Graco Inc. 218-745 Paint Sprayer User Manual


 
24
307-712
SERVICE
Piston Removal and Repair
1. To disconnect the fluid hose (31) from the cover
plate (41), screw the nut (34) off the adapter (35).
See Fig 21.
2. Note the position of the trigger adjusting nut (24) for
reinstallation, then screw it off the piston  shaft.
3. Remove the screws (61) and lock washers (82) from
the cover plate (41). Remove the cover plate (41),
spring (38), and retainer cap (74).
4. Unscrew and remove the air valve guide (26) and
needle packing (27) from the gun body (1),
5. Push on the end of the piston shaft, and remove the
piston assembly.
NOTE: DO NOT remove the uĆcup packing (37) from
the piston shaft except to replace it as removal
will damage this packing.
6. Clean and inspect parts for wear or damage. ReĆ
place parts as needed.
7. When reassembling the piston assembly, lubricate
the oĆrings (30 & 79) and the uĆcup packing (42) on
the piston with petroleum jelly. Pack the spring (38)
with petroleum jelly. Apply Teflon tape to the air valve
guide (26).
8. Install the new packing (27) and guide (26) in the
gun body (1); screw the guide in loosely.
NOTE: DO NOT fully tighten the guide (26) yet. The
guide must be loose to avoid damaging the
packing (27) when pushing the piston shaft
through the guide.
9. If replacing the uĆcup packing (37), slide it onto the
piston (42) so the lips of the packing will face toĆ
wards the front of the gun when the piston is inĆ
stalled. Then install the bunaĆn oĆring (30) and
Vitonr oĆring (79) on the piston.
10. Install the piston assembly into the gun body (1),
being careful not to damage the piston's lip seal.
11. Install the retainer cap (74) into the cover plate (41).
12. Install the cover plate (41), spring (38), and retainer
cap (74) with the screws (61) and lock washers (82).
13. Actuate the trigger and tighten the air valve guide
(26) with a wrench.
14. Screw the trigger adjusting nut (24) onto the piston
shaft to its previously noted position.
15. Connect the fluid hose (31) to the adapter (35).
Fig 21
KEY
1 Gun Body
24 Trigger Adjusting Nut
26 Air Valve Guide
27 Needle Packing
30 BunaĆn OĆRing
31 Fluid Tube
34 Nut
35 Adapter
37 UĆCup Packing
38 Spring
41 Cover Plate
42 Piston
61 Screws
74 Retainer Cap
79 Viton OĆRing
82 Lock Washers
26
Apply
Teflon
tape
24
31
34
27
41
35
82
61
30
79
37
38
74
Pack with
lubricant
42
1