47Chain and Bar Manual
5.3 Checking the Chain
Sprocket
The drive link tangs dig into the
flanks of the teeth and cause the
chain sprocket and chain to wear.
On the spur sprocket the tips of the
teeth wear (arrows). This is caused
by the bottoms of the cutters and tie
straps.
On the rim sprocket wear is
primarily visible on the
circumference (arrows), which is
caused by the bottoms of the cutters
and the tie straps.
Checking sprocket wear
Spur sprocket
Rim sprocket
Place the reference gauge
0000 893 4101 on the chain
sprocket. The sprocket must be
replaced if the wear marks are the
same depth (0.5 mm) or deeper
than the gauge lugs (1).
A chain sprocket will normally last
the equivalent of two chains.
The sprocket and saw chains
should be broken in together and
wear at the same rate. This avoids
abnormal wear on the sprocket and
chain. It is therefore advisable to
always use two saw chains in
rotation.
When fitting a new chain, always
check the chain sprocket and
replace it if necessary.
A worn sprocket will quickly ruin a
new chain.
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