Chain Brake; Checking Operation; Removing - Stihl MS 650 Manual

1
: Screw home the clutch (1),
hexagon facing outward, and
tighten it down firmly – b 3.5
The clutch has a left-hand thread.
– Remove locking strip from the
cylinder.
Reassemble all other parts in the
reverse sequence.
22
5.5

Chain Brake

5.5.1

Checking Operation

5.5.2

Removing

The chain brake is one of the most
important safety devices on the
chainsaw. Its efficiency is measured
in terms of the chain braking time,
i.e. the time that elapses between
activating the brake and the saw
chain coming to a complete
standstill. The shorter the braking
time, the better the efficiency and
protection offered against being
injured by the rotating chain.
Contamination (with chain oil, chips,
fine particles of abrasion, etc.) and
smoothing of the friction surfaces of
the brake band and clutch drum
impair the coefficient of friction.
This, in turn, reduces the frictional
forces and thus prolongs the
braking time. A fatigued or stretched
brake spring has the same negative
effect.
– Start the engine.
– With the chain brake activated
(locked), open the throttle wide
for a brief period (max. 3
seconds) – the chain must not
rotate.
– With the chain brake released,
open the throttle wide and
activate the brake manually – the
chain must come to an abrupt
stop.
The braking time is in order if
deceleration of the saw chain is
imperceptible to the eye.
If the chain brake does not operate
properly, see troubleshooting chart
– b 4.1.
2
1
– Troubleshooting chart – b 4.1
– Remove the chain sprocket
cover, chain, bar and clutch drum
– b 5.1
: Take out the screw (1).
: Remove the inner side plate (2).
– Engage the chain brake by
pushing the hand guard away
from the front handle.
: Take out the screws (arrows).
: Remove the cover.
MS 650, MS 660