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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 BOOM, STICK, AND BUCKET CIRCUITS Service Training Meeting Guide (STMG) 320D-336D HYDRAULIC EXCAVATORS TIER III ENGINES BOOM, STICK, AND BUCKET CIRCUITS 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 implement circuits - boom, stick, and bucket 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 correct operation of the boom, stick, and bucket on the 320D-336D hydraulic excavators, and diagnose problems in the boom, stick, and bucket circuits 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: 1/2 Hours Illustrations: 44 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 Implements TABLE OF CONTENTS INTRODUCTION Boom Circuit Stick Circuit 34 Bucket Circuit .52 Cylinders .53 CONCLUSION 55 SERV1852-02 08/08 -4- Text Reference Implements 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 Implements IMPLEMENT CIRCUITS 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 presentation covers in more detail each implement circuit used for the 320D-336D Hydraulic Excavators The circuits to be covered include: - boom - stick - bucket The idler pump provides oil to the boom and stick control valves The drive pump provides flow to the bucket, boom 1, and stick control valves The boom, stick, and bucket control valves are shifted by pilot oil from the joystick pilot valves when they are activated NOTE: The main control valve group and return system are covered in another presentation The attachment/auxiliary circuits will be covered in the electronic or tool control section The ISO schematics were created primarily from "325D Hydraulic Schematic" (KENR6157) Hydraulic schematics for other 320D-336D excavators may/will have variations from illustrations shown SERV1852-02 08/08 -6- Text Reference Implements 2 The boom circuit uses two control valves to control the boom operation, boom (1) and boom (2) Both spools shift when fast boom movement is required Both pumps provide flow to the boom for this condition Boom valve provides single pump flow, whenever the boom is shifted for slow movement The stick circuit also uses to two control valves to control the stick operation, stick (3) and stick (4) Both spools shift when fast stick movement is required The boom circuit and stick circuits also use regeneration valves and drift reduction valves The regeneration valves (not shown) provide improved efficiency and require less engine horsepower for BOOM LOWER and STICK IN The drift reduction valves reduce cylinder drift when the boom or stick are in NEUTRAL Only one control valve is required to control the bucket The bucket circuit is supplied with oil only from the drive pump SERV1852-02 08/08 -7- Text Reference Implements The two joysticks in the cab are used to control the movements of the boom, stick, swing and bucket circuits - right joystick (1) to control the bucket and boom (SAE excavator pattern) - left joystick (2) to control the swing and stick (SAE excavator pattern) SERV1852-02 08/08 -8- Text Reference Implements MAIN HYDRAULIC SYSTEM Boom Cylinders BOOM CIRCUIT COMPONENTS Drift Reduction Valve Boom Boom NFC Orifice Main Relief Boom Regen Valve Swing / Stick Pilot Valve Heavy Lift Solenoid Boom / Bucket Pilot Valve Idler Pump Pilot Pump M Drive Pump Boom Priority Valve AEC Pressure Switch Pilot Manifold Boom Circuit The boom circuit consists of the following major components: - boom spool - boom spool - two boom cylinders - drift reduction valve - Heavy Lift solenoid - boom priority valve (pressure reducing) - boom lowering control valves (if equipped - not shown)) - boom regeneration valve - SmartBoom™ (if equipped - not shown)) NOTE: 325D Hydraulic Schematic (KENR6157) was used to develop the ISO schematics SERV1852-02 08/08 -9- Text Reference Implements Boom Spool: The boom spool controls oil flow from the drive pump The boom spool receives a BOOM RAISE pilot signal on the bottom of the valve, and a BOOM LOWER pilot signal on the top of the valve Boom Spool: The boom spool controls oil flow from the idler pump The boom spool receives a BOOM RAISE pilot signal from the joystick on the top of the valve stem, when active The boom spool does not operate during BOOM LOWER The boom spool has no provisions for return oil from the boom cylinders Boom Cylinders: The boom cylinders work in parallel to control the raise and lower movement of the boom When oil is supplied to the head end of the boom cylinders, the boom will raise When oil is supplied to the rod end of the boom cylinders, the boom will lower Boom Drift Reduction Valve: The boom drift reduction valve prevents oil from leaking from the head end of the boom cylinders For BOOM LOWER, pilot oil from the joystick is used to unlock the lock check valve in the drift reduction valve Heavy Lift Solenoid: The heavy lift solenoid is activated to increase the maximum system pressure for lifting (Refer to the "Main Control Valve Group and Return Group" for more details on Heavy Lift operation.) Boom Priority Valve: The boom priority valve (pressure reducing) is used to reduce the pilot pressure to the stick valve whenever both the BOOM RAISE and STICK IN are activated at the same time The higher the boom pilot pressure to the boom priority valve the less pilot pressure is available to shift the stick control valve, resulting in more pump flow going to the boom cylinders Boom Lowering Control Valves: The boom lowering control valves are infinitely variable, pilot operated control valves that control the movement of the boom during lowering The boom lowering control valves prevent boom cylinder drift with valving mounted directly on each of the boom cylinders, that controls boom cylinder head end oil flow Because the valves are mounted directly to each of the boom cylinders, the boom lowering control valves will prevent the boom from falling, even if a hose becomes defective from the main control valve to the cylinders The boom lowering control valves also work in conjunction with the SmartBoom™ system to control the boom with the function active Regeneration Valve: The regeneration valve allows return oil from the head end of the boom cylinders to be directed into the rod end of the cylinders when the boom is lowered fast SmartBoom™: The SmartBoom™ attachment enhances operation of the boom function and significantly reduces cycle times of the machine The SmartBoom™ is essentially a boom float attachment, which allows the operator to lower the boom under its own weight or for the boom to raise up due to stick force The SmartBoom™ attachment is typically used in EAME SERV1852-02 08/08 - 10 - Port A Text Reference Implements Port B Load Check Valve CONTROL VALVE NEUTRAL Line Relief and Makeup Valve Pilot Valve Pilot Valve Parallel Feeder Passage Center Bypass Passage Control Spool As previously discussed, the control valve operation is similar for all of the valves in the main control valve group including the boom, stick, and bucket valves Pump flow is provided by the drive and/or idler hydraulic pump Which pump is used depends on the circuit The centering spring force holds the valve spool to NEUTRAL when there is no pilot oil pressure directed to shift the spool In NEUTRAL the valve spool allows oil to flow unrestricted through the center bypass passage, which directs a high NFC pressure signal to the pump control valve The high NFC pressure causes the pump to destroke to a standby condition, as explained previously SERV1852-02 08/08 - 41 - Text Reference Implements MAIN HYDRAULIC SYSTEM STICK IN - FAST WITH REGENERATION AND STICK Stick Cylinder Drift Reduction Valve Stick Regen Valve 860 kPa Blocked >600 kPa Boom Stick 11270 kPa NFC Orifice >900 kPA Main Relief Stick Variable Swing Priority Valve Stick Unloading Valve Swing / Stick Pilot Valve Boom / Bucket Pilot Valve Swing Priority Valve Idler Pump Boom Priority Valve Heavy Lift Solenoid M Drive Pump Pilot Pump Pilot Manifold AEC Pressure Switch 32 If the boom circuit was not activated, higher pilot pressure available to the stick valve would cause the stick control valve to shift The stick control valve does not allow return oil from the rod end to return to the tank through the stick control valve Drive pump supply oil is now available to supply the stick cylinder as well as the idler pump supply oil As long as the combined pump supply pressure does not exceed the spring pressure setting of the unloading valve spring, the return oil from the rod end will be used to add to the two pump flow SERV1852-02 08/08 Stick In Pilot (>860 kPa) Check Valve - 42 - Text Reference Implements STICK REGENERATION VALVE Stick Regeneration Valve From Stick Control Valve REGENERATION ACTIVE Head End Pressure 600 kPa Boom Stick 11270 kPa NFC Orifice >900 kPa Main Relief Stick Variable Swing Priority Valve Stick Unloading Valve Swing / Stick Pilot Valve Boom / Bucket Pilot Valve Swing Priority Valve Boom Priority Valve Idler Pump Heavy Lift Solenoid M Drive Pump Pilot Pump Pilot Manifold AEC Pressure Switch 34 Fast STICK IN - Unloading: Whenever the head end supply pressure exceeds the setting of the unloading valve spring [11270 kPa (1630 psi)] the unloading valve shifts and allows the return oil from the cylinder rod end to flow directly to the tank Typically this will occur whenever the stick reaches the vertical position or as the stick moves from the vertical position and in closer to the machine NOTE: If the stick control valve is also supplying drive pump oil to the stick circuit along with the idler pump supplying oil, the head end pressure may increase above 11270 kPa (1630 psi), prior to the stick reaching a vertical position to the ground, when being lowered from a raised position SERV1852-02 08/08 Stick In Pilot (>860 kPa) Check Valve - 44 - Text Reference Implements STICK REGENERATION VALVE Stick Regeneration Valve From Stick Control Valve UNLOADING ACTIVE Head End Pressure >11270 kPa Stick Unloading Valve To Stick Control Valve A A A-A 35 Stick unloading occurs when the stick reaches vertical to the ground and as the stick moves further in towards the machine A pressure spike occurs which helps to open the unloading valve to rapidly reduce rod end pressure When the unloading valve opens, the oil flow to the stick cylinder may be from one or both pumps (Stick flow depends on whether other circuits are in operation at the same time.) When the regeneration valve is shifted and the supply oil to the head end of the stick cylinder is higher than the return oil from the rod end, the check valve will close No return oil from the rod end enters the passage to the head end At the same time the pressure in the head end of the cylinder increases and moves the unloading valve down When the unloading valve moves down, most of the return oil from the rod end of the cylinder returns to the tank past the unloading valve instead of through the stick control valve When the stick unloading moves down, regeneration no longer occurs SERV1852-02 08/08 - 45 - Text Reference Implements Summary of stick regeneration functions: The main purpose of the regeneration valve is to allow smooth stick in operation, whenever the pump flow is also being used by other circuits Typically, the operator will use the stick, boom, swing, and bucket circuits simultaneously for some applications The regeneration valve will actually allow the stick to lower for a stick in operation with little or no additional pump flow Stick regeneration allows the returning oil from the rod end of the cylinders to combine with main pump flow to move the stick cylinder out The regeneration valve also prevents cylinder cavitation, which prevents swing wag from occurring NOTE: If both pump flows were are available for the stick cylinder, the regen valve would have limited use The back pressure valve and the makeup valve would probably be sufficient to prevent swing wag, except for when there is an extremely heavy suspended load on the stick circuit The unloading valve allows a means to relieve the back pressure from the returning rod end oil, when the oil is no longer needed for regeneration SERV1852-02 08/08 - 46 - Text Reference Implements STICK DRIFT REDUCTION VALVE A From Stick and Stick Control Valve NEUTRAL B To Stick Cylinder Rod End To Stick Cylinder Rod End B From Stick Control Valve A From Stick and Stick Control Valve From Stick Control Valve Stick In Pilot Pressure Shuttle Valve Lock Check Valve To Stick Cylinder Rod End Drain B-B Stick Out Line Relief Valve 36 The stick drift reduction valve is located in the stick circuit on the main control valve group as part of the stick spool The stick drift reduction valve prevents oil from leaking from the rod end of the stick cylinder The stick drift reduction valve has the following components: - shuttle valve - lock check valve - line relief valve In the NEUTRAL position, the shuttle valve and lock check valve are closed by spring force Oil is blocked between the stick control valve and the stick cylinder SERV1852-02 08/08 - 47 - Text Reference Implements STICK DRIFT REDUCTION VALVE A From Stick and Stick Control Valve STICK OUT B To Stick Cylinder Rod End To Stick Cylinder Rod End B From Stick Control Valve A From Stick Control Valve From Stick and Stick Control Valve Stick In Pilot Pressure Shuttle Valve Lock Check Valve To Stick Cylinder Rod End Drain B-B Stick Out Line Relief Valve A-A 37 For STICK OUT, the shuttle valve does not shift The shuttle valve allows oil from the stick control valves to act on one end of the lock check valve Oil pressure from the stick control valves acts on the other end of the check valve The check valve opens (due to the pressure differential on the check valve) to allow oil flow to the rod end of the stick cylinder SERV1852-02 08/08 - 48 - Text Reference Implements A To Stick Control Valve STICK DRIFT REDUCTION VALVE STICK IN To Stick Control Valve B From Stick Cylinder Rod End From Stick Cylinder Rod End B A To Stick Control Valve To Stick Control Valve Stick In Pilot Pressure From Stick Cylinder Rod End Stick Out Line Relief Valve Shuttle Valve To Stick Control Valve Drain B-B A-A 38 For STICK IN, the shuttle valve is moved down by pilot oil from the joystick The shuttle valve allows oil in the lock valve spring chamber to flow to the tank Return oil from the stick cylinder rod end moves the lock check valve to the left against the lock check valve spring The open lock check valve allows oil flow from the rod end of the stick to return to the stick control valve and the regeneration valve SERV1852-02 08/08 - 49 - Text Reference Implements STICK HYDRAULIC CIRCUIT WITH LOWERING CONTROL VALVE Stick Cylinder NEUTRAL Stick Lowering Control Valve Stick Regen Valve Check Valve Straight Travel Stick Boom Spool Stick Unloading Valve Stick In Stick Main Relief Stick Out PRV1 Pilot Oil Heavy Lift Solenoid M 39 The stick circuit can be equipped with a boom lowering control valve (or load control valve), which is attached directly to each of the boom cylinders For 325D and 300D MH (material handlers), these machines are equipped with two cylinders, with lowering control valves for each cylinder When the machine is equipped with a lowering control valve, the drift reduction valve is not required The schematic above shows the lowering control valve and the stick circuit control valves in NEUTRAL Both pumps are destroked NOTE: Operation of the stick lowering control valve is similar to the boom lowering valve The stick regen valve will also affect the stick in operations of the stick circuit Refer to the cutaway illustrations of the boom lowering control valves shown earlier in the presentation as needed SERV1852-02 08/08 - 50 - Text Reference Implements STICK LOWERING CONTROL VALVE GROUP NEUTRAL Line Relief and Makeup Valve STICK OUT Check Valve Line Relief and Makeup Valve STICK IN WITH REGENERATION Line Relief and Makeup Valve Check Valve Boom Lowering Control Valve Spool Manual Lower Stick Control Valve Stick Control Valve Stick In Pilot Boom Lowering Control Valve Spool Stick Control Valve Stick In Pilot Stick Control Valve Check Valve Stick In Pilot Stick Control Valve Stick Control Valve 40 The components of the stick lowering control valve are much the same as for the boom lowering control valve and include: - rod end line relief and makeup valve - check valve: which provides as the similar function - stick lowering control valve spool - manual lower These components provide a similar function as they did on the boom lowering control valve When no stick function is performed the stick lowering control valve is in NEUTRAL In NEUTRAL no oil flows to or from the boom cylinders, and the boom does not move SERV1852-02 08/08 - 51 - Text Reference Implements In NEUTRAL, the check valve is seated by the combination of the spring force and the high pressure oil in the rod end of the stick cylinder The lowering control valve spool is seated by spring force The boom lowering control valves have no effect on the flow of oil to/from the rod end of the boom cylinders NOTE: Manual lower may be done differently depending on the lowering control valves used Some machines may have a manual lowering valve separate from the lowering control valves When STICK OUT is performed the lowering control valve allows oil to pass from the main control valve, through the check valve, and to the rod end of the stick cylinder High pressure oil from the main control valve enters the lowering control valve As the supply pressure increases, the check valve opens and allows oil to flow to the rod end of the stick cylinder The boom lowering control valve spool remains seated due to spring force For STICK IN, pilot pressure is required to unseat the lowering control valve spool to allow return oil from the rod end of the stick cylinder to return to the main control valve group Depending on how high the pilot pressure is will determine whether the lowering control valve fully shifts or partially shifts Depending on the position of the stick and how slow or fast of a STICK IN is being done, will determine whether the regen valve is open or closed, as well as whether the unloading valve shifts - For a metered STICK IN, the regen valve and unload valve are closed - For a fast STICK IN the regen valve will shift and allow return oil from the rod end to be used as additional supply oil for the head end of the cylinder - If the pressure increase in the head end is high enough, the unloading valve will shift and the return oil from the rod end will flow through the unloading valve to the tank During STICK in the check valve remains closed SERV1852-02 08/08 - 52 - Text Reference Implements MAIN HYDRAULIC SYSTEM BUCKET CLOSE Bucket Cylinder Bucket NFC Orifice Main Relief Swing / Stick Pilot Valve Heavy Lift Solenoid Boom / Bucket Pilot Valve Idler Pump Pilot Pump M Drive Pump AEC Pressure Switch Pilot Manifold 41 Bucket Circuit The bucket circuit control valve operates as previously discussed Two line relief valves and makeup valves are used to protect the lines from high pressures The bucket is only supplied by the drive pump Pilot oil from the joystick is directed to the bucket control valve to shift the control spool When the control spool shifts, the NFC signal to the drive pump is reduced and the pump upstrokes to provide flow For BUCKET CLOSE, the return oil from the rod end of the cylinder is restricted by the control spool to control the bucket speed SERV1852-02 08/08 - 53 - Text Reference Implements Boom Cylinder Snubber Snubber Stick Cylinder Bucket Cylinder 42 Cylinders The boom, stick, and bucket use dual acting cylinders The boom has a snubber for the rod end, while the stick uses snubbers on the rod and head end Snubbers slow the speed of the cylinder as the cylinder reaches the end of the cylinder stroke SERV1852-02 08/08 - 54 - SNUBBER OPERATION Text Reference Implements Passage Snubber BOOM AND STICK CYLINDER EXTENDING ROD Snubber Passage STICK CYLINDER RETRACTING ROD 43 As the boom or stick cylinder moves to the end of the extension stroke, oil in the passage will be restricted by the snubber, which will slow the extension of the cylinder As the stick cylinder moves to the end of the retraction stroke oil in the passage will be restricted by the snubber, which will slow the retraction of the cylinder SERV1852-02 08/08 - 55 - Text Reference Implements 44 CONCLUSION This presentation has provided information for the 320D-336D Caterpillar Hydraulic Excavators This section of the presentation covered the boom, stick, and bucket circuits 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 ... 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, the 33 0D HD HW changed to the 33 6D HD HW SERV185 2-0 2 08/08 -5 - Text... stick, and bucket on the 32 0D- 33 6D hydraulic excavators, and diagnose problems in the boom, stick, and bucket circuits REFERENCES 32 0D Hydraulic Excavator Specalog 32 3D L and 32 3D LN Hydraulic... idler pump and the drive pump is supplied to the head end of the boom cylinders Boom control valve and boom control valve are both shifted during high speed operation SERV185 2-0 2 08/08 - 14 -