HOUSING-FLYWHEEL 1742276 - Caterpillar

Diesel Engine Panel
Engine Supervisory System Functional DiagramElectronic Panel Description
The Engine Supervisory System is a microprocessor based system designed to provide superior monitoring and control for Caterpillar engines.Electronic sensors are used to monitor engine functions. The electronic gauge modules display this information and provide customer-defined alarms and shutdowns for these functions. The control logic provides prelubing and cranking features as well as manual emergency stop operation.The Engine Supervisory System may operate in either the Energize-to-Run (ETR) or the Energized-to-Shutdown (ETS) mode.In the ETR mode, the engine will shutdown if control power is lost. In the ETS mode, the engine will continue to run if control power is lost. Changing the operating mode involves moving a jumper in the panel, changing a flag value within the electronic modules, and installing a different Electronic Governor Fuel Shutoff Solenoid (EGFSOS).The Engine Supervisory System Functional Diagram shows the general flow of signals between the various components of the control system.Operation of the Sensors
There are three types of sensors used to monitor the engine:* Contact Switches* Magnetic Pick-up Units (MPU)* Ratiometric Electronic SensorsThe contact switches provide the switch inputs to the control module. They may include level switches, solid state switches, or relay contacts.The magnetic pick-up units are the same units used on other Caterpillar engines. They provide an alternating current signal whose frequency is the product of the engine's revolutions per second times the number of gear teeth on the flywheel where the unit is mounted.The ratiometric electronic sensors act as a function controlled voltage divider. Electrically, they perform like a variable resistor as shown below.
FUNCTIONAL DIAGRAM OF SENSORThe electronic gauge modules provide a supply voltage (VS) to the sensors. The signal (SIG) is a fraction of the supply voltage. Example:Consider a temperature sensor. Changes in temperature functionally cause the position of the "wiper" to change. The electronic gauge module compares the ratio of the signal voltage to the supply voltage.Therefore, slight fluctuations in the power supplied to the sensor have no effect on the accuracy of the reading. The ratio of the signal voltage compared to the supply voltage is converted to a temperature value in Fahrenheit (°F) or Celsius (°C) by the electronic gauge module.Operation of Electronic Gauge Modules
The electronic gauge modules monitor the engine using the sensors described previously. Each module has a liquid crystal display (LCD) which can be used to display the signal received from a sensor.The lower portion of each module contains three touch buttons. The engine or auxiliary equipment function being displayed is identified by the "carrot" (black triangular pointer) directly above the ISO symbol of the function being displayed. To view a function, press the center of the button with the ISO symbol for that function. If more than one symbol is on a button, press the same button a second or third time until the "carrot" points to the desired symbol on the button.When the electronic gauge modules sense that the engine is running, continuity exists between the engine running terminal and the battery