Yanmar 4LHA-HTP Operation Manual page 386

Chapter 3 Fuel Injection Equipment
6. Governing Mechanism
Variable Speed Governor and Combination Governor
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^ig. 33 Variable speed governor characteristics
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ig. 34 Combination governor characteristics
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V
Full-load position
Injection pump speed »-
Damper spring operation range
Partial load spring operation range
Partial load spring stroke
Injection pump speed
The governor spring's set force in a variable
speed governor changes in accordance with
changes in the accelerator pedal position. (Fig.
33: points 1 -5).
For example, when the flyweights' centrifugal
force and the governor spring's set force are
balanced (Fig. 33; point A) and the accelerator
pedal is released a little to decrease speed, the
control sleeve will move to the non-injection
position as shown by the solid line in Fig. 33.
Then, in response to the change in the gov-
ernor spring's set force (gradient 3). the control
sleeve will move in the fuel-increase direction
and will stop in the positon where the injection
quantity necessary for the load at this time can
be obtained (i.e. point B ; the flyweights' centi-
fugal force and the governor spring's set force
are balanced). The variable speed governor
governs in the engine's all-speed range in re-
sponse to accelerator pedal position or varia-
tions in engine load.
With the combination governor the set force of
the partial load spring and the control sleeve
position (Fig. 34 : lines 1-5) are varied in re-
sponse to accelerator pedal position to regulate
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the fuel injection quantity.
If the accelerator pedal is released slightly to
decrease speed during partial load operation
(Fig. 34 : point A), when the flyweights' centri-
fugal force and the partial load spring's set
force are balanced, the control sleeve will
move from point A to point B, as shown by the
solid line in Fig. 34.
As can be seen from the solid line in Fig. 34
showing
speed decreases, the combination governor's
control sleeve travel is less, and the variation in
fuel injection quantity is also decreased.
This results in a reduction in the shock caused
by sudden variations in fuel injection quantity
and an improvement in accelerator "feeling"
when speed is reduced.
control sleeve movement
4LHA Series
when