COVER-CONDUIT 4359845 - Caterpillar

Emergency Shutoff Devices and Alarms
Alarms and Shutoff Devices
Alarm systems provide either an audible or a visual warning, or both, when certain abnormal operating conditions occur. These conditions can be low fuel supply, low oil pressure, or high engine coolant temperature. The alarm will be activated until the cause for the condition is corrected. The alarm sensor will then return to its normal position, and shut off the alarm circuit.If no action is taken when the alarm is activated for lack of lubrication or coolant, the engine can be damaged. To prevent this from occurring to unattended engines, shutoff devices should also be used.At a slightly different temperature or pressure range than that which activates the alarm system, the shutoff device stops the engine. The Engine Failure Light on the control panel and one or more of the indicators will either light, or pop out to indicate the problem. Repairs must be made before starting is attempted.Electronic Overspeed Shutoff Switch
This switch uses a magnetic pickup mounted in the flywheel housing to sense engine speed.Low Oil Pressure Shutoff Switch
This device is usually mounted on the side of the engine with oil lines connected to the switch. Low oil pressure closes the switch. Manually operated systems require resetting by pushing the button until it latches. After the engine starts and develops oil pressure, the oil pressure will push the button to the extended running position.
If the reset knob does not move to the extended position after the engine starts, the engine will not be protected by this switch.
If the button remains in the reset position, the engine oil pump is not developing normal oil pressure and a check should be made.Automatic start-stop systems use a pressure switch which resets itself.Overspeed Shutoff
Should the engine overspeed, the magnetic pick-up will close the circuit to the fuel shutoff solenoid and stop the engine.The shutoff switch can be checked for proper operation at 75% overspeed condition:1. Determine the full load RPM of the engine from the serial number plate.2. Operate the engine at the speed shown in the OVERSPEED TEST RPM Column of the chart. 3. While maintaining test RPM, push and hold the VERIFY button. The engine should stop.If the engine does not stop at the specified test RPM, contact your Caterpillar dealer. As the engine stops, the yellow light (2) will go on. The RESET button (1) must be pushed before starting the engine.Electronic Overspeed Shutoff Switch With Cranking Termination
After the starting motor has cranked the engine, the pinion gear can remain engaged with the flywheel as engine speed increases. At 600 RPM, the magnetic pickup opens the circuit to the starter motor, which allows the pinion to disengage. The circuit remains open until the flywheel stops. This prevents energizing the starter motor again while the flywheel is turning.This switch has a 75% VERIFY button (1), a RESET button (2) and an indicator light (3) similar to the speed switch. The operation of this portion of the switch is identical in all respects