Chapter 2 Basic Engine
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3
,
41
H
3
(B)(C)E
8.
Flywheel and Housing
The function of the flywheel is through inertia, to rotate the
crankshaft in a uniform and smooth manner by absorbing
the turning force created during the combustion stroke of
the engine, and by compensating for the decrease
in
turn-
ing force during the other strokes.
The flywheel is mounted and secured by 6 bolts on the
crankshaft end
at
the opposite end to the gear case;
it
is
covered by the mounting flange (flywheel housing) which
is bolted to the cylinder block.
the fitting surface for the damper disc
is
on
the crankshaft
side
of
the
flywheel.
The
rotation of the
crankshaft
is
transmitted
through
this
disc
to the
input
shaft of
the
reduction and reversing gear. The reduction and reversing
gear is fitted to the mounting flange.
The flywheel's unba!anced force on the shaft center must
8-1
Specifications of flywheel
Engine
Model
3JH3(B)(C)E
Outside
dia.
of
flywheel
mm
,f
300
Width
of
flywheel
mm
74
Weight
of
flywheel
kg
20.4kg
(including
ring
gear)
GD
2
value kg·m'
1.15
Circumferential speed
m/s
59.
7 (al 3800rpm)
Speed
fluctuation
rate
(Y
1/128
(al 3800rpm)
Allowable amount
of
unbalance g·cm
32
Pitch
circle
mm
170
Fixing
part of
dia.
of
bolts
damper disc
No.
of
bolts
6-M8 thread
Xbolt
dia.
equally spaced
Pitch
circle
mm
66
dia.
of
bolts
Fixing part
of
No.
of
mm
6-M10
crankshaft thread holes
Fit
jo·1nt
dia.
¢ 85.000~85.035
Model
of
reduction
and
KM3P, KM3A
reversing gear
Ring
gear
Center
dia.
mm
322.58
No
of
teeth
127
2-26
be kept below the specified value for the crankshaft
as
the
flywheel rotates with the crankshaft at high speed.
To achieve this, the balance is adjusted
by
drilling holes
in
the side of the flywheel, and the unbalanced momentum is
adjusted by drilling holes in the circumference.
The ring
gear
is shrink fitted onto the circumference of the
flywheel, and this ring gear serves to start the engine by
meshing with the starter motor pinion.
The stamped letter and line which show top dead center
of each cylinder are positioned on the flywheel circumfer-
ence, and by matching these marks with the arrow mark
at the hole of the flywheel housing, the rotary position of
the crankshaft can be ascertained in order to adjust tappet
clearance or fuel injection timing.
4JH3(B)(C)E
¢ 300
74
20.4kg
1.15
59.7(at 3800rpm)
1/409
(at
3800rpm)
32
170
6-M8 thread
equally spaced
66
6-M10
¢ 85.000~85.035
KM3P, KM3A
322.58
127
Printed in Japan
HINSHI-H8009
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