TM      10-4320-343-14 filter   housing   and   directs   oil   to   the   injection   pump. Excess   oil   in   the   injection pump  spills  into  the  timing  cover. In   addition,   the   low   oil   pressure   switch   and sending   unit   are   located   at   the   oil   filter   housing   discharge. The   oil   pressure switch   is   set   to   automatically   open   when   the   oil   pressure   drops   below   4   psi (27.579   kPa). 1.14.2.5.3         Cooling Fan. The   cooling   fan   is   attached   to   the   engine   and   is   driven   by   a V-belt   connected   to   the   drive   pulley. The   cooling   fan   causes   forced   air   flow across   the   top   of   the   engine   cylinder   heads   and   oil   cooling   coil. Forced   air   flow cools   the   cylinder   heads   and   oil. This   cooling   process   prevents   overheating   of   the engine. 1.14.2.5.4        Cylinder Head and Valves. The  350  GPM  Pumping  Assembly  uses  three  cylinder heads. Each  cylinder  head  functions  the  same  and  can  be  removed  separately. The cylinder   head   contains   an   intake   valve   and   exhaust   valve. The   intake   and   exhaust valves   open   and   close   intake   and   exhaust   ports. The   intake   port   is   connected   to the   intake   manifold   and   the   exhaust   port   is   connected   to   the   exhaust   manifold. 1.14.2.5.5        Crankshaft Block. The   crankshaft   block   provides   mounting   for   various   engine components. It   has   an   intake   manifold   that   provides   a   connection   to   air   assembly. Air   is   taken   from   the   air   assembly   through   the   intake   manifold   into   the   combustion chamber   of   the   cylinder   head. A   breather   pipe   is   connected   to   release   gases   from the   combustion   chamber   to   prevent   excess   pressure   buildup. 1.14.2.5.6      Camshaft and Timing Gears. The   camshaft   and   timing   gears   control   valve opening  and  closing  times. The   speed   at   which   valves   open   and   close   is   also determined  by  the  camshaft  and  timing  gears. The   time   at   which   valves   open   and   close   (valve   timing)   and   duration   of   valve opening   are   stated   in   degrees   of   crankshaft   rotation. Timing  is  determined  by  the timing   gears. Timing   gears   are   driven   by   the   engine’s   camshaft. The  engine’s camshaft   drives   the   engine   components   that   close   the   intake   and   exhaust   valves.   In addition, timing   gears   control   the   fuel   infection   and   oil   lubrication. Timing  of the   engine   is   critical   to   prevent   damage. 1.14.2.5.7          Pistons and Connecting Rods. The   pistons   are   connected   to   connecting   rods that  are  attached  to  the  crankshaft. The   pistons   provide   the   force   to   drive   the engine’s   flywheel. As   the   crankshaft   is   turned,   connecting   rods   force   the   pistons upward and downward. Since   the   pistons   are   in   sealed   cylinders,   the   pistons compress   air   that   is   brought   into   the   intake   openings   as   described   in paragraph   1.14.2.5.1. The   up   and   down   movement   of   pistons   forces   connecting   rods to   turn   the   crankshaft   and   flywheel. Refer   to   paragraph   1.14.2.5.1   for   a   more detailed   operation   of   the   four   stroke   piston   operation. 1.14.2.5.8       Crankshaft and Flywheel. The   crankshaft   and   flywheel   provide   transfer   of   heat energy   from   the   pistons   into   mechanical   energy. When   the   pistons   are   forced downward   by   the   ignition   of   fuel,   the   crankshaft   turns, causing   the   flywheel   to turn. In   addition,   the   crankshaft   forces   the   other   pistons   connected   to   the crankshaft   upward. Each   time   a   piston   is   forced   downward,   another  piston  is  forced to TDC. The  piston  at  TDC  causes  another  combustion  to  occur  and  is  forced downward. The  350  GPM  Pumping  Assembly  uses  three  pistons  that  are  timed  together by   timing   gears   connected   to   the   engines   camshaft. The   crankshaft   is   also connected   to   a   timing   gear   of   the   engine’s   camshaft. Each  time  the  crankshaft turns,    it   forces   the   camshaft   to   turn. The   pump   assembly   is   connected   to   the flywheel. Since  the  flywheel  must  turn  with  the  crankshaft,  the  pump  assembly  is driven   at   the   speed   of   the   engine. 1-19