TECHNICAL PRESENTATION
MEETING GUIDE 682
SLIDES AND SCRIPT
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 basic maintenance information and describes the systems operation of the engine, power train, steering, hoist and the air system and brakes for the 793C Off-highway Truck. The Automatic Retarder Control (ARC) and the Traction Control System (TCS) are also discussed.
OBJECTIVES
After learning the information in this meeting guide, the serviceman will be able to:
1. locate and identify the major components in the engine, power train, steering, hoist and the air system and brakes;
2. explain the operation of the major components in the systems; and 3. trace the flow of oil or air through the systems.
REFERENCES
793C Off-highway Truck Service Manual SENR1440
793C Off-highway Truck Parts Book SEBP2503
Vital Information Management System (VIMS) Service Manual SENR6059
Fluid Power Graphic Symbols User's Guide SENR3981
PREREQUISITES
Interactive Video Course "Fundamentals of Mobile Hydraulics" TEVR9001 Interactive Video Course "Fundamentals of Electrical Systems" TEVR9002
STMG 546 "Graphic Fluid Power Symbols" SESV1546
Estimated Time: 8 Hours Visuals: 184 (2 X 2) Slides
Serviceman Handouts: 4 Data Sheets Form: SESV1682
SUPPLEMENTAL MATERIAL
Specification Sheets
793B Off-highway Truck AEHQ5061
793C Off-highway Truck AEHQ5186
Salesgrams
Vital Information Management System (VIMS) TELQ4478
793B Rear Axle Improvements TELQ3736
785B/789B/793B Introduction TELQ3725
789B/793B Feature Status TELQ4477
Video Tapes
793C Off-highway Truck--Service Introduction SEVN4016
793C Marketing Introduction AEVN3742
3500 EUI Service Introduction SEVN2241
Intelligence of Powerful Connections AEVN2974
Suspension Cylinder Charging TEVN2155
TPMS Management/Technical Information AEVN2211
TPMS Operating Tips AEVN2212
Automatic Electronic Traction Aid (AETA) Introduction SEVN9187
Service Training Meeting Guides
STMG 625 "793 Off-highway Truck" SESV1625
STMG 660 "785B/789B/793B Off-highway Trucks--Maintenance" SESV1660 STMG 681 "3500B Engine Controls--Electronic Unit Injection (EUI)" SESV1681
Technical Instruction Modules
Vital Information Management System--785B/789B/793B Off-highway Trucks SEGV2610
Vital Information Management System--Introduction SEGV2597
3500 Electronic Engine Controls--Introduction SEGV2588
3500 Electronic Engine Controls--Off-highway Trucks SEGV2589
Electronic Programmable Transmission Control (EPTC II) SEGV2584 769C - 793B Off-highway Trucks--Torque Converter
and Transmission Hydraulic Systems SEGV2591
785B/789B/793B Off-highway Trucks--Steering System SEGV2587
769C - 793B Off-highway Trucks--Hoist System SEGV2594
769C - 793B Off-highway Trucks--Air System and Brakes SEGV2595
Automatic Retarder Control System SEGV2593
Automatic Electronic Traction Aid SEGV2585
SUPPLEMENTAL MATERIAL (Continued)
Booklets
Know Your Cooling System SEBD0518
Diesel Fuels and Your Engine SEBD0717
Oil and Your Engine SEBD0640
Special Instructions
Using the ECAP NEXG4521 Machine Functions Service Program Module SEHS9343 Using the 8T8697 Electronic Control Analyzer Programmer (ECAP) SEHS8742
Using the 7X1700 Communication Adapter Group SEHS9264
Use of 6V3000 Sure-Seal Repair Kit SMHS7531
Use of CE Connector Tools SEHS9065
Servicing DT Connectors SEHS9615
Use of 8T5200 Signal Generator/Counter Group SEHS8579
Repair of 4T8719 Bladder Accumulator Group SEHS8757
Suspension Cylinder Servicing SEHS9411
Using 1U5000 Auxiliary Power Unit (APU) SEHS8715
Using the 1U5525 Attachment Group SEHS8880
Brochures
Caterpillar Vital Information Management System (VIMS) AEDK2946
Caterpillar Electronic Technician NEHP5614
Caterpillar DataView NEHP5622
Diesel Engine Oil (CG4) Product Data Sheet PEHP5026
How to Take a Good Oil Sample PEHP6001
Air Filter Service Indicator PEHP9013
Intelligence of Powerful Connections AEDK2966
Caterpillar Fully Automatic Transmission AEDQ0066
Caterpillar Oil-cooled Multiple Disc Brakes AEDK2546
Caterpillar Automatic Retarder Control AEDK0075
Miscellaneous
Electronic Diagnostic Code Pocket Card NEEG2500
Pressure Conversion Chart SEES5677
793B Transmission Assembly Wall Chart SENR6834
793B Final Drive Assembly Wall Chart SENR8602
TABLE OF CONTENTS
INTRODUCTION ...7
WALK AROUND INSPECTION...11
OPERATOR'S STATION...36
ENGINE...49
Cooling System...66
Lubrication System ...77
Fuel System...80
Air Induction and Exhaust System ...85
POWER TRAIN ...90
Power Train Components...91
Power Train Hydraulic System ...103
Electronic Programmable Transmission Control (EPTC II)...120
STEERING SYSTEM ...128
HOIST SYSTEM ...157
AIR SYSTEM AND BRAKES ...177
Operator Controls...179
Air Charging System...182
Parking and Secondary Brake System ...188
Service and Retarder Brake System...195
AUTOMATIC RETARDER CONTROL (ARC) ...206
TRACTION CONTROL SYSTEM (TCS)...211
CONCLUSION...221
SLIDE LIST...222
• 3516B DITA engine
1
793C OFF-HIGHWAY TRUCK
C 1997 Caterpillar Inc.
INTRODUCTION
This presentation provides an introduction to the Caterpillar
793C Off-highway Truck. Included in this package is a walk around inspection which provides information about daily service requirements and identifies the locations of the major components. The major systems of the truck will also be discussed. The major systems include the engine, power train, steering, hoist, and the air system and brakes.
The 793C is the largest rigid frame truck produced by Caterpillar. The 793C is equipped with a Caterpillar 3516B engine rated at 1716 kW (2300 gross hp) and 1616 kW (2166 flywheel hp). The load carrying capacity is 218 Metric tons (240 tons) at a Gross Machine Weight (GMW) of 376488 kg (830000 lbs.).
This slide shows a view of the left side of the truck. Notice that the body canopy is extended over the cab to protect the front of the truck from falling objects.
The fuel tank is located on the left side of the truck.
• Fuel tank • Extended body
2
Shown is the right side of the truck. The large air tank on the right platform supplies air for starting the truck and for the service and retarder brake system.
The main hydraulic tank is also visible. The hydraulic tank supplies oil for the hoist system and the brake system.
On the 793B truck, torque converter oil is also supplied from the main hydraulic tank. A transmission oil supply tank is located in front of the main hydraulic tank.
The 793C now uses the torque converter case as the supply tank for the torque converter and the transmission.
• Main system air tank: - Air starting
- Service/retarder brakes
• Main hydraulic tank: - Hoist system - Brake system
• Torque converter case used as sump for converter and transmission
• 789B and 793C are similar
• 793C has four air filters
3
The 793C is similar in appearance to the 789B and may be difficult to recognize from a distance. The 793C can be recognized by the four air filters and the diagonal access ladder. The 789B has only two air filters mounted in the same locations and is equipped with two vertical ladders.
• Truck body
4
The truck body has a dual-slope main floor and a "vee" bottom to center the load and reduce spills. The steel used to construct the body has a yield strength of 6205 bar (90000 psi).
The rear suspension cylinders absorb bending and twisting stresses rather than transmitting them to the main frame.
• Rear suspension cylinders
5
• Read the Operation and Maintenance Manual
793C
MAINTENANCE
793C Service Procedure
WALK AROUND INSPECTION
WALK AROUND INSPECTION
Before working on or operating the truck, read the Operation and Maintenance Manual (Form SEBU6995) thoroughly for information on safety, maintenance and operating techniques.
Safety precautions and Warnings are provided in the manual and on the truck. Be sure to identify and understand all symbols before starting the truck.
The first step to perform when approaching the truck is to make a thorough walk around inspection. Look around and under the truck for loose or missing bolts, trash build-up and for coolant, fuel or oil leaks. Look for indications of cracks. Pay close attention to high stress areas as shown in the Operation and Maintenance Manual.
• Front wheel bearing inspection plug (arrow)
6
The front wheel bearing oil level is checked and filled by removing the plug (arrow) in the center of the wheel bearing cover. The oil should be level with the bottom of the plug hole.
Check the tire inflation pressure. Operating the truck with the wrong tire inflation pressure can cause heat build-up in the tire and accelerate tire wear.
NOTE: Care must be taken to ensure that fluids are contained while performing any inspection, maintenance, testing, adjusting and repair of the machine. Be prepared to collect the fluid in suitable containers before opening any compartment or disassembling any component containing fluids. Refer to the "Tools and Shop Products Guide" (Form NENG2500) for tools and supplies suitable to collect and contain fluids in Caterpillar machines. Dispose of fluids according to local regulations and mandates.
1. Front wheel bearing axle housing breather 7 1 2
Inspect the condition of the front wheel bearing axle housing breather (1). The breather prevents pressure from building up in the axle housing. Pressure in the axle housing may cause brake cooling oil to leak through the Duo-Cone seals in the wheel brake assemblies.
Two grease outlet fittings (2) are located on the front of each suspension cylinder. The grease supply line for the Auto Lubrication System is located at the rear of the suspension cylinder. No grease outlet fittings should be located on the same side of the suspension cylinder as the grease fill location. Having an outlet fitting on the same side of the suspension cylinder as the grease fill location will prevent proper lubrication of the cylinder.
Make sure that grease is flowing from the outlet fittings to verify that the suspension cylinders are being lubricated and that the pressure in the cylinders is not excessive.
2. Suspension cylinder grease outlet fittings
• Make sure grease flows from outlet fittings
1. Rear brake oil coolers 2. Parking brake release filter 3. Torque converter charging filter 4. Automatic lubrication injector bank 8 4 2 1 3
Located behind the right front tire are the rear brake oil coolers (1), the parking brake release filter (2), and the torque converter charging filter (3).
One of the three injector banks (4) for the automatic lubrication system is also in this location. These injectors are adjustable and regulate the quantity of grease that is injected during each cycle (approximately once per hour).
A solenoid air valve provides a controlled air supply for the automatic lubrication system. The solenoid air valve is controlled by the Vital Information Management System (VIMS), which energizes the solenoid ten minutes after the machine is started. The VIMS energizes the solenoid for 75 seconds before it is de-energized. Every 60 minutes thereafter, the VIMS energizes the solenoid for 75 seconds until the machine is stopped (shut down). These settings are adjustable through the VIMS keypad in the cab.
INSTRUCTOR NOTE: For more detailed information on servicing the automatic lubrication system, refer to the Service Manual Module "Automatic Lubrication System" (Form SENR4724).
• Hoist and brake hydraulic tank
• Oil level sight gauges (arrows)
9
Shown is the hoist and brake hydraulic tank and the oil level sight gauges (arrows). The oil level is normally checked with the upper sight gauge. The oil level should first be checked with cold oil and the engine stopped. The level should again be checked with warm oil and the engine running. The lower sight gauge can be used to fill the hydraulic tank when the hoist cylinders are in the RAISED position. When the hoist cylinders are lowered, the hydraulic oil level will increase. After the hoist cylinders are lowered, check the hydraulic tank oil level with the upper sight gauge as explained above.
• Final drives
• Check magnetic plugs (arrow) for metal
10
The rear axles are equipped with double reduction planetary final drives. The magnetic plug (arrow) should be removed from the final drives at regular intervals and checked for metal particles. For some conditions, checking the magnetic plug is the only way to identify a problem which may exist.
The rear axle is a common sump for the differential and both final drives. If a final drive or the differential fails, the other final drive components must also be checked for contamination and then flushed. Failure to completely flush the rear axle after a failure can cause a repeat failure within a short time.
NOTICE
The rear axle is a common sump for the differential and both final drives. If a final drive or the differential fails, the other final drive components must also be checked for contamination and then flushed. Failure to completely flush the rear axle after a failure can cause a repeat failure within a short time.
• Flush all axle components after a failure
1. Differential oil level sight glass 11 2 2 4 1 5 3
The differential oil level is checked by viewing the oil level sight glass (1). The oil should be level with the bottom of the inspection hole. Two oil level sensors (2) provide input signals to the VIMS which informs the operator of the rear axle oil level.
A rear axle oil filter (3) is used to remove contaminants from the rear axle housing.
Check the charge condition of the rear suspension cylinders when the truck is empty and on level ground.
The second of three injector banks (4) for the automatic lubrication system is mounted on the top rear of the differential housing.
Above the lubrication injectors is a breather (5) for the rear axle. Inspect the condition of the breather at regular intervals. The breather prevents pressure from building up in the axle housing. Excessive pressure in the axle housing can cause brake cooling oil to leak through the Duo-Cone seals in the wheel brake assemblies.
INSTRUCTOR NOTE: For more detailed information on servicing the suspension system, refer to the Special Instruction "Suspension Cylinder Servicing" (Form SEHS9411).
2. Rear axle oil level sensors
3. Rear axle housing oil filter • Rear suspension cylinders 4. Automatic lubrication injector bank
• Cable holds body up
12
The cable that holds the body up is stored below the rear of the body. Whenever work is to be performed while the body is raised, the safety cable must be connected between the body and the rear hitch to hold the body in the raised position.
The space between the body and the frame becomes a zero clearance area when the body is lowered. Failure to install the cable can result in injury or death to personnel working in this area.
• Fuel tank
13
The fuel tank is located on the left side of the truck. The fuel level sight gauge (arrow) is used to check the fuel level during the walk around inspection.
• Fuel level sight gauge (arrow)
1. Primary fuel filter
14
2
3 1
The primary fuel filter (1) is located on the inner surface of the fuel tank. Open the drain valve (2) to remove condensation from the fuel tank. A fuel level sensor (3) is also located on the fuel tank. The fuel level sensor provides input signals to the VIMS which informs the operator of the fuel level.
3. Fuel level sensor 2. Condensation drain
15
1 2
Supply oil for the torque converter and the transmission is contained in the torque converter case. Sight gauges (1) are used to check the oil level for the torque converter and the transmission.
Torque converter and transmission oil is added at the fill tube (2). When filling the torque converter and transmission oil sump after an oil change, fill the sump with oil to the top of the upper sight gauge. Turn off the engine manual shutdown switch (see slide No. 23) so the engine will not start. Crank the engine for approximately 15 seconds. The oil level will decrease as oil fills the torque converter and transmission system. Add more oil to the sump to raise the oil level to the FULL COLD mark. Crank the engine for an additional 15 seconds. Repeat this step as required until the oil level stabilizes.
Turn off the engine manual shutdown switch and start the engine. Warm the torque converter and transmission oil. Add more oil to the sump as required to raise the torque converter and transmission oil level to the FULL WARM mark.
NOTICE
Failure to correctly fill the torque converter and transmission oil sump after an oil change may cause transmission clutch damage.
1. Torque converter and transmission oil level sight gauges
2. Torque converter and transmission oil fill tube
• Torque converter and transmission oil fill procedure
16
1 4
2
3
Shown is the location of the torque converter outlet screen (1). Oil flows from the torque converter outlet relief valve through the torque converter outlet screen to the torque converter and transmission oil cooler located on the right side of the engine. Oil from the torque converter and transmission oil cooler returns to the torque converter housing. Shown is the location of the transmission charging filter (2).
Transmission charging oil flows through the transmission charging filter to the transmission control valves on top of the transmission and to the torque converter lockup clutch valve located on top of the torque converter.
The scavenge screen for torque converter and transmission oil is located behind the cover (3).
Torque converter and transmission oil samples can be taken at the Scheduled Oil Sampling (S•O•S) tap (4).
1. Torque converter outlet screen 2. Transmission charging filter 3. TC/Transmission scavenge screen 4. TC/Transmission S•O•S tap
• Brake cylinder breather (arrow)
17
Inspect the condition of the two breathers (arrow, one visible) for the brake cylinders. The second breather is located behind the cross tube. Oil should not leak from the breathers. Oil leaking from the breathers is an indication that the oil piston seals in the brake cylinder need
replacement. Air flow from the breathers during a brake application is an indication that the brake cylinder air piston seals need replacement.
• Front brake oil cooler filters (arrow)
18
Located in front of the fuel tank are the front brake oil cooler filters (arrow). Oil not used to raise or lower the hoist cylinders flows from the hoist valve through the front brake oil filters to the front brake oil cooler located above the torque converter.
The third injector bank for the automatic lubrication system is also located in this area.
• Automatic lubrication injector bank
• Front suspension cylinder
19
1
2
Check the charge condition of the front suspension cylinders when the truck is empty and on level ground.
The air dryer (1) is located in front of the left front suspension cylinder. The air system can be charged from a remote air supply through a ground level connector (2) inside the left frame.
INSTRUCTOR NOTE: For more detailed information on servicing the suspension system, refer to the Special Instruction "Suspension Cylinder Servicing" (Form SEHS9411).
1. Air dryer
2. Remote air supply connector
• Engine oil filters 1. Engine oil fill tube 2. Engine oil dipstick
20
2
1
3 4
The engine oil filters are located on the left side of the engine. Engine oil should be added at the fill tube (1) and checked with the dipstick (2).
Engine oil samples can be taken at the Scheduled Oil Sampling (S•O•S) tap (3).
The engine lubrication system is equipped with two oil pressure sensors (4). A sensor is located on each end of the oil filter base. One sensor measures engine oil pressure before the filters. The other sensor measures oil pressure after the filters. The sensors provide input signals to the second generation Advanced Diesel Engine Management
(ADEM II) engine Electronic Control Module (ECM). The ECM provides input signals to the VIMS which informs the operator of the engine oil pressure. Together, these sensors inform the operator if the engine oil filters are restricted.
4. Engine oil pressure sensor
1. High speed oil change connector
21
1 3
2
Engine oil can be added through the high speed oil change connector (1) located in the left front corner of the oil pan.
Two engine oil level switches (2 and 3) provide input signals to the engine ECM. The engine ECM provides an input signal to the VIMS, which informs the operator of the engine oil level.
If the truck is equipped with the engine oil renewal system attachment, the upper oil level switch (2) tells the operator when engine oil must be added. The ADD ENG OIL message is a Category 1 Warning.
The lower oil level switch (3) tells the operator when the engine oil level is low and it is unsafe to operate the truck without causing damage to the engine. The ENG OIL LEVEL LOW message is a Category 2 or 3 Warning.
2. Add engine oil level switch
3. Engine oil level low switch
• Secondary fuel filters • Fuel priming pump
(arrow)
22
The secondary fuel filters and the fuel priming pump (arrow) are located above the engine oil filters on the left side of the engine.
NOTE: If the fuel system requires priming, it may be necessary to block the fuel return line during priming to force the fuel into the injectors.
1. Manual engine shutdown switch 23 3 5 6 1 2 4
Before climbing the truck ladder, make sure that the manual engine shutdown switch (1) is OFF. The engine will not start if the manual shutdown switch is ON. If necessary, the switch can be used to stop the engine from the ground level.
The toggle switches (2) control the lights in the engine compartment and above the access ladder.
The RS-232 service connector (3) is used to connect a laptop computer with VIMS PC software to upload new source and configuration files, view real time data or download logged information from the VIMS. The battery disconnect switch (4) and VIMS service connector key switch (5) must be in the ON position before the laptop computer with VIMS software will communicate with the VIMS.
The blue service lamp (6) is part of the VIMS. The service lamp will turn on to notify service personnel that the VIMS has an active machine or system event. The service lamp flashes to indicate when an event is considered abusive to the machine.
2. Engine and access ladder light switches
3. RS-232 connector for VIMS
4. Battery disconnect switch
5. Key switch for VIMS service connector 6. VIMS service lamp
• Inspect radiator • Check air cleaner
indicators (arrow)
24
While climbing the ladder, make a thorough inspection of the radiator. Be sure that no debris or dirt is trapped in the cores. Check the air cleaner indicators (arrow) located on both sides of the truck. If the yellow pistons are in the red zone (indicating that the filters are plugged), the air cleaners must be serviced.
• Engine cooling systems:
- Jacket water cooling system
- Aftercooler cooling system
1. Engine coolant shunt tank
2. Coolant level gauges 3. Coolant level sensor
25
3
2 1
The cooling system on the 793C is divided into two systems. The two systems are the jacket water cooling system and the aftercooler cooling system. These two systems are not connected. When servicing the cooling systems, be sure to drain and fill both systems separately.
The engine cooling system shunt tank (1) is located on the hood above the radiator. The coolant levels are checked at the shunt tank. Use the gauges (2) on top of the shunt tank to check the two coolant levels. A coolant level sensor (3) is located on each side of the shunt tank to monitor the coolant level of both cooling systems (guard removed for viewing sensor). The coolant level sensors provide input signals to the VIMS which informs the operator of the engine coolant levels.
26
2
3
1
Located on the right platform are the automatic lubrication system grease tank (1), the main air system tank (2) and the steering system tank (3). Check the level of the grease in the automatic lubrication system tank with the grease level indicator located on top of the tank.
A drain valve is located at the bottom right of the main air system tank. Drain the condensation from the air tank each morning.
1. Automatic lubrication tank 2. Main air system tank 3. Steering system tank
27 6 3 7 1 2 5 4
The oil level for the steering system tank is checked at the upper sight gauge (1) when the oil is cold and the engine is stopped. After the engine is started, the oil level will decrease as the oil fills the steering
accumulators.
After the accumulators are filled, the oil level should be checked again at the lower sight gauge (2). When the engine is running and the
accumulators are fully charged, the oil level should not be below the ENGINE RUNNING marking of the lower gauge. If the ENGINE RUNNING level is not correct, check the nitrogen charge in each
accumulator. A low nitrogen charge will allow excess oil to be stored in the accumulators and will reduce the secondary steering capacity.
Before removing the cap to add oil to the steering system, be sure that the engine was shut off with the key start switch, and the steering oil has returned to the tank from the accumulators. Then, depress the pressure release button (3) on the breather to release any remaining pressure from the tank.
Also located on the tank are the main steering oil filter (4) and the steering pump case drain filter (5).
1. Upper sight gauge
2. Lower sight gauge
4. Main steering oil filter
5. Steering pump case drain filter
3. Steering tank pressure release button
If the steering pump fails or if the engine cannot be started, the
connector (6) is used to attach an Auxiliary Power Unit (APU). The APU will provide supply oil from the steering tank at the connector (6) to charge the steering accumulators. Steering capability is then available to tow the truck.
The steering oil temperature sensor (7) provides an input signal to the VIMS which informs the operator of the steering system oil temperature.
INSTRUCTOR NOTE: For more detailed information on servicing the steering accumulators, refer to the Service Manual Module "793C Off-highway Truck Steering System" (Form SENR1452) and the Special Instruction "Repair of 4T8719 Bladder Accumulator Group" (Form SEHS8757). For more information on using the APU, refer to the Special Instructions "Using 1U5000 Auxiliary Power Unit (APU)" (Form SEHS8715) and "Using the 1U5525 Attachment Group" (Form SEHS8880).
6. APU supplemental steering connector
7. Steering oil
1. Parking/secondary brake air tank drain valve (arrow)
28
2 1
Another small air tank (not visible) is located behind the cab (see Slide No. 156). The air tank behind the cab supplies air to the parking and secondary brakes. Drain the moisture from the tank daily with the drain valve (1).
Check the fluid level of the windshield washer reservoir (2).
2. Windshield washer fluid reservoir
• Transmission shift lever
- Six speeds FORWARD
- One speed REVERSE • Back-up light switch
(arrow)
29
OPERATOR’S STATION
At the front of the center console is the transmission shift lever. The 793C transmission has six speeds FORWARD and one speed REVERSE. To the right of the shift lever is the back-up light switch (arrow).
INSTRUCTOR NOTE: In this section of the presentation, component locations inside the operator’s station will be shown. Many of the components shown in this section will be further explained in the sections that follow.
• Center console components: 1. Throttle back-up
switch
2. Manual ether start aid switch
3. Key start switch 4. TCS switch 5. Parking brake
switch
6. Windshield washer and wiper switch 7. Cigarette lighter 8. Brake retraction switch - Service hourmeter 30 5 6 7 8 1 2 3 4
Shown is the center console. In the center of the console are the throttle back-up switch (1), manual ether start aid switch (2), key start switch (3) and the Traction Control System (TCS) switch (4).
The throttle back-up switch (1) increases the engine speed to 1300 rpm if the engine ECM detects that the throttle sensor signal is invalid.
The manual ether start aid switch (2) allows the operator to manually inject ether when the coolant temperature is below 10°C (50°F) and engine speed is below 1200 rpm.
The Traction Control System (TCS) switch (4) is used to test the
operation of the TCS (formerly referred to as the "Automatic Electronic Traction Aid").
Shown below these components are the parking brake switch (5), the windshield washer and wiper switch (6), the cigarette lighter (7) and the brake retraction switch (8).
The brake retraction switch (8) is used to release the parking brakes when towing the truck.
• Overhead light switches: 1. Headlights and
parking/taillights 2. Panel lights 3. Interior cab light 4. Front flood/ladder lights 5. Fog lights 31 2 3 4 5 1
Located above the operator's head are several light switches: 1. Headlights and parking/taillights
2. Panel lights 3. Interior cab light
4. Front flood/ladder lights 5. Fog lights
1. Gauge cluster module: - Engine coolant temperature - Brake oil temperature
- System air pressure - Fuel level 2. Speed/tach module: - Analog tachometer - Ground speed - Transmission actual gear 3. Dash backlit indicators: - Left and right turn
signals
- High beam indicator - Action light - Service/retarder brakes ENGAGED light 32 2 1 3
Located on the front dash are two of the VIMS output components. They are the gauge cluster module (1) and the speedometer/tachometer
module (2).
The four gauges in the gauge cluster module (from left to right and top to bottom) are:
- Engine coolant temperature - Brake oil temperature - System air pressure - Fuel level
The speedometer/tachometer module consists of an analog tachometer and a display window which shows the ground speed and the transmission actual gear.
Several backlit indicators will appear in the upper area (3) of the display when they are active. The backlit indicators are:
- Left and right turn signals - High beam indicator - Action light
1. Automatic Retarder Control (ARC) ON/OFF switch 2. Message center module: - Alert indicator - Universal gauge - Message display window 33 3 2 1
To the right of the steering column is the Automatic Retarder Control (ARC) ON/OFF switch (1).
To the right of the ARC switch are two more components of the VIMS. They are the message center module (2) and the keypad
module (3).
The message center module consists of an alert indicator, a universal gauge and a message display window. The alert indicator flashes when a Category 1 Warning is present. The universal gauge displays the status of the sensor selected for viewing by depressing the GAUGE key on the keypad. The message display window shows various types of text information to the operator.
with the VIMS. Some of the functions that can be performed by the keypad are:
- Scroll parameters monitored by VIMS by depressing the GAUGE key.
- Payload Monitor ON/OFF PAYLOAD 7295623
- Calibrate Payload Monitor PAYCAL 729225
- Payload Resettable Totals TOT 868
- Reset Displayed Data RESET 73738
- Display Self Test TEST 8378
- Reset Service Light SVCLIT 782548
- Set Lube Cycle Times LUBSET 582738
- Manual Lube LUBMAN 582626
- Show Acknowledged Events EACK 3225
- Show Event Statistics ESTAT 37828
- Show Event List ELIST 35478
- Start Event Recorder EREC 3732
- Start/Stop Data Logger DLOG 3564
- Reset Data Logger DLRES 35737
- Odometer Set/Reset ODO 636
(requires VIMS PC connection)
- Machine Status MSTAT 67828
- Change Language LA 52
- Change Units UN 86
- Change Backlight BLT 258
- Change Display Contrast CON 266
(requires Updated Message Center)
INSTRUCTOR NOTE: For more detailed information on the VIMS, refer to the Service Manual Module "Vital Information Management System (VIMS)" (Form SENR6059).
34 • VIMS SENSORS ADEM II CONTROL SERVICE LAMP MESSAGE CENTER MODULE GAUGE CLUSTER MODULE KEYPAD MODULE SENSORS VIMS INTERFACE MODULE VIMS INTERFACE MODULE SENSORS VIMS SERVICE TOOL AND SOFTWARE
CAT DATA LINK SERVICE KEYSWITCH ACTION LAMP ACTION ALARM ELECTRONIC TECHNICIAN/ECAP
VIMS MAIN MODULE
DISPLAY DATA LINK VIMS RS-232 PORT AUTO RETARDER CONTROL
CAT DATA LINK
TRANSMISSION CONTROL VITAL INFORMATION MANAGEMENT SYSTEM (VIMS) SPEEDOMETER/ TACHOMETER MODULE 3F 12MPH km/h KEYPAD DATA LINK
As shown in some of the previous slides, the 793C is equipped with the VIMS which receives input signals from many sensors and also
communicates with other electronic controls on the machine. The VIMS provides the operator and the service technician with a complete look at the current and past conditions of all the systems on the truck.
• Behind the operator's seat are: - Fuse panel - ECAP/ET diagnostic connector (arrow) 35
Behind the operator’s seat are the fuse panel and the ECAP/ET diagnostic connector (arrow). The ECAP/ET diagnostic connector is used to connect the Electronic Control Analyzer Programmer (ECAP) or a laptop
computer with the Electronic Technician (ET) software installed.
While VIMS monitors all of the systems on the truck, the ECAP or ET is used for programming, running diagnostic tests and retrieving logged information from the engine, transmission and automatic retarder controls.
• Electronic Technician (ET)
36
Shown is the communication adapter and a laptop computer with the Electronic Technician (ET) diagnostic software installed. The
communication adapter is connected to the diagnostic connector shown in the previous slide.
• VIMS connector (arrow)
37
Shown is a laptop computer with the VIMS PC diagnostic software installed. The laptop computer is connected to the VIMS diagnostic connector (arrow).
• Hoist control lever (arrow)
38
The operator controls include the hoist lever (arrow) which is located to the left of the operator’s seat. The four positions are RAISE, HOLD, FLOAT and LOWER.
The truck should normally be operated with the hoist lever in the FLOAT position. Operating with the hoist lever in the FLOAT position allows the hoist valve to provide some downward hydraulic pressure on the hoist cylinders and prevents an empty body from bouncing on rough haul roads.
The 793C hoist system is different from previous trucks. The hoist system is electronically controlled.
INSTRUCTOR NOTE: The hoist system will be explained in more detail in the HOIST SYSTEM section of this presentation.
• Electronically controlled hoist system
• Hoist lever in FLOAT for normal operation
• Operator controls: - Secondary brake
lever (red) - Retarder lever
(black)
1. Tilt steering lock 2. Turn signal and
hazard switch
39
2 1
The operator controls on the steering column are the secondary brake lever (red), the retarder lever (black), the tilt steering lock (1) and the turn signal and hazard switch (2).
1. Service brake pedal 2. Throttle pedal 3. Throttle position sensor 40 2 1 3
On the floor to the right of the steering column are the service brake pedal (1) and the throttle pedal (2). A throttle position sensor (3) is attached to the throttle pedal. The throttle position sensor provides the throttle position input signals to the engine ECM.
The engine ECM provides an elevated engine idle speed of 1300 rpm when the coolant temperature is below 60°C (140°F). Above 60°C (140°F), the elevated idle rpm is gradually reduced until the coolant temperature reaches 71°C (160°F). Above 71°C (160°F), the engine will idle at 700 rpm.
Increasing the low idle speed helps prevent incomplete combustion and overcooling. To temporarily reduce the elevated idle speed, the operator can depress the throttle momentarily, and the idle speed will decrease to 700 rpm for 10 minutes.
On the floor to the left of the steering column are the horn button and the high beam switch (not shown).
• Horn button and high beam switch (not shown)
• Elevated low idle reduced with throttle pedal
• 793C uses 3516B engine
41
ENGINE
The 793C is equipped with the Caterpillar 3516B engine with a gross power rating of 1715 kW (2300 hp) and a net flywheel power rating of 1615 kW (2166 hp) at 1750 rpm.
42 • 3516B electronic control system component diagram A/C PRESSURE SWITCH CRANKCASE PRESSURE GROUND LEVEL SHUTDOWN SWITCH FUEL FILTER SWITCH PRE-LUBRICATION RELAY OIL LEVEL SWITCH (LOW) OIL LEVEL SWITCH (ADD)
FAN FAN SPEED SENSOR FAN CLUTCH SOLENOID SERVICE TOOL EPTC II ARC VIMS CAT DATA LINK
ENGINE COOLANT TEMPERATURE
ADEM II CONTROL MODULE GROUND BOLT 15 AMP BREAKER MAIN
POWER RELAY KEY STARTSWITCH
SPEED/TIMING SENSOR
ENGINE OIL PRESSURE (UNFILTERED)
COOLANT FLOW SWITCH TIMING PROBE
CONNECTOR
ETHER SOLENOID DISCONNECT SWITCH
3516B ELECTRONIC CONTROL SYSTEM COMPONENT DIAGRAM
ELECTRONIC UNIT INJECTORS
TURBO OUTLET PRESSURE (BOOST) RIGHT TURBO INLET PRESSURE ATMOSPHERIC PRESSURE ENGINE OIL PRESSURE (FILTERED)
THROTTLE
ENGINE OIL RENEWAL SOLENOID SHUTTER SOLENOID
REAR AFTERCOOLER TEMPERATURE
LEFT TURBO INLET PRESSURE RIGHT TURBO EXHAUST
LEFT TURBO EXHAUST
THROTTLE OVERRIDE SWITCH MANUAL ETHER SWITCH EXHAUST WASTEGATE SOLENOID 24 V
Shown is the electronic control system component diagram for the 3516B engine used in the 793C. Fuel injection is controlled by the second generation Advanced Diesel Engine Management (ADEM II) engine Electronic Control Module (ECM).
Many electronic signals are sent to the ADEM II ECM by sensors, switches and senders. The engine ECM analyzes these signals and determines when and for how long to energize the injector solenoids.
When the injector solenoids are energized determines the timing of the
engine. How long the solenoids are energized determines the engine speed.
• ECM (arrow)
43
Fuel injection is controlled by the ADEM II ECM (arrow) located on the right front of the engine.
The previous ECM had one 70-pin connector. The ADEM II ECM has two 40-pin connectors.
The engine ECM is cooled by fuel. Fuel flows from the fuel transfer pump through the ECM to the secondary fuel filters.
• ECM has two 40-pin connectors
44
The atmospheric pressure sensor (arrow) is located adjacent to the engine ECM. Formerly, this sensor was located in the compartment behind the cab. The engine ECM uses the atmospheric pressure sensor as a reference for calculating boost and air filter restriction and for derating the engine at high altitudes.
The engine ECM also uses the atmospheric pressure sensor as a reference when calibrating all the pressure sensors.
• Atmospheric pressure sensor (arrow)
45
• 3516B improvements
3516B IMPROVEMENTS
INPUT SWITCHES AND SENSORS
• COOLANT FLOW
• REAR AFTERCOOLER TEMPERATURE
• ENGINE OIL LEVEL
• TURBOCHARGER TEMPERATURE
• ENGINE OIL FILTER PRESSURE/RESTRICTION
• ENGINE FAN SPEED
• FUEL FILTER RESTRICTION
• AIR CONDITIONER COMPRESSOR PRESSURE
• CRANKCASE PRESSURE
The 3516B engine has many improvements over the original 3516 engine. Some of the improvements are accomplished by adding additional switch and sensor inputs to the engine ECM. Adding additional inputs to the engine ECM allows the ECM to control the engine more precisely. Additional inputs to the 3516B ECM are:
- Coolant flow is monitored.
- Rear aftercooler temperature is measured. - Engine oil level is monitored.
- Two turbocharger temperature sensors measure exhaust temperatures. - Two engine oil pressure sensors are located on the oil filter base to
measure oil pressure and oil filter restriction.
- Engine fan speed is measured (with variable fan speed attachment).
INSTRUCTOR NOTE: The following slides will show some of the engine ECM input components. The remaining inputs to the engine ECM will be discussed when the systems they monitor are shown.
46
2
1
Fuel filter restriction is monitored with a fuel filter bypass switch (1) located on the fuel filter base. The fuel filter bypass switch provides an input signal to the engine ECM. The ECM provides a signal to the VIMS which informs the operator if the secondary fuel filters are restricted. If the fuel filter restriction exceeds 138 kPa (20 psi), a fuel filter
restriction event is logged. No factory password is required to clear this event.
An air conditioner compressor switch (2) is located at the rear of the air conditioner compressor. If the truck is equipped with the variable fan speed attachment, the air conditioner compressor switch informs the engine ECM when the air conditioner system is ON. When the air conditioner system is ON, the ECM sets the variable speed fan at MAXIMUM rpm.
Disconnecting the air conditioner compressor switch will also signal the ECM to set the fan speed at MAXIMUM rpm.
1. Fuel filter bypass switch
2. Air conditioner compressor switch • Fuel filter restriction
• Crankcase pressure sensor (arrow)
47
The crankcase pressure sensor (arrow) is located on the right side of the engine above the engine oil cooler. The crankcase pressure sensor provides an input signal to the engine ECM. The ECM provides the signal to the VIMS which informs the operator of the crankcase pressure. High crankcase pressure may be caused by worn piston rings or cylinder liners.
If crankcase pressure exceeds 3.6 kPa (.5 psi), a high crankcase pressure event will be logged. No factory password is required to clear this event.
• Crankcase pressure event
48
3516B IMPROVEMENTS
PREVIOUS LOGGED EVENTS
• AIR FILTER RESTRICTION
• LOW OIL PRESSURE
• HIGH COOLANT TEMPERATURE
• ENGINE OVERSPEED
The 3500B ECM logs the four events of the previous 3500 engine plus some additional events. The four events logged by the 3500 ECM and the 3500B ECM are:
Air filter restriction: Greater than 6.25 kPa (25 in. of water). Maximum derate of 20%.
Low oil pressure: From less than 100 kPa (15 psi) at LOW IDLE to less than 300 kPa (44 psi) at HIGH IDLE.
High coolant temperature: Greater than 107°C (226°F). Engine overspeed: Greater than 2200 rpm.
NOTE: Factory passwords are required to clear all the events listed above.
• Events logged by 3500 ECM and 3500B ECM
49
• Additional logged events
3516B IMPROVEMENTS
ADDITIONAL LOGGED EVENTS
• OIL FILTER RESTRICTION • HIGH CRANKCASE PRESSURE
• FUEL FILTER RESTRICTION • LOW COOLANT FLOW
• HIGH EXHAUST TEMPERATURE • USER DEFINED SHUTDOWN
• HIGH AFTERCOOLER TEMPERATURE • LOW BOOST PRESSURE
• ENGINE OIL LEVEL LOW • HIGH BOOST PRESSURE
Additional events logged by the 3500B ECM are:
Oil filter restriction: Greater than 70 kPa (10 psi). No factory password required. Greater than 200 kPa (29 psi). Factory password required. Fuel filter restriction: Greater than 138 kPa (20 psi). No factory password required.
Exhaust temperature high: Greater than 760°C (1400°F). Maximum derate of 20%. Factory password required.
Aftercooler coolant temperature high: Greater than 107°C (226°F). Factory password required.
Engine oil level low: No factory password required.
Crankcase pressure high: Greater than 3.6 kPa (.5 psi). No factory password required.
Coolant flow low: Factory password required.
User defined shutdown: Parameters determined by the user.
Boost pressure high: 20 kPa (3 psi) greater than desired. Maximum derate of 10%. No factory password required.
Boost pressure low: 30 kPa (4 psi) lower than desired. Maximum derate of 10%. No factory password required.
50
3516B IMPROVEMENTS
SYSTEMS CONTROLLED BY ECM
• ETHER INJECTION
• RADIATOR SHUTTER CONTROL
• COLD CYLINDER CUTOUT
• ENGINE START FUNCTION
• ENGINE OIL PRE-LUBRICATION
• VARIABLE SPEED FAN CONTROL
• ENGINE OIL RENEWAL SYSTEM
• EXHAUST BYPASS AT HIGH BOOST
The engine ECM also regulates other systems by energizing solenoids or relays. Some of the other systems controlled by the ECM are:
Ether Injection: Ether injection is controlled by the engine ECM or manually. The engine ECM will energize the ether injection relay only if:
- The coolant temperature is below 10°C (50°F). - Engine speed is below 1200 rpm.
Radiator Shutter Control: On trucks that operate in cold weather, shutters can be added in front of the radiator. Installing shutters in front of the radiator allows the engine to warm up to operating temperature
quicker. If a truck is equipped with the attachment radiator shutter control, the shutters are controlled by the engine ECM.
• Engine ECM controls other systems
• Ether injection
• Radiator shutter control
function to reduce white exhaust smoke after start-up and during extended idling in cold weather.
After the engine is started and the automatic ether injection system has stopped injecting ether, the engine ECM will cut out one cylinder at a time to determine which cylinders are firing. The ECM will disable some of the cylinders that are not firing.
The ECM can identify a cylinder which is not firing by monitoring the fuel rate and engine speed during a cylinder cut-out. The ECM averages the fuel delivery and analyzes the fuel rate change during a cylinder cut-out to determine if the cylinder is firing.
Disabling some of the cylinders during Cold Mode operation will cause the engine to run rough until the temperature increases above the Cold Mode temperature. This condition is normal, but the operator should be aware it exists to prevent unnecessary complaints.
Engine Start Function: The Engine Start function is controlled by
ADEM II and the Electronic Programmable Transmission Control (EPTC II). The engine ECM provides signals to the EPTC II regarding the engine speed and the condition of the engine pre-lubrication system. The EPTC II will energize the starter relay only when:
- The shift lever is in NEUTRAL. - The parking brake is ENGAGED. - The engine speed is 0 rpm.
- The engine pre-lubrication cycle is complete or turned OFF.
NOTE: To protect the starter, the starter is disengaged when the engine rpm is above 300 rpm.
INSTRUCTOR NOTE: The remaining improvements are described in the slides that follow.
• Engine runs rough during cold mode
51
2
1
Engine Oil Pre-lubrication: Engine oil pre-lubrication is controlled by
the ADEM II and EPTC II. The EPTC II signals the ADEM II when to energize the pre-lubrication pump relay (1). The ADEM II signals EPTC II to crank the engine when:
- Engine oil pressure is 27 kPa (5 psi) or higher.
- The pre-lubrication pump (2) has run for 15 seconds. (If the system times out after 15 seconds, a pre-lubrication fault is logged in the ADEM II.)
- The engine has been running in the last 2 minutes. - Coolant temperature is above 50°C (122°F).
NOTE: The ECAP and ET can enable or disable the pre-lubrication feature in the ADEM II. On some trucks, the pre-lubrication pump is located near the right front of the engine.
• Engine oil pre-lubrication
1. Pre-lubrication pump relay
• Variable speed fan control: 52 1 3 2
Variable Speed Fan Control: If the engine is equipped with a variable
speed fan, the engine ECM regulates the fan speed. Fan speed varies according to the temperature of the engine. The ECM sends a signal to the variable speed fan control solenoid valve (1) and engine oil pressure engages a clutch as needed to change the speed of the fan.
The jacket water coolant temperature sensor (2) is located in the jacket water temperature regulator (thermostat) housing. The ECM uses the coolant temperature sensor information as the main parameter to control the fan speed. The aftercooler temperature sensors, air conditioner
pressure sensor and brake cooling oil temperature sensors are also used as inputs to determine the required fan speed. A speed sensor (not shown) is located behind the fan pulley and informs the ECM of the current fan speed.
The variable speed fan feature can be turned off using the ECAP or ET service tool. Turning off the variable speed fan feature will set the fan speed at MAXIMUM rpm. Disconnecting the air conditioning
compressor switch will also signal the ECM to set the fan speed at MAXIMUM rpm.
The turbocharger outlet pressure sensor (3) sends an input signal to the ECM. The ECM compares the value of the turbo outlet pressure sensor with the value of the atmospheric pressure sensor and calculates boost pressure.
INSTRUCTOR NOTE: For more information on the variable speed fan, refer to the Service Manual "Variable Speed Fan Clutch" (Form SENR8603).
1. Fan control solenoid valve
• Fan speed sensor (not shown)
• Fan speed overrides
3. Turbo outlet pressure sensor 2. Jacket water coolant
• Engine oil renewal system components: 1. Oil filter 2. Oil renewal solenoid 3. Fuel pressure regulator
• Oil mixes with fuel in fuel tank
53
1
3
2
Engine Oil Renewal System: Located on the right side of the engine are
the components of the engine oil renewal system. Engine oil flows from the engine block through an oil filter (1) to the engine oil renewal
solenoid (2). A small amount of oil flows from the engine oil renewal solenoid into the return side of the fuel pressure regulator (3). 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 EUI injectors to be burned.
When the engine oil renewal system is used, the operator must pay close attention to the ADD OIL message that the VIMS provides to the operator when makeup oil must be added (see Slide No. 54).
The oil does not have to be changed when using the engine oil renewal system. When the engine oil renewal system is used, the engine oil filters, the engine oil renewal system filter, the primary fuel filter and the secondary fuel filters must all be changed at 500 hour intervals.
Engine oil samples must be taken regularly to ensure that the soot level of the engine oil is in a safe operating range.
• Sample engine oil to check soot level
by engine ECM • Engine oil renewal
system parameters
renewal solenoid. Several parameters must be met before the ECM will allow the injection of oil through the engine oil renewal system. The parameters that must be met are:
- Fuel position is greater than 10.
- Engine rpm is between 1300 and 1850 rpm.
- Jacket water temperature is between 63°C (145°F) and 107°C (225°F).
- Oil filter differential pressure at high idle with warm oil is less than 70 kPa (10 psi).
- Fuel filter differential pressure is less than 140 kPa (20 psi).
- Engine oil level switches are sending a valid signal to the ADEM II control.
- Engine has been running more than five minutes.
The engine oil renewal system can be turned ON or OFF with the ECAP or ET service tool. The amount of oil injected can also be adjusted by programming the ECM with the ECAP or ET service tool. The factory setting shown in the service tool is "0" and is equivalent to a 0.5% oil to fuel ratio. The ratio can be changed with the service tool from minus 50 (-50) to plus 50 (+50), which is equivalent to 0.25% to 0.75% oil to fuel ratios.
• Oil renewal adjusted with ECAP or ET
54
1
2
The engine oil level switches (1 and 2) provide input signals to the engine ECM. The ECM provides an input signal to the VIMS which informs the operator of the engine oil level.
If the truck is equipped with the engine oil renewal system attachment, the upper oil level switch (1) will tell the operator when makeup oil must be added. The ADD ENG OIL message is a Category 1 Warning.
The lower oil level switch (2) will tell the operator when the engine oil level is low and it is unsafe to operate the truck without causing damage to the engine. The ENG OIL LEVEL LOW message is a Category 2 or 3 Warning.
If the engine ECM detects a low oil level condition (oil level below the lower switch), the ECM will log a low oil level event. No factory password is required to clear this event.
1. Add engine oil level switch
2. Engine oil level low switch
1. Exhaust bypass valve
55
1
2
Exhaust Bypass Control: An exhaust bypass (wastegate) valve (1)
prevents excessive boost pressure by diverting exhaust gasses away from the turbochargers. The bypass valve is controlled by the engine ECM. Brake system air pressure is reduced to 380 kPa (55 psi) by a valve located outside the right rear of the cab and is supplied to the wastegate solenoid valve (2). If boost pressure exceeds a predetermined value, the ECM will open the wastegate solenoid and send air pressure to open the exhaust bypass valve. When the exhaust bypass valve is open, exhaust at the turbine side of the turbochargers is diverted through the muffler. Diverting the turbine exhaust pressure decreases the speed of the turbochargers which reduces the boost pressure to the cylinders. The wastegate solenoid valve can be controlled with the ECAP or ET service tool for diagnostic purposes. Connect a multimeter to the wastegate solenoid and set the meter to read DUTY CYCLE. Using the service tool, override the wastegate solenoid valve and use the multimeter to measure the corresponding duty cycle.
If the actual boost pressure is 20 kPa (3 psi) higher than the desired boost pressure calculated by the ECM, a high boost pressure event will be logged. If the actual boost pressure is 30 kPa (4 psi) lower than the desired boost pressure calculated by the ECM, a low boost pressure event will be logged. If the ECM detects a high or low boost condition, the ECM will derate the fuel delivery (maximum derating of 10%) to prevent damage to the engine.
2. Wastegate solenoid valve
- Controlled by engine ECM
• Engine wastegate solenoid checked with ECAP or ET
1. Cooling system shunt tank • Engine cooling
systems:
- Jacket water cooling system - Aftercooler cooling system 56 3 1 4 2 Cooling System
The 793C is equipped with a shunt tank (1) to increase the cooling
capacity. The shunt tank provides a positive pressure at the coolant pump inlets to prevent cavitation during high flow conditions.
The cooling system is divided into two systems. The two systems are the jacket water cooling system and the aftercooler cooling system. The only connection between these two systems is a small hole in the separator plate in the shunt tank. The small hole in the shunt tank prevents a reduction of coolant from either of the two systems if leakage occurs in one of the separator plates in the radiator top or bottom tank. When servicing the cooling systems, be sure to drain and fill both systems separately.
The coolant levels are checked at the shunt tank. Use the gauges (2) on top of the shunt tank to check the coolant level.
A coolant level sensor (3) is located on each side of the shunt tank to monitor the coolant level of both cooling systems (guard removed for viewing sensor). The coolant level sensors provide input signals to the VIMS which informs the operator of the engine coolant levels.
Pressure relief valves (4) prevent the cooling systems from becoming over pressurized.
4. Pressure relief valves
3. Coolant level sensor 2. Coolant level gauges
57
The jacket water cooling system uses 17 of the 30 cores on the right side of the radiator (approximately 60% of the total capacity). The jacket water cooling system temperature is controlled by temperature regulators (thermostats).
The aftercooler cooling system uses 13 of the 30 cores on the left side of the radiator (approximately 40% of the total capacity). The aftercooler cooling system does not have thermostats in the circuit. The coolant flows through the radiator at all times to keep the turbocharged inlet air cool for increased horsepower.
• Aftercooler cooling system
• Jacket water cooling system
1. Jacket water pump 2. Bypass tube 3. Jacket water thermostat housing 58 2 1 3
The jacket water pump (1) is located on the right side of the engine. The pump draws coolant from the bypass tube (2) until the temperature regulators (thermostats) open. The thermostats are located in the
housing (3) at the top of the bypass tube. When the thermostats are open, coolant flows through the radiator to the water pump inlet.
If the jacket water cooling system temperature increases above 107°C (226°F), the engine ECM will log an event that requires a factory password to clear.
• High coolant temperature event
• Coolant flow warning switch (arrow)
59
Coolant flows from the jacket water pump, past the coolant flow warning switch (arrow), and through the various system oil coolers (engine, torque converter/transmission and rear brake).
The coolant flow switch sends an input signal to the engine ECM. The ECM provides the input signal to the VIMS which informs 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 this event.
• Low coolant flow event
1. Engine oil cooler 2. Torque converter/ transmission oil cooler 60 1 2
Shown is the right side of the engine. The engine oil cooler (1) and the torque converter and transmission oil cooler (2) are visible in this view. The coolant flows through these coolers to the rear brake oil coolers located on the outside right frame.
• Rear brake oil coolers (arrow)
61
Jacket water coolant flows from the rear brake oil coolers (arrow) to both sides of the engine cylinder block. Coolant flows through the engine block and through the cylinder heads. From the cylinder heads, the coolant returns to the temperature regulators and either goes directly to the water pump through the bypass tube or to the radiator (depending on the temperature of the coolant).
62
• Jacket water cooling system circuit
ENGINE OIL COOLER
TORQUE CONVERTER/ TRANSMISSION OIL COOLER
ENGINE BLOCK
JACKET WATER COOLANT FLOW
REAR BRAKE OIL COOLERS THERMOSTAT HOUSING RADIATOR JACKET WATER PUMP SHUNT TANK
Shown is the jacket water cooling system circuit. Coolant flows from the jacket water pump through the coolers to the engine block. Coolant flows through the engine block and the cylinder heads. From the cylinder heads, the coolant returns to the temperature regulators (thermostats) and either goes directly to the water pump through the bypass tube or to the radiator (depending on the temperature of the coolant).
The shunt tank increases the cooling capacity and provides a positive pressure at the coolant pump inlet to prevent cavitation during high flow conditions.
In this illustration and those that follow, the colors used to identify the various pressures in the systems are:
Red - Supply oil/water pressure
Green - Drain or reservoir oil/water
Red and White Stripes - Reduced supply oil pressure
Brown - Lubrication or cooling pressure
Orange - Pilot or load sensing signal pressure
Blue - Blocked oil
Yellow - Moving components
1. Aftercooler water pump
2. Shunt tank supply tube 3. Aftercooler circuit coolant tubes 63 3 1 2
The auxiliary (aftercooler) water pump (1) for the aftercooler cooling system is located on the left side of the engine. Coolant enters the aftercooler water pump from the radiator or the shunt tank supply tube (2). Coolant flows from the pump to the aftercooler cores through the large tubes (3)
• Rear aftercooler temperature sensor (arrow)
64
Located in a tube at the rear of the aftercooler is the rear aftercooler temperature sensor (arrow). The rear aftercooler temperature sensor provides an input signal to the engine ECM. The engine ECM uses the rear aftercooler temperature sensor signal with the jacket water
temperature sensor signal to control the variable speed fan attachment. The ECM also provides the input signal to the VIMS which informs the operator of the aftercooler coolant temperature.
If the rear aftercooler temperature increases above 107°C (226°F), the engine ECM will log an event that requires a factory password to clear. Another aftercooler temperature sensor is located in a tube at the front of the aftercooler. The front aftercooler temperature sensor does not send an input signal to the engine ECM. The front aftercooler temperature sensor provides an input signal directly to the VIMS.
• Front aftercooler temperature sensor • Rear aftercooler