SECTION 7
HIGH PRESSURE WATER
May 2003
p. 7-7
49831951
7.2.4 HP Plunger Seal Service-- Disassembly / Re-assembly
1. Remove HP and LP piping/ hose, then remove HP cylinder jug following
procedure 7.2.2, above.
2. Thread HP plug and gland fitting (items C1 & C2, Special Tools, Table
7.3) into HP check valve gland nut. Hand tight is sufficient.
3. Stand HP cylinder jug upright with stud nuts resting on platform of wood
blocks or stand tool item (B), Table 7.3.
DANGER: HP cylinder jug is heavy and if it is stood on top pan of the pump,
will present a falling object hazard. Take care to properly support jug so
that it will not fall.
4. Fill HP cylinder bore with water, then fit a used plunger or seal removal
tool (item (E), Table 7.3) into bronze packing follower. Note that wrapping
a shop rag around the plunger at the packing follower avoids splash-
back. Use a dead blow hammer to strike the button end of the plunger as
though attempting to drive the plunger into the HP cylinder. This
technique should ‘hydraulic’ the HP seal components upward onto the
plunger/ tool shaft and out of the HP cylinder.
5. Slip plastic liner tube from bore of HP cylinder, inspect for possible heat
or wear damage or for possible debris. Feel ID of HP cylinder for
approximately 1-inch into bore. Sand any obvious ridges or grooves with
600-grit wet/dry sandpaper. Note that grooves or ridges are typically
caused by seal debris buildup rather than by marks in ID wall of HP
cylinder.
6. Inspect plunger surface for flaws. Rotate plunger 360- degrees by hand
while viewing light reflection on plunger surface to note any dullness,
streaks, pits or other defects. Run fingernail perpendicular to direction of
suspected surface flaws to gage severity of defects. Depending on seal life
achieved with removed HP plunger seal, make judgment regarding
whether to replace plunger. Refer to Paragraph 7.2.6 for procedure
regarding plunger removal/ installation.
7. Lightly coat seal components with FML grease refer to Table 7-2 item 1
prior to installing seal parts on plunger. Install new HP plunger seal
assembly onto plunger, refer to Figure, Detail I, (paragraph 7.2) for
proper seal component orientation. Note that steel spring inside U-cup (if
so equipped) can be easily distorted. Verify that U-cup spring, lips and
cavity appear uniform prior to installation.
NOTE: Bronze packing follower intended to fit tightly on plunger. If follower is
too tight to slip onto plunger, try heating follower in hot water. Then
attempt to slip follower over plunger.
8. Slip plastic cylinder liner tube over plunger.
9. Install HP cylinder jug to hydraulic cylinder head per paragraph 7.2.2.
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