12038 Force WASHER

A frequency generator is used to simulate the signal from the engine speed sensor. The frequency represents the engine rpm. This procedure checks the operation of the speed switch's crank terminate relay, oil step relay, and overspeed relay. The setpoints for the speed switch are adjusted, if necessary.
Turn OFF the power to the monitoring system.
Illustration 1 g00872329
(1) Cover screw for the "OVERSPEED" potentiometer (2) Cover screw for the "CRANK TERM" potentiometer (3) Cover screw for the "OIL STEP" potentiometer (4) Retainer clip (5) "OVERSPEED" indicator (6) "RESET" switch
To gain access to the potentiometers, remove cover screws (1), (2), and (3) .
Connect the positive "+" lead from a source of 24 VDC to "8-40 VDC" terminal 6. Connect the negative "-" lead to "8-40 VDC" terminal 5.
Connect the frequency generator's positive "+" lead to "PICK-UP SIG" terminal 4. Connect the negative "-" lead to "PICK-UP SHLD COM" terminal 3.
Turn ON the 24 VDC for the speed switch.
Adjust the speed switch's crank terminate relay.
Connect the 9U-7330 Digital Multimeter to "CRANK TERM NO" terminal 10 and "CRANK TERM COM" terminal 11. Set the multimeter to the "Ohms" scale.
Turn ON the power to the frequency generator.
Adjust the frequency generator to 0 Hz.
Adjust the frequency to 691 Hz.
Slowly increase the frequency in increments of 1 Hz and observe the resistance between terminals 10 and 11. Continue to increase the frequency in 1 Hz increments until the frequency is 701 Hz.Note: A frequency of 701 Hz corresponds to the setpoint for the crank terminate speed of 165 rpm.Expected ResultThe resistance became less than 5 ohms at a frequency of 701 Hz. The circuit is closed and the crank terminate relay is operating correctly.ResultsOK - The resistance became less than 5 ohms at a frequency of 701 Hz. The circuit is closed and the crank terminate relay is operating correctly. Proceed to Step 7.Not OK - The resistance became less than 5 ohms at a frequency of less than 701 Hz (165 rpm). The crank terminate relay was energized too soon. The setpoint is too low and the setpoint must be adjusted. To reset the relay, turn OFF the power to the speed switch. Use the 4C-4029 Adjustment Tool to turn potentiometer (2) clockwise for two full turns (720 degrees). Continue to provide a frequency of 701 Hz. Turn ON the power to the speed switch and slowly turn potentiometer (2) counterclockwise until the resistance is less than 5 ohms. Then turn OFF the power to the speed switch. Adjust the frequency generator to 0 Hz. Turn ON the power to the speed switch. Repeat Steps 6.d and 6.e until the resistance becomes less than 5 ohms at a frequency of 701 Hz.Not OK - The resistance is greater than 20,000 ohms or out of range at a frequency of 701 Hz (165 rpm). The crank terminate relay did not energize. The setpoint is too high and the setpoint must be adjusted. Continue to provide a frequency of 701 Hz and use the 4C-4029 Adjustment Tool to slowly turn potentiometer (2) counterclockwise until the resistance is less than 5 ohms. Adjust the frequency generator to 0 Hz. To reset the relay, turn OFF the power to the speed switch and wait for at least two seconds before you turn ON the power again. Repeat Steps 6.d and 6.e until the resistance becomes less than 5 ohms at a frequency of 701 Hz.
Disconnect the ohmmeter from terminals 10 and 11. Install cover screw (2). Tighten the screw to a torque of 0.20 0.03 N m (2.000 0.300 lb in).
Adjust the speed switch's oil step relay.
Connect an ohmmeter to normally open terminals 13 and 14.
Adjust the frequency generator to 0 Hz. Then adjust the frequency to 3339 Hz.
Observe the LED in the port for potentiometer (3) and slowly increase the frequency in increments of 1 Hz until the frequency is 3349 Hz. Observe the LED and observe the ohmmeter.Note: A frequency of 3349 Hz corresponds to the setpoint for the oil step speed of 788 rpm.Expected ResultThe LED illuminated at a frequency of 3349 Hz (788 rpm). At nine seconds after the LED illuminated, the ohmmeter reading was less than 5 ohms. The oil step relay is operating correctly. Remove the ohmmeter.ResultsOK - The LED illuminated at a frequency of 3349 Hz (788 rpm). At nine seconds after the LED illuminated, the ohmmeter reading was less than 5 ohms. The oil step relay is operating correctly. Proceed to Step 9.Not OK - The LED illuminated before reaching a frequency of 3349 Hz (788 rpm). The oil step relay was energized too soon. The setpoint is too low and the setpoint must be adjusted. Turn potentiometer (3) clockwise until the LED is extinguished. Continue to provide a frequency of 3349 Hz and slowly turn potentiometer (3) counterclockwise until the LED illuminates. Repeat Steps 8.b and 8.c until the LED illuminates at a frequency of 3349 Hz. Verify that the ohmmeter reads less than 5 ohms at nine seconds after the LED illuminates.Not OK - The LED did not illuminate at a frequency of 3349 Hz (788 rpm). The oil step relay did not energize. The setpoint is too high and the setpoint must be adjusted. Slowly turn potentiometer (3) counterclockwise until the LED illuminates. Repeat Steps 8.b and 8.c until the LED illuminates at a frequency of 3349 Hz. Verify that the ohmmeter reads less than 5 ohms at nine seconds after the LED illuminates.
Install cover screw (3). Tighten the screw to a torque of 0.20 0.03 N m (2.000 0.300 lb in).
Adjust the speed switch's overspeed relay.
Adjust the frequency generator to 0 Hz.
Adjust the frequency to 5033 Hz.
Slowly increase the frequency in increments of 1 Hz and observe "OVERSPEED" indicator (5). Continue to observe the "OVERSPEED" indicator and increase the frequency in 1 Hz increments until the frequency is 5043 Hz.Note: A frequency