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
bo
d
y,
and move
th
e
va
lve
back and
forth
to
be
s.ur
e
(hat
the sliding contact is smooth
wit.hout
evidenc
in
g any excessive
cl
ear
ance
. The
in
je
c-
tion nozzle
as
a whole
mu
S!
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
val
ve
for distortion
or
dam-
age
at its
se
ating pa
rt
and
for
wear
of
its
en
d
fa
ce
i.n
contact
with
th
e pr
es;sure
pln
.
(d) Poor seating contact
may
be
corrected,
if
the
defective condition
is
not
advanced
too
far
J
by
lapping the valve agains' the seat wi
th
a
coat
of
clean lube oil applied
to
the seating faces .
If
tltis
does not help , the
in
jection non:le must
be
rep
l
.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
th
e quality
of
' he
fi
t from
contact patterns obtained
with
the
use
of
r
ed
lead
pasle: defective fit
will
be evidenced by an abnor-
mally
high rate
of
return
o
il
(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
pressur
e
pin
for
wear
at
ils
ond
fa.ces.,
one
for
pressure
spong.
and
the
other
for
needle v
alve
.
(4) l.eak..,ff pipe packing
If
the
packing
is
found
in
deteriorated
condition,
replace
il.
InjectioD nozzle lesting
IIlld
adjustment
(
I)
Inj
ection
p~
The
pressure
at
which
Ihe
needle
v
alv
e
unseats
lts.lf
.gain.t
the force
of
th'
pressure spring
is
referred 10
as
"valve opening pressure" or "begin-
ning.()r~injection
pressure,"
bu
t
will
be
called
here
'!injection
pre
s
S"uTl~"
for
mort.
The
value
of
{his
pressure
is
sp
ecified
~
it
is
checked
and
ad
justed
as
follows
:
(a) Install
the
injection
no",
l.
in
the
nou
le tester,
and
opera
te the manual pumping
hand
le
of
tile
tester
several
strokes
to
prime
the
nozzle.
(b)
MAINTENANCE
AND
ADJUSTMENT
Move
the
Ieyer
up
and
dow
n slowly, completing
each
up·.nd-down
cycle in
.bo
ut , second,
10
pressurize
the
injection nozzle, while
observing
the indication
of
the
lest pressure
gau
ge. As
the
no
zzl
e
begins
to
spray
.
the
indicating
pointer
of
Ihe gauge being deflected
will
start
perceptiv'ly
o<ciUaling: read the pressure right then
as
the
in
jection
pressure
.
Unit:
kg/em'
(ps
i)
Standard
Repair
Item
li
mit
120 ± 5 110 (
15
64
.2
),
Injection
pressure
(17
06
.4
±
7J.J)
minimum
(c)
If
the
r
eadins
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
sto
ck 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&iite
r
(2)
Spr1lY
pattern
The
injection noules u
sed
in
the
present
engine
are
of
throttle
type
, Some throttling action
lak"
place
when
the
needle v
alve
begins
to
unse.at,
thereby
limiting the amo
unt
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
thro
ttled
spray
and
terminatmg
main
spray
.
When
tested on the nozzle tester, the
in
jection
nozzle
can
be
made
to
produce
th
ese
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
pe
r minute
(up
and
down
in
77
To Next Page
Loading...
