Graco 236685 Instructions And Parts List page 33

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. 27. Refer to
Fig. 28 to isolate any 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. 25.
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. 26. 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.
9. Test the gun resistance as instructed on page 26.
10. Install the gun shroud and air cap assembly.
11. Install the gun onto the manifold and bracket as
instructed on page 37.


There should be a 0.125 in. (3 mm) gap between the actuator arm
(19) and the fluid packing rod nut (U).
19
Fig. 26
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. 27
Description Function
O-Ring (23a)
Shaft Air Seal
O-Ring (23b)
Front Air Seal
O-Ring (23c)
Back Air Seal
U-cup (23f)
Cylinder Air
Seal
23b
Fan Air Side
Fig. 28
04823

23d
23f
23g
23a

It seals the cylinder air along the piston
rod. If the air leaks along the piston rod
(23g), replace this o-ring (23a).
It is the air shut-off seal. If the air leaks
from the air cap when the gun is detrig-
gered, replace these o-rings.
It separates the cylinder air pressure from
the fan and atomizing air pressure.
If the air leaks from the small vent hole in
the back of the manifold when the gun is
triggered, replace the u-cup.
23c
23a
Atomization Air Side
308442
23e


03530
23f
03531
33