure in relation to the actual speed of the engine The power shift pressure is set to specific fixed values dependent upon the position of the engine speed dial The fixed power shift pressures assist cross sensing pressure (not shown) with constant horsepower control SERV1852-02 08/08 -7- Text Reference Main Pumps When the engine speed dial is on position 10 and a hydraulic load is placed on the engine, this condition causes the engine speed to decrease below the engine's target rpm When this decrease occurs, the Machine ECM signals the power shift PRV solenoid valve to send increased power shift pressure to the pump control valve groups The increased power shift signal causes the pumps to destroke, and reduce the horsepower demand placed on the engine With a decreased load from the hydraulic pumps the engine speed increases This function is referred to as engine underspeed control Engine underspeed control prevents the engine from going into a "stall" condition where engine horsepower cannot meet the demands of the hydraulic pumps The power shift signal to the pump control valve groups enables the machine to maintain a desired or target engine speed for maximum productivity Power shift pressure has the following effect on the main hydraulic pumps: - As power shift pressure decreases, pump output increases - As power shift pressure increases, pump output decreases Power shift pressure ensures that the pumps can use all of the available engine horsepower for the hydraulic system at all times without exceeding the output of the engine NOTE: The target rpm is the full load speed for a specific engine "no load" rpm Engine target rpm is determined by the opening of one of the implement, swing, and/or travel pressure switches at the end of an operation The Machine ECM then waits 2.5 seconds and records the engine speed This specific rpm is the "new" no load rpm The Machine ECM then controls the power shift pressure to regulate pump flow to maintain the full load (target) rpm for the recorded no load rpm Target rpm can change each time the pressure switches open for more than 2.5 seconds SERV1852-02 08/08 -8- Text Reference Main Pumps PROPORTIONAL REDUCING SOLENOID VALVE PWM SIGNAL INCREASE Solenoid Plunger Spring Tank Power Shift Pressure Pilot Pressure The proportional reducing solenoid valve (PRV) for the power shift pressure is located on the drive pump control valve group The proportional reducing solenoid 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 sent from the Machine ECM causes the proportional reducing solenoid valve to regulate the pilot pressure to the pump control valve groups to a reduced pressure This reduced pressure is called power shift pressure (PS) The output flow of the drive pump and the idler pump is controlled in accordance with the power shift pressure The power shift pressure is used to control the maximum hydraulic pump output in relation to the engine rpm A decrease in engine speed causes an increase in power shift pressure and a decrease in pump flow SERV1852-02 08/08 -9- Text Reference Main Pumps When the speed dial is at dial position 10, if the Machine ECM senses a decrease in engine speed below target rpm, the Machine ECM increases the PWM signal sent to the solenoid The magnetic force of the solenoid increases As the magnetic force of the solenoid becomes greater than the force of the spring, the spool moves down against the force of the spring The downward movement of the spool blocks the flow of oil to the tank More power shift pressure oil is now directed to the pump control valve group The increased power shift pressure acts on the drive pump control valve group and the idler pump control valve group If both pumps are upstroked, then both pumps will destroke as a result of the increase in power shift pressure If only one pump is upstroked, only the upstroked pump will destroke SERV1852-02 08/08 - 10 - Text Reference Main Pumps PROPORTIONAL REDUCING SOLENOID VALVE PWM SIGNAL DECREASE Solenoid Plunger Spring Tank Power Shift Pressure Pilot Pressure If engine speed is above the target rpm, the Machine ECM decreases the power shift pressure to increase the pump flow When the Machine ECM senses an increase in engine speed above the target speed the Machine ECM decreases the PWM signal sent to the proportional reducing solenoid valve As the magnetic force of the proportional reducing solenoid valve becomes less than the force of the spring, the spool moves up The upward movement of the spool restricts the pilot oil flow to the power shift passage and opens the power shift passage to the drain The power shift pressure is reduced The reduced power shift pressure acts on the drive pump control valve group and the idler pump control valve group Depending on which circuits are activated, the drive pump and/or the idler pump will upstroke as a result of a decrease in power shift pressure SERV1852-02 08/08 - 22 - Text Reference Main Pumps 13 This is a view of the drive pump pump control valve group The pump control valve group is located above and behind the power shift PRV solenoid valve This illustration shows: - the drive pump negative flow control adjustment (1) - the drive pump horsepower control adjustment (2) The idler pump control valve group has similar adjustment screws SERV1852-02 08/08 - 23 - Text Reference Main Pumps 330D / 336D PUMP COMPONENTS AND INPUTS Right NFC Control Orifice Horsepower Control Spool Drive Pump Cross Sensing Signal Torque Control Spool Idler Pump Cross Sensing Signal NFC Spool Drive Pump Output Pressure Sensor Actuator P Destroke Main Control Valve (Right Side) Drive Pump M Pilot Pump Pilot Pump Power Shift (PRV) Solenoid Valve Idler Pump 14 Each pump receives four different signals to control the output flow of the pumps: - power shift pressure - system pressure from that pump - cross sensing pressure (from the other pump) - Negative Flow Control (NFC) pressure Power Shift Pressure: The power shift PRV receives a control signal from the ECM The ECM sends an electrical signal to the power shift PRV to regulate power shift pressure in relation to the engine speed The power shift signal to the pump control valve groups enables the machine to maintain the target engine speed for maximum productivity SERV1852-02 08/08 - 24 - Text Reference Main Pumps If the Machine ECM senses that the engine is below the target speed due to a high hydraulic load from the main pumps, the Machine ECM will increase the power shift pressure The target speed is the full load for the no load engine speed (The new no load speed is taken 2.5 seconds after the implement/swing and the travel pressure switches open when the joysticks and the travel control pilot controls are returned to NEUTRAL) As power shift pressure increases, the pump control valve groups destroke the main pumps accordingly This reduces the load on the engine, and consequently enables the engine to maintain the target engine speed If the engine speed is above the target speed, the Machine ECM will decrease power shift pressure, causing the pumps to upstroke and produce more flow Cross sensing Control Pressure: Each pump control valve group gets a cross sensing control pressure from the other pump system pressure Cross sensing pressure is essentially an average pressure from the output of the drive pump and the idler pump Negative Flow Control (NFC): NFC is the primary controlling signal for the main pump output The NFC signal to the main pump control valve group is generated in the main control valve group The NFC signal is delivered to the left and right pump control valve groups from the left and right halves of the main control valve group, respectively When the joysticks or travel levers are in the NEUTRAL position, the oil flows from the main pumps through the open center bypass passages of the control valves The oil flows to the valves and returns to the tank by way of the NFC control orifices The restriction of the NFC orifices causes a pressure signal to be sent to the right and left pump control valve groups, respectively, as an NFC signal When the main pump control valve groups receive a high NFC signal from the main control valves, the pumps remain at a standby output flow at or near minimum pump displacement When a joystick or travel lever is moved from a NEUTRAL position, the open-center passage of the corresponding implement/travel function is closed in proportion to spool movement This reduces the NFC signal to the main pump control valve and the pump output flow is increased proportionally When the control valve is fully shifted, the NFC pressure is reduced to slow return check valve pressure The use of an NFC hydraulic system maximizes efficiency of the machine by only producing flow from the pumps when the flow is needed NOTE: A high NFC signal will always overcomes the horsepower control and decrease pump flow to minimum SERV1852-02 08/08 - 25 - Text Reference Main Pumps Right NFC Control Orifice Torque Control Spool 330D / 336D HYDRAULIC PUMPS STANDBY Horsepower Control Spool NFC Spool Actuator Main Control Valve (Right Side) Drive Pump Pilot Pump Drive Pump Output Pressure Sensor P M Power Shift PRV Idler Pump Actuator Pilot System Destroke P Pilot Pump Main Control Valve (Left Side) Idler Pump Output Pressure Sensor Left NFC Control Orifice 15 This illustration shows the pumps in STANDBY condition Each pump control valve group senses the Negative Flow Control (NFC) signal, the power shift pressure, the cross sensing pressure, and the system pressure for that pump When one of more circuits are activated, the pump control valve groups will upstroke or destroke the pumps to maintain the pump flow depending on the four signal pressures to the pump control valve groups The pump control valve group controls oil pressure to the left side of the actuator This controls the angle of the pump swashplate The 330D/336D hydraulic pumps are always trying to upstroke to increase flow The pump control valve groups vary the oil pressure used to destroke the hydraulic pumps SERV1852-02 08/08 - 26 - The idler pump supplies oil to the following valves: - left travel control valve - swing control valve - stick I control valve - boom II control valve - idler (left) pump negative flow control valve - auxiliary valve (if equipped) The drive pump supplies oil to the following valves: - right travel control valve - standard attachment control valve - bucket control valve - boom I control valve - stick II control valve - drive pump negative flow control valve Text Reference Main Pumps SERV1852-02 08/08 - 27 - Torque Control Lever PUMP CONTROL GROUP Horsepower Control Sleeve Text Reference Main Pumps Negative Flow Control Lever Pivot Pin Pivot Pin Horsepower Control Spool Horsepower Control Section Feedback Lever Pin Torque Control Section Negative Flow Control Spool Maximum Torque Control Piston Feedback Lever Small End Of Actuator Piston Minimum Large End Of Actuator Piston Torque Control Spool 16 Pump Control Valve Group This illustration shows the three separate control sections of the pump control group The three control sections are connected with a series of pins and linkages The separate control sections work together to regulate pump flow by changing the angle of the pump swashplate, according to demand and hydraulic horsepower requirements Pump supply pressure is directed to the small end of the actuator piston to upstroke the pump toward maximum angle A regulated pressure signal is directed to the large end of the actuator piston to destroke the pump toward the minimum angle The horsepower control section directs some of the system pressure oil to and from the large end of the large actuator piston The lower end of the feedback lever is connected to the actuator piston The feedback lever works as a follow-up linkage to move the horsepower control spool when the large actuator piston moves The negative flow control (NFC) section works in conjunction with the horsepower control section to destroke the swashplate when all hydraulic controls are in NEUTRAL or during implement or travel MODULATION The torque control section works in conjunction with the horsepower control section to regulate pump flow when the hydraulic circuits are actuated SERV1852-02 08/08 - 28 - Torque Control Lever Large Hole Text Reference Main Pumps Horsepower Control Spool Pivot Pin Pivot Pin Torque Control Spool Feedback Lever Pin NFC Lever NFC Spool Actuator Piston Feedback Lever Swashplate PUMP CONTROLS END VIEW 17 This illustration shows an end sectional view of the pump controls The NFC spool is connected to the lower end of the NFC lever with a pin The upper end of the NFC lever pivots on a fixed pin in the housing The torque control spool is connected to the lower end of the torque control lever with a pin The upper end of the torque control lever also pivots on a fixed pin in the housing The upper end of the feedback lever is connected to the horsepower control spool with a pin The lower end of the feedback lever is connected to the actuator piston The feedback lever pin fits tightly into the feedback lever The feedback lever pin extends into large holes in the torque control lever and the NFC lever The large holes permit individual control from the torque control lever and the NFC lever Movement of the actuator piston causes the feedback lever to pivot on the feedback lever pin and move the horsepower control spool SERV1852-02 08/08 - 29 - Text Reference Main Pumps 330D / 336D PUMP CONTROL GROUP STANDBY - FULL DESTROKE Horsepower Control Spool Pivot Pin Feedback Lever Pin NFC Spool NFC Lever NFC Lever Pin NFC Pressure NFC Adjustment Screw Feedback Lever Minimum Angle Stop Swashplate Maximum Angle End of Actuator Piston Minimum Angle End of Actuator Piston 18 This illustration shows the NFC portion of the pump control group When all hydraulic control valves are in NEUTRAL, a high NFC pressure (system pressure) from the NFC orifice is directed to the left end of the NFC spool The NFC pressure pushes the NFC spool to the right against the spring force In the STANDBY condition, the horsepower control spool directs a signal pressure, which is part of system pressure, to the minimum angle end of the actuator piston The increase in pressure moves the actuator piston to the right against the minimum angle stop screw The pump flow will remain constant until the NFC pressure from the control valve decreases The NFC adjusting screw changes the effect of the NFC pressure on the NFC spool Turning the screw in (clockwise) causes the NFC pressure to increase higher before the NFC spool moves This condition causes the pump to upstroke sooner (less modulation) when the hydraulic control valve is ACTIVATED Turning the screw out (counterclockwise) causes the NFC spool to move at a lower NFC pressure This condition causes the pump to upstroke later (more modulation) when the hydraulic control valve is ACTIVATED SERV1852-02 08/08 - 30 - Text Reference Main Pumps 330D / 336D PUMP CONTROL GROUP FLOW INCREASE - START OF UPSTROKE Horsepower Control Sleeve Orifice Horsepower Control Spool Pivot Pin Feedback Lever Pin NFC Lever NFC Piston NFC Lever Pin NFC Pressure Feedback Lever Maximum Angle Stop Swashplate Minimum Angle End of Actuator Piston Maximum Angle End of Actuator Piston 19 This illustration shows the pump control group at the beginning of an upstroke caused by a decrease in NFC pressure The pivot pin is fixed to the pump control housing The NFC lever pivots around this point When a hydraulic control valve in the main control valve is shifted, the NFC pressure is decreased Due to reduced NFC pressure, spring force moves the NFC piston to the left The NFC piston moves the lower end of the NFC lever to the left As the lower end of the NFC lever moves to the left, the large hole through the lever also moves to the left As the large hole moves to the left, spring force pulls the horsepower control spool and the upper end of the feedback lever to the left because the feedback lever pin is allowed to move to the left The minimum angle actuator piston is opened to case drain through the right orifice in the horsepower control sleeve and the right end of the horsepower control spool System supply pressure pushes the maximum angle actuator piston to the left to upstroke the pump SERV1852-02 08/08 - 31 - Text Reference Main Pumps 330D / 336D PUMP CONTROL GROUP CONSTANT FLOW Horsepower Control Sleeve Orifices Pivot Pin Feedback Lever Pin Horsepower Control Spool NFC Piston NFC Lever NFC Lever Pin NFC Pressure Feedback Lever Maximum Angle Stop Swashplate Minimum Angle End of Actuator Piston Maximum Angle End of Actuator Piston 20 As the actuator piston moves, the lower end of the feedback lever moves to the left The feedback lever rotates clockwise with the feedback lever pin as the pivot point The upper end of the feedback lever pulls the horsepower control spool to the right until the right land on the horsepower control spool reaches a balance point between the orifices through the horsepower control sleeve Flow to and from the minimum angle end of the actuator piston is metered by the horsepower control spool and the horsepower control sleeve The swashplate angle remains constant until the NFC pressure is again changed SERV1778 08/08 - 32 - Text Reference Main Pumps 330D / 336D PUMP CONTROL GROUP FLOW INCREASE - FULL UPSTROKE Horsepower Control Sleeve Orifice Pivot Pin Feedback Lever Pin Horsepower Control Spool NFC Lever NFC Piston NFC Lever Pin NFC Pressure Feedback Lever Maximum Angle Stop Swashplate Minimum Angle End of Actuator Piston Maximum Angle End of Actuator Piston 21 The amount of reduction in NFC signal pressure determines the amount of pump upstroke If NFC pressure is reduced to minimum, the pump will upstroke until the actuator piston contacts the maximum angle stop screw NOTE: A decrease in power shift pressure will cause an increase in flow from the pump in the same manner as described for a decrease in system pressure, since both power shift pressure and system pressures act on the torque control piston SERV1852-02 08/08 - 33 - Text Reference Main Pumps 330D / 336D PUMP CONTROL GROUP FLOW DECREASE - START OF DESTROKE Horsepower Control Spool Orifice Torque Control Lever Pin Torque Control Piston Pivot Pin Feedback Lever Pin Torque Control Lever Horsepower Adjustment Screw Power Shift Pressure Horsepower Control Springs Cross Sensing Signal Torque Control Spool Maximum Angle End of Actuator Piston Minimum Angle End of Actuator Piston 22 This illustration shows the torque control piston and horsepower control spool sections of the pump control valve group with the pump in the upstroked position at the beginning of DESTROKE due to an increase in the load on the system For the purpose of this presentation, assume that power shift pressure from the power shift PRV solenoid valve remains constant The pivot pin is fixed to the pump control housing The torque control lever pivots around this point The large horsepower adjustment screw regulates the pressure or point that the pump starts to destroke (large spring adjustment) The small adjustment screw regulates the rate that the pump destrokes (small spring adjustment) Power shift pressure from the power shift PRV solenoid valve enters the pump control group and pushes on the plug at the left end of the torque control piston System supply pressure from this pump enters the pump control valve group and goes to the right shoulder area on the torque control piston SERV1852-02 08/08 - 34 - Text Reference Main Pumps The cross sensing signal pressure from the other pump goes to the left shoulder area on the torque control piston The combination of power shift pressure and the two system supply pressures push the torque control piston to the right against the force of the horsepower control adjustment springs The horsepower control spool directs the signal pressure to the minimum angle end of the actuator piston to destroke the hydraulic pump When the system supply pressures and power shift pressure push the torque control piston to the right: The torque control spool moves to the right to compress the horsepower control springs The torque control spool moves the lower end of the torque control lever to the right with the fixed pin on the upper end of the torque control lever as the pivot point The torque control lever pulls the feedback lever pin and the upper end of the feed back lever to the right The feedback lever pulls the horsepower control spool to the right against the spring force System supply pressure is directed around the horsepower control spool through the center orifice of the horsepower control sleeve and to the minimum angle end of the actuator piston The increase in pressure in the minimum angle piston moves the actuator piston to destroke the pump SERV1852-02 08/08 - 35 - Text Reference Main Pumps 330D / 336D PUMP CONTROL GROUP FLOW DECREASE - END OF DESTROKE Horsepower Control Spool Orifices Pivot Pin Feedback Lever Pin Torque Control Lever Torque Control Piston Torque Control Lever Pin Power Shift Pressure Cross Sensing Signal Feedback Lever Swashplate Minimum Angle End of Actuator Piston Maximum Angle End of Actuator Piston 23 This illustration shows the pump control group at the end of a DESTROKE due to an increase in load on the system When the actuator piston moves toward minimum angle, the lower end of the feedback lever moves to the right, turning the lever counterclockwise with the feedback lever pin as the pivot point The feedback lever movement shifts the horsepower control spool to the left so system supply pressure is metered through the two orifices to and from the minimum angle end of the actuator piston Pump flow is held constant until one of the signal pressures changes An increase in power shift pressure will cause a decrease in flow from the pump in the same manner as described for an increase in system pressure since both the power shift pressure and system pressure act on the torque control piston SERV1852-02 08/08 - 36 - Text Reference Main Pumps 24 CONCLUSION This presentation has provided information for the Caterpillar 320D-336D Hydraulic Excavators This presentation covered the main hydraulic pump groups and controls Additional presentations are available for each system used on these machines When used in conjunction with the service manual, the information in this package should permit the technician to a thorough job of analyzing a problem in these systems For service repairs, adjustments, and maintenance, always refer to the Operation and Maintenance Manual, Service Manuals, and other related service publications ... for the 32 5D MH and 33 0D MH did not change - The nomenclature for the 32 5D FM and 33 0D FM did not change - The 32 5D HD HW did not change into 32 9D HD HW This model is being discontinued However,... operation, diagnostic equipment, and procedures for testing and adjusting CONTENT This presentation provides an introduction and describes the components and systems operation of the 32 0D- 33 6D main hydraulic... to destroke, and reduce the horsepower demand placed on the engine With a decreased load from the hydraulic pumps the engine speed increases This function is referred to as engine underspeed control