Hobart Brothers 6910, Operation And Maintenance Manual With Illustrated Parts List

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In GENERATE position, power is maintained to the governor control box and to the excitation
relay
(3, Fig. 7)
. When the switch is placed in IDLE position, power is disconnected so that
the engine returns to idle speed and the exciter field is deenergized.
(b) Contactor control switch
This is another three-position, toggle switch (7, Fig. 9) identical to the engine-generator con-
trol switch. When placed in the spring loaded CLOSE position, it provides 115-V AC power di-
rectly to a rectifier which supplies DC power for closing the load contactor. When released it
returns to the normal ON position and continues to provide power to the rectifier, but in this
switch position, AC power must pass through the plug interlock and fuse interlock relays. In
OFF position the switch opens the AC circuit to the rectifier, thereby cutting off the source of
DC power to the contactor coil which allows the contactor to open.
(c) Instrument light and switch
A shielded, instrument panel light (1) is mounted at the left side of the control panel. It is con-
trolled by a toggle switch
(3)
, which also controls instrument lights on the control box.
(d) Engine starting circuit
The pushbutton start switch
(15)
and permissive toggle switch
(18)
serve to connect power
for closing an auxiliary solenoid switch. The auxiliary switch then connects power to the
starter solenoid which functions to engage the starter gear with the flywheel ring gear and ap-
ply power to the starter motor to crank the engine. The auxiliary solenoid switch is necessary
because the start pushbutton switch is not capable of carrying the high amperage flow to the
starter solenoid which would result if the starter gear and ring gear should fail to engage. The
permissive toggle switch
(18) also stops the engine when the toggle is placed in the down
(STOP) position.
(e) Indicating lights
A green indicating light (14) glows to indicate that power is available to the engine protective
system. The light operates only when the engine is running and fuel pressure is sufficiently
high to close a fuel pressure switch. The purpose of the pressure switch is to deactivate the
protective circuit when the engine is stopped and prevent battery discharge. Another green
indicating light
(9, Fig. 9) glows when the generator output load contactor is CLOSED and
power is available at the generator output terminal panel (13, Fig. 3).
(f) Cold weather starting aid control
The push-pull control (11) controls operation of a cold weather starting aid (Fig. 3). The start-
ing aid consists of a group of items designed to inject a highly volatile fluid into the engine air
intake system to assist ignition of fuel when air temperature is too low for the heat of compres-
sion to ignite a normal fuel mixture. The starting aid consists of a cylindrical, fluid container
and a valve
(see 1-3, Fig. 4) which are mounted on the lifting yoke. The valve is operated by
the control (11, Fig. 9) . Pulling the control outward allows fluid to flow into the valve. Pushing
the control IN forces fluid through a small tube and an atomizing nozzle into the inlet mani-
fold. The addition of atomized, highly volatile fuel into the inlet air assists in igniting the diesel
fuel mixture.
(g) Fuse
A 10-ampere fuse (13) protects the 12-V DC engine control circuit, hourmeter, illuminating
light circuit, and 12-V DC system in the main generator protective system.
(3) Air cleaner indicator
The air cleaner indicator (12) is mounted on the engine control panel for easy viewing. Its function
was explained in Para. 6, C,
(3) (see Fig. 6).
OM-2028
May 1/91 Revised 1-1
Page 19