Stihl MS 391, Safety Manual

Page: 42 / 68

MS 311, MS 391
English
20
Locking the chain
– in an emergency
– when starting
– at idling speed
The chain brake is activated by pushing
the hand guard toward the bar nose with
your left hand – or by inertia in certain
kickback situations: The chain is
stopped and locked.
Releasing the chain brake
N
Pull the hand guard back toward the
front handle,
The chain brake is also activated by the
inertia of the front hand guard if the
kickback force of the saw is high
enough: The hand guard is accelerated
toward the bar nose – even if your left
hand is not behind the hand guard, e.g.
during felling cut.
The chain brake will operate only if the
hand guard has not been modified in any
way.
Check operation of the chain brake
Before starting work: Run engine at idle
speed, engage the chain brake (push
hand guard toward bar nose) and open
the throttle wide for no more than
3 seconds – the chain must not rotate.
The hand guard must be free from dirt
and move freely.
Chain brake maintenance
The chain brake is subject to normal
wear. It is necessary to have it serviced
and maintained regularly by trained
personnel. STIHL recommends that you
have servicing and repair work carried
out exclusively by an authorized STIHL
servicing dealer. Maintain the following
servicing intervals:
Chain Brake
143BA011 KN
Always disengage chain brake
before accelerating the engine
(except when checking its
operation) and before starting
cutting work.
High revs with the chain brake
engaged (chain locked) will
quickly damage the powerhead
and chain drive (clutch, chain
brake).
143BA012 KN
Full-time usage: every 3
months
Part-time usage: every 6
months
Occasional usage: every 12
months