SERVICE MANUAL Then after the release bolt has been backed off,  the  air pressure   must   be   released   from   the   parking   brake system  by  placing  the  brake  control  in  "apply"  position. In  this  manner,  you  will  have  the  air   pressure   in   the system to assist in caging the spring. Do  not  apply  more  than  68  N.m  (50  ft  lbs)  torque  to release bolt. If  the  release  bolt  should  bind,  apply "Liquid Wrench" or   equivalent   to   the   bolt   and   allow   to   soak   into   the threads. In   the   event   the   air   source   has   been   depleted,   the release  bolt  may  be  backed  off  in  the  same  manner; however, turning the release bolt will require more effort since the parking brake spring will be fully extended, and when   turning   the   bolt   you   will   actually   be   pulling   or collapsing the spring manually. MANUAL SET OF SPRING BRAKE If  the  release  bolt  threads  are  dry  apply  a  light    coat  of "Never  Seez" lubricant  or equivalent to the  threads. Do not  apply "Never Seez" lubricant supplied in an aerosol can. To  manually  reset  parking  brake  at  each  spring  brake chamber,  screw  release  bolt  down  into  unit  until  nut  is bottomed  against  the  head  insert.    Torque  nut  to  61-68 N.m (45-50 ft lbs) and reinstall breather caps with arrow pointing toward ground. MAINTENANCE The breather cap must be in place and the arrow on the breather cap must point down.  The breather cap should be   checked   periodically.      If   dirty   or   clogged,   a   new breather cap should be installed.  When the breather cap is  removed,  check  the  release  bolt  nut  to  assure  it  is tightened (clockwise) to 68 N.m (50 ft lbs) torque. The   spring   brake   and   service   brake   chamber   clamp rings should be checked periodically to insure the clamp is evenly sealed and clamp bolt nuts are tightened to 27- 34 N.m  (20-25 ft lbs) torque. WARNING To  avoid  personal  injury  never  remove  the spring   brake   clamp   ring   unless      manual release    mechanism    has  been  applied  as instructed in MANUAL RELEASE of SPRING  BRAKE  and  assembly  is  placed  in a caging fixture. Visually    inspect    exterior    surfaces    of    assembly    for damage. Be  sure  to  check  mounting  stud  nuts  are  tightened  to 136-156 N.m (100-115 ft lbs). Air  line  fitting  should  be  checked  to  be  sure  they  are torqued to 34 N.m (25 ft lbs). Check  service  brake  chamber  pushrod  to  insure  it  has free   motion   and   is   in   straight   alignment   from   service chamber  to  slack  adjuster.    Worn  yoke  pins  are  to  be replaced and are locked in place with a cotter pin.  Make sure the jam nut is tight. CAUTION, Some   parts,   such   as   air   brake   chamber diaphragm,   should   be   inspected   once      a year    or    every    80,000    km  (50,000  miles) and   replaced   if   considered      unserviceable for  further use. LUBRICATION Regular lubrication of the double diaphragm spring brake chamber   is   not   required;   however,   when   the   unit   is disassembled, all parts must be washed in clean solvent and    IH    251H    EP    grease    or    equivalent    NLGI    #2 multipurpose   lithium   grease   applied   to   release    bolt, pushrod,      seals    and    white    plastic  guides,  outside  of diameter   edge   of   spring   piston   and   guide   surface   of head. If the threads on the release bolts are dry a light coat of "Never Seez" lubricant should be applied to the threads. Do not use "Never Seez" lubricant supplied in an aerosol can. REMOVE 1. Block the wheels of the vehicle to prevent it from moving. 2. Manually   release   the   spring   brakes   (refer   to MANUAL    RELEASE    OF    SPRING     BRAKE). After releasing brakes release the air pressure in she    parking    brake    system    by    placing        the parking    brake    control    in  ’apply"  position.    Be sure that the service brakes are released also. 3. Remove    air    hoses    fron    parking    brake    and service      brake      chambers.         Tag   hoses      for proper identification at reassembly. 4. Loosen jam nut at service brake pushrod yoke. 5. Disconnect  service  brake  pushrod  yoke from slack adjuster. CTS-4101W - Page 5