SERVICE MANUAL MAINTENANCE Every   160,000   km   (100,000   miles)   or   every   year, remove,   disassemble,   clean   and   inspect   all   parts.   If signs   or   wear   or   deterioration   are   found,   install   new parts. It is recommended all rubber parts be replaced. SERVICE CHECKS  Operation Test Block vehicle and hold by  means  other  than  vehicle brakes.   Charge   air   brake   system   to   governor   cut-out pressure. 1. Place     parking     control     valve     in     the     "apply" position. Observe that the spring brake actuators apply    promptly.        In    the    delivery    port    of    the inversion valve  install  a  test  gauge  known  to  be accurate.  Place  the  parking  control  valve  in  the "release" position. Observe that the spring brake actuators release fully. 2. With  the  parking  control  valve  in  the  "release" position,     note     the     gauge     pressure     reading (should be approximately the same as gauge on instrument   panel).      If   the   pressure   reading   is incorrect, the valve must be repaired or replaced. 3. Place   the   parking   control   valve   in   the   "apply" position,  the  gauge  reading  should  drop  to  zero promptly.    A    slow    release    of    pressure    could indicate faulty operation of the single check valve (within  the  Modulating  Valve).    At  approximately 48-241 kpa (7-35 psi) the spring parking brakes should be fully applied. 4. Place  the  parking  control  valve  in  the  "release" position. Locate the number one service reservoir and drain it completely. 5. Apply   the   foot   brake   valve   several   times   and note   that   the   pressure   reading   on   the   gauge decreases   each   time   the   foot   brake   valve   is applied.   After   the   foot   brake   valve   has   been applied several times, pressure on the gauge will drop   to   the   point   where   release   of   the   spring brake actuators will no longer occur. Leakage Test With   air   system   fully   charged   and   parking   brake control valve in "release" position, use the Leak Detector Tester around valve cover and exhaust port to detect air leakage. A slight leakage is permitted. If   inversion   valve   does   not   function   as   described above  or  leakage  is  excessive,  it  is  recommended  that the valve either be replaced or repaired. REMOVE 1. Apply parking brakes and drain all air reservoirs. 2. Mark or identify all air lines before disconnecting from inversion valve. Then disconnect air lines. 3. Remove  the  two  mounting  bolts  from  valve  and remove valve. INSTALL 1. Install   inversion   valve   using   the   two   mounting bolts. 2. Connect air lines. Make sure they are installed at the  same  ports,    3.  Before  releasing  vehicle  for service, perform SERVICE CHECKS as outlined. DISASSEMBLY (Refer to Fig. 2) 1. Remove socket head pipe plug at check valve. 2. Remove   check   valve   spring,   spring   guide   and check valve. 3. Remove two Phillips screws and remove exhaust cover. 4. Separate exhaust diaphragm from cover. 5. Remove inlet and exhaust valve assembly. 6. Remove   inlet   and   exhaust   valve   cap   nut   and separate cap nut O-ring. 7. Remove  valve  stop,  valve  spring  and  inlet  and exhaust valve. 8. Remove four Phillips head screws and lockwashers that secure cover to the body. CAUTION Cover  is  under  a  spring  load  and  should  be  held  while removing screws to prevent bodily injury. 9. Remove cover and three piston springs. 10. Remove small piston and small and large O-ring, 11. Remove large piston and large and small O-ring from it. CTS-4079 - CHAPTER VII - Page 6