YOKE AS 6Y8137 - Caterpillar

This section contains some general information about typical engine protective devices.The operation of all alarms and shutoffs utilize components which are actuated by a sensing unit. The alarms and shutoffs are set at critical operating temperatures, pressures, or speeds in order to protect the engine from damage.Alarms function in order to warn the operator when an abnormal operating condition occurs. Shutoffs function in order to shut down the engine when a more critical abnormal operating condition occurs. The shutoffs help to prevent damage to the equipment.If an engine protective device shuts off the engine, always determine the cause of the shutoff. Make the necessary repairs before attempting to start the engine.Shutoffs may cause unburned gas to remain in the air inlet and in the exhaust manifold.
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.
Become familiar with the following information:
Types of the alarm and shutoff controls
Locations of the alarm and shutoff controls
Conditions which cause each control to function
Resetting procedure that is required before starting the engineOn G3300 Engines, protective devices are available for the following conditions:
Low oil pressure
High coolant temperature
Overspeed
Low coolant levelFurther protection is supplied by an emergency stop button.Three basic protection systems are available:
Self-powered shutoff
Automatic start/stop system
Customer supplied shutoffNote: For an energize-to-shutoff system, the gas shutoff valve must be energized to shut off gas to the engine. For an energize-to-run system, the gas shutoff valve must be energized in order to supply gas to the engine.Power for the self-powered system is supplied by the magneto. The self-powered system can be used with an air starting motor or an electric starting motor. An energize-to-shutoff gas valve and an instrument panel are required for this system.Power for the automatic start/stop system is supplied by an external 24 volt electrical source. The automatic start/stop system can be used with an air starting motor or an electric starting motor. An energize-to-run gas valve and one of these controls are required:
Automatic start/stop switchgear
Engine Control LogicFor the customer supplied shutoff system, the customer must supply all of the wiring and the shutoffs. This includes the emergency stop button and wiring.The features of the shutoff systems are listed in Table 1.
Table 1
G3300 Engine Protective Systems    
Item     Type of System    
Self-Powered Automatic Start/Stop     Customer Supplied (1)    
High coolant temperature     Yes     Yes     Yes    
Low oil pressure     Yes     Yes     Yes    
Overspeed     No (2)     Yes     Yes    
High inlet manifold air temperature     No     No     Yes (3)    
High aftercooler water temperature     No     No     Yes (3)    
Emergency stop     Yes     Yes     Yes    
( 1 ) The customer is responsible for supplying the shutoffs and