CHAPTER 7
(3)
Camp
or
hold the metering stem in
the down position.
( 4)
Loosen the setscrews
in
the cam hub
and rotate
or
move the cam to a position
where it does not interfere with the stem
removal.
(5) Withdraw the metering valve stem
and spring. Do not drop
or
mishandle.
Cleek
for nicks
or
scratches. Check that
the pin holding the metering
portion is
not protruding. Back
off
the packing
gland.
(6) Remove the capscrews holding the
jack
shaft support
br~cket
so
that the
bracket can
be moved. It may be neces-
sary to also loosen the supporting bracket
on the far end
of
the shaft.
(7) Remove the existing packing rings
and guides.
Do
not reuse these.
(8)
Lightly
coat
the
stem
with
the
lubricant provided with the packing
kit.
Place the new packing,
0-rings
and
guides onto the stem in the sequence
shown in Fig. 7
..
s.
The beveled face
of
the guides and the teflon rings must face
upward, with the exception
of
the upper
brass guide which
is
faced down. Make
sure that the
0-rings
are properly located.
(9) Using the stem as a guide, insert the
assembled packing into the cavity; then
withdraw the stem.
CHAPTER 7·14
INSPECTION AND MAINTENANCE
(1
0) In the event the packing is too high,
remove one teflon packing from each
side
of
the middle brass guide as needed.
Under no circumstances eliminate the
two teflon packings on only one side
of
the brass guide.
(11) Replace the gasket, put the
support
in
place, and secure all fastenings.
(12) Replace the metering stem and
spring. Lightly lubricate the stem to
facilitate
insertion and easy movement.
Use care when inserting so that the orifice
and the stem are not damaged.
(13)
Snug the packing gland, but only
sufficiently
to place slight tension on the
packing. The stem must move freely from
the force
of
the spring.
(14) Work the stem
up and down several
times
to insure that it moves freely.
(15) Depress the valve stem and replace
the cam. Mate the match marks and
secure the setscrews. Make sure the cam
spring is centered
in
the roller.
(16)
Restore the oil flow. Test fire the
burner at various firing rates making cer
•
tain that the metering stem freely follows
the cam.
(17) Tighten the packing gland after a
period
of
operation, if required,
to
main-
tain proper tension on the packing.
Do
not
overtighten.
7SQ..150
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