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 allows fuel
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.
Metering Sleeve Operation
The metering sleeve is positioned by the operating
lever of the governor control unit, Figure
22.
An
eccentric pin on the end of the control shaft engages a
slot in the metering sleeve
so
that a slight rotation of
the control shaft causes the sleeve 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
transmit rotation to the plunger. Rotating the plunger
aligns the plunger outlet groove with the proper
injection line outlet for the injector to be fired on each
pump stroke.
FIGURE
23.
SHIM
THICKNESS
Removing Tappet
Be sure to hold the pump drive securely to the
pump body when removing the tappet, Figure
24.
If
not, the pump
will
come apart and be difficult to reassemble.
Also, the metering sleeve may drop
off
the plunger into the sump
when the plunger is removed.
If
the mechanic
Is
not aware
of
it, he
could put the pump back together, but it will not operate.
If
the
plunger port is not enclosed by the sleeve, there will be no fuel
delivery.
'
SLEEVE
Use a pair
of
channel
lock
pliers or a screwdriver to remove the
tappet
from
the O-ring
in
the drive gear.
MAXIMUM
THROTTLE
STOP SCREW
STAMPED CODE
LETTER
OF
BUTTON
USED
FIGURE
22.
METERING CONTROL
Pump Installation Shims
If
the pump is removed from the engine, be sure the
steel shims between the pump and the crankcase
mounting are the same on reassembly to maintain
proper gear backlash, Figure
23.
The number
stamped on the crankcase indicates the proper shim
thickness. This thickness does not change when a
new pump is installed.
It
only changes when a new
crankcase is installed, and then the thickness of the
proper shims is stamped on the new crankcase.
TTON
O-RING KEEPS TAPPET IN
DURING HANDLING
FIGURE
24.
TAPPET REMOVAL
24
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