Operation & Maintenance Instruction
Page 14 of 24
August, 2003
4225-50, S.6
7.5.21 Install the high pressure spool valve with o-rings (16,
15) into the body (58).
7.5.22 Install the high pressure spool valve return spring
(13) into the high pressure spool valve (16).
7.5.23 Install a NEW thimble type air strainer (21) into the
emergency accelerated check valve seat of the body (58).
Secure the thimble type air strainer (21) into the body (58)
with the retaining ring (20).
7.5.24 Install a NEW emergency accelerated release check
valve (19) and check valve spring seat (18) and the check
valve spring (17) into the body (58).
7.5.25 Install a NEW 1
3
/
4
" O.D. ring gasket (22), two NEW
1
1
/
2
" O.D. ring gaskets (23) and a NEW 1
1
/
8
" O.D. ring gasket
(24) into their grooves in the top cover (2).
7.5.26 Place the top cover assembly (2) with ring gaskets
(22, 23, 24) on the body (58) making sure that the diaphragm
(5) and ring gaskets (22, 23, 24) remain in position.
7.5.27 Secure the cover (2) to the body (58) by installing
the four
1
/
2
" x 1
3
/
4
" hex head screws (1). Torque the screws
between 35 and 55 foot-pounds.
7.5.28 Vent Valve, Inshot Piston, Emergency Accelerated
Release Spool
7.5.29 Install a NEW inshot diaphragm (41) on the inshot
piston (43) so that the flat surface of the diaphragm which
shows the part number faces away from the piston.
7.5.30 Install the diaphragm follower (40) on the piston (43)
so that the small diameter of the follower (40) is facing the
diaphragm (41). Secure the follower (40) and the diaphragm
(41) on the inshot piston (43) by installing a NEW
3
/
8
-16 self-
locking hex nut (39). Torque the nut to 9 to 12 foot-pounds.
7.5.31 Apply #2 Silicone Grease, Wabtec Corporation
Specification M-07680-02, to the surfaces of a NEW
3
/
8
" O.D.
o-ring (42). Also lightly lubricate the O-ring groove on the
shaft of the inshot piston (43) and the bearing surfaces of the
inshot piston bushing of the body (58).
7.5.32 Install the NEW lubricated
3
/
8
" O.D. o-ring (42) into
its groove on the shaft of the inshot piston (43).
7.5.33 Install the inshot diaphragm piston assembly (39 to
43) into the body (58). Be sure that the bead of the diaphragm
(41) is properly seated in the bead groove of the body (58).
7.5.34 Install the inshot piston spring (38) over the nut (39)
on the exposed end of the inshot piston (43) so that the
spring seats in the diaphragm follower (40).
7.5.35 Using a foam-tipped swab applicator, evenly
spread a light coating of Triple Valve Oil, Wabtec
Corporation Specification M-07611-20 (AAR Specification
M-912), to the large diameter surface of the stem of the
vent valve piston (37). Carefully insert the vent valve piston
(37) into the body (58).
7.5.36 Place a NEW vent valve piston diaphragm (36) on
the vent valve piston (37) ensuring that the part number on
the diaphragm faces the piston. With the aid of the hand
tool, shown in Figure 6, properly position the diaphragm
(36) so that the loop of the diaphragm sits between the piston
(37) and body (58).
7.5.37 Install a NEW
15
/
16
" O.D. ring gasket (34) and a NEW
5
/
8
" O.D. ring gasket (35) in their grooves in the vent valve
cover (33).
7.5.38 Place the vent valve cover (33) on the body (58) and
install the two
1
/
2
x 1
1
/
8
hex head screws (31), the
METAL
IDENTIFICATION TAG
(29a), and the
1
/
2
x 1
3
/
4
hex head
cap screw (32).
7.5.39 Small Vent Valve, Inshot Check Valve
7.5.40 Install a NEW inshot check valve (27) and the inshot
check valve spring (26) into the body (58). Align properly and
secure these parts in place by installing the inshot spring
retainer (25).
7.5.41 Using a foam-tipped swab applicator, evenly spread
a light coating of Triple Valve Oil, Wabtec Corporation
Specification M-07611-20 (AAR Specification M-912), to the
outer diameter surfaces of the small vent valve piston (30).
Install the small vent valve piston assembly (30) seal end
first, into the body (58).
7.5.42 Install the small vent valve piston spring (29) into the
small vent valve (30) and secure it in place by installing the
spring retainer (28) in the body (58). Be sure that the retainer
(28) is properly secured.
