EMERGENCY FIELD REPAIR
PILOT CONTROL VALVE
PLUNGER AND
PLUNGER HOUSING SECTION
side with crack free chrome plate. If plunger is
In order to manufacture a high quality control
damaged, replace with new one and refit in sim-
valve with a minimum amount of leakage, it is nec-
ilar manner.
essary to individually hone and fit the plungers to
their respective bores in the plunger housing. Spe-
5. Evenly grind, lap or hone re-plated plungers so
cial machinery is required.
they are straight and round within .0002" (0,005
mm) and have a surface finish of 12 RMS or
Should an emergency situation require rebuild-
smoother.
ing of the valve in the field, the following proce-
dures can be followed:
6. Obtain an automotive brake cylinder repair type
hone with fine stones, equal to or greater than
1/3 the plunger section bore length.
1. Remove valve from equipment and thoroughly
clean all external surfaces.
7. Evenly hone plunger bore until a smooth sliding
fit is obtained with the plunger. Avoid removing
2. Disassemble tie rods and sections completely,
more stock at ends than in middle. Permissible
(being careful not to lose circuit load checks,
c l e a r a n c e between bore and plunger is .0002"
springs, and O-rings), tagging plungers for their
to .0005" (0,005 to 0.013 mm).
respective bores and clean all internal parts of
the section requiring repair. Caution must be
8. T h o r o u g h l y f l u s h p l u n g e r s e c t i o n b o d y a n d
taken not to damage plunger and section seals.
c l e a n all internal parts. Grease detents and
other sliding parts with a good cup grease and
3. Carefully examine plunger bores for deep
reassemble valve sections. Again, caution must
s c o r e s , cracks, or other faults which would
b e taken not to forget circuit load parts and
make repair impossible.
d a m a g i n g plungers. It is suggested to follow
a s s e m b l y instruction outlined in another sec-
4 . If plungers are not scored or damaged, have
tion of this manual.
them plated .001" to .002" (0,04 to 0,05 mm) on a
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