..
Injection-quantity equalizing
adjustment
The three pumping elements are required
to
deliver the same
quantity
of
fuel for each
control rack position. The
requirement
is
satis-
fied by allowing the
two
plunger barrels to be
angularly repositioned while the third barrel
is
kept
fixed in place. There are two adjusting
plates, each functioning
as
a cam
to
angularly
reposition the barrel.
o
rr:;;J3)
..
W
0-.-
Cam
mechanism for equalizing injection quantities
Delivery valve
This
is
a spring-loaded valve similar
in
con-
struction
to
a relief valve. In operation, the valve
opens when the plunger rises
to
develop a very
high fuel pressure within the barrel.
As
the
pressure falls, the valve snaps back to its closed
position in such a way as to draw back a tiny
amount
of
fuel from the injection pipe. By this
retracting action, the nozzle is prevented from
producing an after-injection dribble. In
other
words, each injection
is
sharply articulated.
Injection in progress
End
of
injection
Del
ivery valve action
ENGINE
Injection nozzles
and
nozzle holders
The nozzle
l:l.Older
and nozzle
constitute
a
unit,
as
will be
noted
in this partial cutaway
view.
Body
Flange
Nipple
Shim
washer
Spring
Pin
Distance piece
Retaining
nut
Nozzle
Nozzle holder and nozzle - Sectional view
In operation, the highly pressurized
shot
of
fuel
admitted
into the top
part
of
the
holder
acts on the face, near the spray tip,
of
the
needle valve and forces the needle valve upward
against
the
force
of
the spring
to
burst
into
the
combustion
chamber.
through the spray
orifices in
the
tip. The drop
of
fuel pressure
to
terminate the
shot
is
so
abrupt
that
the needle
valve seats itself sharply. Fuel spilled from the
nozzle returns through overf1ow pipe
to
the
fuel tank.
DISASSEMBLY
[NOTE]
a) Do
not
remove the two adjusting
plates (locking the two rotatable
plunger barrels)
if
pump
testing equip-
ment
is
not
available.
It
is
on
the
equipment
(pump tester)
that
the
pump
can be adjusted and set for
proper
injection
quantity.
b) Internal moving parts, particularly
plungers, barrels, delivery valves and
the like, are high-precision parts and,
upon
pump
disassembly, must be
protected
against rusting.
Be
sure
to
keep
them
immersed in a clean diesel
fuel contained in a suitably sized pan
or tray.
2-35
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