OPERATING
LEVER
I
PUMP TAPP
CAM GEAR
FIGURE
19.
INJECTION PUMP TO
CAMSHAFT RELATIONSHIP
0
PE
L
PSU
Pump Operation
The pump face gear mates with and is rotated by a
drive gear on the engine camshaft, Figure
19.
The
face gear, pilot ring, and the reciprocating plunger in
the pump are rotated continually to assure positive
fuel distribution. The plunger is reciprocated up and
down by a multi-lobed cam on the camshaft which
bears against a tappet assembly on the pump.
Pump Cutaway View
The cutawayview in Figure 20shows the control unit
operating lever, metering sleeve, delivery valve, plun-
ger 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
so
phased that only one fuel injector is served
during theaffective 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 afine mist into the combustion
chamber. Fuel delivery control, full load, and shutoff
are regulated by
the
up-and-down movement of the
fuel metering sleeve. The sleeve is controlled by the
operating lever on the outside
of
the pump. Fuel is
injected only during the high velocity portion of each
plunger up stroke.
HYD RAULlC
OUTLET
1
PLUNGER
i
METERING
SI
\
HY
-EEVE
TIMING BUTTON
FIGURE
20.
PSU PUMP (CUTAWAY
VIEW)
29
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