ENGINE AR 4W9054 - Caterpillar

Illustration 1 g00564355
7W-2743 Electronic Speed Switch (ESS) (1) Push button for Overspeed Verification (2) Reset button (3) Overspeed indicator lamp (4) Seal screw plug for adjusting the engine overspeed (5) Seal screw plug for adjusting the crank terminate speed (6) Seal screw plug for adjusting the oil step pressure speed settingThe Overspeed Verification Test ensures that the overspeed switch in the electronic speed switch will cause engine shutdown when the engine is running at 75% or more of the overspeed setting.Run the engine at the rated speed and press the overspeed verification button (1) for a moment. The button energizes the switch which causes the engine to shutdown. When the engine rpm is 75% or more of the overspeed setting, engine shutdown should occur when the button is pressed. The engine overspeed setting is 118% of the rated engine rpm.This is an example of calculating the correct engine overspeed setting. An engine with a rated speed of 1800 rpm has an overspeed setting of 2125 rpm. Refer to the Speed Specification Chart. The overspeed verification test will cause engine shutdown at 75% of the overspeed setting. The overspeed setting is 118% of the rated engine rpm. In this example, 75% of 2125 is 1594 rpm. When the engine speed is 1594 25 rpm or more and the overspeed verification button is pressed, the engine will shut down.After engine shutdown because of engine overspeed, the overspeed indicator lamp (3) will remain on until reset button (2) is pressed. Before you start the engine, press reset button (2) for a moment. The overspeed indicator lamp (3) will turn off. The air inlet shutoff lever and the emergency stop switch (ES) must also be reset before the engine can be started.