Manual nuevo

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TECHNICAL PRESENTATION

994F WHEEL LOADER

INTRODUCTION

Service Training Meeting Guide

(STMG)

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MEETING GUIDE 804

AUDIENCE

Service personnel who understand the principles of machine systems operation, diagnostic equipment, and testing and adjusting procedures.

CONTENT

This presentation describes the location of the basic components on the engine, and the operation of the power train, implement, steering, and brake systems for the 994F Wheel Loader.

OBJECTIVES

After learning the information in this presentation, the serviceman will be able to:

1. locate and identify the major components in the engine, power train, implement, steering, and brake systems;

2. explain the operation of each component in the power train, implement, steering, and brake systems; and

3. trace the flow of oil through the power train, implement, steering, and brake systems.

REFERENCES

994F Wheel Loader Specalog AEHQ5460

994F Wheel Loader Service Manual RENR2500

994F Wheel Loader Parts Book SEBP2793

Video "994F Wheel Loader - Introduction" SEVN4643 TIM "992G Wheel Loader - Steering and Brake Systems " SERV2632-01

PREREQUISITES

Interactive Video Course "Fundamentals of Mobile Hydraulics" TEMV9001 Interactive Video Course "Fundamentals of Machine Electronics" TEMV9002

Estimated Time: 12 Hours Visuals: 210 Illustrations Handouts: 39 line drawings Form: SERV1804

Date: 7/05

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Component Location...8

Similarities and Differences ...9

ENGINE ELECTRICAL BLOCK DIAGRAM...11

Engine Right Side ...13

Turbocharger Inlet Pressure Sensor...15

Primary Speed Timing Sensor ...16

Rear Pump Drive Lubrication...17

Atmospheric Pressure Sensor ...18

Permanent Speed Timing Sensor...19

Aftercooler Temperature Sensor...24

Engine Coolant Flow Switch...26

Jacket Water Temperature Sensor...27

Crankcase Pressure Sensor ...28

ENGINE COOLING SYSTEM...30

Turbocharger Cooling System ...32

Radiator Group ...33

Fuel Filter Differential Switch...35

Electric Fuel Priming Pump ...36

Fuel System...37

Engine Oil System ...38

Throttle lock...39

Throttle Lock ...40

Throttle Lock Circuit ...41

Engine Derates...42

Engine Air Start System ...46

Air Start System - De-energized...48

Air Start System - Energized ...49

Service Fill...50

Oil Renewal System (ORS)...51

Service Fill...53

Oil Renewal Tank ...54

Metering Valve...55

Variable Clutch Fan Control ...57

POWER TRAIN ...60

Power Flow ...60

Power Train Electrical System ...61

Power Train Electronic Control System (ECM)...64

Engine Speed Sensor ...66

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This presentation discusses the component locations and systems operation of the 994F Wheel Loader. Basic engine and machine component locations will be discussed. Also, the operation of the power train, the implement hydraulics, the steering, and the braking system’s component location will be covered.

The 994F Wheel Loader is the largest wheel loader in the Caterpillar product line. The loading capacity is matched with the 785 Off-highway Truck (Standard Machine), the 789 Off-highway Trucks (High Lift) and 793 Off-highway Truck (Super High Lift). The new 994F Super High Lift can be equipped with a 35.9 cubic meter (47 cubic yard) coal application bucket.

The 994F Wheel Loader operating weight is approximately 160,200 Kg (429, 300 lbs) for a Standard Machine, 160,800 Kg (430,900 lbs) for the High Lift, and 174,300 Kg (467,000 lbs) for the Super High Lift.

The serial number prefix for the 994F Wheel Loader is 442. 1

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2

Component Location

This illustration shows the basic component locations on the 994F. The component locations on the 994F are basically the same as the 994D but are restated as a reminder.

Power for the 994F is supplied by the 3516B High Displacement (HD) engine. The engine is connected to the rear pump drive with a spring coupling. Power flows from the rear pump drive to the torque converter, to the input drive shaft, and through the input transfer gear to the transmission. Power from the transmission flows through the output transfer gears to the drive shafts, to the bevel gears in the differentials, and then to the double reduction final drives. The 994F also has an auxiliary drive shaft that turns the front pump drive. The front pump drive is located in the loader frame.

The secondary steering pump is splined to the output transfer gears. The secondary steering pump is ground driven.

3516B HD Engine Transmission Final Drive Final Drive Transmission Pump Output Transfer Gear Input Transfer Gear Drive Shaft Parking Brake Spring Coupling

Rear Pump Drive

Torque Converter Input Drive Shaft Secondary Steering Pump

Front Pump Drive Auxiliary

Drive Shaft

Engine Power Train Hydraulics

Implement Valve Implement Pumps Hydraulic Tank Steering Pump Brake Pump Pilot Pump Tilt Cylinders Radiator Group and Coolers Moving Parts

994F WHEEL LOADER

COMPONENT LOCATION

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Similarities and Differences

This illustration compares the basic features of the 994F Wheel Loader to the previous 994D Wheel Loader.

The machine appearance and the implement hydraulic system are basically the same as the 994D with the addition of a variable displacement piston pump in tandem with the center fixed displacement piston pump on the front pump drive.

The main relief pressures have been increased from 30400 kPa (4400 psi) on the 994D to 32775 kPa (4750 psi) on the 994F. The 994F is equipped with a 3516B HD EUI as compared to the 3516B EUI in the 994D. The new engine delivers 1,436 horsepower. This is an increase of 14%. The 994F features new turbochargers, high-capacity air filters, and dual 80-amp alternators.

Access to the implement pump case drain filters and the transmission and torque converter filters has improved from the previous version of the 994D. The 994F is installed with a lift linkage position sensor supporting in the cab control of the variable lift kickouts. Also, the 994F is equipped with remote pressure taps for the various hydraulic systems.

FEATURES

DIFFERENT SIMILAR SAME

Machine Appearance

Operator's Station

Engine

X

Transmission

Implement Hydraulic System

X

Steering System

Brake System

Monitoring System

Maintenance Items

X

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The 994F has both starter and transmission lockout switches and an engine shutoff switch at ground level for easy access. Also, the 994F has the optional Oil Renewal System (ORS) which offers a means to reduce the amount of oil changes and increased machine availability. The power train difference between the 994F and 994D is the removal of the free wheel stator and the torque converter outlet relief valve. The 994F power train is now equipped with two additional air-to-oil coolers in order to increase cooling of the power train system. The 994F has a fully modulated impeller clutch torque converter with flexibility of reducing rimpull using the left brake pedal. The pedal fully modulates the rimpull through the range of 100% to 35%. Also, the 994F power train has remote pressure taps installed.

The braking system on the 994F has increased circuit pressure and now features a split control system.

The operator station on the 994F has a larger cab with an approximate 75dBa sound level. A Caterpillar seat with state of the art suspension is installed. Also, the cab has a trainer seat with a padded seat and back. The new cab has 50% more glass area increasing visibility. The 994F retains the Steering and Transmission Integrated Control (STIC) power train which enables the operator to use small movements of a single hand to steer the machine and make direction/gear changes.

The maintenance items on the 994F are similar to the 994D. The major changes in the maintenance are access to the filters on the 994F.

The 994F is equipped with the latest Vital Information Management System (VIMS) that is similar to the 994D.

NOTE: For more information on the VIMS refer to the VIMS Service Manual

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ENGINE ELECTRICAL BLOCK DIAGRAM

This block diagram of the engine electrical system shows the components that are mounted on the engine which provide input signals to and receive output signals from the Engine Electronic Control Module (ECM).

Based on the input signals, the Engine ECM energizes the injector solenoid valves to control fuel delivery to the engine, and energizes the cooling fan proportional solenoid valve to adjust pressure to the optional cooling fan clutch.

The two machine interface connectors provide electrical connections from the engine to the machine including the Cat Data Link.

Some of the components connected to the Engine ECM through the machine interface connectors are: the throttle pedal position sensor, the throttle lock switches, the throttle lock enabled indicator, the right brake pedal switch, the ether start control solenoid, and the ground level shutdown switch.

16 Electronic Unit Injectors Primary Speed Timing Sensor

Coolant Flow Switch Left Exhaust Temperature Sensor

Right Exhaust Temperature Sensor

Ground Bolt

Right Turbocharger Inlet Pressure Sensor Left Turbocharger Inlet Pressure Sensor Filtered Oil Pressure Sensor

Turbocharger Outlet Pressure Sensor

Atmospheric Pressure Sensor

Crankcase Pressure Sensor Permanent Speed Timing Sensor Jacket Water Temperature Sensor

J1 _ECM

Aftercooler Coolant Temperature Sensor Oil Level Add Switch

Unfiltered Oil Pressure Sensor Cooling Fan Speed Sensor

(Attachment)

Main Power Relay Coil

Ground Level Shutdown Switch Engine Shutdown Relay To EUI

Machine Interface Connector

Machine Interface Connector Cooling Fan Proportional Valve

(Attachment) Fuel Filter Differential Switch

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Input Components:

Primary speed timing sensor - The speed timing sensor sends a fixed voltage level signal to the Engine ECM in order to determine the engine speed, direction, and timing.

Oil level switch - The oil level switch (lower) is a float type switch mounted in the side of the engine oil sump. The Engine ECM monitors the engine oil level switch to alert the operator when the oil level is low.

Coolant flow switch - The coolant flow switch mounts in the coolant passage near the engine coolant pump. When the coolant is flowing past the switch the paddle moves and closes the switch contacts. The Engine ECM alerts the operator when there is no coolant flow while the engine is running.

Exhaust temperature sensors - The exhaust temperature sensors communicate the exhaust temperature to the Engine ECM.

Permanent speed timing sensor, cooling fan speed sensor (if equipped), - These speed sensors are passive speed sensors that provide a signal similar to a sine wave that varies in amplitude and frequency as speed increases. The permanent speed timing calibration sensor monitors the speed and position of the flywheel.

Jacket water temperature sensor, aftercooler coolant temperature sensor - These

temperature sensors are analog temperature sensors that provide a signal to the Engine ECM. Crankcase, atmospheric, turbocharger outlet, filtered and unfiltered oil, left and right turbocharger inlet pressure sensors - These sensors are analog sensors that provide a voltage signal to the Engine ECM. The signal varies to a level that corresponds with a calibrated pressure. The Engine ECM calibrates the pressure sensors to the atmospheric pressure when the key start switch is moved to the ON position for 10 seconds without the engine running. Fuel filter differential switch - The fuel filter differential switch is a pressure switch. The contacts open when there is a restriction in the fuel line from the secondary fuel filters.

Note: The cooling fan proportional valve and the cooling fan speed sensor are

attachments. The valve and the sensor are installed with the variable speed cooling fan system (Rockford Fan System).

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Engine Right Side

This view shows the right side of the engine that is accessed from the left side of the machine. Components which can be seen are:

- Turbocharger (1)

- Coolant regulator housing (2) - Engine oil cooler (3)

- Electric fuel priming pump filter (4) - Alternator (5)

- Transmission cooler (coolant-to-oil) (6) - Permanent speed timing sensor (7) - Crankcase pressure sensor (8)

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This illustration shows the machine controls that are located at the rear of the machine. The following is a list of the ground level components:

- Ground level shutdown (1) - Hood lamp (2)

- Ground level stair lamp (3) - VIMS key switch (4)

- VIMS serial download port (5) - Hour meter (6)

- Start lockout indicator (7) - Transmission lockout LED (8) - Transmission lockout switch (9) - Start lockout switch (10)

- Locks (11) 6 1 2 3 4 5 6 7 8 9 10 11

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Turbocharger Inlet Pressure Sensor

This illustration shows the left turbocharger inlet pressure sensor (2) and right turbocharger inlet pressure sensor (3). The illustration shows the sensors on the turbochargers (1) that are installed on the front of the engine (located toward the rear of the machine). These analog sensors read the pressure in the turbo inlets and send a corresponding signal to the Engine ECM. The left turbocharger inlet pressure sensor (2) and the right turbocharger inlet pressure sensor (3) communicate with the Engine ECM. The Engine ECM provides an input to the VIMS module informing the operator of an air filter restriction.

When an air filter becomes plugged and restricts air available for combustion resulting in elevated exhaust temperatures, the Engine ECM sends a signal to the injectors to decrease the flow of fuel.

The Engine ECM receives signals from the turbocharger inlet pressure sensors and determines inlet air restriction by subtracting the turbocharger inlet air pressure that is measured by the turbocharger inlet air pressure sensors from the atmospheric air pressure.

The Engine ECM derates the power by 1% when the inlet air restriction reaches 6.5 kPa (25 inches of water). This derate will increase at a rate of 2% kPA of restriction until the maximum derate of 20% is reached. The engine will default to a maximum derate of 20% if the Engine ECM detects a fault in the circuits for the left or right turbocharger inlet pressure sensors.

Also shown are the inlet tubes (4).

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Primary Speed Timing Sensor

The primary speed timing sensor (1) is positioned near the rear of the left camshaft. The sensor signals the speed, direction, and the position of the camshaft by counting the passing teeth and measuring the gaps between the teeth on the timing wheel that is mounted on the camshaft. The primary speed timing sensor receives has an input voltage of 12 VDC.

If the Engine ECM does not receive an input signal from the sensor, the engine will not start. Also shown is the Engine ECM (2).

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9

Rear Pump Drive Lubrication

The rear pump drive is attached to the engine and drives the steering pumps, brake pump, the steering and brake cooling pump, and the brake cooling pump. The rear pump drive is

lubricated with oil from the torque converter outlet that has been cooled by air-to-oil coolers or the coolant-to-oil coolers. The oil lubricates the bearings and gears in the rear pump drive.

From Transmission

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10 Atmospheric Pressure Sensor

The atmospheric pressure sensor (1) is located towards the rear of the machine next to the Engine ECM (2). The Engine ECM uses the atmospheric sensor as a reference for calculating boost pressure, and air filter restriction. The sensor also is used to supply information to the Engine ECM to derate the engine at high altitudes. The atmospheric pressure sensor uses 5 VDC that is supplied by the Engine ECM.

The sensor is used for altitude derate. If the machine is operating above 10,000 feet, the engine will derate 1% for every kPa of atmospheric pressure below 70 kpa or 3% per 1,000 foot increments above 10,000 feet.

If the Engine ECM detects a loss of the signal from the atmospheric pressure sensor, the ECM will derate the engine to a maximum derate of 24%. The Engine ECM uses the atmospheric pressure sensor as a reference when calibrating the pressure sensors.

The pressure sensor calibration receives an auto calibration enable command 10 seconds after ECM power-up. The auto calibration will occur when auto calibration is enabled and engine speed is 0 rpm. All pressure sensors will be sampled at 30 msec. The calibration function will then perform a 2 second average on the individual sensors for calibration.

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11

Permanent Speed Timing Sensor

The permanent speed timing sensor is used for timing calibration through Electronic Technician (ET). The permanent speed timing sensor is located on the left side of the machine and

installed in the torque converter housing. 1

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This illustration shows two engine oil level switches. Oil level switch (3) communicates with the Engine ECM. This switch opens the circuit when the oil level is below the necessary level. Oil level switch (2) communicates with the VIMS module. The oil level switch (2) signals that oil should be added to the engine. If the machine is equipped with the optional Oil Renewal System (ORS), level switch (2) will disable the ORS when the oil level is low.

Also shown is the engine oil filler tube (1). 12 1

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This illustration show the right side turbo inlet exhaust temperature sensor (1). The engine is also equipped with a turbo inlet exhaust temperature sensor on the left side (not shown). The sensors communicate with the Engine ECM. The Engine ECM provides an input signal to the VIMS module to inform the operator of the exhaust temperature.

Some causes of high exhaust temperature may be faulty injectors, plugged air filters, or a restriction in the turbochargers.

When the highest temperature of the right or left turbine inlet temperatures goes above 750º C (1382º F) for 15 seconds, the torque map is reduced by 2%. If the measured temperature does not return to below 750º C (1382º F) within a 15 second interval, the torque map will be reduced by 2%. This will continue in 2% steps with each step lasting 15 seconds until the temperature drops below 750º C or the maximum derate of 20% is reached. The last derate level reached will remain active until the engine is powered down.

If a failure is detected in either the left or right exhaust temperature sensor circuits, the Engine ECM will default to the maximum derate value of 20%. An exhaust temperature derate occurrence will log an Engine Event in the Engine ECM that requires a Level 3 password to clear.

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The illustration above shows the location of the Engine ECM (1) and the atmospheric pressure sensor (2).

The Engine ECM is an ADEM III module and is equipped with two 70 pin connectors. The Engine ECM (1) is mounted on the engine on the right side of the machine. The engine ECM is accessed from below the machine.

The Engine ECM makes decisions based on control program information in memory, switch inputs, analog input signals, and sensor input signals.

The Engine ECM responds to machine control decisions by sending a signal voltage to the appropriate circuit which creates an action. For example, as the operator depresses the throttle pedal, the Engine ECM interprets the input signal from the throttle pedal position sensor, evaluates the engine status, and sends a signal to the injectors to increase fuel.

The Engine ECM receives three different types of input signals:

1. Switch input: Provides the signal line to battery, ground, or open.

2. PWM input: Provides the signal line with a square wave of a specific frequency and a varying positive duty cycle.

3. Speed signal: Provides the signal line with either a repeating, fixed voltage level pattern signal or a sine wave of varying level and frequency.

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2. PWM solenoid driver: Provides the output device with a square wave of fixed frequency and a varying positive duty cycle.

3. Controlled current output driver: The ECM will energize the solenoid with 1.25 amps for approximately one half second and then decrease the level to 0.8 amps for the

duration of the on time. The initial higher amperage gives the actuator rapid response and the decreased level is sufficient to hold the solenoid in the correct position. An added benefit is an increase in the life of the solenoid.

The Engine ECM receives signals from the speed timing sensors, oil level switch, coolant flow switch, exhaust temperature sensors, coolant temperatures sensors, engine pressure sensors, and the current engine operating status. The Engine ECM interprets signals and determines the appropriate output signals to the engine. Different conditions of the inputs affect the output conditions.

The Engine ECM communicates through the CAT Data Link. The CAT Data Link allows high speed proprietary serial communications over a twisted pair of wires. The CAT Data Link allows different systems on the machine to communicate with each other and also with service tools such as Caterpillar Electronic Technician (ET).

The Engine ECM has built-in diagnostic capabilities. As the Engine ECM detects a fault condition developed by the engine, The ECM logs the faults in memory and displays them on the VIMS. The fault codes can also be accessed using the ET service tool. VIMS software can be used to view faults logged by the VIMS.

INSTRUCTOR NOTE: Engine ECM faults displayed on the VIMS relating to the Engine ECM will have a Module Identifier (MID) of "36." For more information, refer to the Service Manual module "Engine, Systems Operation Testing and Adjusting"

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15

Aftercooler Temperature Sensor

The aftercooler temperature sensor (arrow) is located at the rear of the engine at the firewall. The sensor reads the temperature of the coolant that is flowing through the aftercooler. The sensor sends an analog signal voltage to the Engine ECM. The sensor along with the water jacket temperature sensor to control the engine timing and cold mode functions.

If the aftercooler temperature sensor exceeds 107° C (226° F), the Engine ECM will log an event that requires a factory password to clear.

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This is a partial view of the front right side of the engine. The illustration is showing the location of the following components on the right front side of the engine:

Components which can be seen are: - Electric fuel priming pump filter (1) - Alternator (2)

- Air conditioning compressor (3) - Engine oil cooler (4)

- Fuel transfer pump (5) - Coolant flow switch (6)

- Coolant pump for jacket water (7)

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5

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17

Engine Coolant Flow Switch

The coolant flow switch monitors the amount of coolant that is flowing from the water pump through the various oil coolers. The coolant flow switch (1) sends an input to the Engine ECM. and the ECM provides an input signal to the VIMS module informing the operator of the

coolant flow status.

If the ECM detects a low coolant flow condition, a low coolant flow event will be logged. A factory password is required to clear the event.

Jacket water coolant samples can be taken at the Scheduled Oil Sampling (S•O•S) port (2). 1

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Jacket Water Temperature Sensor

In this illustration, the jacket water temperature sensor (1) is located on the right side of the machine in the end of the jacket water. The sensor sends an analog signal to the Engine ECM. Then, the Engine ECM sends a signal to the VIMS module displaying the engine coolant temperature.

The Engine ECM uses the coolant temperature information for cold mode functions such as: a timing change, elevated idle, cold cylinder cut-out, and ether injection.

If the jacket water cooling system temperature exceeds 107° C (226° F), the Engine ECM will log an event that requires a factory password to clear.

Also shown is the turbocharger outlet pressure sensor (2). 18

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Crankcase Pressure Sensor

The crankcase pressure sensor (arrow) is located on the right side of the engine above the engine oil cooler. The sensor provides an input to the Engine ECM, which informs the operator of the crankcase pressure.

High crankcase pressure may be caused by worn piston rings or cylinder liners.

The crankcase pressure sensor initiates an event when the crankcase pressure is above 3.6 kPa (0.5 psi) for three seconds. No factory password is required to clear the event

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This illustration shows the left side of the 3516B HD engine which can be accessed from the right side of the machine

Components that can be seen include: - Left side alternator (1)

- S•O•S port for the Separate Circuit After Cooler (SCAC) coolant (2) - Fuel filters (3)

- Engine oil filters (4) - Air compressor (5)

- Separate Circuit After Cooler (SCAC) water pump (6) - Engine oil fill tube (7)

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21

ENGINE COOLING SYSTEM

This illustration shows the flow of the engine coolant from the main coolant pump through the radiator, the engine, the oil coolers. Also, the machine is equipped with a Separate Circuit After Cooler (SCAC) coolant through the after coolers.

The 994F has been updated with Next Generation Modular Radiator (NGMR) two-pass cores for both the engine coolant and the SCAC.

In the engine cooling system, the main coolant pump draws the cooled coolant from the radiator, or the regulator housing when the regulators are in bypass, and sends coolant through the engine oil cooler, the brake oil cooler, the power train oil cooler, and then into the engine block. The engine coolant flows through the engine coolant passages and exits the engine block through the regulator housing. The radiator bypass circuit allow coolant flow through the engine and coolers when the engine is below operating temperature.

When the temperature of the coolant approaches 81° C (179° F) to 84° C (183° F), the water regulator begins to open. At 92° C (199° F) the water regulator is fully opened. The flow of coolant is sent through the radiator for cooling.

Hottest

Coldest

Hot SCAC Coolant Increasing

Coolant

Temperature Power Train

Oil Cooler Engine Oil Cooler Main Coolant Pump Aux. Coolant Pump Regulator Housing Aftercoolers Engine Coolant Radiator Separate Circuit Aftercooler (SCAC) Radiator Brake Oil Cooler Direction of Air Flow Direction of Air Flow Radiator Bypass

994F ENGINE COOLING SYSTEM

NEXT GENERATION MODULAR RADIATOR (NGMR)

To / From Service Brakes

To / From Transmission

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nearest the engine after the coolant has been cooled.

The location of the brake oil cooler has not changed. The cooler is mounted below the engine on the inside of the left rear frame rail. The brake oil cooler is an oil to coolant cooler and cools the oil from the service brake cooling circuit not the brake application hydraulic oil.

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22

Turbocharger Cooling System

This illustration shows the coolant flow through the turbochargers. The coolant flow from the pump through the oil coolers, the engine, and the regulator housing. From the regulator housing, the coolant flows through tubes along the engine and is connected to the

turbochargers. From the turbochargers, the coolant flows to a tee that is connected to the return tube for the radiator.

Hottest Coldest Increasing Coolant Temperature Power Train Oil Cooler Engine Oil Cooler Main Coolant Pump Regulator Housing Engine Coolant Radiator

994F TURBOCHARGER COOLING

NEXT GENERATION MODULAR RADIATOR (NGMR)

Brake Oil Cooler Direction of Air Flow Turbochargers SCAC Coolant Radiator Radiator Bypass To / From Service Brakes To / From Transmission

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Radiator Group

The illustration shows the radiator cores that are used to cool the engine. The Next Generation Modular Radiator cores are divided into two groups. Each core has nine fins per inch with two pass coolant travel. The five cores (1) on the left make up the Separate Circuit Aftercooler (SCAC) Radiator. The SCAC cools the aftercoolers.

The 13 cores (2) on the right side are used to cool the engine.

Also, included in the radiator group are the engine oil cooler, the brake oil cooler, and the power train oil coolers that are not shown in the illustration. These coolers are located between the cooling cores and the fan blade.

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This illustration shows the left side of the engine near the front. This side of the engine can be accessed by the right side of the machine.

The illustration shows the following components: - Secondary fuel filters (1)

- Electric fuel priming pump switch (2) - Fuel differential pressure switch (3) - Oil pressure sensor filtered (4)

- S•O•S fluid sampling oil port (engine oil) (5) - Engine oil dipstick (6)

- Oil pressure sensor unfiltered (behind the secondary fuel filters) (7) - Engine oil filters (8)

24 2 6 5 7 8 3 1 4

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25

Fuel Filter Differential Switch

The fuel filter differential switch (1) is located on the filter base above the secondary filters. The pressure switch sends an input signal to the Engine ECM. If the fuel pressure exceeds 138 kPa (20 psi) due to a restriction in the secondary fuel filters, an open circuit signal will be sent to the Engine ECM. Then, the Engine ECM will send an input to the VIMS module informing the operator that the secondary fuel filters are probably restricted. An event will be logged but no factory password is required to clear the event.

This is a switch to ground input to the Engine ECM.

Also shown are the fuel priming pump switch (2) and the secondary fuel filters (3). 3

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26

Electric Fuel Priming Pump

The electric fuel priming pump (1) is located on the electric fuel priming pump filter base. The filter base and the pump are located on the right side of the engine and the left side of the machine. The electric fuel priming pump is used to fill the filters after the filters have been changed.

The electric fuel priming pump is activated by a switch that is shown in Illustration 25 on the fuel filters base.

In order to activate the electric fuel priming pump, the engine start switch must be in the OFF position and the disconnect switch in the ON position. 24 ± 2 VDC is the normal operating voltage.

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27

Fuel System

Fuel is drawn from the tank through a fuel heater (if equipped), by the fuel transfer pump. Fuel flows from the fuel transfer pump to the secondary fuel filters.

Fuel flows from the secondary fuel filter base through the fuel injectors in the cylinder heads. Return fuel from the injectors flows through the fuel pressure regulator before returning

through the fuel heater to the fuel tank. The fuel system is equipped with an electric fuel pump. The secondary fuel filter base is equipped with a switch controlling the voltage to the electric fuel priming pump that is located on the primary filter base.

If the engine is equipped with a Oil Renewal System (ORS), engine oil flows from the engine block through an oil filter to the engine oil renewal system manifold. A small amount of used engine oil flows from the engine oil renewal system manifold into the return side of the fuel pressure regulator. The engine oil returns to the fuel tank with the return fuel. The engine oil mixes with the fuel in the tank and flows with the fuel to the injectors to be burned.

The engine is equipped with a electric fuel priming pump. When the filters are replaced or service to the fuel system is completed, the priming pump is used to fill the system.

Fuel Tank Fuel Transfer Pump Primary Fuel Filter Secondary Fuel Filters Cylinder Head Cylinder Head Fuel Pressure Regulator Fuel Heater (Optional) Engine Oil Renewal Solenoid (Optional) Electric Fuel Priming Pump Fuel Filter Differential Switch Electric Fuel Priming Pump Switch Supply Fuel Return Fuel Suction Fuel Engine Oil

Fuel Pressure Legend

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28

Engine Oil System

The engine oil pump draws oil from the oil pan through a screen. The engine also has a scavenge pump at the rear of the engine to transfer oil from the rear of the oil pan to the main sump.

Oil flows from the pump through an engine oil cooler bypass valve to the engine oil cooler. The bypass valve for the engine oil cooler permits oil flow to the system during cold starts when the oil is thick or if the cooler is plugged. Oil flows from the engine oil cooler to the oil filters. The oil flows through the filters and enters the engine cylinder block to clean, cool, and lubricate the internal components and the turbochargers.

Some wheel loaders are equipped with an optional engine oil renewal system. Engine oil flows from the engine block through an oil filter to an engine oil renewal system manifold. A small amount of oil flows from the engine oil renewal system manifold into the return side of the fuel pressure regulator. The engine oil returns to the fuel tank with the return fuel.

Engine Oil Cooler Engine Oil Filters Engine Oil Pump Scavenge Pump Bypass Valve Engine Oil Renewal

System Solenoid (Optional) To Fuel

Tank

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Throttle Lock

The throttle lock enable switch (1) is located in the dash. The throttle lock switches that are mounted in the cab to the right of the operator's seat are the set/decelerate (2) and the resume/accelerate switch (3).

Also shown are button (4) for the horn and control levers (5).

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Throttle Lock

The throttle lock lamp (1) is lit when the throttle lock switch is in the enable position.

Depressing the right brake pedal (2) will cause the desired engine speed to return to low idle. An invalid brake switch signal will also cause the desired engine speed to return to low idle. The throttle pedal (3) is used in order to select the desired engine speed. The throttle position sensor is located on the throttle pedal. The sensor provides the signal to the Engine ECM. The throttle position sensor receives a regulated 8.0 VDC from the Engine ECM. The throttle position sensor output is a pulse width modulated signal that is expressed as a percentage between 10% and 90%.

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32

Throttle Lock Circuit

The Throttle Lock feature is very similar to a cruise control system used on automotive and truck applications. The main difference is that this system uses engine speed as its reference instead of vehicle speed. Therefore, engine speed is maintained, unlike other applications which control ground speed.

The Throttle Lock control is within the Engine ECM. The other components are: - Throttle Lock Enable Switch

- Set/Deceleration Switch - Resume/Acceleration Switch - Right Brake Pedal Switch

- Throttle Lock lamp does not communicate with the engine ECM. The Throttle Lock Lamp ON/OFF is controlled by the Throttle Lock Enable Switch.

Throttle Lock Lamp 113-OR Batt+ F706-PU Engine ECM J1 21 22 5 64 61 62

Throttle Lock Rh Brake (NO) Throttle Lock Rh Brake (NC) Digital Return

Throttle Lock Set / Decelerate Throttle Lock Resume / Accelerate Throttle Lock On / Off

998-BR Right Brake Pedal Switch

F721-GY F722-OR F717-YL F718-BU F719-BR 998-BR 998-br 998-BR 998-BR 998-BR Throttle Lock Set / Deceleration Sw Throttle Lock Resume / Acceleration Sw Throttle Lock Sw 200-BK or Ground

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3516B HD ENGINE DERATES

-

Altitude Compensation

-

Exhaust Temperature

-

Air Inlet Restriction

Engine Derates

The 994F derates for the 3516B HD Engine are as follows: - Exhaust Temperature Derate

- Altitude Compensation Derate - Air Inlet Restriction Derate

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34

Exhaust Temperature Derate: The engine power will be derated when the turbine inlet

temperatures reach a critical level that may cause engine damage. The Engine ECM measures the turbo inlet temperatures using the signals from the left and right exhaust temperature sensors.

In the illustration above, 0% engine derate equates to a temperature of 750º C (1382º F) or below with 15 seconds as the trigger for the derate.

When the highest of the right or left turbine inlet temperatures goes above 750º C (1382º F) for 15 seconds, the torque map is reduced by 2%. If the measured temperature does not return to below 750º C (1382º F) within a 15 second interval, the torque map will be reduced by 2%. This will continue in 2% steps with each step lasting 15 seconds until the temperature drops below 750º C or the maximum derate of 20% is reached. The last derate level reached will remain active until the engine is powered down.

If the condition reoccurs and the Engine ECM has not been powered down, the fuel will be limited in the same manner starting from the previous derate level.

If a failure is detected in either the left or right exhaust temperature sensor circuits, the Engine ECM will default to the maximum derate value of 20%. An exhaust temperature derate

occurrence will log an Engine Event in the Engine ECM requiring a Level 3 password to clear.

0 2 4 6 8 10 12 14 16 18 20 0 15 30 45 60 75 90 105 120 135 150 165 180 195 Engine Derate (%) Time (Sec)

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35

Altitude Compensation Derate: The Engine ECM derates engine power according to operating altitude in order to reduce exhaust temperatures. The engine ECM calculates the operating altitude of the machine based on the signal received from the atmospheric pressure sensor.

The Engine ECM derates the engine power approximately 3% per 305 m (1000 ft) when the machine is operated above 3050 m (10,000 ft). The maximum altitude derate for the engine is 18% at 5180 m (17,000 ft).

Altitude compensation derate does not log an event in the Engine ECM. 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 0 1 Division = 1000 Ft of Altitude Engine Derate (%) 2 4 6 8 10 12 14 16 18 20 22 24 ALTITUDE COMPENSATION DERATE

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36

Air Inlet Restriction Derate: The Engine ECM derates engine power when the air inlet or filter becomes plugged and restricts air available for combustion resulting in elevated exhaust temperatures. The above illustration shows the engine derates in relation to the air inlet restriction.

The Engine ECM determines inlet air restriction by subtracting the turbocharger inlet air

pressure that is measured by the turbocharger inlet air pressure sensors from the atmospheric air pressure.

The Engine ECM derates the power by 1% when the inlet air restriction reaches 6.5 kPa (25 inches of water). This derate will increase at a rate of 2% kPA of restriction until the maximum derate of 20% is reached. The engine will default to a maximum derate of 20% if the Engine ECM detects a fault in the circuits for the left or right turbocharger inlet pressure sensors or the atmospheric pressure sensor.

An air inlet restriction event will be logged in the Engine ECM when the engine starts derating. A password is not required to clear an air inlet restriction event.

NOTE: Multiple engine derate percentages can add up and result in a total engine

power derate greater than 20%. 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Inlet Restriction (kPa)

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37

Engine Air Start System

This illustration shows the location of the engine air start components on or near the the rear frame.

Components that can be seen include: - Air dryer (1)

- Air horns (2) - Air start tank (3) - Air horn solenoids (4) - Air compressor (5) - Air start motor (6) - Air start solenoid (7) - Air relay (8)

- Gauge (service fill) (9) - Socket (service fill) (10)

1 2 3 4 5 6 7 ₈ 9 10

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This illustration shows the air engine starter (1) and the air starter solenoid valve (2). This photo shows the air engine starter from under the machine on the right side. The air engine starter solenoid valve receives starting current from the Power Train ECM (not shown).

38 1

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39 Air Start System Schematic - De-energized

This illustration shows the air start tank charged with air pressure and the solenoids

de-energized. The engine air start system supplies the required amount of air in order to turn the air start motor.

At initial start-up, the air start tank is bled down, or through leakage the air tank will need to be charged to the adequate pressure. The socket located in the service fill area is used to provide the required air to pressurize the tank. The air from the socket flows around the air dryer and into the air tank. The air in the tank will charge the line going to the relay valve. Also, air flows to the air horn solenoids, the gauge, the air start solenoid, and to the unloading valve on the air compressor. When the air compressor has fully charged the tank and the lines, the unloading valve will signal the air compressor to stop.

The pressures switch communicates with the VIMS module informing the operator of a low air pressure in the tank.

If the pressure on the unloading line (between the air tank and the air compressor) decreases, the unloading valve will signal the compressor to resume supplying air for the air tank. At this time, no air pressure is directed to the air start motor or to the air horns.

Pressure Switch Pressure Protection Valve

Air Start Solenoid Air Compressor Air Dryer Gauge (Service Fill) Relay Valve Air Start Motor Socket (Service Fill) Drain Valve Check Valve

994F WHEEL LOADER

ENGINE AIR START SYSTEM

Air Horn Relay Air Horn

Relay

SOLENOIDS NOT ENERGIZED

Air Start Tank

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40

Engine Air Start System - Energized

This illustration shows the air start tank charged with air pressure and the air start solenoid energized. When the engine start switch is turned to the ON position, a signal is sent to the Power Train ECM. Then, the Power Train ECM sends a voltage signal to the coil on the air start solenoid to open and allow air to pass through the solenoid valve. The air will flow through the air solenoid valve and flow to the air start motor. The pinion (not shown) will move into the fly wheel. Then, the air flows to the relay valve to signal the relay valve to open and allow air to flow directly from the tank to the air start motor. When the engine is started, release the key and the Power Train ECM will de-energize the air start solenoid valve. Also, the Power Train ECM will de-energize the air start solenoid valve when the ECM gets a signal that the engine is rotating at least 400 rpm for 10 seconds.

Pressure Switch Pressure Protection Valve

Air Start Solenoid Air Compressor Air Dryer Gauge (Service Fill) Relay Valve Air Start Motor Drain Valve Check Valve Air Horn Relay Air Horn Relay Air Start Tank

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41

Service Fill

The air start system is equipped with a socket (2) in the service fill. The socket is used to recharge the air start tank if the supply is depleted for an initial startup or in the case of a air leak. The service bay is equipped with a gauge (1) for checking the air pressure in the air start tank.

1

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42

Oil Renewal System (ORS)

The Oil Renewal System (ORS) is intended to increase the time between oil changes without shortening the life of the engine. Also, the system will decrease the amount of required disposable used engine oil. The ORS removes used engine oil from the engine sump and meters that oil into the fuel return line. The used oil will be consumed by the engine during the normal process of combustion.

Normal oil analysis will help to determine whether the engine oil should be changed. The Oil Renewal System is an integrated system that requires the installation of additional components on the machine. The Engine ECM monitors fuel rate for 5 minutes. Then, the ECM determines how much oil to inject. The ORS valve has a fixed injection of oil per "pulse." The Engine ECM calculates how many times it must drive the ORS valve. Each injection last only a few seconds so the actual oil injections based on the previous 5 minute fuel cycle last approximately 30 seconds. The Engine ECM waits until the next 5 minute fuel cycle to start another set of oil injections. The target concentration for this operation is approximately 0.5% oil to fuel.

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There are several parameters that are monitored to determine if it is appropriate to inject oil. If any of these are not true then operation of the ORS strategy is halted until all conditions are met or the ECM power is recycled.

The parameters that are monitored are as follows:

- Engine Speed must be greater than 1100 rpm. If engine speed exceeds 1100 rpm, oil will be injected at the end of the 5 minute sampling period.

- Engine must be running for 5 minutes

- Coolant Temperature must be between 63° C and 107° C before ORS start up - Coolant Temperature sensor fault check (open or short to ground)

- Oil pressure sensor fault check (open or short to ground) - Oil pressure Event check (active or inactive)

- Fuel Level must be equal or greater than 10% - Fuel Level sender fault from VIMS

- Engine Oil Level Status

The following callouts are locations of the components for the Oil Renewal System. - Renewal tank (1)

- Metering valve (2) - Service fill (3)

To install the Oil Renewal System, the ORS will be configured through the Power Train ECM. This will take a factory password. Also, the enabling the ORS is configured through the Power Train ECM.

Configuration of the Oil Renewal Rate setting is performed through the Engine ECM. The CID code for the ORS solenoid valve is 2271. The code is read in the Engine ECM and relayed to the VIMS module for display.

FMI O5 Open circuit/Short to + battery FMI O6 Short to ground

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43

Service Fill

The tank for the Oil Renewal System is filled at the service fill located on the right side of the rear frame near the articulation hitch. The tank filler (1) is used in order to fill the renewal tank (not shown). LED (2) will light when the upper level switch in the renewal tank (not shown) is activated. Access the tank filler by opening the cover over the service fill. The illustration shows the cover removed.

1 2

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44

Oil Renewal Tank

The renewal tank (1) holds oil which will eventually be metered into the engine sump. The tank is equipped with two separate level switches. The upper level switch (2) is used to illuminate the blue LED in the service fill. The lower level switch (3) communicates with the VIMS module giving a signal the oil renewal system tank is empty. VIMS does display a warning saying ORS OIL LVL LO but does not instruct the operator to take any action.

NOTE: The Oil Renewal System will not be shut down until the upper level switch for

the engine oil sump shows a low level event.

1

2

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Metering Valve

The metering valve (1) draws clean, pressurized oil from a port on the engine block and sends that oil to to the fuel return line. That oil flows through the fuel line to the fuel tank to mix with the fuel. At the same time, the engine oil sump is back filled with oil from the renewal tank.

The metering valve is made up of a check valve (3), a shuttle valve and a solenoid valve. When the solenoid valve (2) is energized, pressurized engine oil from the crankcase fills the used oil side of the valve moving the shuttle. Then, forcing oil in the new oil side of the shuttle to the engine sump. When the shuttle is completely shifted to new oil side, no more oil is moving. 45 46 1 2 3

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When the solenoid is de-energized, a spring moves the shuttle back which sends the oil from the used oil side of the shuttle to the fuel return line and draws oil form the make-up tank to the new oil side of the shuttle. When the shuttle is shifted completely to the used oil side, no more oil is moved.

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47

Variable Clutch Fan Control

The variable clutch fan control is used to meet the changing cooling requirements, thus reducing the horsepower that is used to drive the fan in cooler ambients or light duty cycle work conditions. The Rockford fan controls and limits fan speed by proportionally modulating engine oil pressure to the clutch.

The speed of the fan will increase or decrease to compensate for a temperature change through feedback from the temperature sensors. The Engine ECM receives feedback from three

sensors: the hydraulic oil temperature sensor, coolant temperature sensor, and the aftercooler temperature sensor. Each sensor has a target temperature programmed into the ECM. When one or more of the sensors read a temperature above the key target temperature, the ECM will will send a reduced current to the solenoid. This will increase the oil pressure to the fan clutch and decrease slipping of the clutch. If the temperatures at the sensors are all below the key target temperatures, full current is sent to the the solenoid and reduce the oil pressure to the fan clutch. The fan speed will reduce to minimum.

The variable clutch fan is equipped with a speed sensor within the clutch assembly. The speed sensor monitors the speed of the fan and send feedback to the Engine ECM that the fan is rotating at the required speed.

2

3

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The following is a list of components in the variable clutch fan control. - Fan clutch (1)

- Control valve (2)

- Engine oil pressure supply port (3) - Return to the engine sump port (4)

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48

The variable clutch fan system system has two different engine oil circuits. The lubrication circuit is the flow of engine oil from the engine oil pressure port (brown) through the clutch and back to the engine sump through the line (green) at the bottom of the clutch. The engine oil pressure port is located on the front engine cover. The oil pressure in the front cover is supplied by oil from the engine oil pump that is drawn from the engine sump. This circuit is used mainly to cool the fan clutch.

In the second circuit (control), oil (red) is taken from the engine oil pressure port in the front cover. The oil flows into the pressure port in the variable control valve, through the orifice, and out of the valve output to the clutch piston (not shown)

With no current, the maximum oil flows out of the valve and maximum pressure is acting on the clutch piston. The maximum pressure on the clutch piston develops a force on the clutch plates rotating the fan at maximum speed. In case of a voltage loss in the electrical system, the valve will shift to the open position and the fan is defaulted to maximum fan speed.

As the current to the coil assembly starts to increase, the oil flow through the control valve is decreased proportionally to the increase in current and a small amount of oil will flow over the tank orifice to the engine sump through the tank line (green) assisting in decreasing the fan speed. Engine Sump Fan Clutch Engine Oil Pressure Port Engine Oil Pump Coil Assembly To Engine Sump To Fan Clutch

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49

POWER TRAIN Power Flow

Power from the 3516B HD engine is sent from the flywheel through the spring coupling to the rear pump drive. The rear pump drive is splined to the torque converter. Other components (not shown on this illustration) that are driven by the rear pump drive are: the two steering pumps, the brake actuation pump, the brake cooling pump, and the steering cooling pump. Two universal joints and the input drive shaft connect the torque converter to the transmission input transfer gear.

The input transfer gear is splined to the transmission input shaft. The transmission output shaft is splined to the output transfer gear. Power from the output transfer gear is sent through the front drive shaft and it’s respective pinion, bevel gear, differential carrier, and axles to the front final drives and similarly to the rear final drives.

3516B HD Engine Transmission Final Drive Final Drive Transmission Pump Input Transfer Gear Drive Shaft Parking Brake Spring Coupling Rear Pump Drive Torque Converter Input Drive Shaft Secondary Steer Pump 994F WHEEL LOADER

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50

Power Train Electrical System

This illustration of the Power Train Electrical System shows the components which provide input signals to the Power Train ECM.

Based on the input signals, the Power Train ECM energizes the appropriate transmission control valve solenoids for speed and directional clutch engagement. The Power Train ECM also energizes the starter relay when starting the machine and the back-up alarm when the operator selects a reverse gear.

When required, the Power Train ECM energizes the impeller clutch control valve solenoid, the lockup clutch control valve solenoid, and the reduced rimpull indicator lamp.

The CAT Data Link connects the Power Train ECM to the Engine ECM. The data link also connects the ECMs to the Vital Information Management System (VIMS) and electronic service tools such as Caterpillar Electronic Technician (ET).

Back-up Alarm Clutch 3 3rd Gear Solenoid Lockup Clutch Solenoid Impeller Clutch Solenoid Clutch 4 2nd Gear Solenoid Clutch 5 1st Gear Solenoid Clutch 2 Forward Solenoid Clutch 1 Reverse Solenoid Reduced Rimpull Indicator Lamp Reduced Rimpull Selection Switch Parking Brake Pressure Switch Lockup Clutch Enable Switch Torque Converter Pedal Position Sensor

Air Start Solenoid STIC

Upshift, Downshift, Forward, Neutral,

Reverse Key Start Switch

Torque Converter Output Speed Sensor Transmission Output Impeller Clutch Engine Speed Sensor

Auto Lube Solenoid Auto Lube Pressure Sensor Bumper Transmission Bumper Transmission Lockout LED Parking Brake Position Switch Steering / Transmission Lock Switch

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Power Train ECM Inputs:

STIC: Combines control of the vehicle steering system and the transmission shifting system in a single input device.

Key Start switch: Provides a signal to the Power Train ECM when the operator wants to start the engine. The STIC directional switch must be in the NEUTRAL position before the Power Train ECM will permit engine starting.

Reduced rimpull selection switch: The rotary selection switch sends an input signal to the Power Train ECM requesting the desired maximum rimpull torque.

Park brake pressure switch: Monitors the park brake hydraulic pressure and the Power Train ECM can determine when pressure is applied to release the park brake.

Parking Brake Position Switch: Provides an input to the Power Train ECM to signal whether the parking brake is engaged or disengaged.

Lockup clutch enable switch: When in the ON position, enables the lockup clutch to

ENGAGE when the machine operating conditions are correct. The lockup clutch enable lamp is turned on by electrical contacts in the switch whenever the lockup clutch is enabled.

Steering and transmission lock switch: When in the LOCK position, causes the Power Train ECM to shift the transmission to NEUTRAL.

Torque converter pedal position sensor: Signals the position of the torque converter pedal to the Power Train ECM. The Power Train ECM uses the position information to vary torque to the drive train through the impeller clutch. The actual value of torque reduction is determined by a combination of different input signals.

Torque converter speed sensor: Provides a signal the Power Train ECM uses to determine the output speed and direction of the torque converter.

Transmission speed sensors: Provides a signal the Power Train ECM uses to determine the output speed of the transmission.

Impeller clutch pressure sensor: Provides a pulse width modulated signal the Power Train ECM uses to determine the impeller clutch hydraulic pressure.

Bumper Transmission Lockout Switch: Provides a ground level input to the Power Train ECM that will neutralize the transmission until the switch is moved to the UNLOCK position. Engine Speed Sensor: A passive speed sensor that uses the passing teeth of the flywheel to provide a frequency input to the Power Train ECM.

Auto Lube Pressure Sensor: Provides a signal to the Power Train ECM to determine the status of the auto lube pressure.

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Reduced rimpull indicator lamp: The Power Train ECM illuminates the reduced rimpull indicator lamp when the appropriate machine operating conditions are met and the Power Train ECM is providing reduced rimpull.

Clutch solenoids: The solenoids control oil flow to the speed and directional control spools. Impeller clutch solenoid: The Power Train ECM energizes the impeller clutch modulating valve in order to control hydraulic pressure to the impeller clutch.

Lockup clutch solenoid: The Power Train ECM energizes the lockup clutch modulating valve in order to control pressure to the lockup clutch when the correct machine conditions have been met.

Back-up alarm relay: The Power Train ECM energizes the back-up alarm when the operator selects the REVERSE direction with the STIC. The backup alarm relay energizes the two backup alarms.

Auto Lube Solenoid: The energizes the auto lube solenoid for the next lube cycle. Bumper Transmission Lockout LED: The Power Train ECM illuminates the bumper transmission lockout LED when the bumper transmission lockout switch is in the LOCKED position.

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Power Train Electronic Control Module (ECM)

The Power Train ECM (1) is located on the left side of the machine under the door on the platform (cover must be removed).

The Power Train ECM makes decisions based on control program information in memory and switch and sensor input signals.

The Power Train ECM responds to machine control decisions by sending a signal to the

appropriate circuit which initiates an action. For example, the operator selects an upshift using the STIC. The Power Train ECM interprets the input signals from the STIC, evaluates the current machine operating status and energizes the appropriate solenoid valve.

The Power Train ECM receives three different types of input signals: 1. Switch input: Provides the signal line to battery, ground, or open.

2. PWM input: Provides the signal line with a square wave of a specific frequency and a varying positive duty cycle.

3. Speed signal: Provides the signal line with either a repeating, fixed voltage level pattern signal or a sine wave of varying level and frequency.

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2. PWM solenoid driver: Provides the output device with a square wave of fixed frequency and a varying positive duty cycle.

3. Controlled current output driver: The ECM will energize the solenoid with 1.25 amps for approximately one half second and then decrease the level to 0.8 amps for the

duration of the on time. The initial higher amperage gives the actuator rapid response and the decreased level is sufficient to hold the solenoid in the correct position. An added benefit is an increase in the life of the solenoid.

The Power Train ECM controls the transmission speed and directional clutches and the operation of the impeller clutch and lockup clutch. The Power Train ECM interprets signals from the STIC, the torque converter pedal position sensor, the lockup clutch enable switch, and the current machine operating status to determine the appropriate output signals to the systems. Different conditions of the inputs affect the output conditions. These conditions will be

discussed later.

The Power Train ECM communicates through the CAT Data Link. The CAT Data Link allows high speed proprietary serial communications over a twisted pair of wires. The CAT Data Link allows different systems on the machine to communicate with each other and also with service tools such as Caterpillar Electronic Technician (ET).

The Power Train ECM has built-in diagnostic capabilities. As the Power Train ECM detects fault conditions in the power train system, it logs the faults in memory and displays them on the VIMS. The fault codes can also be accessed using the ET service tool. VIMS software can be used to view faults logged by the VIMS.

INSTRUCTOR NOTE: Power Train ECM faults displayed on the VIMS relating to the Power Train ECM will have a Module Identifier (MID) of "81." For additional

information, refer to the Service Manual module "994F Wheel Loader Power Train, Troubleshooting, Testing and Adjusting" (Form RENR6306).

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52

Engine Speed Sensor

The engine speed sensor (1) is a passive two wire speed sensor that is positioned on the top of the flywheel housing. The sensor uses the passing teeth of the flywheel to provide a frequency output. The sensor sends the the engine speed signal to the Transmission ECM.

Also shown are the primary speed timing sensor (2) and the Engine ECM (3). 1

2 3

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The STIC (1) is bolted to the seat at the front of the left armrest. The transmission directional control switch (2) is a three position rocker switch that the operator uses to select NEUTRAL, FORWARD, or REVERSE. The transmission speed upshift switch (3) and the transmission speed downshift switch (4) are momentary contact switches that the operator uses to select the desired speed.

When the operator selects REVERSE by depressing the top of the directional control switch, the Power Train ECM energizes the reverse directional solenoid. The Power Train ECM also activates the back-up alarm. When the operator selects FORWARD by depressing the bottom of the directional control switch, the Power Train ECM energizes the forward directional solenoid.

When the operator selects NEUTRAL by placing the directional control switch in the center position, the Power Train ECM de-energizes both the forward and the reverse directional solenoids. After two seconds, the Power Train ECM energizes speed solenoid No. 3 and the transmission is in NEUTRAL until the operator selects a different gear.

When the operator presses the upshift switch, the Power Train ECM energizes the appropriate speed clutch solenoid to select the next higher gear, and the transmission upshifts. When the operator presses the downshift switch, the Power Train ECM energizes the appropriate speed clutch solenoid to select the next lower gear, and the transmission downshifts.

The switches must be released and pressed again to continue shifting. If the operator presses and holds the upshift or the downshift switch, the transmission will shift once and remain in that speed until the switch is released and pressed again.

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Manual nuevo

TECHNICAL PRESENTATION

994F WHEEL LOADER

INTRODUCTION

Service Training Meeting Guide

(STMG)

MEETING GUIDE 804

AUDIENCE

CONTENT

OBJECTIVES

REFERENCES

PREREQUISITES

TABLE OF CONTENTS

994F WHEEL LOADER

FEATURES

DIFFERENT SIMILAR SAME

Machine Appearance

Operator's Station

Engine

X

Transmission

Implement Hydraulic System

X

Steering System

Brake System

Monitoring System

Maintenance Items

X

X

X

X

X

X

X

994F ENGINE COOLING SYSTEM

994F TURBOCHARGER COOLING

3516B HD ENGINE DERATES

-

Altitude Compensation

-

Exhaust Temperature

-

Air Inlet Restriction

994F WHEEL LOADER

ENGINE AIR START SYSTEM