Chapter 3 Fuel Injection Equipment
7. Timer Construction and Operation
4LHA SerieA
Load
Timer
Governor
shaft
Control
port
Governor
sleeve
a r
Low
pressure side
Flyweight
Feed
pump
L
Fig.
51
Load
timer construction and operation
The
load timer functions to retard injection tim-
ing under partial loads in the low and in-
termediate speed range, and to reduce exhaust
emission
and engine noise.
With the load timer, the governor
sleeve,
the
governor
shaft, and the injection pump housing
are
specially constructed to facilitate the
escape
of fuel oil in the injection pump cham-
ber
from the governor sleeve control
port,
through a passage in the governor shaft and
pump housing to the low pressure
side.
When
the flyweights are
closed,
the control
port
and the governor shaft passage are not
aligned.
When
the flyweights begin to open
with
an in-
crease
in the engine
speed,
the control
port
and
the governor shaft passage barely align
and
injection pump chamber pressure begins
to decrease as the pump chamber fuel oil
flows to the fuel inlet (i.e. low pressure side)
through this
passage.
When fully open pres-
sure
reduction is complete.
As
a result, the timer's advance angle is only
retarded an amount equal to the value of the
pressure
reduction.
Furthermore,
the flyweights' (governor
sleeve's)
position changes in accordance
with
control lever position (engine load).
3-1-42
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