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5.
Chain Sprockets
The chain sprocket transmits the
engine's torque to the saw chain.
The teeth of the chain sprocket
engage the rear flanks of the drive
link tangs and thus drive the chain.
The number of teeth on the chain
sprocket has a direct influence on
the cutting power and the velocity of
the saw chain:
Large number of teeth
– Larger diameter
– Higher chain speed
– Less lugging power on saw chain
– more sensitive to feed pressure
– Higher driving power required
Small number of teeth
– Smaller diameter
– Lower chain speed
– Higher lugging power on saw
chain – less sensitive to feed
pressure
– Lower driving power required
The diameter of the chain sprocket
is exactly matched to the guide bar
tail as this determines the angle of
drive link run-in to the bar groove.
For this reason only chain sprockets
designed for a specific chainsaw
model may be used in each case.
The pitches of the chain sprocket,
saw chain and the nose sprocket on
Rollomatic bars must match.
46
5.1
Spur Sprocket
This chain sprocket is made from a
highly wear resistant star-section
bar. On gasoline saws the spur
sprocket is permanently attached to
the clutch drum. On electric saws
the chain sprocket is mounted
separately on the output shaft.
The spur sprocket is usually
standard equipment on chainsaws
for occasional users, farmers and
the construction industry. Country-
specific variations are possible.
5.2
Rim Sprocket
3
2
This rim sprocket (1) is made from
sintered steel and is ring-shaped.
The teeth are enclosed on both
sides by a circular wall. The
sprocket can move axially on the
hub (2) of the clutch drum (3) and is
positively located by means of
splines.
The bottom faces of the chain links
ride on the circumference of the rim
and the side walls of the rim keep
the chain in line.
Most chainsaws for the forestry
industry are equipped with a rim
sprocket. Country-specific
variations are possible.
Chain and Bar Manual
1
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