SERVICE MANUAL GENERAL INSTRUCTIONS Air brake equipment on trucks and truck-tractors provides  a  means  of  controlling  the  brakes  through  the medium    of    compressed    air.        Air    brake    equipment consists  of  a  group  of  devices;  some  maintain  a  supply of  compressed  air,  some  direct  and  control  the  flow  of compressed    air    and    others    transfer    the    energy    of compressed  air  into  the  mechanical  force  and  motion necessary to apply the brakes.  Different types and sizes of  devices  are  in  use  on  different  types  of  vehicles  to meet operating requirements. Refer to AIR BRAKE SYSTEM FMVSS 121 AIR SYSTEM (SECOND GENERATION), GENERAL INFORMATION   for   description   of   the   dual   air   system used on the particular vehicles covered by Federal Motor Vehicle Safety Standard 121 (FMVSS 121). The components used to make up a typical dual air  system  on  a  chassis  are  listed  in  this  section  with  a brief description, operation, service checks and maintenance procedures.  Disassembly and reassembly instructions are provided for some components. CAUTION Whenever any component is serviced or removed from the air system, be sure to set  the  parking  brake  and/or  block  the vehicle  to  prevent  it  from  moving  while the service is being performed. The  various  components  which  apply  directly  to the   Antilock   System,   as   well   as   trouble   shooting   the system, will be found in ANTILOCK section. LUBRICANT SPECIFICATIONS Throughout the text whenever reference is made to    a    particular    lubrication    note    or    a    particular    item number,  refer  to  the  following  list  of  item  numbers  and use the lubricant specified. Item 1 IH  251H  EP  grease  or  equivalent  to  NLGI  #2 multi-purpose  lithium  grease  (same  as  BW  226M  and 204M lubricant). Item 2 Bendix    239277    (57    g    -    2oz)    molybdenum disulfide lubricant in liquid carrier.  A lubricant  suited  for O-ring powder suspended in synthetic lubricant (polyalkylene  glycol  derivative)  and  rubber  parts  as  well as metal lubrication, especially at low temperatures. Item 3 Bendix  291126  (7.08  g  -  1/4  oz)  or  BW  291127 (57   g   -   2   oz)   silicone   grease   intended   primarily   for dynamic  lubrication  between  oil   resistant   rubber   seals and metal parts.  Meets MIL-L-4343A requirements.  Can be used in serviceable range of -54 C (-65 F) to +426 C (+800 F).  Causes less swelling and hardness change of rubber  parts  than  normally  encountered  with  petroleum based lubricants (apprbved source: Dow Corning Corporation -- DC-55 pneumatic grease). LEAKAGE TESTS In some cases where leakage tests are performed  on  various  components,  a  soap  bubble  test can  be  made  to  determine  if  the   items   need   repairs. However, to assist in locating any leakage at connections or at any components, we suggest that a Leak Detector Tester (SE-2326) be used to locate any air leaks. With special attachments contained in the tester a very small air leak can be detected easily; for example, in a confined area where a brush with soap is obstructed. Fig.  1 Leak Defector Tester (SE-2326) 1 Amplifier 4 Sound Concentrator 2 Contact Probe 5 Hand Probe 3 Headphone PRINTED IN UNITED STATES OF AMERICA CTS-4079 - GENERAL Page 2