ARMY TM 9-6115-604-12
NAVY NAVFAC P-8-633-12
(3)
Air box shutdown relays L2A and L2B will energize to close the air control valves in the air intake
duct lines to the engine air intake manifold. The engine, cut off from its air supply, will decelerate
very rapidly. Solenoids L2A and L2B are not rated for continuous duty, air box disconnect switch
OP3 will disconnect the solenoids from ground as soon as failing engine oil pressure allows OP3 to
open. When OP3 does open, solenoids L2A and L2B deenergize. The back-EMf caused by their
collapsing fields will be shorted by diode CR3. This prevents arcing from occurring at the contacts of
pushbutton S7.
i.
EMERGENCY SHUTDOWN Control. The EMERGENCY SHUTDOWN control is mounted on the left side
of the skid base below the engine compartment access doors. It is a mechanical pull which cuts off fuel to
the engine. The resulting loss of engine speed rapidly leads to the tripping of a shutdown circuit as the
voltage and frequency output of generator G1 falls.
4-20. MAINTENANCE OF BATTERY CHARGER . Battery charger BC1 provides 24 V dc to charge the generator set
batteries. Maintenance of the battery charger consists of testing, adjustment, and replacement.
a.
Test See Figure 4-26.
(1)
Test the ac input fuse ACF and dc output fuse DCF as follows:
(a)
Set BATTERY CHARGER circuit breaker CB116 to OFF.
(b) Remove the ac input fuse ACF and dc output fuse DCF from the fuse board inside the battery
charger BC1.
(c) Using a multimeter set to the RX1 scale, check continuity across both fuses. Multimeter should
indicate zero resistance.
(2)
Test the dc AMMETER A as follows.
(a)
Set BATTERY CHARGER circuit breaker CB116 to OFF.
(b)
Remove battery charger leads from the battery.
(c)
Install a multimeter set to read dc amps across + and - output leads from the battery charger
BC1.
(d)
Set BATTERY CHARGER circuit breaker CB116 to ON and set equalizer TIMER ET to ON.
(e)
DC AMMETER A reading should be within 5 percent of multimeter installed In step b, above.
(f)
Reinstall battery charger leads.
(3)
Test Input and output voltages as follows:
(a)
Set BATTERY CHARGER circuit breaker CB116 to OFF.
(b)
Install a multimeter set to read AC volts across the input leads to battery charger BC1.
(c)
Set BATTERY CHARGER circuit breaker CB116 to ON.
(d)
AC multimeter reading should be 120 V ac.
(e)
Set BATTERY CHARGER circuit breaker CB116 to OFF.
(f)
Install a multimeter set to read dc volts across the + and - output leads from battery charger
BC1.
(g)
Set BATTERY CHARGER circuit breaker CB116 to ON and set equalizer TIMER ET to ON.
(h)
Multimeter should read 27 2 V dc.
b.
Remove. See Figure 4-26.
(1)
Set BATTERY CHARGER circuit breaker CB116 to OFF.
(2)
Tag and disconnect wiring to the battery charger BC1 (5).
(3)
Remove the battery charger BC1 (5) and drip shield cover (4) by removing hexagonal nuts (2), lock
washers (3), and vibration isolators (1) at base of the battery charger BC1. Loosen the hexagonal nuts (2)
and lock washers (3) at the top of the battery charger BC1, and lift the battery charger BC1 upward and
away from the upper vibration isolators (1).
4-72
