Stihl 038 - Chain tension; Chain sprocket

Chain tension
Apart
from
chain
lubrication,
chain
tension
is
the
factor
that
has
the
greatest
influence
of
the
cutting
attachment’s
use-
ful
life.
It
is
therefore
necessary
to
check
chain
tension
before
starting
work
and
at
regular
short
intervals
during
cutting
work.
Chain
tension
is
correct
in
the
cold
condition
when
the
chain
fits
snugly
against
the
underside
of
the
bar
and
can
still
be
pulled
along
the
bar
by
hand
(wear
gloves!).
As it warms up to normal operating temperature the chain
expands and sags noticeably. The saw chain must be
retensioned when the drive links begin to come out of the
groove on the underside of the bar. If this is not done, there
is a risk of the chain jumping off the bar.
If the chain is retensioned during cutting work it must
always be slackened off again after finishing work. This is
necessary because high contraction stresses would other-
wise occur as the chain cools down to ambient tempera-
ture, especially at extremely low outside temperatures,
and cause damage to the crankshaft and bearings.
A new chain must be retensioned more frequently than a
used one because it stretches during the initial break-in
period.
Chain sprocket
The stress and strain on the chain sprocket are particularly
high. If the wear marks on the teeth are very pronounced
(about 0.5 mm/0.02 in deep), the sprocket should be
replaced.
A
worn
sprocket
reduces
the
service
life
of
the
Worn chain sprocket
saw chain. The chain sprocket should be replaced as a
matter of routine with every second Oilomatic chain. It is
best to use saw chains alternately with one sprocket.
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