Injection-Quantity Equalizing Adjustment; Delivery Valve; Injection Nozzles And Nozzle Holders; Disassembly - Mitsubishi MT160 Repair Manual

.. 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.
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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.
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