4-22. AIR SYSTEM - Continued
Install shim (16) and spring (15) in body (1).
Install new seal (12) and thrust ring (13) on piston (14). Lubricate seal with petroleum jelly (item 21,
Appendix E) prior to installation. Be sure seal opening faces upwards.
Insert piston (14) carefully in body (17). Be sure seals are not torn on insertion. Check piston moves
freely up and down in body.
Install push rod (2) and boot (1) into upper body assembly.
Install O-ring (10) on barrier plate (11) and install O-ring (9) on cover. Install barrier plate in cover
Aline lower assembly with cover assembly. Be sure inlet and outlet ports point away from the pointed end
of the treadle plate. Install screws (18) and tighten to 24 in. lb (2.7 Nm).
Install treadle as detailed in b preceding.
Install and test foot throttle valve assembly in truck as detailed in INSTALLATION preceding.