SEAT GP-SUSPENSION 1198263 - Caterpillar

MMS is equipped with two parallel engine overspeed devices. The two devices are the engine speed switch and the Programmable Logic Control. The overspeed setpoint is 113 percent of the rated speed of the engine. For example, an engine that has a 900 rpm rating will have an overspeed setpoint of 1017 rpm. A magnetic pickup sensor is used in order to send a signal to the engine speed switch and the PLC. The frequency of the magnetic pickup sensor is based on the number of flywheel teeth. The equivalent frequency at 1017 rpm is 4322 Hz.Note: On-site testing of the maximum approved engine overspeed is not recommended due to the use of non-Caterpillar input devices. Therefore, the engine overspeed should NOT be tested above 1050 rpm. The engine design has been approved by Marine classification societies. A demonstration of the engine overspeed's capability should not be required on-site.Note: When you are simulating the engine speed in the following procedures, ensure that the fuel control switch on the MECP is in the ON position. After reaching the overspeed condition, the air shutoff will close. The air shutoff must be moved back to the normal operating position. The engine will not start when the air shutoff is closed. After an overspeed condition occurs, the "OFF/RESET" switch must also be switched to the RESET position before the engine will start.Overspeed Test
Test the engine speed switch at 75 percent of the overspeed setting.
While the engine is running, increase the engine speed above 75 percent of the overspeed setting. Alternately connect a 163-0096 Diagnostic and Calibration Tool to the engine speed switch in order to simulate engine speed. See Table 1 for speeds and frequencies.
Connect the jumper wire for 75 percent verify in the engine speed switch. The engine will shut down. Output 0 of the engine speed switch will turn on.
In order to reset the