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Caterpillar hydraulic excavators serie D

320D336D HYDRAULIC EXCAVATORS

-TIER III ENGINES

DEMAND FAN SYSTEMS

Service Training Meeting Guide

(STMG)

GLOBAL SERVICE LEARNING

TECHNICAL PRESENTATION

TIER III ENGINES

DEMAND FAN SYSTEMS

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 hydraulic excavator demand fan systems Additional presentations willcover 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 beused 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 demand fan systems used on the 300D Series

hydraulic excavators for engine cooling, and

2 diagnose problems in the fan systems

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: 41

Form: SERV1852-02

Date: September 2008

© 2008 Caterpillar

TABLE OF CONTENTS

INTRODUCTION 5

HYDRAULIC DEMAND FAN SYSTEM 6

Cat ET Screens for the Hydraulic Cooling Demand Fan 19

Monitor Screens for the Hydraulic Cooling Demand Fan 20

VISCONIC DEMAND FAN SYSTEM (ATTACHMENT) 33

Cat ET Screens for the Visconic Cooling Demand Fan 46

Monitor Screens for the Visconic Cooling Demand Fan 51

CONCLUSION 52

"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.

- Visconic demand fan system (320D, 321D, 323D, 324D, 325D, 328D and 329D): Thevisconic demand fan system uses a viscous coupling between the engine mounted, beltdriven fan drive hub and the fan assembly

NOTE: The cooling fan viscous coupling is sometimes called the fan clutch A fan

clutch is a thermostatically-controlled device When the engine is cool or even at

normal operating temperature, the fan clutch partially disengages the engine's

mechanically-driven cooling fan This decoupling saves power since the engine does not have to fully drive the fan.

If engine temperature rises above the fan clutch's engagement temperature setting, the fan becomes fully engaged, When the fan clutch is fully engaged, the fan draws a

higher volume of ambient air through the radiator, which in turn serves to maintain or lower the engine coolant temperature to an acceptable level

1

320D - 336D EXCAVATORS - TIER III ENGINES

DEMAND FAN SYSTEMS

© 2008 Caterpillar

HYDRAULIC DEMAND FAN SYSTEM

The hydraulic demand fan system is made up of a fan motor and fan pump to cool the hydraulicoil, engine radiator, fuel cooler, and the ATAAC

The electronically controlled, variable displacement, piston fan pump is driven off of the mainhydraulic system drive pump The fan pump flow output is controlled by the angle of theswashplate

A solenoid on the fan pump receives a PWM signal from the Machine ECM to control thepump swashplate

When the machine is running, the hydraulic oil temperature sender and the engine coolanttemperature sensor sends signals to the Engine ECM The Engine ECM then sends this

information to the Machine ECM The Machine ECM picks up the hydraulic temperaturethrough the monitor

Hottest

Coldest

Increasing Coolant Temperature

> 92 C

< 81 C

87 C

Water Pump

Engine Oil Cooler

330D/336D HYDRAULIC DEMAND FAN

COOLING SYSTEM ENGINE AT OPERATING TEMPERATURE

Cab Heater Thermostat

Housing

To Cylinder Block

Coolant Expansion

Bypass Tube

Coolant Temp Sensor Fill Cap

Engine ECM

CDL

Fan Drive Pump

Main

Return

Filter

Hydraulic Circuits

Case Drain Filter

Hydraulic Oil Temp Sender

Monitor

CAN Data Link

Intake Manifold Air Temperature Sensor

OK

Machine ECM

The Machine ECMs interpret the information from these inputs to send a PWM signal to thefan pump solenoid to control the angle of the pump swashplate to control the pump flow.

A higher temperature input will cause the Machine ECM to send a reduced PWM signal to thefan pump solenoid The reduced signal causes the pump to upstroke to increase pump flow,which increases the speed of the fan for more cooling capacity

The variable displacement fan pump is driven off of the drive pump, which is part of the mainpump group (2)

The pump control valve group (3) features a pressure control solenoid (4), which is controlled

by the Engine ECM

The pump control valve group has two adjustment screws:

- The upper screw, next to the pump control solenoid, is below the cap (5) This screw isused to adjust the pump control spool

- The lower screw (6), below the pump control valve group, is used to adjust the pressurecontrol spool

The reservoir supply line (7) is below the fan pump housing, while the pump supply line (8) tothe motor is above the housing

NOTE: In most cases, the two adjustment screws should not be used The solenoid can

be calibrated through Cat ET or the monitor to correctly set the fan pump control.

The 330D/336D engine fan (1) is hydraulically driven by a fixed displacement motor (2)

The variable displacement fan pump supplies oil to rotate the fan motor Fan speed is varied toprovide optimized cooling The optimum fan speed is calculated using engine coolant

temperature and hydraulic oil temperature

Case drain oil from the fan motor is combined with the case drain oil from the swing and travelmotors Return oil from the fan motor is sent to the return filters and into the hydraulic tank

An internal makeup valve in the fan motor is used to prevent cavitation when flow from the fanpump stops

The direction of the engine fan can be reversed on machines equipped with the reversible fanoption The fan motor rotation can be changed with the monitor The reversal of the fan motor

is used to clear debris and dust from the radiator and hydraulic oil cooler

4 1

2

The radiator access compartment is located in front of the counterweight The door is hinged

on the right and has a locking latch on the left side to keep it closed This door provides accessfor cleaning some of the cooling system components as servicing some of the fuel system andcooling system components

- hydraulic oil cooler (1)

- Air to Air After Cooler (ATAAC) (2)

This illustration is a schematic of the fan system with the fan at maximum controlled pressure,resulting in maximum controlled fan speed

The hydraulic demand fan is standard on the 330D/336D Hydraulic Excavators The fan is part

of the hydraulic system, but it is controlled by the Machine ECM

The intake manifold air temperature sensor and the coolant temperature sensor are inputs intothe Engine ECM The Engine ECM provides information to the Machine ECM from these twosensors The Machine ECM also receives information from hydraulic temperature sensorthrough the monitor

The Machine ECM evaluates these three sensor inputs for controlling the fan A target speedfor the cooling fan is assigned for each engine speed based on the output of the various

temperature sensors The target values for the maximum fan speeds are assigned by specificsoftware designed for the 330D/336D machine models

The Machine ECM sends a PWM signal to the fan pump proportional solenoid to control theflow from the pump The pump flow is directed to the fan motor, to rotate the motor, whichcauses the fan to turn to provide engine cooling

Fan Motor with Makeup Valve

Pressure Control Solenoid Fan Pump Group

Pump Control Valve

Small Actuator Piston

Large Actuator Piston

Machine ECM

Coolant Temp Sensor

Hydraulic Oil

Temp Sender

Main Return Filter

OK

Minimum PWM Signal

330D / 336D STANDARD HYDRAULIC FAN DRIVE SYSTEM

MAXIMUM CONTROLLED FAN SPEED

When engine coolant and/or hydraulic oil temperatures are high, the fan speed is increased Ifthe temperatures are low, the fan speed is decreased The higher the ambient temperature, thehigher the fan speed, as well.

For high temperature readings the Machine ECM sends the minimum software controlled PWMsignal to the fan pump pressure control solenoid to upstroke the hydraulic pump to increase thepump flow

When maximum pump flow is sent to the fan motor, the fan rotates at the maximum softwarecontrolled rpm

Cat ET or the monitor can be used to check or calibrate the fan speed Refer to the 330D/336DTest and Adjust Manual for the calibration procedures

Maximum mechanical pump pressure and maximum fan speed (high pressure cut-off) can beachieved by disconnecting the electrical connection to the solenoid or by using Cat ET to turnOFF the fan control (Engine ECM/Configuration screen)

If communication is lost between the Engine ECM and the fan pump pressure control solenoid,the fan will default to the maximum mechanical pressure setting (high pressure cutoff) Thisaction results in a higher system pressure This pressure is higher than the maximum pressurecontrolled through the software The fan speed is also higher than the maximum fan speednormally controlled by the software

The makeup valve in the fan motor is used to prevent cavitation when flow from the fan pumpstops

This movement blocks most of the pump output oil in the pump control spool spring chamberfrom draining to tank through the case drain passage, which causes the pump control spoolspring chamber to become pressurized

The force of the spring at the top of the pump control spool, plus the pressure of the oil, is nowgreater than the oil pressure at the bottom of the pump control spool The pump control spoolmoves down, blocking pump output oil from entering the signal passage to the large actuatorpiston in the pump The large actuator piston is open to drain around the pump control spool

Pump Output

to Fan Motor

Large Actuator

Small Actuator and Bias Spring

Swashplate

Drive Shaft

Piston and Barrel Assembly

Pump

Control

Spool

Pressure Control Spool Spring Pin

Signal Passage

to Actuator Piston

Springs

Case Drain Passage

Adjustment Screw

Orifice

330D /336D FAN PUMP AND CONTROL VALVE

MAXIMUM CONTROLLED FAN SPEED

The bias spring and the small actuator move the pump swashplate to an increased angle, whichcauses the pump to UPSTROKE This condition provides a controlled maximum flow of oil tothe fan motor and creates the maximum controlled fan pump system pressure, which results inthe maximum controlled fan speed If the solenoid fails (no current to the solenoid), the pumpgoes to maximum displacement

With no current to the pressure control solenoid, the pump control spool (high pressure cut-off)will limit the maximum pressure and the fan speed to its maximum rpm This state can beachieved by disconnecting the fan pump control solenoid or by using Cat ET to turn the fancontrol OFF This procedure is required when making adjustments to the fan system pressuresettings

The mechanical high pressure cutoff is adjusted using the adjustment screw When the

adjustment screw is turned in (clockwise), it increases the force of the pressure control spoolspring, which increases the the pump pressure required to unseat the land of the upper pumpcontrol spool, thereby increasing maximum cutoff pressure

Maximum cutoff pressure will be lowered when the screw is turned out (counter-clockwise)

NOTE: The 330D/336D service manual currently does not provide test procedures for

checking the maximum and minimum fan speeds outside the control of the software.

The D8T and D9T Track-type Tractor uses a similar cooling fan system The D8T and D9T test procedures for checking the maximum and minimum fan speeds can be used as reference, however, the specifications will be different A tee for a pressure tap will also have to be installed in the line to the fan motor.

The pump control spool is also shown as being adjustable Increasing the spring setting would create higher system pressures and higher fan speeds for a given PWM signal to the pressure control solenoid and vice versa for decreasing the spring setting If the

spool is adjusted a pressure control solenoid calibration should be done to compensate for the change to the pump control spring.

This illustration is a schematic of the hydraulic fan system with the fan at minimum speed

When the Machine ECM sends the maximum software controlled PWM signal to the fan pumppressure control solenoid, the pump destrokes to the minimum swashplate angle At the

minimum swashplate angle the pump produces the minimum controlled flow resulting in thefan turning at the minimum fan speed

When the fan pump pressure control solenoid is at the maximum software controlled PWMsignal, the pressure control spool is unseated by the solenoid, allowing some of pump supplyoil to drain to the tank This action reduces the pressure in the spring chamber of the pumpcontrol spool and the pump control spool shifts up due to the higher pump supply pressure

When the pump control spool moves up, pump flow is directed to the large actuator As

pressure builds in the large actuator, the large actuator overcomes the bias spring and the smallactuator piston to the destroke pump With the pump destroked, oil flow to the fan motor isreduced which reduces the fan speed

Fan Motor with Makeup Valve

Pressure Control Solenoid Fan Pump Group

Pump Control Valve

Small Actuator Piston

Large Actuator Piston

Main Return Filter

Coolant Temp

Sensor Intake Manifold

Air Temperature Sensor

Hydraulic Oil

Temp Sender

OK

Maximum PWM Signal

330D / 336D STANDARD HYDRAULIC FAN DRIVE SYSTEM

MINIMUM CONTROLLED FAN SPEED

This illustration shows the fan control valve with the fan pump at minimum displacement

If the input temperatures are below a certain value, the Machine ECM sends an increased PWMsignal to the pressure control solenoid to reduce the pump flow The solenoid plunger and pinpush the pressure control spool down

With the pressure control spool pushed down, the spring chamber above the pump control spool

is open to case drain around the seat on the lower end of the upper pressure control spool

There is a pressure drop across the orifice above the pump control spool The system pressure

is now greater than the pump control spool spring and the pressure above the pump controlspool The supply pressure pushes the pump control spool up to block oil in the signal passage

to the actuator piston from going to drain

The pump control spool now allows pump supply oil to flow to the large actuator piston Theflow causes an increase in pressure in the large actuator piston The large actuator overcomesthe combined forces of the bias spring and small actuator to move the swashplate toward

minimum angle Pump flow decreases and therefore fan speed decreases

330D / 336D FAN PUMP AND CONTROL VALVE

MINIMUM FAN SPEED Pump Output

to Fan Motor

Large Actuator

Small Actuator and Bias Spring

Swashplate

Drive Shaft

Piston and Barrel Assembly

Signal Passage

to Actuator Piston

Case Drain Passage

With cold oil or at cold start-ups, the Machine ECM PWM signal to the pressure controlsolenoid is at the maximum The pump control spool moves up and supply pressure is sent tothe large actuator piston to move the swashplatetoward minimum angle The large actuatorstops moving when the vent hole through the large actuator piston is open to case drain Thepump flow is decreased to minimum to reduce the fan speed to minimum

The Machine ECM will automatically activate the fan reversing solenoid valve at

predetermined intervals, if the machine is equipped with the optional reversing fan Fan

reversing duration may be re-configured using Cat ET or through the monitor

When the reversing solenoid valve is energized, pilot oil is directed to the reversing spool Thereversing spool shifts causing the flow of oil to the fan motor to be reversed The fan motorrotates in the opposite direction

The relief valve opens momentarily whenever there are any pressure spikes in the system Therelief valve also opens when the fan is first commanded to change directions (either reverse orforward) The momentum of the fan prevents the fan motor from immediate directional changewhen the flow of oil is reversed The relief valve helps dissipate excess pressure that maydamage the system during a directional change

Fan Motor

330D /336D REVERSING HYDRAULIC FAN DRIVE SYSTEM

Pressure Control Solenoid Fan Pump Group

Pump Control Valve

Small Actuator Piston

Large Actuator Piston

Main Return Filter

Hydraulic Oil

Temp Sender

Pilot Oil

Makeup Valve

Relief Valve Reversing Spool

Reversing Solenoid Valve

Radiator

OK

Cat ET Screens for the Hydraulic Cooling Demand Fan

Using Cat ET, the status of the fan control system can be monitored

The system status information can be helpful when troubleshooting the cooling system

After connecting Cat ET, go to the configuration screens

Under Machine Control, open up the Machine Attachments parameters to view the four coolingfan parameters

The Engine Cooling Map parameter can be changed on all machines, but is not recommended.This parameter requires special factory passwords to change the parameter

If the machine is equipped with a reversing fan then the Engine Reversing Feature InstallationStatus and the Engine Reverse Operation Time can also be changed

The Engine Reversing Feature Installation Status is used to change from "Installed" to

"Disabled or Not Installed."

The Engine Reverse Operation Time allows for changing the length of time the fan reversesduring a reversing cycle

The Standard cooling map is currently not being used by any of the factories.

Factory passwords are required to change the cooling fan map for the 330D/336D

NOTE: The technician should never be required to change the cooling map This

parameter is for factory use only At the first release of the 330D the software did allow the technician to change the cooling map without a factory password, but new software was sent out to prevent this from happening.

The configuration screen allows the technician to change from "Installed" to "Not Installed" forreversing feature for the cooling fan

If a reversing fan attachment is not installed on the machine, changing this parameter will have

no affect on the fan operation

On machines equipped with a reversing fan attachment, this parameter allows the technician toturn off the reversing feature if required

On the Override Parameter screen there are three cooling fan parameters that can be overridden

Parameter overrides can be used to perform various system tests that may or not be found in theService Manual

One suggested use for the Engine Coolant Fan Sol Current Override is to enter a value of 0% todetermine the maximum mechanical system pressure and 100% to determine the minimumpressure These two values are not part of one any of the fan cooling maps

NOTE: The 330D/336D service manual currently does not provide test procedures for

checking the maximum and minimum fan speeds outside the control of the software.

The D8T Track-type Tractor uses a similar cooling fan system The D8T test procedures for checking the maximum and minimum fan speeds can be used as reference, however, the specifications will be different A tee for a pressure tap will also have to be installed

in the line to the fan motor.

- minimum fan speed calibration

- maximum fan speed calibration

- finish or "succeeded"

The above screen shows the standby state

Follow the directions on each screen as it appears After the conditions are met, select "Next."

This screen shows the minimum fan speed calibration being performed

To adjust the current to the solenoid, click on the arrows below the Proportional ReducingValve Adjustment Command bar

- Select the right button to increase the current to the fan pressure reducing valve (PRV)solenoid to reduce the fan speed

- Select the left button to decrease the current to the pressure reducing valve (PRV)

solenoid to increase the fan speed