AIR BRACKES-GENERAL INFORMATION OPERATIONAL    CHECKS    OF    SPLIT    AIR    BRAKE SYSTEM GENERAL OPERATIONAL CHECK OF AIR SYSTEM 1. Block wheels to prevent vehicle from moving. 2. Inspect  primary  and  secondary  reservoir  check valve operation. a. Build 758 kPa (110 psi) of air in system. b. With   ignition   switch   "ON,"   open   drain   cock   at supply air reservoir and completely drain reservoir.  Low air pressure buzzer should come on at approximately 483 kPa (70 psi). c. Both  primary  and  secondary  reservoirs   should retain air pressure. d. If    loss    of    air    is    noted    in    either    system    by observing the air gauges, the check valve could be faulty. 3. With  the  park  brake  control  (yellow)  and  trailer supply   control   (red)   positioned   in,   open   drain cocks in primary and secondary reservoirs. Trucks The park brake control (yellow) knob should automatically apply between 48-103 kPa (7-15.psi). Tractors a. The red knob should pop out when reservoir with highest pressure reaches 276 + 27.6 kPa (40 + 5 psi).  The  red  knob  could  pop  immediately  if  air is depleted quickly at the trailer supply (emergency) line. b. When    air    pressure    in    reservoir    with    higher pressure  reaches  207  +  27.6  kPa  (30  +  5  psi) the   yellow   knob   may   pop   out.      When   air   is depleted  to  172  +  27.6  kPa  (25  +  5  psi),  the yellow knob must pop out. 4. Close all reservoir drain cocks. 5. Build    up    air    supply     in     chassis     system     to approximately 758 kPa (110 psi). 6. With    red    knob    pushed    in,    disconnect    trailer emergency coupling from bracket.  The red knob -should pop out instantaneously. 7. If red knob pops out, reconnect trailer emergency   coupling.      Position   yellow   knob   in released  position  (in)  and  red  knob  in  applied position (out). 8. Check air pressure  for  leakage  by  observing  air gauges  on  instrument  panel.    Leakage  should not   be   greater   than   13.8   kPa   (2   psi)   in   one minute. 9. Open   drain   cock   in    secondary    air    reservoir. Drain cock must be opened all the way for quick loss of air. You will note loss of air by observing air  gauges.  One  system  will  show  a  loss  of  air. With  ignition  switch  on,  low  pressure  indicator buzzer  should  sound  at  approximately  483  kPa (70 psi). 10. Apply   service   brakes   and   observe   the   slack adjusters and service brake chamber push rods. Movement   of   the   brake   chamber   push   rods should occur at axles as follows: a. Rear axles on all 4x2 vehicles and rear axles on 6x4 vehicles with initial split air system. b. Front  and  rear  rear  axles  on  6x4  vehicles  with spring  suspension  system  and  refined  split  air system. c. Steering and forward rear axles on 6x4 vehicles with  air  suspension  and  refined  split  air  system. If movement is noted at other axles, the primary reservoir  was  bled.    Refer  to  Step  13.    If  brake chamber    push    rod    travel    movement    is    as described, the primary system is good. 11. Close drain cock in secondary air reservoir. 12. Build  air  supply  in  air  system  to  758  kPa  (110 psi). 13. Open  drain  cock  in  primary  reservoir.    Observe opposite air pressure indicator for loss of air.  Be sure to open drain cock all the way. 14. Apply   service   brakes   and   observe   the   slack adjusters and service brake chamber push rods. There  should  be  movement  of  brake  chamber push rod travel as follows: a. Steering axle on all 4x2 vehicles and on straight trucks   with   initial   split   air   system   the   spring brakes  will  apply  and  release  until  air  pressure drops  to  48-241  kPa  (7-35  psi),  then  full  spring brake application will occur. b. Forward  rear  axle  on  6x4  vehicles  with  refined split air system. c. Rear     rear     axle along with parking brake application  and  release  at  forward  rear  axle  on 6x4 vehicles with air suspension and refined split air system.  When  checking  system  the  parking brakes  will  automatically  apply  on  tractors  when air pressure is depleted to 172 + 27.kPa  (25  +  5 psi). 15. If movement of brake chamber push rods are as described,  the  secondary  system  is  functioning as it should. 16. Close    all    drain    cocks    and    return    vehicle    to service. CTS-4154Y - Page 20