TM  10-3930-638-24&P b. Instrument Panel Switches and Gage Lights (cont). 5. IGNITION SWITCH. Four position key switch; unmarked position (key turned to left) applies power to VEHICLE LIGHTS switch enabling lights to be turned on; OFF position disconnects power from ignition and light system;  ON  position  applies  power  to  VEHICLE  LIGHTS switch. gages. indicators (oil pressure and alternator lamps will illuminate), fuel pump. fuel injection pump, back-up 1-20.   TRANSMISSION   AND   DRIVE SHAFTS alarm  switch,  and  START  swith;  LAMP  TEST  position applies  power  to  illuminate  HYDRAULIC  FILTER, transmission temperature, and engine temperature indicators. 6. START SWITCH. Applies power to energize starter relay by means of lockout relay and neutral start switch. With starter relay energized, starter solenoid energizes, in turn, cranking starter motor to start engine. 1.  FRONT  DRIVE  SHAFT.  Connected  between center drive shaft and front axle; connected to front axle yoke by universal joint and to center drive shaft by a yoke with internal splines. Rear of front drive shaft is supported  by  a  bearing. 2.  CENTER  DRIVE  SHAFT.  Connected  between transmission  output  shaft  and  front  drive  shaft.  Connection accomplished  by  universal  joints. 3. REAR DRIVE SHAFT. Connected between trans- mission output shaft and rear axle by universal joints. 4. TORQUE CONVERTER. Integral part of trans- mission;  multiplies  engine  power. 5. TRANSMISSION. Consists of torque converter, transmission,  charging  pump  and  filter,  control  valve assembly,  modulation  valve,  and  parking  brake.  Includes declutch feature which neutralizes transmission. This accomplished by declutch valve spool in control valve assembly. Flow of hydraulic oil to declutch valve spool is controlled by declutch valve, which is mechanically linked to operator’s declutch pedal. 6.  CHARGING  PUMP  AND  FILTER.  Draws  oil  from transmission  sump  through  oil  suction  screen  and  directs the oil through pressure regulating valve and filter. Filter removes  impurities  from  oil. 7.  CONTROL  VALVE  ASSEMBLY.  Directs  oil  under pressure  to  the  desired  directional  and  speed  clutch. Directional and speed control valves connected by push- pull  type  cables  to  operator’s  transmission  direction  and speed selector levers. 8. AXLE DISCONNECT. Controls engagement and disengagement  of  transmission  drive  to  front  and  rear axles. Pulling lever outward disconnects drive to front and rear axles; pushing lever inward engages drive. This is used only when the truck is to be towed to a new location. 9.  TRANSMISSION  OIL  COOLER.  Mounted  at  rear of  truck,  in  front  of  radiator;  cools  transmission  hydraulic oil. 1-11