Chain Brake; Checking Correct; Operation - Stihl MS 440 Service Manual

2 1
: Fit the clutch shoes over the
arms (1) of the clutch carrier so
that the series number (2) is on
the same side as the longer
hexagon (3).
: Clamp the clutch in a vise.
2
1
: Attach one end of each spring (1)
to the clutch shoes.
: Use the hook (2) 5910 890 2800
to attach other end of the spring
and press it firmly into the clutch
shoe.
MS 440, MS 440 C
3
: Screw home the clutch, turning
counterclockwise, and tighten it
down firmly – b 3.5
– Remove locking strip from the
cylinder.
– Turn in the spark plug and tighten
it down firmly – b 3.5
– Plug the boot onto the spark plug.
– Refit the shroud.
– Fit the clutch drum / chain
sprocket – b 5.1
Ensure that the grooves in the
shroud are correctly positioned
when assembling the parts.
5.4

Chain brake

5.4.1

Checking correct

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.
If the chain brake does not operate
properly, see troubleshooting
chart – b 4.1.
17