ARMY TM 9-2805-258-14
AIR FORCE TO 38G2-89-21
NAVY NAVFAC P-8-614-14E
Section Ill. PRINCIPLES OF OPERATION
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Principles of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...1-5
1-14. Principles of Operation.
a. G e n e r a l -. The 10 Hp Military Standard engine is a four cycle two cylinder, air cooled, gasoline powered
internal combustion engine. The engine develops its full rated capacity at a governed 3600 r.p.m.
b. Simplifed Principles of Operation.
The engine can either be pull started, or started using the electric
starter. A starter rope pulley mounted on the front of the engine provides a means to connect the starter when pull
starting the engine. When the engine is mounted to an end item that has a separate power supply, the electric
starter can be used to start the engine. An inline fuel filter cleans the fuel supplied to the engine. On the fuel filter
is a fuel cutoff valve, which stops fuel flow to the engine when closed. The engine is equipped with a dry element
air cleaner, with a service indicator, and air inlet control. The service indicator signals when the air cleaner
element requires cleaning. The air inlet control adjusts the amount of heated air entering the air cleaner. An oil
pan baffle directs the flow of cooling air. The baffle is usually set in the back or open position to allow cooling air
to flow around oil pan to help cool the engine. When the baffle is set to the forward or closed position, the cooling
air no longer flows around the oil pan and the engine will run warmer.
c. Detailed Principles of Operation.
(1) Fuel system. The fuel system is composed of a fuel filter, fuel pump, fuel line, and carburetor. The fuel
filter is a bowl type with a filtering screen. The screen filters dirt and other foreign materials from the fuel, The
fuel pump draws fuel from an external fuel supply through the fuel filter, and delivers it to the carburetor. The fuel
pump, a diaphragm type, driven by the camshaft. The carburetor mixes the air, from the air cleaner, and the fuel.
This is then delivered to the combustion chamber where it is compressed and burned.
(2) Coo/ing system. The flywheel fan draws cool air into the flywheel fan housing where it is then directed
by the top, left, and right shrouds, cylinder baffles, oil pan baffle, and oil pan cover. The airflows around the
cylinder heads, cylinders, and oil pan and cools the engine.
(3) Air supply. The air cleaner cleans the air going to the carburetor. The dry element air cleaner uses a
dry fiber element to remove dirt from the air. As the element gets dirty, airflow through it decreases and creates a
vacuum in the air cleaner. When airflow decreases too much, the service indicator shows a red signal and
indicates the element requires cleaning.
(4) Speed regulation. Both models of the engine are equipped with a centrifugal flyweight governor
connected to the carburetor by a control rod. The governor determines the fastest speed at which the engine will
run. The engines are equipped with a throttle control, which overrides the function of the governor. The throttle
control allows the engine speed to be adjusted between idle and full governed speed.
(5) Ignition system. A high voltage electrical charge is generated by a magneto, and is delivered to the
spark plug, in the cylinder head, through a shielded cable. The electrical charge creates a spark at the electrode
end of the spark plug. This spark ignites the air/fuel mixture in the cylinder, and generates power.