AIR BRAKES - GENERAL INFORMATION DETAILED     OPERATIONAL     CHECK     OF     TRAILER SUPPLY AND PARK BRAKE SYSTEMS Modular Control Valve 1. Use two air test gauges 0-1103 kPa  (0-160  psi) or Duplex gauge (SE-2325’) with hoses and two additional trailer couplings (service and emergency);  attach  the  gauges  to  service  and emergency couplings on vehicle. 2. With  the  trailer  supply  knob  (red)  and  parking brake   knob   (yellow)   out,   charge   primary   and secondary   air   systems   to   448   kPa   (65   psi). Push red knob in. The red knob should remain in and  air  pressure  at  instrument  panel  and  test gauge   at   trailer   emergency   port   should   read approximately the same.  Test gauge at service connection should show no pressure. 3. Push   yellow   knob   in   and   apply   foot   valve   to deplete air supply.  The red knob should pop out when   the   reservoir   with   the   highest   pressure reaches  276  +  27.6  kPa  (40  +  5  psi).    The  red knob   could   pop   immediately   if   air   is   depleted quickly. 4. Apply  foot  valve  to  further  deplete  air  pressure. Air should escape the exhaust port of the trailer supply  portion  of  valve.    When  air  pressure  in reservoir with the higher pressure reaches 207 + 27.6 kPa (30 + 5 psi), the yellow knob may pop out (park brake application). 5. Deplete  the  air  system  even  further  using  foot valve. At 172 + 27.6 kPa (25 + 5 psi), the yellow knob must pop out (park brake application). 6. Rebuild  air  supply  to  at  least  276  kPa  (40  psi), push yellow knob in.  It should remain in. 7. Push red knob in and pull yellow knob out.  The red knob must pop out almost instantaneously. 8. Rebuild air supply to 689-861 kPa (100-125 psi) in both primary and secondary reservoirs.  Push red   and   yellow   knobs   in.      Pressure   at   trailer emergency connection should equal pressure in primary reservoir. 9. Reduce air pressure in primary reservoir. Pressure at trailer emergency connection should descend  to  724-621  kPa  (105-90  psi)  at  which point   the   double   check   valve   in   the   modular control   valve   should   switch   to   the   secondary reservoir and pressure at emergency connection should  adjust  (equalize)  to  secondary  reservoir pressure.  Close off leak at primary reservoir. 10. With the red knob in and the hand control valve released,  apply  brake  valve.    Pressure  at  trailer service   should   be   within   27.6   kPa   (5   psi)   of gauge at instrument panel. 11. Replenish  air  system  to  689-861  kPa  (100-125 psi). Slowly vent the secondary reservoir pressure with yellow knob in.  As the secondary pressure and trailer emergency pressure descend,   between   793-724   kPa   (115-105   psi) the   double   check   shuttle   in   the   valve   should switch to the primary reservoir and the pressure should adjust to the primary reservoir pressure. 12. With   the   red   knob   pushed   in,   disconnect   the trailer  emergency  coupling  from  the  test  gauge. The red knob should pop out instantaneously.  If red knob pops out, reconnect the trailer emergency coupling to gauge. 13. Replenish  air  in  system.    With  the  red  knob  in, apply the hand control valve.  There should be a minimum  of  586  kPa  (85  psi)  at  trailer  service gauge. 14. Release hand control valve and apply foot valve. Pressure at service port should be within 35 kPa (5     psi)     of     the     pressure     indicated     at the instrument panel. 15. Close   all   vents   or   leakage   points   and   charge system   to   689-861   kPa   (100-125   psi).      Apply brake  valve,  pull  red  knob  out  (yellow  knob  in). The air gauge connected to the service connection  should  record  the  same  value  (689- 861 kPa or 100-125 psi) as gauge at instrument panel.    Gauge  at  emergency  connection  should indicate "0." 16. With red knob out and yellow knob in, develop a leak  in  the  spring  brake  delivery  (line)  and  hold yellow  knob  in.    The  primary  reservoir  pressure must   reduce   to   zero   and   secondary   reservoir pressure   to   138-207    kPa    (20-30    psi).        The double check valve in the modular control should cycle several times during the leak down period. If  the  foregoing  checks  perform  as   described, the chassis is ready for service.  Remove air test gauges from trailer couplings. If  the  operational  checks   revealed   malfunctions   within the system, a more detailed investigation of components will  be  required.    Refer  to  COMPONENTS  Section  for detailed  information  regarding  service  check  on  various components. Separate     Spring     Brake     and     Tractor     Protection Controls 1. Using   two   air   gauges   (0-160   psi)   or   Duplex gauge (SE-2325*) with hoses and two additional trailer couplings (service and emergency), attach the   air   gauges   to   the   service   and   emergency couplings on vehicle. 2. Build up air pressure in chassis air system. * At one time the Sealco duplex air gauge (model 110122) was available under Tool Equipment No.  SE-2325. CTS-4154Y - Page 21