TM   5-3805-258-24-1 S T E E R I N G      S Y S T E M S U P P L E M E N T A L     S T E E R I N G     S Y S T E M The main components for the supplemental steer- ing system are: supplemental steering pump (18), diverter valve (17) and flow switch (16). The supplemental steering pump is a ground dri- ven pump; it is turned as long as the machine moves. The pump gets its power from the output transfer gears of the transmission. When  the  engine  is  running,  primary  steering pump section (7) sends oil through diverter valve (17) to steering control valve (9). This oil is  used to operate  the  steering  cylinders. As soon as the machine starts to move, oil is also sent  from  supplemental  steering  pump  (18)  to  the diverter  valve.  When  the  machine  moves  and  the engine rpm is less than 1450 ± 150 rpm, the oil from the  supplemental  steering  pump  and  primary  steer- ing  pump  section  is  combined  (flows  together)  in the  diverter  valve.  This  oil  flows  from  the  diverter valve  to  the  steering  control  valve. When  the  machine  moves  and  the  engine  rpm  is more than 1450 ± 150 rpm, the diverter valve sends the   oil   from   the   supplemental   pump   back   to   the hydraulic  tank.  The  oil  supply  for  the  steering  con- trol   valve   will   then   come   only   from   the   primary steering   pump   section.   If,   under   this   condition, there  is  a  primary  steering  pump  failure,  the  diver- ter   valve   will   immediately   send   the   oil   from   the supplemental  pump  back  to  the  steering  control valve. Flow switch ( 16) is installed on the elbow for the primary steering pump section. It is shown on the schematic  between  the  primary  steering  pump  sec- tion and diverter valve. This flow switch warns the operator of a failure of the primary steering pump section or lines. DIVERTER  VALVE The main components of the diverter valve are: diverter spool (1), check valves (8) and (11), and reversing  spool  (14). When the engine is running, the oil from the pri- mary steering pump section goes through inlet (10) and orifice (7) to check valve (8). The force of the oil opens the check valve. The oil flows past the check valve, and through outlet (5) to the steering control valve. Check valve (11) will not let the primary oil flow into passage (3). The pressure of the oil before orifice (7) is more than the pressure of the oil after the orifice. These pressures are also felt through passage (9) and (6) respectively. S  Y  S  T  E  M  S       O  P  E  R  A  T  I  O N DIVERTER   VALVE   SCHEMATIC (Low   Idle  and   Machina   ia   Stopped) 1.  Diverter  spool.   2.   Return   paasage   to  hydraulic   tank.   3. Passage.   4.  Spring.   5.  Outlet   to  steering   control   valve.  6. Paasage.    7.    Orifice.    6.   Check    valve.   9.   Paasage.   10.   Inlet from   primary   steering   pump   section.   11.  Check  valve.  12. Supply     paasage     for    supplemental      steering     pump.     13. Spring.    14.   Reversing    spool.    15.   Paeaage    to   left   end    of spool.   16.  Paasage.   17.  Paasage.  18.  Paaaage   to  right  and of  spool. The  pressure  of  the  oil  is  the  same  before  the orifice and to the left end of diverter spool (1). The pressure of the oil after the orifice is the same as the pressure of the oil to the right end of the spool. As  the  engine  rpm  increases,  the  flow  from  the primary  steering  pump  section  increases  also.  Be- cause  of  this  increased  flow  past  orifice  (7),  there is  an  increase  in  the  difference  of  the  oil  pressure before  and  after  the  orifice.  When  the  force  of  the oil on the left end of the spool is more than the total force of the oil and the spring on the right  end,  the diverter spool will move to the right. This takes place when the engine rpm is 1450 ± 150 rpm. There is no oil sent from the supplemental steering pump  until  the  machine  moves.  When  the  machine moves, the pump is turned by the output transfer gears. Oil from the hydraulic tank is supplied to the supplemental pump through passage (12). Oil flows from the hydraulic tank through passage (12), to reversing spool (14). When the machine moves in a forward direction, the supplemental pump sends pressure oil into pas- sage (17). The pressure of this oil is felt through 3-68