VALVE GP-EXHAUST GAS (NRS) 3496734 - Caterpillar

This section contains some general information about the function of typical engine protective devices.The alarms and shutoffs are set at critical operating temperatures, pressures, or speeds in order to protect the engine from damage.An alarm warns the operator when an abnormal operating condition occurs. The shutoffs shut down the engine if a more critical operating condition occurs. The shutoffs help to prevent damage to the engine.
Unburned gas in the air inlet and exhaust system may ignite when the engine is started. Personal injury and/or property damage may result.Before starting an engine that may contain unburned gas, purge the unburned gas from the air inlet and exhaust system. Refer to the topic on purging unburned gas in the "Starting the Engine" section.
If an engine protective device shuts off the engine, always determine the cause of the shutoff. Always make the necessary repairs before attempting to start the engine. Refer to Troubleshooting.Become familiar with the following information:
Types of the alarms and shutoffs
Locations of the alarm and shutoff controls
Conditions which cause each control to function
Resetting procedure that is required before starting the engine Testing Alarms and Shutoffs
Alarms must function properly in order to provide timely warning to the operator. Shutoffs help to prevent damage to the engine. It is impossible to determine if the engine protective devices are in good working order during normal operation. Malfunctions must be simulated in order to test the engine protective devices. Refer to this Operation and Maintenance Manual, "Engine Protective Devices - Check" for more information.Prevention of Start-up
The engine will not start if any of the conditions that cause a shutoff are present. An overcrank will also prevent starting of the engine. If any situation that causes a shutoff occurs, the following conditions must be met before the engine can be started:
The condition that prevented starting is not present.
The engine control switch is turned to the "OFF/RESET" position.Setpoints for Alarms and Shutoffs
Some of the setpoints for the alarms and shutoffs can be programmed with an electronic service tool (ET). Some of the parameters cannot be programmed. For information on programming of parameters, refer to the Systems Operation/Testing and Adjusting. For the default setpoints, refer to the Troubleshooting Guide.