Chain Brake - Stihl MS 270 User Manual

Clamp the clutch in a vise.
Use protective jaws so as not to
damage the clutch.
2
1
Attach one end of each spring (1)
to the clutch shoes.
Use the hook (2) 5910 890 2800
to attach other ends of springs
and press them firmly into the
clutch shoes.
20
TOP
1
Push cover washer (1), "TOP"
(arrow) facing outward, onto the
crankshaft.
Screw on the clutch and tighten it
down – see 3.5.
– Remove locking strip from the
cylinder.
– Screw home spark plug and
tighten it down – see 3.5.
– Fit boot on the spark plug.
– Fit the shroud.
– Install clutch drum/chain sprocket
– see 5.1.
5.4

Chain Brake

5.4.1 Checking Operation
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.
MS 270, MS 280