TM10-3930-660-34 e. MLRS  Attachment  System.    The  MLRS  attachment  function  is  controlled  by  the  electric  joystick  and  the  MLRS control valve.  Hydraulic oil flow from the axial piston pump supplies oil pressure and flow for MLRS control valve pilot and function operations.  A load sensing line from the MLRS control valve to the piston pump adjusts the pump output.  Pilot shuttles in each valve section, allow the pressure of the function with the greatest load to be sensed by the pump.  As the load of the MLRS control valve changes, the position of the swash plate angle changes in the piston pump. When the electric joystick is in the center position, all solenoids of the MLRS control valve are de-energized and centering springs keep the control valve spools in the center (hold) position. By moving the electric joystick forward, the top left solenoid is energized.  The solenoid allows pilot oil to flow through the solenoid  and  push  the  spool  in  the  top  section  towards  the  right  of  the  machine.    The  main  flow  of  hydraulic  oil  goes through the top section, pilots open a load check poppet and allows oil to flow from the work port to the MLRS attachment cylinder.  Oil enters the left (rod end) port of the cylinder.  The oil pilots open the counterbalance valve on the head end of the cylinder, allowing oil to flow from the head end of the cylinder.  The cylinder retracts, lowering the MLRS attachment. Oil  from  the  cylinder  enters  the  work  port  of  the  top  section  of  MLRS  control  valve  and  is  directed  to  the  return  circuit where it is sent to the hydraulic reservoir through the hydraulic filter. The load compensating check valve moves up and down as the load and pump pressure change.  If the load increases, the pressure in the work port increases and pushes on the spring side of the load compensating check valve to block oil passage to the work port.  At  this  short  instance,  the  load  compensating  check  valve  is  operating  as  a  load  hold  check valve.  Increased work port pressure is also sent to the piston pump through the sensing line.  The pump output pressure increases  sufficiently  to  maintain  the  400  psi  (2758  kPa)  pressure  differential.    The  increase  in  pump  pressure  is  now sensed at the smaller end of the load compensating check valve and the valve moves up allowing oil flow to the work port again. If the electric joystick is moved rearward, the top right solenoid is energized.  The oil flow through top section of the MLRS control valve is similar to the retract function but the oil flow to the cylinder is reversed.  Oil pressure unseats the ball check in the counterbalance valve on the head end and forces the rod out of the cylinder.  The cylinder extends and raises the MLRS attachment. The maximum pressure in all the circuits of the MLRS control valve is controlled by the maximum discharge of the pump which is 3000 psi (20685 kPa). f. Carriage  Tilt  System.    The  carriage  tilt  function  is  also  controlled  by  the  electric  joystick  and  the  MLRS  control valve.  Hydraulic oil from the piston pump flows  through  the  control  valve  the  same  as  for  the  above  MLRS  attachment system. Move the electric joystick to the left and the second from the top right solenoid is energized.  The solenoid allows pilot oil to flow through the solenoid and push the spool in the second section towards the left of the machine.  Oil flows through the second section, pilots open a load compensating 16-7