Chain Brake - Stihl MS 390 Instruction Manual

English / USA

Chain Brake

Locking chain with chain brake
– in an emergency
– when starting
– at idling speed
The chain is stopped and locked when
the hand guard is pushed toward the bar
nose by the left hand –
or when brake is activated by inertia in
certain kickback situations.
32
Releasing the chain brake
: Pull the hand guard back toward the
front handle.
Always disengage chain brake
before accelerating engine and
before starting cutting work. The
only exception to this rule is when
you check operation of the chain
brake.
High revs with the chain brake
engaged (chain locked) will quickly
damage the powerhead and chain
drive (clutch, chain brake).
The chain brake is designed to be
activated also by the inertia of the
front hand guard
if the forces are sufficiently high. The
hand guard is accelerated toward the
bar nose - even if your left hand is not
behind the hand guard, e.g. during a
felling cut. The chain brake will operate
only if it has been properly maintained
and the hand guard has not been
modified in any way.
Check operation of chain brake
Before starting work:
Run engine at idle speed, engage the
chain brake (push hand guard toward
bar nose). Accelerate up to full throttle
for no more than 3 seconds – the chain
must not rotate. The hand guard must be
free from dirt and move freely.
MS 290, MS 310, MS 390