OPERATOR STATION FOR 797B OFF-HIGHWAY TRUCK

OPERATOR'S STATION.

The operator station for the 797B Off-highway Truck offers a superior level of operator comfort and efficiency.

The VIMS controls the Truck Production Management System (TPMS) on the 797B Trucks.  There are two sets of TPMS external loading lamps on the truck.  One set of lamps is on the left side of the cab (arrow) and the other set is on the right platform. The standard lamps are green and red.  The lamps inform the loader operator of the loading progress toward a target payload weight (set through the VIMS Keypad).  The lamps are active only during the loading cycle and are off at all other times.


During loading, the green (continue loading) lamps will be ON until the payload is 95% of the target weight setting.  Then, the red (stop loading) lamp will light.  A "last pass" indication can be programmed into the system using the VIMS Keypad.  With last pass indication, the VIMS calculates an average loader pass size and predicts payload weight.  If the predicted weight after the NEXT loader pass will be above 95% of the target weight setting, the red lamps FLASH.  The red lamps will be ON continuously after the last pass (when fully loaded).  A minimum of three loader passes are required for the "last pass" indication option to function correctly.

Hoist control lever (arrow)

The 797B hoist system is electronically controlled.  The hoist control lever (arrow) activates the four positions of the hoist control valve.  The four positions are: RAISE, HOLD, FLOAT and LOWER.  A fifth position of the hoist valve is called the SNUB position. The operator does not have control over the SNUB position. The body position sensor (see Visual No. 80) controls the SNUB position of the hoist valve. When the body is lowered, just before the body contacts the frame, the Chassis ECM signals the hoist solenoids to move the hoist valve spool to the SNUB position.  In the SNUB position, the body float speed is reduced to prevent hard contact of the body with the frame.

The truck should normally be operated with the hoist lever in the FLOAT position.  Traveling with the hoist in the FLOAT position will make sure the weight of the body is on the frame and body pads and not on the hoist cylinders.

If the transmission is in REVERSE when the body is being raised, the hoist lever sensor is used to shift the transmission to NEUTRAL. The transmission will remain in NEUTRAL until:
1. The hoist lever is moved into the HOLD or FLOAT position; and

2. the shift lever has been cycled into and out of NEUTRAL.


NOTE:  If the truck is started with the body raised and the hoist lever in FLOAT, the lever must be moved into HOLD and then FLOAT before the body will lower.

Telescopic/Tilt Steering Column adjustment lever

The operator controls to the left of the steering column are
1. Telescopic/Tilt Steering Column adjustment lever
* push for telescoping
* pull for tilt

2. Intermittent wiper/washer, turn signal control, and dimmer switch

3. Steering wheel mounted electric horn control

4. Cigarette lighter--the cigarette lighter socket receives a 12 Volt power supply. This socket can be used as a power supply for
12 Volt appliances.  Another 12 Volt power port is provided behind the operator's seat.

Windshield washer.

Shown is a closer view of the intermittent wiper/washer, turn signal control, and dimmer switch.
Windshield washer--push the button at the end of the lever to activate the electrically powered windshield washer.

Intermittent wiper--there are six positions for the wiper switch.

* -- OFF

* 1 bar -- intermittent position 1

* 2 bars -- intermittent position 2

* 3 bars -- intermittent position 3

* I -- low speed continuous wiper

* II -- high speed continuous wiper


Dimmer switch--pull the lever toward the operator for BRIGHTS and push the lever away from the operator for DIMS.

Turn signals--lift the lever for a RIGHT turn and lower the lever for a LEFT turn.

Retarder lever (black)

Located on the right side of the steering column is the manual retarder lever (black).  The manual retarder lever is used to modulate engagement of the service brakes on all four wheels.  The retarder lever can control the modulation of the service brakes more precisely than the service brake pedal located on the cab floor.  The retarder will not apply all of the normal braking capacity.

When ENGAGED, the manual retarder lever sensor sends a PWM signal to the Brake/Cooling ECM.  The further the lever is moved, the higher the PWM signal. The Brake/Cooling ECM then turns ON a supply solenoid and sends a current between 0 and 950 milliamps to the control solenoid (see Visuals No. 97 and 106 STMG-2).

Located on the dash to the right of the retarder lever are (from left to right):
* Key start switch

* Temperature variable knob

* Fan speed switch

NOTICE

Do not use the retarder control as a parking brake or to stop the machine.

Secondary brake pedal

Located on the floor of the cab are
* Secondary brake pedal (1):  Used to modulate application of the parking brakes on all four wheels.

* Service brake pedal (2):  Used to modulate engagement of the service brakes on all four wheels.         For more precise modulation of the service brakes, use the manual retarder lever on the right side       of the steering column.

* Throttle pedal (3):  A throttle position sensor 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 engine oil temperature is below 60°C (140°F).  The rpm is gradually reduced to 1000 rpm between 60°C (140°F) and 71°C (160°F).  When the temperature is greater than 71°C (160°F), the engine will idle at Low Idle (700 rpm).

Increasing the Low Idle speed helps prevent incomplete combustion and overcooling. To temporarily reduce the elevated idle speed, the operator can release the parking brake or depress the throttle momentarily, and the idle speed will decrease to LOW IDLE for 10 minutes.

Transmission shift lever.

To the right of the operator's seat is the shift console.  Located on the shift console are the transmission shift lever (1) and the parking brake
switch (2).

The parking brake switch sends a signal to the Brake/Cooling ECM.  The Brake/Cooling ECM then sends a signal to the parking brake solenoid located on the cab brake valve (see Visuals No. 97 and 106 STMG-2).

The 797B truck transmission has SEVEN speeds FORWARD and ONE speed REVERSE.  The top gear limit and the body up gear limit are programmable through the transmission and Chassis ECMs using a laptop computer with the Electronic Technician (ET) software installed.  The top gear limit can be changed from FIRST to SEVENTH.  The body up gear limit can be changed from FIRST to THIRD.

The window switch (3) controls the electric powered window on the left side of the cab. If the attachment electric powered window for the right side of the cab is installed, another switch will be located to the right of switch (3).

A Customer Transmission Lockout feature provides the customer with a secure method of locking out the transmission during service work. The user interface is a single switch to ground that goes directly to the Transmission ECM on Pin J1-31.  The Transmission ECM reads this input and determines if the transmission should be locked out.
Below are the conditions that the Transmission ECM looks for before allowing the transmission lockout status to change state.
Transmission Lockout Status OFF
The only way that the lockout status can go ON is if all of the following conditions are met:
* Shift lever is in neutral
* Ground speed is 0.0 km/h (0.0 mph)
* Transmission Lockout Switch ON (switch open)

Otherwise, the Transmission Lockout Status will stay OFF.  As long as the lockout status is OFF, the transmission will shift as normal.

Transmission Lockout Status ON
The only way that the lockout status can go OFF is if all of the following conditions are met:
* Shift lever is in neutral.
* Transmission Lockout Switch OFF (switch grounded).

Otherwise, the Transmission Lockout Status will stay ON.  As long as the lockout status is ON, the transmission will be held in NEUTRAL.

Note that the transmission lockout feature will never cause a shift into NEUTRAL.  The actual gear of the transmission will always be in NEUTRAL before the status can go from OFF to ON.

Likewise, the transmission lockout feature will never cause a shift out of NEUTRAL.  The requested gear (after the lockout goes away) will always be NEUTRAL after the status goes from ON to OFF.

A Customer Parking Brake Lockout function provides the customer with a secure method of locking out the parking brakes during service work. The Brake/Cooling ECM requests a "machine lockout" status from the Transmission ECM.  If the Transmission Lockout Status is ON, the Transmission ECM will send a "machine lockout"status ON signal to the Brake/Cooling ECM.  The "machine lockout" strategy holds the parking brakes in the ENGAGED position.  The Customer Parking Brake Lockout function can only be released if the parking brakes are ON and there is no ground speed.

Overhead switches.

Located above the operator's head are several switches:

* Hazard lights (1)
* Headlights and parking/taillights (2)
* Back-up lights (3)
* Front flood/ladder lights (4)
* Fog lights (5)
* Strobe lights (6)

NOTE:  The strobe light switch is not currently used.  This switch can be used for running-lights or customer installed lights.

797B trucks use only circuit breakers

Shown is the circuit breaker panel located behind the operator's seat.  The 797B trucks use only circuit breakers to protect the electrical circuits.

A 12-Volt/5 amp power port (1) provides a power supply for 12-Volt appliances, such as a laptop computer.

A laptop computer with the VIMS software installed can be connected to the diagnostic connector (2) to obtain diagnostic and production information from the VIMS Electronic Control.

A laptop computer with the Electronic Technician (ET) software installed can be connected to the CAT Data Link connector (3) to obtain diagnostic information and perform programming functions on all of the electronic controls.

Center dash panel.

Shown is the center of the front dash panel.  Eight dash indicators, the four-gauge cluster module, and the speedometer/tachometer module are visible.

The four dash indicators to the left of the four-gauge cluster module are (from top to bottom):

* Left Turn.

* Body Up:  Lights when the body is up.  Input is from the body position sensor.

* Reverse:  Lights when the shift lever switch is in REVERSE.

* High Beam.

The four dash indicators to the right of the Speedometer/Tachometer Module are (from top to bottom):

* Right Turn.

* Action Lamp:  Lights when a Category 2, 2-S or Category 3 Warning is active.

* Retarder:  Lights when the retarder is ENGAGED (Auto or Manual). Flashes rapidly when a fault in the ARC system is detected.

* TCS: Lights when the Traction Control System (TCS) is ENGAGED.

The four systems monitored by the Four-Gauge Cluster Module are (top and bottom, left to right):

* Engine Coolant Temperature: Maximum operating temperature is 107°C (225°F).

* Brake Oil Temperature (right rear sensor):  Maximum operating temperature is 121°C (250°F).

* Steering Oil Level.

* Fuel Level:  Minimum operating levels are 15% (Category 1) and 10% (Category 2).

The three systems monitored by the Speedometer/Tachometer Module are:

* Tachometer:  Displays the engine speed in rpm.

* Ground speed:  Displayed in the left side of the three-digit display area and can be displayed in miles per hour (MPH) or kilometers per hour (km/h).

Actual gear:  Displayed in the right side of the three-digit display area and consists of two digits that show the actual transmission gear that is engaged.  The left digit shows the actual gear (such as "1," "2," etc.).  The right digit shows the direction selected ("F"-Forward, "N"-Neutral or "R"-Reverse.

Rocker switches (top row).

To the right of the Speedometer/Tachometer Module are several rocker switches.  The rocker switches control the following systems:

Top row (from left to right)

* Throttle Back-up:  Raises the engine speed to 1300 rpm if the throttle sensor signal is invalid.
* Ether Starting Aid: Allows the Operator to manually inject ether if the engine oil temperature is           below 10°C (50°F) and engine speed is below 1900 rpm. The manual ether injection duration is           five seconds.
* ARC: Activates the Automatic Retarder Control (ARC) system.
* Brake Release/Hoist Pilot: Used to release the parking brakes for towing and provide hoist pilot oil     to lower the body with a dead engine. NOTE:  Pressure will increase slowly.  Allow approximately     five minutes to fill the accumulator and the brake pistons.
* TCS Test:  Tests the Traction Control System (TCS).  Use this switch when turning in a tight circle     with the engine at LOW IDLE and the transmission in FIRST GEAR.  The brakes should                     ENGAGE and RELEASE repeatedly.  The test must be performed while turning in both directions     to complete the test.

Bottom row (from left to right)

* Panel Lights:  Use this switch to DIM the panel lights.
* Air Conditioning:  Use this switch to turn ON the air conditioner.

Message center module:

Shown is the Vital Information Management System (VIMS) message center module (1) and the keypad module (2).

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, 2, 2-S, or 3 Warning is present.

The universal gauge displays active or logged data (machine) and maintenance (system) events. The universal gauge will also display the status of a sensor parameter selected for viewing by depressing the GAUGE key on the keypad.

The message display window shows various types of text information to the operator, depending on the menu selected with the keypad. An active event will override most displays until acknowledged by depressing the OK Key.

ELECTRONIC SYSTEMS

Located in the compartment at the back of the cab is the ABL2M VIMS Main Module (1).  The ABL2M VIMS Main Module has two 70-pin connectors and is capable of receiving and sending many signals.  There are no Interface Modules. The VIMS Main Module also receives all of the input information from the other ECMs through the CAT Data Link. The VIMS Main Module analyzes all of the input information and sends output signals to the dash modules, the action lamp and alarm, the VIMS service lamp, the autolube solenoid, and the payload lamps. 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.

The VIMS Main Module hardware is ABL2M version 4.0.  The main module must be programmed with Flash File software using ET before the VIMS will function.

Also in this location is the Transmission ECM (2), the Chassis ECM (3), the Brake/Cooling ECM (4), and the Road Analysis Control ECM (5). All of these controls are ABL2C ECMs and have two 70-pin connectors, capable of receiving and sending many signals.  These ECMs are Flash programmable through the CAT Data Link using a laptop computer with the Electronic Technician (ET) software installed.

797B Electronic system integration.

Shown is a diagram of the 797B electronic system integration.

The Transmission ECM controls the shifting of the transmission and torque converter lockup.  Included in this control is fail in gear protection, neutral coast inhibiting, Control Throttle Shifting (CTS), Directional Shift Management, overspeed protection, speed limiting, torque limiting, and top gear limit.

The Chassis ECM controls the neutral start function, back-up alarm, load counter, body up gear limit, starter protection, hoist system, reverse neutralizer, and accumulator bleed down.

The Brake/Cooling ECM controls the Automatic Retarder Control (ARC), the Traction Control System (TCS), parking brakes, engine fan speed control, brake cooling pump speed control, and rear axle cooling and pressure control.

All of these electronic controls, along with the three engine controls, communicate with each other over the CAT Data Link.  All of the information from these controls can be accessed through the VIMS message center or a laptop computer with the VIMS-PC or ET software.

The Road Analysis Control (RAC) system will provide on-board monitoring of the truck usage versus component life consumed. If the customer exceeds the nominal ton-rating of the truck or poor road conditions are sensed, the RAC will record shortened component life predictions in cost per hour.  Component life predictions will be provided for the major truck components (main frame, engine, transmission, final drives, brakes, etc.).  The ECM can be downloaded to provide the customer with a report of the remaining operational life of a component.

A Tire Monitoring electronic control system is planned for future production.  The tire monitoring system is a tire supplier device that will receive radio signals from sensors installed in the tires.  The sensors may include temperature and pressure.  The information from the tire monitor will be transmitted to the VIMS through the CAT Data Link.  Tire life predictions can be provided to the customer based on the type of truck usage.

Vital Information Management System (VIMS)

Shown is a diagram of the VIMS electronic system.  Shown on the left are the components on the machine that provide inputs directly to the ABL2M VIMS Main Module.  The VIMS Main Module analyzes these inputs along with the inputs from the other ECMs and sends output signals to the components shown on the right side of the diagram.

The VIMS also provides clock synchronization for all of the ECMs
The "ECM location code" is similar to the "harness code" designation referred to on earlier electronic controls.  The ECM location code consists of four pins (J1-20 to 23) in the ABL controls that can be either OPEN or GROUNDED. The combination of OPEN or GROUNDED pins determines which function the ABL control will perform.  For example, if pins J1-20 and J1-21 are GROUNDED and pins J1-22 and J1-23 are OPEN, that ABL control will function as the Transmission ECM.  When connecting a laptop with ET software, ET will also automatically show this ABL control as the Transmission ECM.  The ECM location code is especially important when uploading new "flash files." Without the location code, ET would not know which ECM to FLASH.

Message center and keypad modules.
Shown are the message center and keypad modules used on 797B Trucks. The keypad module allows the operator or a service technician to interact with the VIMS.  Some of the functions that can be performed by the keypad are:

OK Key: Used to complete keypad entries and to acknowledge events. Acknowledging an event will remove the event from the display temporarily.  Severe events cannot be acknowledged.

F1 Key: Provides additional information on the current event being displayed.  For maintenance (system) events, the MID, CID, and FMI are displayed.  For data (machine), the current parameter value is displayed (temperature, pressure, rpm).

F2 and F3 Keys:  Not used on 797B Trucks.

GAUGE key:  Used to request the universal gauge and the message display window to show the value of any sensor parameter.  Depressing the arrow keys will scroll through the parameters.  Entering the parameter number and then the GAUGE key selects that parameter.

Numeric Keys: Used to enter numeric information such as the individual gauge parameter number, service program codes, and responses to VIMS requests.

NOTE:  Service program codes can be found in the Serviceman's Handouts.

Left ARROW Key:  Used to scroll backwards through the current display selection.

Right ARROW Key:  Used to scroll forward through the current display selection.

ID Key: Used by the operator to enter his or her identification number. This number is stored with all event information that may follow, until a new identification number is entered. Printed reports show this number with each event.

Red indicator:  Located above the OK Key, a red indicator is flashed each time a key is pressed.  This tells the operator or service technician that the keystroke was accepted.

Data Logger Indicator Dots: Located in the upper right corner of the message center module are four indicator dots.  The VIMS can store up to 30 minutes of information from all of the sensors installed on the truck. This information can be stored by turning on the data logger with the keypad (DLOG). When the data logger is turned on with the keypad, the data logger indicator dots will scroll until the data logger is turned off.

NOTE: The data logger indicator dots will not scroll if the data logger is turned on with the VIMS PC

The VIMS provides three Warning Categories.  The first category requires only operator awareness.  The second category states that the operation of the machine and the maintenance procedure of the machine must be changed.  The third Warning Category states that the machine must be safely shut down immediately.

Warning Category 1
For a Category 1 Warning, the alert indicator will flash.  The universal gauge may display the parameter and a message will appear in the message display window.  A Category 1 Warning alerts the operator that a machine system requires attention.  The "OK" key on the keypad can be used to acknowledge the warning. Some warnings will be silenced for a predetermined period.  After this time period, if the abnormal condition is still present, the warning will reappear.

Warning Category 2
For a Category 2 Warning, the alert indicator and the action lamp will flash.  The universal gauge may display the parameter and a message will appear in the message display window.  A Category 2 warning alerts the operator that a change in machine operation is required to avoid possible damage to the indicated system. The "OK" key on the keypad can be used to acknowledge the warning. Some warnings will be silenced for a predetermined period.  After this time period, if the abnormal condition is still present, the warning will reappear.

Warning Category 2-S
For a Category 2-S Warning, the alert indicator and the action lamp will flash and a continuous action alarm will sound, which indicates a SEVERE Category 2 Warning.  The universal gauge may display the parameter and a message will appear in the message display window.  A Category 2-S Warning alerts the operator to immediately change the operation of the machine to avoid possible damage to the indicated system. When the change in operation is made to an acceptable condition, the action alarm will turn off.

Warning Category 3
For a Category 3 Warning, the alert indicator and the action lamp will flash and the action alarm will sound intermittently.  The universal gauge may display the parameter and a message will appear in the message display window.  A Category 3 Warning alerts the operator that the machine must be safely shut down immediately to avoid damage to the machine or prevent personal injury.  Some Category 3 Warnings cannot be stopped by pressing the "OK" key.

VIMS connector (RS-232)

Shown is a laptop computer with the VIMS-PC diagnostic software installed. The laptop computer is connected to the VIMS diagnostic connector (RS-232).

Some of the operations that can be performed with a laptop computer with VIMS-PC installed are:
* View real time data (similar to the status menu of ET)

* View payload data

* Start and stop a data logger

* Calibrate the payload system

* Assign serial and equipment numbers

* Reset onboard date, time, and hour meter

* Download event list, data logger, event recorder, payload data, trend data, cumulative data, and histogram data.

CAT Data Link

The CAT Data Link consists of a pair of twisted wires that connect to all of the Electronic Control Modules (ECMs) on a machine.  The wires are twisted to reduce electrical interference from unwanted sources such as radio transmissions.  All sensors and switches that provide an input to an ECM can be shared with other ECMs over the CAT Data Link.  The ability to share the inputs eliminates the need for more than one sensor in the same system. A  laptop computer with the Electronic Technician (ET) diagnostic software installed can also be connected to the CAT Data Link and view the information that is being transmitted between the ECMs.

Shown is the 171-4400 Communication Adapter and a laptop computer with the ET diagnostic software installed.  The communication adapter is connected to the CAT Data Link diagnostic connector located on the circuit breaker panel.

The ABL electronic controls do not have diagnostic windows to access diagnostic information.  In order to perform diagnostic and programming functions in the ABL electronic controls, the service technician must use a laptop computer with ET or VIMS-PC.

NOTE:  The 7X1700 Communication Adapter has been replaced by the 171-4400 Communication Adapter II. Both Communication adapters will work on the 797B trucks.