Sistema electrohidraulico[1]..pdf

7/24/2019 Sistema electrohidraulico[1]..pdf

1/33

Service Training

SERV2682-01

December 2002

TEXT REFERENCE

PART OF TECHNICAL INSTRUCTION MODULE SERV2682-01

988G WHEEL LOADER

IMPLEMENT HYDRAULIC SYSTEM

SUPPLEMENTAL INFORMATION


2/33

- 2 -SERV2682-01

12/02

TABLE OF CONTENTS

Visuals PageIntroduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1 . . . . . . . . . . . . 3

Electro-Hydraulic Implement System Block Diagram . . . . . . . . . . . . . . . . . . . . . . . .2 . . . . . . . . . . . . 4

Electro-Hydraulic Implement System Components . . . . . . . . . . . . . . . . . . . . . . . . . . .3 . . . . . . . . . . . . 5

Electro-Hydraulic Implement System Block Diagram . . . . . . . . . . . . . . . . . . . . . . .14 . . . . . . . . . . . . 6

Implement Electronic Control System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15 . . . . . . . . . . . . 7

Implement Pump Control Valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34-36 . . . . . . . . . . . . 8

Radiator and Hydraulic oil Cooler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .50 . . . . . . . . . . . 11

Air-to-Air Aftercooler (ATAAC) and Air Conditioning Condenser . . . . . . . . . . . . .51 . . . . . . . . . . . 12

Fan Drive System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .57 . . . . . . . . . . . 13

Implement Control Strategy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .58 . . . . . . . . . . . 14

Implement System Calibrations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .59-72 . . . . . . . . . . . 16

Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .73 . . . . . . . . . . . 31

Visual List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32


3/33

- 3 -

Introduce course

1

SERV2682-01

12/02

INTRODUCTION

This presentation and the "988G Wheel Loader Hydraulic Systems

Operation" Service Manual module (Form RENR2170) discuss the

component locations, systems operation, and calibration procedures for

the Implement Hydraulic System and Fan Drive System on the 988G

Wheel Loader.

This presentation includes implement hydraulic system supplemental

information not included in the Systems Operation Service Manual

module. This information and the Service Manual module should be used

for preparation and self study.

The visuals in the Text Reference have numbers that correspond to the

visuals in the presentation. The visuals in SENR2170 are in order.

However, the visuals in SENR2170 have numbers that are different thanthose in the presentation. The instructor should refer to the visual itself

and not just the visual number when locating the information for a

particular visual.

998888GGWWHHEEEELLLLOOAADDEERR

IIMMPPLLEEMMEENNTTHHYYDDRRAAUULLIICCSSYYSSTTEEMM

2002 Caterpillar Inc.

Objectives 1 and 2

Visuals 1 - 23


4/33

2

- 4 -SERV2682-01

12/02

Brake charging valve

LIFTLEVER

SENSOR

TILTLEVER

SENSOR

LEFTLIFT

CYLINDER

RIGHTLIFT

CYLINDER

TILTCYLINDER

SHUTTLEVALVE

PRESSUREREDUCING

VALVE

PILOTPRESSURE

SUPPLYVALVE CHECK

VALVE

BUCKETKICKOUTDETENT

SOLENOID

IMPLEMENTLOCKOUTSWITCH

RAISE/LOWER/TILTKICKOUT SET

SWITCH

TILT LINKAGEPOSITION SENSOR

LIFT LINKAGEPOSITION SENSOR

ELECTRONICCONTROLMODULE

RAISEKICKOUTDETENT

SOLENOID

LOWERKICKOUTDETENT

SOLENOID

CATDATALINK

ELECTRO-HYDRAULICIMPLEMENT SYSTEM

IMPLEMENTCONTROL

VALVE

IMPLEMENTPUMP

PILOTRELIEFVALVE

RELIEFVALVE

CHECK VALVE

FILTER

BRAKE/PILOTPUMP

ELECTRONIC SYSTEM PILOT HYDRAULIC SYSTEM MAIN HYDRAULIC SYSTEM

LOOSEMATERIAL

SWITCH

BALLVALVE

BRAKECHARGING

VALVE

Electro-Hydraulic Implement System Block Diagram

This schematic has been updated to include the brake charging valve,

which provides oil from the brake/pilot pump to the implement pilot

hydraulic system.


5/33

3

- 5 -SERV2682-01

12/02

Manual lower ball

valve

IMPLEMENT

PUMP

BRAKE/PILOT

PUMP

IMPLEMENT PUMP

CONTROL VALVE

PILOT

RELIEF

VALVE

ELECTRONIC

CONTROL MODULE

IMPLEMENT CONTROL

LEVER MODULE

IMPLEMENT

CONTROL

VALVE

TILT

CYLINDER

HYDRAULIC

TANK

LIFT LINKAGE

POSITION SENSOR

LIFT

CYLINDER

TILT LINKAGE

POSITION SENSOR

PILOT

PRESSURE

SUPPLY

VALVE

PILOT

FILTER

ELECTRONIC SYSTEM

PILOT HYDRAULIC SYSTEM

MAIN HYDRAULIC SYSTEM

HYDRAULIC TANK

MANUAL

LOWER

BALL

VALVE

ELECTRO-HYDRAULIC IMPLEMENT SYSTEM COMPONENTS

Electro-Hydraulic Implement System Components

This profile of the 988G Wheel Loader implement system components

has been updated to include the manual lower ball valve location.


6/33


7/33

15

- 7 -SERV2682-01

12/02

Implement pump

pressure sensor

LIFT/LOWER/TILTKICKOUT SET SWITCH

IMPLEMENTLOCKOUT SWITCH

LIFT LINKAGEPOSITION SENSOR

TILT LEVERSENSOR

LIFT LEVERSENSOR

PILOT PRESSURE SUPPLYSOLENOID VALVE

BUCKET KICKOUT DETENT COIL

RAISE KICKOUT DETENT COIL

LOWER KICKOUT DETENT COIL

IMPLEMENT PUMP SOLENOID

TILT RACK BACK SOLENOID

TILT DUMP SOLENOID

LIFT LOWER SOLENOID

LIFT RAISE SOLENOID

CAT DATA LINK

IMPLEMENT ELECTRONICCONTROL MODULE (ECM)

IMPLEMENT ELECTRONICCONTROL SYSTEM

INPUT COMPONENTS OUTPUT COMPONENTS

LOOSE MATERIALMODE SWITCH

TILT LINKAGEPOSITION SENSOR

IMPLEMENT PUMPPRESSURE SENSOR

AXLE COOLINGBYPASS SOLENOID

LOOSE MATERIALMODE INDICATOR

ANALOG TO DIGITALCONVERTER

Implement Electronic Control System

This diagram has been updated to include the following components:

Implement pump pressure sensor: This sensor sends an implement

pump output pressure analog signal to the analog to digital converter. The

signal is converted to digital and sent to the Implement ECM.

Axle cooling bypass solenoid: This solenoid allows axle oil to bypass

the fan motor and rear oil cooler when the axle oil is below a certaintemperature.

Loose material mode indicator: Illuminates to indicate that the loose

material mode is ON.

INSTRUCTOR NOTE: This visual is illustration No. 23 in the "988G

Wheel Loader Hydraulic System Operation" Service Manual module

(From RENR2170).

Loose material mode

indicator

Axle cooling bypass

solenoid


8/33

34

- 8 -SERV2682-01

12/02

UPSTROKE

IMPLEMENT PUMP CONTROL VALVEUPSTROKE

CASEDRAIN

FLOW CONTROLVALVE SPOOL

FLOW CONTROLVALVE SLEEVE

TO LARGE ENDOF ACTUATOR

FEEDBACKLEVER

HIGH PRESSURECUTOFF SPOOL

SIGNAL OILFROM RESOLVER

FROM PUMPSOLENOID

Implement Pump Control Valve

This view shows the oil flow in the implement pump control valve during

implement pump UPSTROKE. When the machine is started and system

pressure increases, signal oil from the ball resolver flows to the small end

of the actuator (in the pump) to upstroke the pump.

In the pump control valve, the signal oil is blocked at the high pressure

cutoff spool. The signal oil also flows to the flow control valve. Spring

force holds the flow control valve spool to the right, which blocks thesignal oil from flowing to the large end of the actuator (in the pump).

Oil from the large end of the actuator is directed through the flow control

valve to case drain.

When the actuator (in the pump) upstrokes the pump, the feedback lever

causes the flow control valve sleeve to move to the right against spring

force and in the same direction as the flow control valve spool. The

sleeve and valve spool meter oil flow to and from the large end of the

actuator to limit actuator movement.


9/33

35

- 9 -SERV2682-01

12/02

Mechanical/hydraulic

DESTROKE

IMPLEMENT PUMP CONTROL VALVEMECHANICAL/HYDRAULIC DESTROKE


FEEDBACKLEVER


CASEDRAIN




FROM PUMPSOLENOID

The implement pump control valve also provides a mechanical/hydraulic

pump DESTROKE.

When the pump UPSTROKES, the feedback lever moves the flow control

valve sleeve to the right. When the pump upstrokes to the maximum flow

position, signal oil from the resolver is directed past the flow control valve

to the stationary high pressure cutoff spool. The signal oil is sent through

another passage to the large end of the actuator (in the pump), which

causes the pump to DESTROKE.

The sleeve and valve spool meter oil flow to and from the large end of the

actuator to maintain the actuator position.


10/33

36

- 10 -SERV2682-01

12/02

Electronic DESTROKE

IMPLEMENT PUMP CONTROL VALVEELECTRONIC DESTROKE


FEEDBACKLEVER


CASEDRAIN




FROM PUMPSOLENOID

During certain machine conditions, which will be explained later, the

Implement ECM will electronically destroke the pump to decrease the

pump flow and the load on the engine. The pump solenoid valve is

ENERGIZED by the Implement ECM. The pump solenoid valve directs

pilot oil to the right end of the slug which presses against the flow control

spool and the spool moves to the left against spring force. The pump

solenoid can be modulated by the Implement ECM to vary the pressure

against the slug.

Signal oil at the flow control valve is directed to the large end of the

actuator (in the pump), which causes the pump to DESTROKE.

When the actuator destrokes the pump, the feedback lever causes the flow

control valve sleeve to move to the left in the same direction as the flow

control valve spool. The sleeve and valve spool meter oil flow to and

from the large end of the actuator to maintain the actuator position. The

pump solenoid valve controls the amount of destroke by controlling the

pressure to the right end of the slug.


11/33

- 11 -

1. AMOCS radiator

2. Hydraulic oil cooler

50

SERV2682-01

12/02

Radiator and Hydraulic Oil Cooler

This view shows the AMOCS radiator (1) and hydraulic oil cooler (2)

installed in the radiator housing.

12


12/33

- 12 -

51

SERV2682-01

12/02

Air-to-Air Aftercooler and Air Conditioning Condenser

This view shows the air-to-air after cooler ATAAC (1) and air

conditioning condenser (2) installed in the radiator housing.1. ATAAC

2. Air conditioning

condenser

12


13/33

57

- 13 -SERV2682-01

12/02

Fan drive hydraulic

system:

- HIGH PRESSURE

CUTOFF

WAXCAPSULE

BYPASS VALVE

FANPUMP

FANMOTOR

CHECKVALVEFAN

OILCOOLERBYPASS

VALVEFAN DRIVE SYSTEMHIGH PRESSURE CUTOFF

DESTROKE

ACTUATOR

FLOWCONTROL

SPOOL

PRESSURECUTOFFSPOOL

FLOW/PRESSURECOMPENSATOR VALVE

Fan Drive System

The pressure cutoff spool limits the maximum system pressure for any

given pump displacement. The pressure cutoff spool is held in the left

position during normal operation by spring force.

When fan hydraulic system pressure is at maximum, pump supply

pressure increases and the pressure cutoff spool moves right against spring

force. The pressure cutoff spool directs supply oil to the destroke actuator

piston.

The increase in pressure allows the destroke actuator piston to overcome

the combined force of the upstroke actuator piston and spring to destroke

the pump. The pump is now at minimum flow and pump supply pressure

is at maximum. This condition is maintained to control maximum fan

speed.

This feature eliminates the need for a main relief valve in the fan

hydraulic system. Maximum system pressure is adjusted by turning the

pressure compensator adjustment screw.


14/33

58

- 14 -SERV2682-01

12/02

Implement control

strategy features:

- Dig trigger

- Loose material mode

- Tilt back structural

protection

- Tilt dump structural

protection

- FRAC

- Lower feather catch

- Float

- Lift snubbing

- Raise inversion with

FDLAC

IMPLEMENT CONTROL STRATEGY Dig Trigger Loose Material Mode Tilt Rack Structural Protection Tilt Dump Structural Protection FRAC Lower Feather Catch

Float Lift Snubbing Raise Inversion With FDLAC

Implement Control Strategy

The 988G Wheel Loader implement control strategy consists of the

following features:

Dig Trigger: The pump is destroked to 60% and the Power train Torque

Strategy is active when the machine is in first gear forward and the boom

is below horizontal.

Loose Material Mode: When the loose material mode is activated andthe machine goes into Dig Trigger, the pump produces maximum flow and

the Power Train Torque Strategy is still active.

Tilt Back and Tilt Dump Structural Protection: The spool command is

limited when the linkage is close to contacting the tilt back or dump stops,

or bottoming out the cylinder.


15/33

- 15 -SERV2682-01

12/02

Full Rack Angle Control (FRAC): During lifting, the Implement ECM

automatically adjusts the bucket angle in the dump direction when the

boom is slightly above horizontal to prevent spillage and maintain a level

bucket.

Lower Feather Catch: Brings the linkage to a smooth stop when a

lower command is abruptly stopped.

Float: Occurs when the boom is below horizontal and the lever is moved

into lower detent. (used for dozing and cleanup).

Lift Snubbing: When the boom is at the maximum lift position and the

lift lever is moved to hold and back to raise, lift snubbing is cancelled

resulting in main relief pressure in the head end of the lift cylinders. This

procedure can be used for checking main relief pressure and implement

stall conditions. The implement hydraulic service mode eliminatessnubbing.

Raise Inversion with Full Dump Lift Angle Control (FDLAC): The

raise command is limited when the bucket is against the dump stops to

prevent excessive stress on the dump stops and linkage pins.


16/33

59

- 16 -SERV2682-01

12/02

IMPLEMENT SYSTEM CALIBRATIONS

Lever Sensors Linkage Sensors

Implement Valve Solenoids

Implement System Calibrations

Implement system calibrations consists of lift and tilt lever sensor

calibrations, lift and tilt linkage sensor calibrations, and implement pilot

valve solenoid calibrations. Calibrations must be performed in the order

listed in this visual.

The sensor calibrations determine the minimum and maximum sensor

duty cycles associated with the respective minimum and maximum

linkage and lever angles.

A sensor calibration must be performed for any of the following reasons:

Sensor replaced

ECM replaced

Required by a service code

Sensor calibration


17/33

- 17 -SERV2682-01

12/02

The solenoid calibration determines the current required to initiate

movement of the pilot valve spool to allow oil flow and initiate movement

of the main control spool. The main spool shifts until pressure increases

enough to initiate the movement of the implement in a desired direction.

When the operator moves the implement lever during normal operation,

the Implement ECM begins energizing the corresponding solenoid with

the calibrated current level. Using the calibrated current level to initiate

movement results in consistent implement movement and helps to

eliminate the deadband (free travel) in the implement control levers.

A solenoid calibration must be performed for any of the following

reasons:

Solenoid replaced

ECM replaced

Required by a service code

The implement system calibrations can be performed using the Caterpillar

Monitoring System and the 4C-8195 Control Service Tool or the

Caterpillar Electronic Technician (ET) Service Tool.

INSTRUCTOR NOTE: For more information on implement system

calibrations, refer to the Service Manual module "988G Wheel

Loader Hydraulic System Troubleshooting Testing and Adjusting"

(Form RENR2171).

Solenoid calibration

Calibration methods


18/33

60

- 18 -SERV2682-01

12/02

Interior of cab:

1. 4C-8195 Control

Service Tool

2. Service connector

3. Display window

4. Machine service

connector

Implement system calibrations can be performed by entering the

Caterpillar Monitoring System Calibration mode. The 4C-8195 Control

Service Tool (1) allows the proper electrical connection at the service

connector (2) to perform the calibration procedures.

The display window (3) of the Caterpillar Monitoring System main

display module shows the calibration codes.

Also visible in this view is the machine service connector (4), which

provides the connection point for the ET Service Tool.

INSTRUCTOR NOTE: The Caterpillar Monitoring System access

procedures are found in the Service Manual module "Caterpillar

Monitoring System Operation, Testing and Adjusting"

(Form SENR1394).

1

2

4

3


19/33

61

- 19 -SERV2682-01

12/02

Calibration codes:

- Calibration submode

number

- Calibration step

number

- Calibration error

codes

CALIBRATIONSUBMODE

CALIBRATIONSTEP NUMBER

CALIBRATIONERROR CODES

CALIBRATION CODES

The calibration codes displayed in the Caterpillar Monitoring System

display window are six digit codes. The six digits are divided into three

two-digit fields.

The first two digits provide the calibration submode number. In this view,

"61" indicates tilt linkage position sensor calibration mode.

The center two digits are the calibration step number. In this view, step

number five is displayed.

The last two digits are used for calibration error codes. When no error

codes are present, the last two digits are blank.

NOTE: For more information on calibrations codes, refer to the

Service Manual module "988G Wheel Loader Hydraulic System

Troubleshooting Testing and Adjusting" (Form RENR2171).


20/33

62

- 20 -SERV2682-01

12/02

Calibrations using the

ET Service Tool

Implement system calibrations can also be performed using the ET

Service Tool. In this view of the the ET Service Tool screen, the ET

Service tool is connected with the machine.

To perform implement system calibrations, select the bottom menu item

"Implement 988G."

The menu shown is the ECM selection menu, which is displayed when ET

first establishes connection to the various ECMs on the machine. Thismenu can be accessed using the "Data Link" pull down menu and clicking

on "Select ECM", if ET is already in use.


21/33

63

- 21 -SERV2682-01

12/02

Calibrations menu:

- Lift linkage sensor

calibration

- Tilt linkage sensor

calibration

- Implement valve

solenoid calibration

- Lever calibrations

Once the Implement ECM has been selected, select the "Service" menu

and then the calibrations menu. The following items can be found under

the "Calibrations" menu:

Lift linkage sensor calibration

Tilt linkage sensor calibration

Implement valve solenoid calibration

Lever calibrations

This view also displays the available ECMs on the machine, information

about the machine components and the ET software version.


22/33

64

- 22 -SERV2682-01

12/02

Calibration successful This view shows successful calibration of the lift linkage sensor. The ET

Service Tool checks each step after the technician successfully performs

the step. The check marks indicate that all the steps were performed.


23/33

65

- 23 -SERV2682-01

12/02

Implement valve

solenoid calibration

An implement valve solenoid calibration can be selected. This calibration

is performed to determine the amount of current required to initiate

movement of the implement for each solenoid. The Implement ECM uses

the current value obtained during this calibration as a starting point when

the implements are used. Using the preset value to begin movement

ensures smooth movement from the HOLD position.

NOTE: Performing the implement valve solenoid calibration is

similar to setting the pilot initiation pressure on a pilot operated (nonelectro-hydraulic) implement system.


24/33


25/33

67

- 25 -SERV2682-01

12/02

Lift lever calibrations From this screen, the lift lever calibrations can be selected. This view

shows that the lift lever calibration has been selected.


26/33

68

- 26 -SERV2682-01

12/02

Tilt lever calibration This screen shows the tilt lever calibration in process. The

"ATTENTION" message on the screen provides information to the

technician before completing the next step.


27/33

69

- 27 -SERV2682-01

12/02

Diagnostic tests Diagnostic tests can be performed on the implement electronic control

system. At this time, only the main implement relief test can be

performed.


28/33

70

- 28 -SERV2682-01

12/02

Machine configuration

information

This screen displays machine configuration information and the status of

various machine functions.


29/33

71

- 29 -SERV2682-01

12/02

Implement lift circuit

status

The implement lift circuit electronic components preset group 2 status is

displayed as follows:

The implement lockout switch is not locked.

The lift lever is positioned completely forward (100%)

The lift cylinder is extended 354 mm

The lift link sensor has moved 38% from maximum position

The raise solenoid current is 1.953 amps

The lower solenoid current is 0 amps

The implement pump pressure is 1080 psi

The ET user can setup groups as desired.


30/33

72

- 30 -SERV2682-01

12/02

Logged diagnostic

codes

This screen displays the logged diagnostic codes for the 988G Wheel

Loader. The codes are listed in numeric order by machine system.


31/33

- 31 -

73

SERV2682-01

12/02

CONCLUSION

This presentation has provided 988G Wheel Loader implement system

supplemental information. This information should be used in

conjunction with the "988G Wheel Loader Hydraulic Systems Operation"

Service Manual module.


32/33

- 32 -SERV2682-01

12/02

VISUAL LIST

1. Model view

2. Electro-Hydraulic implement system

block diagram


components

4. Pump compartment

5. Components above implement pump

6. Hydraulic oil filters

7. Pilot control actuators

8. Manual lower ball valve

9. Implement control valve

10. Hydraulic tank11. Components on front of hydraulic tank

12. Pilot on/off valve

13. Ride control valve


block diagram

15. Implement electronic control system

block diagram

16. Lift and tilt cylinders

17. Electronics bay

18. Implement control levers19. Tilt lever sensor

20. Lift lever sensor

21. Kickout detent coil

22. Left overhead console switches

23. Right overhead console switches

24. Pilot control actuator (HOLD)

25. Pilot control actuator (LEFT

SOLENOID ENERGIZED)

26. Pilot control actuator (LEFT

ACTUATOR BALANCED)

27. Implement control valve (HOLD)

28. Implement control valve (LOWER)

29. Implement pump cutaway

30. Pump control valve cutaway

31. Pump and control valve operation


(UPSTROKE)


(ELECTRONIC DESTROKE)

34. Implement pump control valve cutaway

(UPSTROKE)


(MECHANICAL/HYDRAULIC

DESTROKE)


(ELECTRONIC DESTROKE)

37. Implement hydraulic system (HOLD)

38. Implement hydraulic system (TILT

BACK)39. Implement hydraulic system (RAISE)

40. Implement hydraulic system (LOWER)

41. Implement hydraulic system (FLOAT)

42. Implement hydraulic system (LOWER

ENGINE OFF)

43. Implement hydraulic system (MANUAL

LOWERING)

44. Implement hydraulic system (RIDE

CONTROL ON)

45. Ride control switch46. Ride control valve

47. Ride control accumulator

48. Fan pump

49. Fan motor

50. Radiator

51. ATAAC

52. Wax capsule valve

53. Fan system case drain oil filter

54. Fan hydraulic drive system (LOW

PRESSURE)

55. Fan hydraulic drive system

(UPSTROKE)

56. Fan hydraulic drive system

(DESTROKE)

57. Fan hydraulic drive system (HIGH

PRESSURE CUTOFF)

58. Implement control strategy


33/33

- 33 -SERV2682-01

12/02

VISUAL LIST

59. Implement system calibrations

60. Service connector and 4C8195 Control

Service Tool

61. Calibration codes

62. ET Service Tool calibrations

63. Calibrations menu

64. Lift linkage sensor calibration

65. Implement valve solenoid calibration

66. Implement dump valve calibration

67. Lift lever calibrations

68. Tilt lever calibration

69. Diagnostic tests

70. Machine configuration information

71. Implement lift circuit status

72. Logged diagnostic codes

73. Model view

Sistema electrohidraulico[1]..pdf

Documents

Transcript of Sistema electrohidraulico[1]..pdf