NUT 1A4168 - Caterpillar

Introduction
The information in this section is a supplement to the troubleshooting methods of the previous section. This material is much more descriptive and detailed for the user who is less familiar with these components. The Troubleshooting Section makes constant references to this section when more detailed information is necessary to complete a diagnosis, or to calibrate or test a component.Service Procedure Index
A. Overspeed Verify TestB. Overspeed CalibrationC. Crank Terminate Speed CalibrationD. Oil Step Speed CalibrationE. Magnetic Pickup CheckF. Diode TestG. Pressure Switch TestH. Slave Relay TestJ. Water Temperature SwitchK. Protection System Battery Drain Procedure A
Electronic Speed Switch (ESS) (Typical Example)
(1) Verify button (2) Reset button (3) "LED" overspeed light (4) Seal screw plug (overspeed) (5) Seal screw plug (crank terminate)Overspeed Verify Test
1. Run the engine at rated speed and push verify button (1) in for a moment. This will cause the speed switch to activate and cause engine shutdown. Any time the engine speed is 75% or more of the overspeed setting, engine shutdown will occur if the verify button is pushed.EXAMPLE: For an engine with a rated speed of 1800 rpm, the overspeed setting is 2125 rpm (see Speed Specification Chart and Note A). The overspeed verify test will cause shutdown of the engine at 75% ( 25 rpm) of the overspeed setting of 2125 rpm. In this example, 75% of 2125 rpm is approximately 1600 rpm. If the verify button is pushed at an engine speed of approximately 1600 rpm or above, engine shutdown will occur.The "LED" overspeed light (3) will come on and stay on until the reset button is pushed after an overspeed switch shutdown. Before restarting the engine, push in reset button (2) for a moment. This will reset the speed switch, and the "LED" overspeed light (3) will go off. The emergency stop switch (ES) must now also be manually reset before the engine can be started again. Refer to these notes when using the Speed Specification Chart that follows:NOTE A: The engine overspeed setting rpm is 118% of rated engine rpm.NOTE B: To verify overspeed shutdown system operation, push in the VERIFY button for a moment. The engine must shut down at 75% or more of overspeed setting.NOTE C: The magnetic pickup frequency (HZ) is calculated as follows: ESS input Voltage: Maximum 40 VDC; Minimum 8 VDC. Procedure B
Electronic Speed Switch (ESS) (Typical Example)
(1) Verify button (2) Reset button (3) "LED" overspeed light (4) Seal screw plug (overspeed) (5) Seal screw plug (crank terminate)Overspeed Calibration
1. Remove lockwire and seal from seal screw plugs (4 and 5). Remove seal screw plug (4) from access hole for overspeed adjustment screw.2. Use a small screwdriver and lightly turn overspeed adjustment potentiometer twenty turns in direction of "MAX ARROW" (clockwise). The overspeed adjustment screw is made so that it cannot cause damage to the potentiometer, or be removed, if the adjustment screw is turned too many turns in either direction.3. Run the engine at 75% of desired overspeed setting rpm. Make reference to the Speed