QUICK RELEASE VALVES AND DIFFERENTIAL QUICK RELEASE VALVE SERVICE CHECKS OPERATION TEST Apply the brakes and observe that when the brakes are released,  air  pressure  is  quickly  exhausted  through  the exhaust port of the valve.  Be sure the exhaust port is not restricted. Pressure Test-Differential Quick Release Valve Install pressure gages on the air line from the brake foot valve  and  on  one  of  the  lines  to  the  brake  chamber. Both gages should have the same scale.  The IH special service   equipment   duplex   gage   (SE-2325)   or   gages reading  from  900  kPa  (125  psi)  to  1400  kPa  (200  psi) may  be  used.    The  most  convenient  places  to  connect are at the quick release coupling (glad hand) of the trailer service brake for the foot valve pressure and the air line port  on  the  brake  chamber  for  its  pressure.    Apply  the brakes.      Read   both   gages   with   the   brakes   applied. Subtract the brake chamber reading from  the  foot  valve reading.  To eliminate gage error, switch the gages and repeat   the   procedure.      Add   the   results   of    the    two subtractions and divide by 2.  The answer should be 41 kPa  (6  psi)  +  14  kPa  (2  psi).    If  the  results  are  outside that  range  check  for  leaks  and/or  repair  or  replace  the differential quick release valve. Leakage Test Leak  Detector  Tester  (SE-2326)  may  be  used  to  deter mine  if  air  is  leaking  through  the  exhaust  port  when  the brakes  are  applied.    When  the  brakes  are  released,  be sure the valve releases immediately with the corresponding return movement of foot pedal.  Leakage could  be  caused  by  dirt  on  valve  seat  or  a  defective diaphragm.    Leakage  in  excess  of  a  25  mm  (1")  soap bubble   in   6   seconds   is   not   permissible.      Repair   or replace valve if excessive leakage is found. REMOVAL 1. Disconnect  air  lines  from  quick  release  valve  or differential quick release valve. 2. Remove mounting bolts and valve. INSTALLATION 1. Mount  quick  release  valve  or  differential  quick release valve with mounting bolts and lockwashers.  Make  sure  that  its  exhaust  port  is pointing down. 2. Connect the brake valve line to the top port and the brake chamber lines to the side ports. 3. Make sure that the exhaust port is not restricted. 4. After    the    valve    (new    or    rebuilt)    is    installed, perform   tests   as   outlined   under   OPERATION TESTS. DISASSEMBLY 1. Remove four capscrews and valve cover. 2. Remove   diaphragm   (and   spring   and   baffle   of differential quick release valve). 3. Remove cover O-ring. CLEANING AND INSPECTION 1. Clean all parts in good cleaning solvent. 2. Inspect diaphragm, especially the lower part that contacts  the  exhaust  seat  and  cover  O-ring,  for wear or deterioration.  Replace if necessary. 3. Check the cover exhaust seat for pitting or nicks. This  seat  should  be  smooth  and  sharp.    If  not, use a fine piece of emery cloth to dress the seat. 4. Clean or replace as necessary. The diaphragm should be replaced if worn or deteriorated.    There  are  some  valves  for  which  service repair  kits  are  not  available.    If  inspection  of  a   valve reveals worn parts, the valve will have to be replaced as a unit. REASSEMBLY 1. Position diaphragm in valve body. (On differential   quick   release   valve,   first   assemble baffle  to  diaphragm  and  Install  spring  on  top  of baffle.) 2. Place O-ring in groove in valve body. 3. Assemble valve cover on body. 4. Install capscrews and tighten to 5.7-6.8 N-m (50- 60 in.  lbs.). NOTE - In some special applications, a spring and spring seat will be found In quick releases valves. MAINTENANCE Every  year  or  160,000  km  (100,000  miles),  remove  the quick  release  valve  or  differential  quick  release  valve, disassemble it and clean all parts. CTS-4079A - CHAPTER V - Page 4