PUMP   NEUTRAL   ADJUSTMENT     (continued   from page 6) •7. If the transmission operates as shown by motor shaft  rotation,  reduce  speed  to  idle.    Using  a 3/16inch  internal  hex  wrench,  slowly  turn  the null adjustment screw clockwise or counterclockwise until the transmission does  not  operate.    Repeat  step  6.    Note  that charge  pressure  should  drop  approximately  20 psi with forward or reverse stroking of the pump swashplate   due   to   the   shifting   of   the   shuttle valve in the motor manifold. •8. With a 3/16-inch internal the wrench, slowly turn the   null   adjustment   screw   clockwise until charge   pressure   begins   to   decrease.      Then slowly turn the adjustment screw counterclockwise ,  observing  the  angle  of rotation,  until  charge  pressure  decreases  again (charge  pressure  will  rise  in  neutral  and  drop when going into stroke). ORDERING INFORMATION A  range  of  options  to  the  basic  HDC  allows  it  to  be custom-tailored   to   each   application.      The   control   is specified by filling in each slot of the order number, as is shown  in  Table  B,  with  the  appropriate  model  code. Other options are possible.  Consult Sundstrand Mobile Controls with further questions. TABLE B.  INFORMATION NECESSARY TO SPECIFY THE HYDRAULIC DISPLACEMENT CONTROL. 1. DEVICE IDENTITY This  is  the  basic  HDC.    The  model  code  is MCV106A. 2. CONFIGURATION (including assembly kit) PRESSURE WITH MODEL LIMITER OR ANNULAR CODE PRESSURE CONTROL OVERRIDE 5 NO* NO 6 NO YES 7 YES* NO 8 YES* YES *PRESSURE OVERRIDE ONLY **MODEL CODE 7 DEVICES MAY NOT BE USED ON SERIES   3X   PUMPS   IF   ORDERED   LESS   LINKAGE ASSEMBLY ("9” UNDER THE SERIES PARAMETER). •9. Turn  the  adjustment  screw  clockwise half the amount of the turn observed in step 8.  This should be the center of neutral. •10. Hold the adjustment screw and securely tighten the hex lock nut on the adjustment screw to 14- 18  foot-pounds.    Note  that  if  a  motor  is  used which does not have a manifold, neutral should be adjusted (steps 810) by observing the motor output shaft rotation without a load. •11. Stop the prime mover. •12. Run  the  system  briefly  to  ensure  that  it operates  proportionally  on  both  sides  of the null command. Swashplate movement  can  be  verified  by  watching movement   of   the   swashplate   feedback shaft,  shown  in  Figure  1.  The  Pressure Override and Pressure Limiter accomplish the   same   function-they   shift   the   pump swashplate  toward  neutral  when  system pressure    crosses    a    pre-set    threshold. They  thus  limit  system  pressure,  protect components  from  heat  generated  by  flow across  relief  valves  and  conserve  pump horsepower. Pressure override is available only for Series 2X pumps, and  pressure  limiting  is  available  only  for  Series  3X pumps.    Pressure  limiting  and  annular  control  are  not available together.  If the model code chosen indicates that  the  pressure  override/pressure  limiting  function  is desired (i.e., "yes" is chosen in the second column of the configuration  parameter,  above),  only  pressure  limiting will be provided directly by Sundstrand Mobile Controls (pressure   limiting   is   accomplished   using   a   different porting  spool);  the  Pressure  Override  Valve  must  be obtained  through  Sundstrand  Hydrotransmission.    See below. Stroke  controls  with  annular  control  have  a  groove  cut into the spool bore of the housing that allows for higher flow  from  the  control  ports  when  they  are  uncovered, increasing swashplate response. Kits  are  needed  in  order  to  install  the  HDC  onto  the pump.    Which  kit  is  shipped  with  the  HDC  depends  on which  pump  series  is  ordered.    Included  in  the  kit  are: retaining  rings,  swashplate  pin,  drag  link,  orifice,  hex screws, O-rings and gasket.  In some cases not all of the above  are  necessary  for  installation,  and  they  are  not included  with  the  kit.    Individual  drag  links  will  not  be supplied  by  Sundstrand.    Consult  Mobile  Controls  for replacement parts. ORDERING INFORMATION (continued page 8) Sundstrand Mobile Controls 95-8972 248