(2) Connect the battery cable (4) and wire assembly (5), from ammeter to magnetic switch to one switch
terminal and the starter cable (8) to the other. Connect the wire assembly (6) from starting switch to
magnetic switch and ground wire assembly (7) to the proper coil terminals as shown.
Section IX. INSTRUMENT PANEL
100. Description
The instrument panel is bracket-mounted to the air receiver at the rear of the engine-compressor (fig. 13). A hinged
door swings down to expose the instruments when the unit is in operation.
a. Ammeter. The ammeter indicates battery charge or discharge rate and thus provides a check on the electrical
system of the engine-compressor. When the unit is running at normal speed, the ammeter needle should be in the charge
range. If the ammeter indicates a continuous discharge, the generator, voltage regulator and batteries must be checked to
determine the cause.
b. Starting Switch. The push-button type starting switch is located to the right of ammeter. When the starting button
is pressed, the electrical circuit is completed from the batteries to the magnetic switch. The magnetic switch, in turn, is
energized to complete the circuit between the batteries and the starting motor. The starting motor pinion (Bendix drive)
then engages the flywheel ring gear to start the engine.
c. Hourmeter. The electrically-operated hourmeter is connected to the ignition switch and operates only when the
engine-compressor is in operation. It thus provides an accurate record of elapsed operating time and serves to remind the
operator when to perform the required preventive maintenance services.
d. Ignition Switch. When the lever handle of the ignition switch is snapped to the left, it completes the primary circuit
leading from the battery through the ammeter to the ignition coil. The switch must be turned on before the engine can be
started, and it shuts off the engine when the lever is snapped back to the vertical position.
e. Air Pressure Gage. The air pressure gage indicates the pressure of air within the air receiver. Normal air
pressure readings are 90 psi at the start of the "loading" cycle and 100 psi at the beginning of the "unloading" cycle.
f. Pilot Light. The pilot light is connected to the ignition switch and will glow only when the switch is on. This will
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