Replace End Cap And Air Piston Assembly - Graco GX-7A Instructions Manual

Replace End Cap and Air Piston
Assembly
1. Clean the gun according to Clean Spray Gun,
page 24.
2. Loosen the rear packing nut (E) 1-2 turns.
3. Push the safety lock (H) partially forward, rotate
counterclockwise, and slide the safety lock (H) off
the air cylinder.
4. Remove the valving rod (N). See Remove and
Service Centerline Components, page 26.
5. Disconnect the air supply from the gun.
6. Remove the rear head cap screw (SH) and cylinder
clamp (CC) from the handle.
PA
FS
F . 20 GX-7 DI End Cap and Air Piston Assembly
IG
7. Remove the end cap (EC) from the air cylinder.
8. Inspect the end cap (EC) o-ring. Replace if
damaged. Install a new end cap o-ring after lightly
coating it with Lubriplate grease.
311321W
EC
SP
RS
PS
SH
CC
GX-7 DI Shown
9. Inspect the rear U-cup seal (RS) or o-ring for
damage. Replace if necessary. If removed, ensure
"cup" faces front of the air cylinder when replacing.
10. By hand, pull the piston assembly (PA) out of the air
cylinder and inspect the o-ring for damage.
Replace if necessary. Apply Lubriplate grease prior
to installation.
11. If air was escaping around piston rod (K) during
operation, replace the front u-cup seal (FS) or
o-ring. Apply Lubriplate grease and ensure "cup"
faces rear of the air cylinder.
12. Insert the piston and rod assembly (PA) into the air
cylinder. Take care to not damage the front cup
seal as rod passes through.
13. Insert the piston spring (PS). (For GX-7 DI models,
also insert a piston spacer.)
14. Reinstall the end cap (EC) into the air cylinder.
15. Retighten the rear socket head cap screw (SH) and
cylinder clamp (CC) to handle.
16. Reinstall the valving rod (N). Connect the valving
rod (N) to the draw bar (DB), see F
Lubricate and thread into the end cap (EC).
17. Adjust the valving rod (N); see Adjust Valving Rod,
page 23.
18. Slide the safety lock (H) onto the rear of the air
cylinder. Push the safety lock partially forward and
rotate clockwise to set to OPEN.
19. Set the safety lock (H) to CLOSED (SERVICE).
20. Tighten the rear packing nut (E).
Repair
. 19, page 27.
IG
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