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Crankshaft aligning
Check the aligning and the permissible untrue run using
a special jig with centres and two dial indicators. The
crankshaft must be supported in the centres so that it can
rotate. The maximum permissible relative run-out of the
functional points is 0.016mm. The functional points in
this instance are the shoulders for the bearings. The
design of the crankshaft and the manufacturing process
guarantee this value. Check the run-out or untrue run
before installing the crankshaft in the engine.
Misalignment of the crankshaft is usually caused by a
crash, rough handling during transport, dropping the
crankshaft on the ground or by an unskilled repair. You
will obtain the correct axial (lateral) clearance of the
crankshaft in the crankcase if you maintain the
dimension 38-0.2mm (distance of the shoulders for the
bearings) when pressing the crankshaft together. The
minimum distance of the flywheels in place on the
crankpin must be 12.2mm.
Crankshaft aligning and straightening procedure
Check the alignment of crankpins as illustrated in Fig
23. If the crankshaft halves are mutually set off, remove
the crankshaft from the centres,
and using a suitable copper or aluminium pad and a
hammer of soft material work on it till the crankpins are
aligned as perfectly as possible The two crankshaft
halves are not set off if both dial indicators give the
same readings when rotating the crankshaft. If after this
procedure the mutual run-out of the functional parts is
greater than 0.016mm, straighten the crankshaft (its
axis) by bending both its halves against each other in the
required direction.
This procedure is depicted in Fig. 23. Depending on the
deflection of the crankshaft axis (ascertained by dial
indicators), bend the flywheels toward each other ( - -
readings) or away from each other (+ + readings). If
necessary, repeat the bending on more planes than the
one given in the illustration.
Decisive for the final straightening is the maximum
permissible untrue run of the functional part (surfaces)
of 0.016mm. If you fail to obtain this value by the
described procedure, it means that the crank mechanism
is defective and has to be replaced with a new one. As
this work requires great skill, it should be done by a
highly qualified fitter.
Fig. 23
ZVL model 210 Workshop Manual Page 18 jkw
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