Graco PRO 5500wb Instructions-Parts List Manual page 40

Piston Repair (continued)
4. Push on the piston rod (23g) to push the piston
assembly out the back of the gun.
5. Inspect the o-rings (23a, 23b, 23c) and u-cup
packing (23f) for damage. See Fig. 33. Refer to
Fig. 34 to isolate air leakage problems.
6. Lubricate the o-rings (23a, 23b, 23c) and u-cup
packing (23f) with petroleum jelly.
7. Align the two stems (23d) with the holes in the gun
body and press the piston assembly into the back
of the gun until it bottoms.
8. Installing the Actuator Arm and Nuts:
a. Install the adjustment nut (36), actuator arm
(19), and jam nut (46) onto the piston rod
(23g). See Fig. 32.
NOTE: The jam nut (46) has a slightly larger hex and a
thinner profile than the adjustment nut (36).
b. Thread the jam nut (46) flush with the end of
the piston rod (23g).Tighten the adjustment nut
(36) against the actuator arm (19). When
properly assembled, there should be about a
0.125 in. (3 mm) gap between the actuator
arm (19) and the fluid packing rod nut (U),
which allows the atomizing air to actuate
before the fluid actuates. See Fig. 32. In
addition, there should be 3 to 4 mm of elec-
trode needle travel when the gun is triggered.
If necessary, adjust the jam nut (46) position to
obtain these dimensions.


There should be a 0.125 in. (3 mm) gap between the actuator
arm (19) and the fluid packing rod nut (U).
46 19 36 23g
Fig. 32
40 308496
Service


U


Apply a very light coat of lubricant to the o-rings (23a, 23b, 23c)
and u-cup (23f).

Align the two stems (23d) with the holes in the gun body and
press the piston assembly until it bottoms.



23c


23b
Fig. 33
Description Function
O-Ring (23a) It seals the cylinder air along the piston
Shaft Air Seal rod. If the air leaks along the piston rod
(23g), replace this o-ring (23a).
O-Ring (23b) It is the air shut-off seal. If the air leaks
Front Air Seal from the air cap when the gun is detrig-
gered, replace these o-rings.
O-Ring (23c) It separates the cylinder air pressure from
Back Air Seal the fan and atomizing air pressure.
U-cup (23f) If the air leaks from the small vent hole in
Cylinder Air the back of the manifold when the gun is
Seal triggered, replace the u-cup.
23b
Fan Air Side
Fig. 34
04823
23d


23f
23g
23a

23c
23a
Atomization Air Side
23e
03530
23f
03531