SERVICE MANUAL WARNING To  prevent  personal  injury,  a  heavy  iron  or steel barred shield, or the equivalent  should be  positioned  between    the  operator    and the  spring  brake  when  being  disassembled (Fig. 6). 5. Apply  about  11,120  N  (2,500  lbs)  force  on  the unit.   Remove   clamp   band   bolt   and   nuts   and clamp ring (Fig. 6). 6. Slowly  release  the  shop  press  until  the  spring brake chamber can be separated and the spring brake diaphragm can be removed (Fig. 7). WARNING If  pressure  remains  between  the   ram   and the  actuator,  either  the  spring  brake  unit  is not    manually    released    or    a    failure    has occurred  in  the  release  mechanism.    If  the unit   is   released   but   pressure   is   present, continue  to  relax  the  press  slowly  until  the spring is fully extended and all parts fall free (Fig. 8). Fig.  6 Fig  7 Fig.  8 Fig.  9 7. Lift off  the  head-spring  piston  subassembly  with care  since  the  power  spring  is  caged  between the piston and head (Fig. 9). 8. Remove  the  diaphragm.  When  the  diaphram  is removed, inspect the inside of the flange   case, return  spring,  pushrod plate, screw and plastic guide  rings.  If  the  condition  of  these  parts  are questionable      refer      to      the      text      covering REPLACE SPRING BRAKE SUSPECED DEFErIVE PUSHROD SEAL. 9. Position   new   spring   brake   diaphragm   in   the spring brake head and install both on top of  the flange  case.   Position the complete assembly in the  press  with  a  slit-tube  type  adapter  between the press ram and the head of the spring brake unit. 10. Be sure the parts are lined  up  and  apply  2.668- 3.559  kN  (600-800  lbs)  force  to compress the return   spring   between   the   diaphragm   and   the two housings. 11. While  the  assembly  is  compressed  the  spring brake     chamber     clamp     band     can     now     be assembled.    Tap    the    clap    band    all    the    way around  while  tightening  the  clamp  band    nut    to insure    proper    seating.  Tighten  nuts  to  27-34 N.m (20-25 ft lbs). 12. Reinstall    the    brake    chamber    assembly    and manually reset the spring brake unit as instructed in the REINSTALL instructions. REPLACE     SPRING     BRAKE     UNIT     OR     SERIVICE BRAKE DIAPHRAGM 1. Block wheels to prevent vehicle from moving. 2. Manually   release   the   spring   brakes   (refer   to MIAL   RELEASE   OF   SPRING   BRAKE).      After releasing  brakes  release  the  air  pressure  in  the parking brake system by placingthe parking brake  control  in ’apply position. 3. To    ease    the    installation,    the    service    brake pushrod    should    be  extended.      Extending  the pushrod    can    be    accomplished    by    manually pushing back the slack adjuster or by application of   the   service   brakes.   While   the   pushrod   is extended, a locking type pliers should be used to retain the Pushrod in the extended position (Fig. 10).  Then  release  the  service  brakes  or  slack adjuster. 4. Remove    air    hoses    from    parking    brake    and service  brake chambers.   Tag hoses  for proper identification at reassembly. CIS-4101W - Page 7