Chain Brake; Checking Operation; Removing And Installing; The Brake Band - Stihl MS 200 Service Manual

7.

Chain Brake

7.1

Checking Operation

The chain brake is one of the most
important safety devices on the
chain saw. 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.
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,
which prolongs the braking time. A
fatigued or stretched brake spring
has the same negative effect.
– Chain sprocket cover must be
secured with collar nut.
– 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, refer to troubleshooting,
b 4.2.
22
7.2

Removing and Installing

the Brake Band

1
– Troubleshooting, b 4.2
– Remove the chain sprocket
cover, bar and chain, b 5
: Engage the chain brake by
pushing the hand guard (1)
forwards.
The brake spring on the brake band
is now relaxed.
: Take out the screws (arrows).
: Ease the cover (1) out of its seat
(arrow) and lift it away.
1
: Pry the brake band (1) out of its
seat (arrow).
: Swing the brake band (1)
outwards and disconnect it from
the brake lever (arrow).
Do not over-stretch the brake band.
MS 200, MS 200 T
1
1