947542 Volvo.Penta Flange screw

If the RESET button does not move to the extended position after the engine starts, the engine will NOT be protected by this particular switch.If the RESET button remains in the reset position, the engine oil pump will not develop normal oil pressure. An inspection should be made to correct the problem.
Automatic START/STOP systems use oil pressure to automatically reset.The Engine Protective Devices shutdown controls should be tested every 1000 service hours by authorized personnel.Emergency Stop Push Button
Emergency Stop Push Button (ESPB)The Emergency Stop Push Button (ESPB) requires resetting both the push button and the air inlet shutoff (if equipped) before the engine will start.
Always determine the cause of the engine shutdown. Make necessary repairs before attempting restarting the engine.Emergency shutoff controls are for EMERGENCY use ONLY. DO NOT use Emergency shutoff devices or controls for normal stopping procedure. Refer to the Engine Stopping section of this manual for normal stopping procedures.
Oil Pressure Switch
Typical example of oil pressure switches, mounted in the rear of the junction box.An oil pressure switch has wires connected to the electrical shutoff system for alarm or shutdown functions. The oil pressure switch senses oil pressure at the bearing oil gallery. Switches may close at 48 to 62 kPa (7 to 9 psi) below actual trip point. No resetting procedure is required.Water Temperature Contactor Switch
This contactor switch is a coolant temperature sensor.The water temperature contactor switch is located near the coolant water regulator housing. Excessive water temperature closes the switch. Maximum coolant temperature to trip shutoff is 104°C (219°F). The switch opens as the coolant cools. No resetting procedure is required. The unit has wires connected to the electrical shutoff system for alarm or shutdown functions.
The sensing element must be submerged in the coolant to operate. Be sure to have an adequate water supply in the jacket water system, or engine damage could result.
Coolant Loss Sensor (If Equipped)
The optional coolant loss sensor is usually mounted near the top of the engine expansion tank or radiator. The sensor detects when the coolant level is below a preset minimum level.
This coolant loss switch, shown next to a sight glass, is mounted on the side of a radiator.If the coolant level drops below the minimum level, the sensor may sound an alarm, or cause a shutdown to avoid engine overheating or possible engine damage. Coolant must be added to the radiator or expansion tank to clear or reset the condition. In the event of intermittent engine shutdowns, the coolant water level should be checked. Add premixed coolant water to the fill tank, to within 13 mm (1/2 inch) below the filler tube.Check the expansion tank or radiator daily for proper coolant level.Overspeed Shutoffs
The electrical shutoff for the overspeed switch uses a magnetic pickup mounted in the flywheel housing. The electrical shutoff works through the fuel shutoff solenoid and air inlet shutoff (if equipped).
Magnetic pickup (1), mounted in the flywheel housing (2).Should the engine overspeed, the magnetic pickup will sense the excess speed. If overspeed is sensed, the electrical shutoff closes the air and fuel shutoff solenoids (the fuel rack will move to fuel OFF position).The overspeed shutdown has to be reset. Reset the air inlet shutoff (if equipped) and the overspeed switch. Both switches are located in the junction box or control panel.
Overspeed Shutoff Switch (Electro-Mechanical)This switch is mounted either on the tachometer drive or the governor. Excessive engine speed closes the switch by centrifugal force.If equipped with a Caterpillar Generator Set Control Panel, the devices on the panel must be reset after an overspeed shutoff.
Turn the Engine Control Switch to the OFF/RESET position.Alarm Switches
Alarm switches consist of a sensor or contactor. Examples of sensors are the magnetic pickup for detecting speed, and the pressure and temperature contactors. Sensors are wired to a contactor. The contactor activates an alarm circuit in the Annunciator Panel.Alarm switches and sensors are set at a less critical temperature, pressure, or level limit than the engine shutdown controls.The purpose of the alarm switches is to warn the operator that an unsafe operating condition is beginning to occur.The Annunciator Panel has lights and an audible device to warn the operator of a malfunction or abnormal engine operating condition. Each alarm contactor and switch is electrically connected to an indicator light or audible indicator. The alarm will continue until the condition is corrected.When an alarm is activated, corrective measures must be taken, before the situation becomes an emergency, to avoid possible engine damage.If corrective measures are not taken within a reasonable time, engine damage could result. Alternatively, a corresponding shutdown device (if equipped) will stop the engine.The alarm will continue until the condition is corrected or the alarm is reset by the operator. The alarm circuits merely warn the operator, they do not shut the engine down to protect it from damage.A switch may be installed in the alarm circuit for silencing the alarm while the engine is stopped for repairs. Before starting, be sure the switch is moved to the closed (ON) position and the warning lights are illuminated.If the switch is left in the open (OFF) position when the engine is started, the engine will not be protected.Shutoff and Alarm System Testing
During testing, abnormal operating conditions must be simulated. Perform the tests correctly to prevent possible damage to the engine.
The Engine Protective Devices shutdown controls and alarms on the engine should be tested every 1000 service hours or twice a year for proper operation by authorized Caterpillar dealer personnel.Most control panels are equipped with a test switch. Turn the switch to ON position to check indicator lights for proper operation. Replace defective or burnt bulbs immediately.Abnormal operating conditions must be simulated which could cause engine damage if the tests are performed incorrectly. Refer to the Service Manual for the testing procedures.