SERVICE MANUAL ing the complete spool assemblies and the four (4) O- rings and spring in the dual circuit supply (dual check) valve. Refer to Fig. 10 for numbers in parentheses. 1. Remove  the  screws  from  the  cover  plates  (1) (four screws in each plate). 2. Carefully   pull   on   the   knobs   to   remove   their respective spools from valve body. Fig. 10 Cross Section of Dual Circuit Supply 1.  Plate Cover (2) 6.  O-ring 2.  Knob Control 7.  O-ring 3.  Valve Spool 8.  O-ring 4.  Valve Shuttle 9.  O-ring 5.  Spring Return 3. Remove roll  pins  which  retain  the  control  knobs on  spool  stems.  The  cover  plates  (1)  can  then be removed. 4. The   dual   circuit   supply   (double   check)   valve, located   in   the   tractor   control   (parking   brake) body i disassembled by grasping the web in the top  of  the  valve  spool  (3)  with  a  narrow  nose pliers, twist and pull the valve spool out. The  shuttle  (4)  should  also  come  out  with  the spool. 5. Remove the shuttle return spring (5) and O-rings (6), (7), (8) and (9). CLEANING AND INSPECTION The   acetal   components   which   comprise   most   of   the parts  of  the  MV-2  valve  should  not  be  immersed  in  any solvent  type  cleaner.  Old  lubricant  should  be  wiped  off parts to be reused and the  bores  of  the  body  wiped  out with a clean dry cloth. REASSEMBLY Lubricate     O-rings,     bore     and     sliding     surfaces     with lubricant  listed  in  LUBRICANT  SPECIFICATIONS,  Item 3. 1. Place  the  shuttle  return  spring  (5)  in  the  dual circuit supply valve bore in the body. 2. Install O-rings (6) & (7) on the shuttle (4), and (8) and (9) on the valve spool (3). 3. Insert  the  small  end  of  the  shuttle  in  the  spool and insert the assembly into the valve bore, flush with  top  of  body.  The  dual  circuit  supply  valve spool is retained in the body by the same cover plate    which    also    retains    the    tractor    control (parking brake) spool. New service replacement spools will be prelubricated. 4. Place cover plates over each plunger stem.  The cover    plates    are    identical    and    are    installed convex side up. 5. Place the red knob on the longer spool (for trailer air supply), matching the groove in the knob with the tongue in the cover plate (where applicable), and secure with the roll pin. 6. Place  the  yellow  knob  on  the  shorter  spool  (for tractor   air   supply),   matching   knob   and   cover (where applicable) and secure with the roll pin as before. A new roll pin will be found in each spool package. 7. Insert   the   shorter   spool   assembly   with   yellow knob in the tractor supply bore (housing with the dual  supply  valve).  If  the  entire  valve  assembly has   been   removed,   position   the   assembly   so that   the   tractor   control   body   housing   is   at   3 o’clock.  With  the  open  bore  (trailer  supply)  at  9 o’clock,  rotate  the  button  until  wording  on  top- center is horizontally readable. The stepped side of  the  cover  plate  should  be  covering  the  dual supply valve.  Secure the plate with the four flat head Phillips screws; torque to 2.Nm (25 in. lbs. CTS - 4079 - CHAPTER IX - Page 10