ARMY TM 9-2805-257-14 AIR FORCE TO 38G2-103-2 NAVY NAVFAC P-8-612-14E 1-12. Differences  Between  Models.  All four models of the Military Standard are the same except for the following  differences: a. b. c. d. Models 2A016-1, -2 are equipped with wet air cleaners. Models 2A016-3, -4 have dry air cleaners with service  indicators. Model 2A016-1 is equipped with stop button. Models 2A016-2, -3, -4 are equipped with ignition switches. Model 2A016-4 has a breakerless ignition system. Models 2A016-1, -2, -3 have a breaker point system with condenser. Models 2A016-2, -3, -4 are equipped with throttle controls. 1-13. Safety, Care, and Handling. Observe all WARNINGS, CAUTIONS and NOTES in this manual. This equipment  can  be  extremely  dangerous  if  these  instructions  are  not  followed. Section Ill. PRINCIPLES OF OPERATION 1-14. Principles  of  Operation. a. General. The 3 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.  Simplified  Principles  of  Operation. A starter flange, on the flywheel fan, provides a means to connect the starter rope for pull starting the engine. An inline fuel filter cleans the fuel supplied to the engine. The filter comes equipped with a fuel cutoff valve, that when closed, stops fuel flow to the engine. The engine comes equipped with either an oil bath or a dry element air cleaner. Both types of air cleaners provide the same amount of filtering, but the dry element air cleaner has two unique features, a built in service indicator and an air inlet control. The service indicator signals when the element requires cleaning. The inlet temperature control varies the amount of unheated air entering the air cleaner. On model 2A016-1 a stop button is used to terminate engine operation. models 2A016-2, -3 and -4 a two position ignition switch is used. When the switch is in the RUN position the engine can be started. Setting the switch to OFF terminates engine operation c. Detailed  Principles  of  Operation. On (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 drains fuel from an external fuel supply through the fuel filter, and delivers it to the carburetor. The fuel pump, a diaphragm type, is driven by the camshaft. The fuel pump can be operated manually, using the priming lever. This allows the fuel system, between the pump and the carburetor, to be primed before starting the engine. 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) Cooling system.  The flywheel fan draws cool air into the flywheel fan cover, where it is then directed by the cylinder head covers, and oil pan cover. The air flows around the cylinder and cylinder head assembly and cools the engine. 1-8