TM 9-2350-256-34-1 b. Powerplant  The  powerplant  is  composed  of  the Continental     Model     AVDS-1790-2DR     air-cooled,     12- cylinder,  diesel  engine  and  the  Allison  (GM)  Model  XT- 1410-4    cross-drive    transmission.    The    powerplant    is removed  and  installed  as  a  unit.  Separation  of  engine from  transmission  center  section  is  performed  after  the powerplant   has   been   removed   from   the   vehicle.   The powerplant supplies electrical power through a generator and motive power through the output reduction units. c. Fuel System. The fuel system includes liquid fuel (diesel)    storage    and    delivery    system.    Fuel    storage consists  of  three  separate  fuel  tanks.  Fuel  is  fed  to  the engine  by  an  electric  pump  through  a  system  of  hoses and valves. Fuel is strained at the tank filler openings as the  tanks  are  filled,  and  filtered  through  separate  and renewable   filter   elements   as   it   is   fed   to   the   engine. Combustion air is cleaned by two air cleaners and driven into the engine intake manifolds by two turbosuperchargers. d. Fuel   Tanks.   All   tanks   are   of   a   welded   steel construction. The left rear tank contains the filler cap and filter  assembly.  Fuel  level  sending  units  are  contained within  the  right  rear  and  forward  tanks.  An  electric  fuel pump  is  located  in  the  forward  fuel  tank  sump  cavity, allowing   complete   drainage   of   the   tank   before   tank removal.     All     tanks     are     interconnected     and     shock mounted.    Grounding    straps    are    provided    to    assure discharge of any static electricity which might accumulate. e. Fuel Pump. The electric fuel pump located in the forward fuel tank sump cavity is a centrifugal pusher-type pump designed for submerged operation. It is hermetically  sealed  and  contains  a  24-volt  dc  motor  to operate  the  pump.  A  strainer  is  provided  as  an  integral part of the pump assembly for efficient fuel filtering. The fuel   pump   is   shock   mounted   in   a   support   assembly which   suspends   the   pump   in   the   fuel   tank   and   also provides a housing for fuel and electrical connections. f. Purge  Pump.  The  purge  pump  (fig.  3-8)  handle is located on the floor to the left of the driver’s position. The purge pump is used to pump air from the fuel lines and to facilitate engine starting in cold weather. g. Vehicle Electrical Systems. (1) Main    Engine    Generator    System.    During periods  of  main  engine  operation,  the  vehicle  electrical system derives its power from a 300-ampere, 28-volt dc generator    and    is    driven    by    the    main    engine.    This generator   also   serves   to   charge   the   vehicle   batteries during periods of main engine operation. The vehicle battery system consists of six 12-volt, 100-ampere-hour  batteries  connected  in  series-parallel to  supply  24  volts  dc  to  the  electrical  system  when  the generator  is  not  running.  A  solid  state  voltage  regulator serves to maintain a constant generator output voltage of 28  +0.7  volts  dc  when   the   generator   is   powering   the electrical   system   and   charging   the   vehicle   batteries. Control   of   the   electrical   system   is   maintained   by   the driver   through   a   series   of   instruments   and   switches mounted on control panels in the driver’s area. A system of electrical harnesses interconnects the various components of the vehicle electrical system. Waterproof connections are provided for harnesses and components. (2)   Auxiliary     Generating     System. The auxiliary generating  system  consists   of   a   dc   voltage   generator (fig. 4-1) driven by a diesel engine. A solid-state voltage regulator serves to maintain a constant generator output voltage   of   28   ±   0.7   volts   dc   when   the   generator   is powering  the  system  and  charging  the  batteries.  This voltage  regulator  has  an  internal  current  limiting  circuit which  the  APU  generator  interpole  (APU  regulator  plug pin E) voltage to 0.48 + 0.03 vdc. This corresponds to a nominally  regulated  generator  output  of  160  amps  dc, with a maximum generator output of 180 amps dc. (3)   New  Dual  Voltage  Regulator  System.  The  main and   auxiliary    engine    can    be    operated    together    or individually as desired to recharge the vehicle batteries. (a) With the new dual voltage regulator system, during   periods   of   cold   weather   starting,   the   auxiliary engine  can  now  be  started  and  left  running  to  aid  the vehicle battery charge condition, while attempting to start the main engine. (b) Deleted. (c) Deleted. (d) Deleted. (e) Deleted. (4) Deleted (5) Deleted (6) Deleted 1-12  CHANGE 7