Low Oil Pressure warning Light. The warning light acts as a warn-
ing to the operator if the engine oil pressure becomes too low for
safe operation of the engine. The warning light will glow red when
the battery switch is turned on, and will not g1OW when the engine
is running". If the engine oil pressure drops to 10 psi, the warning
light will glow and the engine must be stopped to prevent damage.
Air Pressure Gage. The gage (fig. 2-3) shows the amount of air
pressure in the shop set air system. During normal operation, it
should read between 125 psi and 150 psi.
Relief Valve. The relief valve (fig. 23) is a safety device to
protect the air system and personnel if a malfunction occurs that will
cause the pressure in the air system to exceed a safe working pres-
sure. The relief valve will open to let the air pressure escape from
the system when air pressure of 180 psi is reached.
Pressure Switch. The switch (fig. 2-3) is a pressure-operated elec-
tric switch that automatically starts and stops the air compressor to
maintain a minimum of 125 psi and a maximum of 150 psi.
Start, Stop, and Reset Switch. The switches (fig. 2-3) are used to
start and stop the air compressor system. The reset switch will
automatically disengage when a mechanical or electrical malfunction
occurs in the air system that causes the electrical circuit to be over
AC Voltmeter. The AC voltmeter (fig. 2-4) indicates the AC voltage
output of the generator portion of the dynamotor-welder, when the
dynamotor-welder is driven by the shop set engine. The output
voltae is regulated by the AC voltage adjusting rheostat, and the
AC voltmter indicates the adusted voltage, which will normally be
240 volts. The same AC voltmeter will indicate only the incoming
voltage when an external source of electrical power is used to run
the dynamotor-welder; or for the emergency circuits, normally 240
volts for the dynamotorwelder and 120 volts for the emergency cir-
Dynamotor Start-Stop Switch. This switch (fig. 2-4) is used to
start and stop the dynamotor-welder when an external electrical
power source is used, and also to close the contractor to provide
AC power when the dynamotor-welder is driven by the shop set en-
gine . To operate the switch, press the button momentarily to stop
AC Voltage Adjusting Rheostat. This rheostat (fig. 2-4) regulates
only the output AC voltage of the generator portion of the dynamo-
tor-welder, from the minimum to the maximum. Turn handle clock-
wise to increase and counterclockwise to decrease AC voltage.
Frequency Switch. The frequency switch (fig. 2-4) should be set
on 60 hertz if 60 hertz external power is used to run the dynamotor-
welder; or, if' the engine governor is adjusted so that the shop set
engine will run at 1,800 rpm to cause the dynamotor-welder to devel-
op 60 hertz AC current. The switch should be set on 50 hertz if
50 hertz external power is used.