TM 10-3930-664-10 SECTION III Principles Of Operation 1-13. GENERAL This section explains how components of the 4KRTFL work together.  A functional description is given for the powertrain system, the fuel system, engine and transmission lubrication systems, engine and transmission cooling systems, electrical system, brake system, steering system, hydraulic system, and mast assembly. 1-14. POWERTRAIN SYSTEM ENGINE.  Diesel fueled, water cooled engine supplies power for moving the 4KRTFL and operating the gear pump for the hydraulic  system.    Converts  the  energy  from  burning  fuel  to  rotary  motion  to  drive  both  the  transmission  and  hydraulic pump. TRANSMISSION.  Driven by the engine through the use of an integral torque converter, which multiplies the power from the engine.  Through internal clutches and gears, provides power to drive the wheels in the selected direction and at the selected speed. DRIVESHAFTS.  Connected to the output shafts of the transmission and input flanges of the axles.  Transmits power from the transmission to the axles. AXLES.  Transfers the rotary motion from the driveshafts to the wheels and tires.  Turns the wheels In the direction and at the speed selected by the driver.  Single reduction planetary gear hubs at each wheel convert the high speed rotation of the axles to the lower speed needed to drive the wheels. DIFFERENTIAL  LOCK.    Hydraulically  operated  to  lock  the  two  front  wheels  together  so  that  they  turn  at  the  same  rate regardless of the traction at each wheel.  This operation overcomes spinning of one wheel due to loss of traction and the accompanying  loss  of  power  to  the  other  wheel.    With  engine  running,  a  toggle  switch  located  on  the  instrument  panel engages or disengages the differential lock.  In the ON position the switch activates a solenoid valve which hydraulically engages the differential lock. 1-8