GMC C Series 1993, Repair Manual

Page: 114 / 264

1. Lubricate all O-rings, O-ring grooves, piston bores,
and metal-to-metal moving surfaces with a barium
base lubricant.
• Use only new rubber seals from the repair Kit.
2. No. 1 piston (39) and O-ring (41).
3. Rubber washer (40) (figure 11).
4. Rubber spring (38).
5. Spring seat (37).
6. Nut (36).
7. No. 1 inlet-exhaust valve assembly (figure 8).
8. Valve retainer (28).
9. Valve spring (27)..
. ■ ..
10. Outer O-ring (24) and inner O-ring (25) in seal
y retainer (26).
11. Retaining ring (23). U 'v : , :
12. No. 1 inlet-exhaust valve retaining ring (22).
13. Relay piston (18) and O-ring (19).
AIR BRAKE VALVES SH-9
Figure 11—Installing the Rubber Washer
CAUTION: Before proceeding with the assem­
bly, refer to Figure 10 and note that the
nylon-insert nut and stem are used to contain
the No. 1 piston return spring, stem spring,
and the relay piston spring. The combined
force of these springs is approximately 22.7
kg (50 pounds) and care must be taken when
assembling the nylon-insert nut as the spring
forces are compressed. Manually or mechani­
cally restrain the relay piston and the No. 1
piston while the nylon-insert nut is being
assembled on the stem. Failure to observe
this caution could result in personal injury.