CONSTRUCTION AND FUNCTION
The
two
- cylinder
and
plunger
-
are
selective!
combined
dunng
manufactu
rt
and
must
be
han
-
dl.d
as
an
inseparable p:ur.
:t~
(2)
~II
Q)~
l·
F
e-ed
hole
2-Cr)ntrol
fjroCM!
eVII"d",)
Pl,lmp
1I._ment
Plunger
3-D
riv
lng facs
Pump
element
A helical slot
is
milled in the top
ponion
of
the
plunger. Called
the
comrol groove, this slot
is
conununicated
to
the
space
above
the
plunger
through
a center
hole
(or
a
vertical
gr
oove
in
other
design,).
The cylinder
has
• feed hole. through which the
internal
space
IS
communicated
(0
the
fu
el
cham-
ber
or
gaUery
out
tide
. F
uel
(under
pressure)
flows
through Ihls hole when the plunger
is
down.
As
the
plunger
rises,
its
top
porti
on
covers
up
th
11)
Bouom
at stroke
'
2~
B.giM
,ng
of
pressu
ri
ta
tlo
n
feed hole and. from this moment on. the plunger
compresses
the
fuel
above
it
until
Hlt
control
groove
meet
s
the
hole. Effecti
ve
stroke
refers
tl
that length
of
the plunger that keeps the feed hole
covered
during
th
e
upward
st
ro
k.e
. This J
en
gth
or
stroke
can
be
inc
rease
d
or
dec
r
eased
by
angularly
displacing the plunger.
b.
Pump
element
operation
The
foUowin
g description
is
re
fe
re
nced
[0
the
fou
r
cutaw
ay
views
below
:
I .
BO
TT
OM
OF STROKE: Fuel
fl
ows into the
insid
e
spac
e - deli
very
chambe
r.
2.
BE
G
INNING
OF
PRESSURIZATION: The cam
p
ush
es
up
the
plunger
an
d,
as
it
r
is
es,
it
s t
op
port
ion
co
vers
the fted
ho
l
e.
3. FUEL DELIVERY: Fu
el
is compressed; it
forces
the
del
ivery
val
ve
against
its
spring
to
unsea
t
the
valve.
From
this
moment,
the
fue
l
Ul
the
line
from
deUlJery
valve
to injection
nozzle
is
pushed by the plunger.
4.
END
OF EFFECTIVE STROKE: Pressuriution
ceases
and
the
delivery
valve
seats
itseIr
under
the
fOlee
of
its
spring.
This
va
l
ve
has
an
annular
recess
. As the valve
comes
down, a
mill
amount
of
fuel
becomes
tr
apped
and
is
ex·
1racted
from
the
injection
line,
so
that
the
pressure
ahead
of
the
val".
drops
very
sharply
to
enab
le
the
injeclion
nozzJe
to
snap
lnto
cl
osed
position.
The
amount
of
fuel
so
drawn
back
is
called
"extraction volume,"
an
i
mpor
4
tant
faclor
of
fue
l injection.
Q
(3. Fuel
dt-
livery
t.-)
End
of
tffectivtt
woke
Pump element operation
(3) lnj<etio
ll
quantity control
26
a.
Plung
er
rot
at
in
g
me
ch
an
ism
The
control
slee
v
e,
around
which
the
co
ntrol
pinion
is f
aste
n
ed,
su
rrou
nds
the
lower portion
of
the cylinder (barrel). The slceve has two nocks Or
slots
in
its
bottom
end
;
the
dn
ving
face
or
flange
formed
of
the plunger is engaged with the,e slots.
so
that
the
pJ
un
ger
rotates
as
t
he
sl
e
ev
e
is
turned
.
The
sl
ots
are
long enough
to
permit
Ule
drive face
or
flange to slide vertically for full plunger
't
roke.
The control pinion
is
engaged with the teeth of
rontrol
rack.
.
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