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 tow saw
chains alternately
with one sprocket.
39
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