SERVICE
5.Carefully remove the fluid needle assembly (45) from the rear part of the gun barrel (18). See Fig 15. If the packing assembly (45a) or insulator (45g) are still in the barrel, insert the packing removal rod (59d) into the front of the barrel to gently push them out. Refer to Fig 16.
NOTE: If the insulator (45g) is removed, be sure to install it so the insulator end with holes is facing the packing assembly (45a).
6.Wipe the internal surfaces of the barrel clean with a soft brush or cloth.
CAUTION
Clean all parts in non±conductive solvent compatible with the fluid being used, such as xylol or mineral spirits. Use of conductive solvents can cause the gun to malfunction.
7.Remove the packing assembly (45a) from the needle (45b).
NOTE: If the position of the adjusting nut (45c) is changed, install the adjusting nut to the approxi- mate dimension shown in Fig 15. (Final adjust- ment will be made in step 15.) If the spring (45f) was removed, reinstall it over the nut (45d).
8. Install the new packing assembly (45a).
CAUTION
Carefully screw needle (45b) into new packing assembly (45a) to avoid damaging the seals.
9.Test the drag on the fluid needle. It should be approxi- mately 2.5±3 lbs (use a small spring scale to meas- ure). If the adjustment is out of tolerance, tighten or loosen the adjusting screw on the packing assembly (45a) slightly and retest. Continue to adjust until the tolerance is correct.
10.Install the entire fluid needle assembly (45) into the gun barrel, from the back of the barrel.
11.Firmly tighten the packing nut (45e) down until it bot- toms.
CAUTION
When checking the fluid needle movement, DO NOT move the needle out of the gun barrel more than 6.35 mm (1/4 in.) to avoid pulling the needle out of the packing area and damaging the pack- ings.
12.Install the barrel as described under Barrel Removal.
13.Install the electrode as described under Electrode Replacement.
14.Install the air cap assembly and fluid nozzle as described in Clean the Air Cap and Fluid Nozzle.
15.Trigger the gun to check the needle adjustment. The air should come fully on before the fluid comes on. Adjust the needle adjusting nut (45c) until the proper lead and lag is achieved.
If the fluid comes on too soon, remove the trigger and back the needle adjusting nut (45c) out (away from the barrel) slightly.
If the fluid comes on too late, tighten the needle adjusting nut (45c) slightly (turn towards barrel).
After adjustment is complete, tighten the locking nut (45d) against the adjusting nut (45c).
KEY
18Gun Barrel
45Fluid Needle Assembly
45c Needle Adjusting Nut
132.7 mm
(5.2 in.)
45c 45
18
Fig 15
KEY
45 | Fluid Needle Assembly | 45d | |
|
| ||
45a | Needle Packing Assembly |
|
|
45b | Fluid Needle |
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|
45c | Adjusting Nut |
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|
45d | Locking Nut |
| 45f |
| |||
45e | Packing Nut |
| |
| |||
45f | Spring | 45c | |
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| ||
45g | Insulator |
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|
45b
45e
45g45 45a
Fig 16
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