\TIMING
BUnoN
FIGURE
44.
INJECTION PUMP (CUTAWAY
VIEW)
Pump Cutaway View
Thecutawayview in Figure44showsthecontrol unit
operating lever, metering sleeve, delivery valve,
plunger, and drilled passages to the plunger and
injection lines.
A
timing button of very precise thickness transmits
motion from the tappet to the plunger and adjusts
plunger timing for the fuel pumped to each injector
during operation. Plunger reciprocation and rotation
are phased
so
that only one fuel injector is served
during the affective portion of each plunger up
stroke. The high hydraulic pressure developed is
required to open the pressure operated fuel injector
nozzles, which inject the fuel in a fine mist into the
combustion chamber. Fuel delivery control, full load,
and shutoff are regulated by the up-and-down move-
ment of the fuel metering sleeve. The sleeve is con-
trolled by the operating lever on the outside of the
pump. Fuel is injected only during the high velocity
portion of each plunger up stroke.
When the tappet slips
off
each lobe of the camshaft,
the
spring loaded plunger is forced down, opening
the fuel supply port to
the
fuel sump. This allowsfuel
under
low
pressure from the transfer pump and fuel
sump to fill the cavity between the top end of the
plunger and the delivery valve. The plunger is then
ready for the up stroke.
,
SLEEVE
Metering Sleeve Operation
The metering sleeve is positioned by the operating
lever of the governor control unit, Figure 45. An
eccentric pin on the end of
the
control shaft engages
aslot
in
the
metering sleevesothat aslight rotation of
the control shaft causes thesleeve to ride up or down
on the plunger.
As
the
camshaft and face gear rotate,
the drive key and a vertical slot in the face gear trans-
mit rotation to the plunger. Rotating the plunger
aligns outlet groove with the appropriate injection
line outletforthe injectorto fireon each pumpstroke.
OPERATING
LEVER
ECCENTRIC
PIN
,.
q
_1_1
SLEEVE
FIGURE
45.
METERING
CONTROL
45
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