5. Inspection and servicing of basic engine parts
213
5.8 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 turning 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 unbalanced force on the shaft
center must be kept below the specified value for
the crankshaft as the flywheel rotates with the
crankshaft at high speed.
To achieve this, the valance 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 circumference, 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.
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