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injection nouJe services
(I)
Needle valv.
and
nozzle body
(a)
lmmerse needle valve and nozzle body in a pool
of
clean
kerosene,
insert
the
valve into the
body, and move
the
valve
back
and
forth to
be
s.ure
(hat the
sliding contact
is
smooth wit.hout
evidencing
any excessive clearance
.
The injec-
tio
n
nozzle
as
a
whole muS!
b. replaced
if
the
lit
is
found
defective
.
(b)
Visually
examine the
nozzle
body
with.
magni-
fying gl"" having
a
pow"
of
4
Or
5.
(c)
Inspec
t
the
needle
valve
for
distort
ion
or dam-
age
at its seating
part
and
for
wear
of its
en
d
face
i.n contact
with
the
pres;sure
pln
.
(d)
Poor seating
contact
may
be
corrected,
if the
defective
cond
ition is
not advanced
too
far
J
by
lapping the valve agains'
the seat
with
a
coat
of
clean
lube
oil applied
to
the seating faces
.
If
tltis
does not
help
,
the injection non:le must
be
repl.ced.
(2) Nozzle bolder
and
distance piece
Check
the
fit
between
nozzle
holder
and distance
piece
and
between
distance piec.e
and
nozzle
holder
,
Delennine
the
quality of
'
he
fi
t
from
contact
patterns
obtained
with
the
use of red lead
pasle
:
defective fit
will
be
evidenced
by
an abnor-
mally
high
rate of
return
oil
(I""d-<>ff)
fiow.
(3)
Pressure spring
and pressun pin
(a) Replace
any
pressure
spring
broken\ cracked
or
otherwi ..
defective
,
or out of
square.
Inspect
each
spring
for the.se defecu,
(b)
lnspect
each
pressure
pin
for
wear at ils
ond
fa.ces., one
for pressure spong.
and
the
other for
needle valve
.
(4)
l.eak..,ff pipe
packing
If the packing
is
found
in
deteriorated
condition,
replace
il.
InjectioD
nozzle lesting IIlld adjustment
(
I)
Injection
p~
The
pressure at
which
Ihe
needle
valve
unseats
lts.lf .gain.t
the
forc
e
of
th' pressure
spring is
referred
10
as "valve opening pressure" o
r
"begin-
ning.()r~injection
pressure,"
but
will
be
called here
'!injection
pre
s
S"uTl~"
for
mort.
The value of {his
pressure
is specified
~
it
is
checked
and adjusted
as
follows
:
(a) Install the injection no",l.
in
the
noule
tester,
and operate
the manual pumping
handle
of
tile
tester
several strokes
to
prime the
nozzle.
(b)
MAINTENANCE AND ADJUSTMENT
Move the Ieyer up and
down
slowly, completing
each up·.nd-down
cycle in .bout , second,
10
pressurize
the injection
nozzle, while observing
the indication of
the
lest
pressure
gauge.
As
the
nozzle
begins
to
spray
.
the
indicating pointer
of
Ihe gauge
being deflected
will
start perceptiv'ly
o<ciUaling:
read
the pressure right then
as
the
injection pressure
.
Unit: kg/em'
(psi)
Standard
Repair
Item
limit
120
±
5
110 (
1564
.2),
Injection pressure
(1706
.4
±
7J.J)
minimum
(c)
If the readins
laken
is
below the limit, increase
the
thickness of-the
shim
used on the pressure
spring. Increasing
tlle
sltim
thickness by 0
.1
mm
(0,0039
in.) raises the injection pressure
by
abour
10
kg/cm' (142 psi).
Adjustinj;
.rum
stock for this purpose is available in
20
sizes,
from
1.0
nUll
(0.0394
in.)
up
to 1.95
mm
(0.0768 in,)
in Incremenls
0(0.05 m.m
(0.0020
in.)
each,
Checking
injection
pres.sure
on
nozzlB
t&iiter
(2) Spr1lY pattern
The
injection
noules
used
in
the present engine
are
of throttle type
,
Some throttling
action lak"
place
when the needle valve begins
to
unse.at,
thereby
limi
ting
the
amount of
fuel
being
.
prayed
out during the initial stage
of
each
fuel
injection.
Thus, each
slug
of fuel sprayed out may b.
regarded as
consisting
of
two
parts:
initial throttled
spray and
terminatmg main
spray.
When tested on the nozzle tester, the injection
nozzle can be made to produce these two kinds of
pray for visual
inspection.
Initial
throttled
spray
comes about
when
the
tester
lever
is. operated
at
a rat-e
of 60
cycles
per
minute
(up
and
down in
77
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