Yanmar 1GM User Manual page 158

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seal properl y if reused. A lways install new washers when
reconnecting a fittin g .
Th e fuel lines are secured with brack ets to pre vent leak s
due to engine vibra tion. Periodi cally check th at fuel lines
are properly secured with brackets. The high-pressure
fuel injection lines are held by a rubber pad in the bracket
(Figure 41). Replace any rubber pads that are missing or
no longer holding the line securely.
GOVER:\OR SYSTE:\I
Operation
The governor components are in the timing gearcasc
(Flg u re 42, typi ca l). The purpose of the go vernor sys tem
is to maintain engine speed regardless of the load im-
posed.
The mechanical governor system utilizes centrifuga l
force
10
monitor and adjust engi ne speed . Refer to Fi2u rc
43. Figure 44 and Figure 45. A set of flyweights are
mountcd on the crankshaft. When engine speed increases,
the flyweights are thrown out. When engine speed de-
creases, the flyweights recede. Trapped between the fly-
weights is a flanged sleeve that moves in and out with the
flyweights, pushing against a forked governor arm. The
forked governo r arm transfers motion to the governor le-
ver, which is connected to the fuel injection pump fuel
control rack. The governor spring tension forces the speed
control lever against the governor lever, which forces the
injection pump speed contro l rack to the full open throttle
position. When load on the eng ine increases and engine
speed decreases, the governor sleeve is withdrawn, which
through the linkage moves the speed control rack to in-
crease fuel injection. When load on the engine decreases
and engine speed increases. the governor sleeve extends,
which moves the linkage to overcome governor spring
CHAPTER SEVEN
tension. The linkage moves the speed control rack and de-
creases fuel injection.
The governor controls engine speed in an operating
range between idle speed and maximum governed speed.
Maximum governed speed is critical as it sets the upper
limit of engine operation. Exceeding the maximum gov-
erned speed can cause overspceding, which may result in
engine failure.
A fuel limiter screw sets maximum injection pump fuel
delivery. When the governor senses a decrease in engine
speed, the fuel control rack moves to the full fuel position.
The factory-adjusted fucllimi ter screw stops the governor
linkage at a point that provides maximum, but not exces-
sive, fuel delivery to the engine.