TM 5-4310-368-14
of air per minute) at 3500 PSI (pounds per square inch pressure) when driven at 1300 RPM (revolutions per minute).
Suppressed idle speed unloading allows the engine to return to idle speed at the same time the unloading system for
the compression system opens to atmosphere, permitting the compressor to run free and stop delivering compressed
air. This happens when the air in the air receiver reaches a pressure of 3500 PSI. When the air pressure in the air
receiver is reduced to about 3200 PSI, the engine speed returns to its full load speed and the compressor pumps
compressed air into the receiver.
Each stage of the compressor is connected to the next higher stage by means of an intercooler tube. The discharge
of the fourth stage is connected to an aftercooler. The purpose of the intercoolers and aftercooler is to improve the
efficiency of the compressor. An oil and moisture separator is installed at the cool end of each cooler to remove the
condensed oil and water vapors produced by the coolers. A drain system with instrument panel control is provided to
drain the accumulation of oil and water in the separators. All four separators are drained at the same time by the
single instrument panel control.
Two air dehydrator cylinders are provided. These chemically reduce the moisture in the compressed air.
c.
Engine. The engine is an air cooled, four cylinder, V-configuration, four stroke cycle, spark ignition, gasoline fueled,
standard commercial type engine modified for military use. Those modifications include electric starting, radio noise
suppression on the ignition system and automatic shutdown systems to stop the engine in case of loss of oil pressure
or high cylinder head temperature. The engine develops a maximum of 29.5 BHP (brake horsepower) at 2800 RPM.
The engine is equipped with an automatic, two speed, solenoid operated governor system. This ensures that the
engine will be operated at only the correct speeds for proper compressor operation.
A multi-disc, oil filled manual clutch is attached to the engine. This permits starting and operation of the engine
without operating the compressor. All engine controls are located at the instrument panel.
d. Air Receiver. The air receiver for the air compressor has a capacity of approximately 1300 cubic inches (.752 cubic
feet or 21.3 liters). It has a maximum working pressure of 3500 PSI. It is certified for conformance to the ASME
(American Society of Mechanical Engineers) code for Unfired Pressure Vessels. The air receiver is equipped with an
instrument panel mounted manual drain valve. In addition, an automatic dump system is provided which will release
all compressed air from the receiver whenever the engine is shut off.
e. Fuel Tank. The frame mounted fuel tank has a capacity adequate for approximately 8 hours continuous operation.
An instrumental panel mounted fuel level indicator is provided. A filter screen is installed in the fuel fill neck of the
tank. A drain plug is installed in the bottom of the fuel tank to permit draining. The tank has an internal baffle to
prevent excessive sloshing of fuel during filling, operation and transportation.
f.
Compartment Heater. An electrically controlled, gasoline fired heater is provided. This heater is intended for use in
very cold weather. The heater is equipped with ducts to direct the hot air to the engine crankcase, compressor
crankcase, battery and general enclosure. A separate electric fuel pump delivers gasoline from the engine fuel tank
to the heater. Operating controls for the heater are installed at the instrument panel.
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