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

Page: 32 / 206

F. Engine Control Panel (See Fig. 9)
The engine control panel is mounted directly below the control box. In addition to engine controls and
instruments, generator output controls are mounted here. A plexiglass window in the canopy rear
door, slants outward at the bottom to form an opening for access to controls when the door is closed.
(1) Engine instruments
Engine operation is monitored by an ammeter (4) , a coolant temperature gage (8) , and an oil pres-
sure gage (10) . An hourmeter (6) records engine operating time.
(a) Ammeter
The ammeter (4) indicates the direction and value of current flow in the 12-V DC electrical
system. Its graduated range is from -60 A through 0 A, to +60 A.
(b) Temperature gage
The temperature gage (8) is a mechanical type of unit construction. It consists of a panel
mounted indicating mechanism which is connected by a capillary tube to a bulb mounted in
the engine cooling system. The gage indicates engine coolant temperature in the range of
100F to 220F.
(c) Oil pressure gage and oil pressure switch
The oil pressure gage (10) is a bourdon tube type and indicates engine lubricating oil pres-
sure. It is graduated from 0 PSI to 75 PSI. An oil pressure switch is mounted in a tee fitting di-
rectly behind the gage. The switch connects 12-V DC power to the engine control system and
to the generator 12-V DC control system when the engine is running.
(d) Hourmeter
The hourmeter (6) is electrically driven from the 12-V DC battery system. The hourmeter
measures and records engine running time and will record up to 9999.9 hours on five revolv-
ing drums. The hourmeter operates only when the engine is running and the oil pressure
switch is closed.
(e) Fuel gage and blocking diodes
An electric fuel gage (2, Fig. 9) accurately indicates the quantity of fuel oil in the tank pro-
vided for the generator set. A sending unit mounted in the trailer or truck mounted unit fuel
tank supplies the signal to the gage. Twelve-volt DC operating power is supplied to the fuel
gage from two sources. The gage functions when the engine is running, or when the instru-
ment lights are ON. Since two power sources are connected to the fuel gage system, a block-
ing diode
(18)
is required in each power source circuit. One diode prevents energizing the
motor-generator control circuit when panel lights are ON. Another diode prevents operation of
the panel lights by the engine-generator circuit when the engine is running. To check fuel
quantity when engine is stopped, use switch
(3) to turn ON panel lights.
(2) Engine and generator controls
(a) Engine-generator control switch
The engine-generator control switch (5) (also identified as the “build-up-voltage, generate,
idle” switch) is a three-position toggle type. It is spring-loaded in one position, BUILD-UP-
VOLTAGE, and will automatically reposition to GENERATE position when released. In
BUILD-UP-VOLTS position it performs a dual function. First, it supplies power to the gover-
nor control box, which allows the engine to operate at normal governed speed; second, it mo-
mentarily supplies current for closing the excitation-deenergization relay
(3, Fig. 7) contacts,
to make three-phase, 115-V AC power available to the voltage regulator, or to the manual
voltage control circuit for excitation of the generator exciter.
OM-2028
1-1 May 1/91 Revised
Page 18