Hệ thống thủy lực máy đào CATERPILLAR SERIE D - P8

Caterpillar hydraulic excavators serie D

TIER III ENGINES

This presentation provides an introduction and describes the components and systems operation

of the 320D-336D swing system Additional presentations will cover the machine walkaround,engines, pilot system, main control valve group, implements, swing system, travel system, andtool 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:

1 identify the correct operation of the swing system on the 320D-336D hydraulic

excavators, and

2 diagnose problems in the swing system

REFERENCES

Self-study "300D Series Hydraulic Excavators, 345C Hydraulic Excavator,

iTIM " '300C' Series Hydraulic Excavators-Electronic Control Systems" SERV2693iTIM "325C Hydraulic Excavators-Hydraulic Systems" SERV2701

Estimated Time: 1 Hour

Illustrations: 32

Form: SERV1852-02

Date: August 2008

© 2008 Caterpillar

TABLE OF CONTENTS

INTRODUCTION 5

Swing System Components 6

Swing System Operation 11

Swing Motor Operation 18

Swing Drive 34

CONCLUSION 39

"Fundamentals of Mobile Hydraulics Self Study Course" TEMV3002

"Fundamentals of Power Train Self Study Course" TEMV3003

"Fundamentals of Electrical Systems Self Study Course" TEMV3004

"Fundamentals of Engines Self Study Course" 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.

- variable swing priority valve (part of the swing control valve)

- swing priority valve

- dual stage, swing line relief valves

- cushion crossover anti-reaction valves

- fine swing control solenoid valve (not available in EAME after October 2008)

- swing brake

- slow return check valve

The idler pump supplies flow for the swing system The swing control valve is shifted by pilotoil from the joystick pilot valves

Main Hydraulic Pumps M

Pilot Pump

The Fan Motor and Pump are only used on the 330D and 336D

SWING SYSTEM

Swing System Components

The swing circuit controls the rotation of the swing motor The idler pump provides the pumpflow for the swing circuit

When either one of the joysticks is moved from the NEUTRAL position, the swing parkingbrake is released The swing motor is mounted on top of the swing drive The swing drive isinstalled on the upper structure and rotates the upper structure

When the hydraulic activation control lever is in the UNLOCKED position, pilot pump oilflows to the swing parking brake solenoid valve in the pilot manifold and to the swing pilotcontrol valve Pilot oil from the pump also flows through the swing priority pressure reducingvalve to the variable swing priority valve and moves the variable swing priority valve fully up

With the swing control valve in NEUTRAL, pump supply oil from the idler pump flows thoughthe center bypass valve of the swing control valve and all other control valves shown to theNFC valve The return oil creates a signal used to destroke the idler pump

SWING SYSTEM

SWING COMPONENTS - NEUTRAL

Swing Motor Group

Swing Control Valve

Swing Priority Pressure Reducing Valve

Idler Pump Drive

Pilot Pump

M

Variable Swing Priority Valve

Anti-Reaction Valves Fine Swing Valve

Slow Return Check Valve

Makeup Valve

Line Relief Valve Motor

Swing Brake

Swing / Stick Pilot Valve

AEC Pressure Switch

R L Out In

Swing Solenoid

Hydraulic Activation Valve Pilot

Manifold

Implement Hydraulic Lockout

Stick 2 Control Valve

The swing brake is currently on so the motor will not rotate.

Since the implement hydraulic lockout solenoid has been energized, the hydraulic activationvalve has shifted Pilot oil is directed to the pilot joystick and to the swing brake solenoid

Swing Priority Pressure Reducing Valve and Variable Swing Priority Valve: These two

valves work together to provide flow priority over the stick control valve when the stick andswing are operated together

Swing Parking Brake Solenoid Valve: When energized the swing parking brake solenoid

valve directs pilot oil to release the swing parking brake The solenoid will energize wheneither one of the joysticks is moved from the NEUTRAL position

Dual Stage, Swing Relief Valves: These relief valves limit the maximum pressure in the left

and right swing circuits The dual stage, swing relief valves open initially at a lower pressure

to reduce jerkiness in the swing circuits at swing start and swing stop or to handle short

duration pressure spikes The relief valves also allow for higher swing circuit pressures toprovide increased swing force

NOTE: The ISO symbol shown on the schematics does not reflect that the relief valves

are dual stage.

Slow Return Check Valve: The back pressure created by the slow return check valve ensures

that makeup oil is available at the swing motor and the various makeup valves in the hydraulicsystem

Anti-reaction or Cushion Relief Valves: These valves dampen pressure spikes in the swing

system whenever the swing is stopped The valves also inhibit counter rotation of the swingmotor when the swing is stopped, which reduces swing "wag." The valves also provide for asmooth swing start-up

Fine Swing Control Solenoid Valve: When energized the fine swing control solenoid valve

improves the swing control during swing deceleration This solenoid valve helps to reduce theshock when the swing stops by connecting the supply and the return sides of the motor so thepressures between the two sides begin to equalize

4

- swing brake release pressure line (2)

- swing drive oil level dipstick (3)

- crossover relief valve (4)

- anti-reaction valve group (5)

- anti-reaction valve (6) (one of two)

- fine swing control solenoid valve (7)

5

6 4

5 6 7

The swing brake solenoid valve (1) is part of the pilot manifold (2) The manifold is locateddirectly below the main control valve The hydraulic activation solenoid (3) must energize toshift the hydraulic activation valve (4) If the hydraulic activation valve is not shifted there is

no pilot oil to the swing brake solenoid valve The swing brake can not be released

There is also no pilot oil available to the joystick pilot valves if the hydraulic activation valve isnot shifted

The swing priority pressure reducing valve (5) is located beneath the main control valve group.The variable swing priority valve (not shown) is located on the main control valve group nearthe boom 2 spool

Swing System Operation

The swing control valve operates as previously discussed

Line relief and makeup valves for the swing circuit are located in the swing motor instead ofthe swing control valve

Parallel

Feeder

Passage

Center Bypass Passage

When the swing joystick is full shifted, pilot oil from the swing joystick flows to the swingcontrol valve to shift the control spool The control valve shifts and blocks the oil in the centerpassage from flowing to the idler pump The idler pump fully upstrokes

At the same time, the AEC switch closes due to sensing pilot pressure from swing pilot valve.The Machine ECM senses the switch is closed and energizes the swing brake solenoid

The swing brake solenoid directs pilot oil to release the swing brake

The load check valve unseats and supply oil from the pump is directed to the swing motor Theanti-reaction valves cushion the start of the swing motor Return oil from the motor flows pastthe swing control valve to the tank

Also, when the swing joystick is fully shifted, the swing pilot oil acts on the swing prioritypressure reducing valve The pressure reducing valve shifts to block the pilot oil to the variableswing priority valve and opens a passage for the pilot oil at the variable swing priority valve toflow to tank The spring above the variable swing priority valve moves the valve fully down

In the illustration above, swing is the only circuit in operation

SWING SYSTEM

FULL SWING LEFT

Swing Motor Group

Stick 1 Control Valve

Swing Control Valve

Swing Priority Pressure Reducing Valve

Idler Pump Drive

Pilot Pump

M

Variable Swing Priority Valve

Anti-Reaction Valves Fine Swing Valve

Slow Return Check Valve

Makeup Valve

Line Relief Valve Motor

Swing Brake

Left Travel Control Valve

Swing / Stick Pilot Valve

AEC Pressure Switch

R L Out In

Swing Solenoid

Hydraulic Activation Valve Pilot

Manifold

Implement Hydraulic Lockout

Stick 2 Control Valve

The swing pilot oil pressure from the swing pilot control valve directly corresponds to theamount of movement or position of the swing joystick The swing pilot oil pressure from thepilot control valve acts on the swing priority pressure reducing valve

When the swing pilot pressure and the downstream pressure to the variable swing priority valve

is less than the the spring setting of the swing priority pressure reducing valve, the swing

priority pressure reducing valve does not shift

The variable swing priority valve is held up to the load check valve position by the pilot oilpressure from the pilot manifold

If the stick 1 circuit is being operated at the same time as a partial swing, flow from the idlerpump unseats the load check valve section of the variable swing priority valve and is directed tothe stick cylinder

The stick cylinder speed is determined by how far the stick spool shifts

The stick 2 control valve also shifts for a full stick out The stick 2 control valve is not affected

by the variable swing priority valve

SWING SYSTEM

PARTIAL SWING LEFT / NO PRIORITY OVER STICK

Swing Motor Group

Stick 1 Control Valve

Swing Control Valve

Swing Priority Pressure Reducing Valve

Idler Pump Drive

Pilot Pump

M

Variable Swing Priority Valve

Anti-Reaction Valves Fine Swing Valve

Slow Return Check Valve

Makeup Valve

Line Relief Valve Motor

Swing Brake

Left Travel Control Valve

Swing / Stick Pilot Valve

AEC Pressure Switch

R L Out In

Swing Solenoid

Hydraulic Activation Valve Pilot

Manifold

Implement Hydraulic Lockout

Stick 2 Control Valve

Stick Cylinder Stick 2

Control Valve

For a partial SWING, the pilot pressure oil from the pilot manifold and from the swing pilotvalve cannot overcome the swing priority pressure reducing valve spring to move the valvedown

Full pilot oil pressure from the pilot manifold is maintained on the variable swing priorityvalve

Pilot oil to the variable swing priority valve moves the valve up against the spring above thevalve

With the variable priority valve held up, the swing priority valve does not restrict oil to the stick 1 control valve

The load check valve will unseat when the idler pump supply pressure in the parallel feederpassages exceeds the stick workport pressure

Unrestricted flow from the idler pump is available to the stick 1 control valve to operate thestick

P2 P1

Swing Pilot Valve Manifold Pilot

Boom 2 Control Valve

Variable Swing Priority Valve

Swing Priority Pressure Reducing Valve

Load Check Valve

Center Pump Supply Passage Parallel Feeder Passage

SWING PRIORITY PRESSURE REDUCING VALVE AND VARIABLE SWING PRIORITY VALVE

NO SWING PRIORITY - STICK 1 FULLY SHIFTED

As the pilot oil to the variable swing priority valve is reduced, the valve moves down andbegins to restrict the idler pump flow to the stick circuit through the stick 1 control valve forSTICK OUT.

The stick slows down The further the swing joystick is shifted, the more the stick cylinderslows for a STICK OUT The stick 2 control valve will fully shift and direct available drivepump flow to the stick cylinder

The maximum flow to the stick for STICK UP is limited by the position of the variable swingpriority valve and not by how far the stick 1 spool has shifted

Stick 2 Control Valve

SWING SYSTEM

FULL SWING LEFT / PRIORITY OVER STICK

Swing Motor Group

Stick 1 Control Valve

Swing Control Valve

Swing Priority Pressure Reducing Valve

Idler Pump Drive

Pilot Pump

M

Variable Swing Priority Valve

Anti-Reaction Valves Fine Swing Valve

Slow Return Check Valve

Makeup Valve

Line Relief Valve Motor

Swing Brake

Left Travel Control Valve

Swing / Stick Pilot Valve

AEC Pressure Switch

R L Out In

Swing Solenoid

Hydraulic Activation Valve Pilot

Manifold

Implement Hydraulic Lockout

Stick 2 Control Valve

Swing priority is controlled by the position of the swing joystick Swing priority over the stick

is hydraulically activated when the swing joystick reaches a certain position

For STICK IN, the stick 1 control valve shifts Due to the regeneration valve (not shown), thestick in speed is not affected unless the stick has reached the vertical position and the stickunloading valve is open Without swing priority, during a full STICK IN, the stick circuitwould receive most if not all of the idler pump flow

NOTE: The focus of this story is on the effect of the swing priority valve over the stick

circuit For a STICK IN, there may also be flow from the stick 1 valve unless the boom

1 valve has shifted for BOOM UP

Since swing priority increases the swing acceleration whenever the stick is also used, swingpriority is useful for loading operations Swing priority is also useful for leveling operationsand trenching operations when higher swing force is required

When the swing pilot valve is fully shifted, the swing priority pressure reducing valve is moveddown to completely drain the pilot oil to the variable swing priority valve to the tank

The variable swing priority valve moves down due to spring force

With the variable swing priority valve held down, supply oil to the stick 1 control valve isrestricted

The stick cylinder speed is reduced

Boom 2 Control Valve

Variable Swing Priority Valve

SWING PRIORITY PRESSURE REDUCING VALVE AND VARIABLE SWING PRIORITY VALVE

SWING PRIORITY ACTIVATED

P2 P1

Stick 1 Supply

Restriction

Spring

Load Check Valve

Center Pump Supply Passage Parallel Feeder Passage

Swing Motor Operation

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

- the rotary group: piston and barrel assembly, shoes, retainer plate, and drive shaft

- the parking brake: brake spring, brake piston, separator plates, and friction plates

- the relief valves and makeup valves

When a swing operation is started, pilot oil from the swing brake solenoid valve is directed tothe swing brake piston As the pilot pressure builds, the brake piston moves against the spring

to release the swing brake The brake separator plates and friction plates are no longer incontact and the motor barrel assembly can rotate freely

During a SWING RIGHT operation, the oil delivery enters the motor head from the swingcontrol valve and flows through a plate in the motor into the piston and barrel assembly tocause the motor to rotate

Return oil flows back from the motor to the motor head and back to the swing control valve toreturn to the tank

SWING MOTOR

SECTIONAL VIEW - SWING RIGHT

Pilot Oil Supply

Swing Parking Brake

Swing Brake Piston

Crossover Relief

Valve

Piston and Barrel Assembly

Spring

Shoes

Drive Shaft

Swing Control Valve

Separator Plate

Friction Plate

Tank Passage to

Slow Return Check Valve

Slow Return

Check Valve

The swing parking brake is located in the swing motor The swing parking brake consists ofthe following components: brake spring, brake piston, separator plates, and friction plates Thefriction plates are splined to the cylinder barrel The separator plates are splined to the motorcase

When the joysticks are moved from the NEUTRAL position, the implement/swing (AEC)pressure switch senses the increase in pilot oil pressure The pressure switch closes and sends

an input signal to the Machine ECM The Machine ECM then energizes the swing brakesolenoid valve

When the swing brake solenoid valve is energized, the spool moves down against the spring.Pilot oil flows to the center of the spool and out to the swing motor

The pilot oil now enters the piston chamber The pilot pressure causes the brake piston to moveupward against the force of the brake spring The separator plates and friction plates are nolonger held together and the motor is able to rotate freely

SWING PARKING BRAKE

OFF

Swing Brake Solenoid Valve

Swing Brake Piston

Pilot Oil

Swing Parking Brake Spring

Separator Plate Friction Plate

Barrel

Spring

Spool