Usage:
Engine Overspeed (OS)
This is an adjustable engine speed setting (normally 127% of rated speed) that prevents the engine from running at a speed that could cause damage.
An overspeed condition will cause relay SR1 to open and deenergize the shutoff solenoid. The deenergizing of the shutoff solenoid will cut the fuel to the engine causing the engine to shutdown.
NOTE: Overspeed Calibration can be done by using the engine or by using 8T5200 Signal Generator/Counter Group. To calibrate overspeed using the engine follow this procedure. To calibrate overspeed using the 8T5200 refer to P-553 ESS Overspeed Test.
1. Remove lockwire and seal from seal screws (4 and 5). Remove seal screw (4) from access hole for overspeed adjustment screw.
2. Use a small screwdriver and lightly turn O.S. (overspeed) adjustment potentiometer twenty turns in the direction of "MAX ARROW" (clockwise).
NOTE: The overspeed adjustment screw is made so that it can not cause damage to the potentiometer or be removed if the adjustment screw is turned too much.
3. Run engine at 75% of overspeed setting rpm, pMake reference to the SPEED SPECIFICATION CHART on next page.
4. With engine at 75% of overspeed setting rpm, push VERIFY pushbutton (1) and hold in. Turn O.S. (overspeed) adjustment potentiometer in the direction of "MAX ARROW" (counterclockwise) slowly until "LED" overspeed light (3) comes on. Engine will shut down since speed switch is connected to the fuel shutoff solenoid.
5. To reset speed switch, push in reset button (2).
6. Slowly turn O.S. (overspeed) adjustment potentiometer approximately one turn clockwise and repeat Steps 3, 4 and 5.
NOTE: More adjustment may be needed to get the correct setting. Turn adjustment potentiometer clockwise to increase speed setting and counterclockwise to decrease speed setting. Turn adjustment potentiometer very slowly only a small amount at a time until adjustment is correct.
7. When the speed setting is correct, install seal screw (4) for overspeed adjustment hole and install lockwire and seal.
Note A: To verify overspeed shutdown system operation, push in for a moment the verify push button. The engine must shut down at 75% or more of overspeed setting.
Note B: Input Voltage: Maximum 37 VDC Minimum 8 VDC
Note C: The magnetic pickup frequency (Hz) at the overspeed or cranking termination setting is calculated with the formula that follows:
MAGNETIC PICKUP FREQUENCY = NO. OF TEETH ON RING GEAR X OVERSPEED OR CRANKING TERMINATION RPM SETTING + 60