Stihl 088

STIHL 088 12
• Attach the brake spring to the
bell crank.
• Use the assembly tool (2)
1117 890 0900 to attach the
brake spring (1) to the anchor pin.
- Fit cover over the chain brake.
- Fit the side plate.
- Install clutch drum/chain
sprocket - see 3.1.
- Mount guide bar and chain
sprocket cover. Tighten sprocket
cover nuts to approx. 15 - 20 Nm
(11 - 15 Ibf.ft).
- Check operation of chain brake -
see 3.3.3.
• Coils of brake spring must locate
tight against one another in
relaxed condition. Install a new
brake spring if necessary.
• Check that protective tube is
correctly positioned:
a = 20 mm (3/4")
b = 42 mm (1 5/8")
3.3.3 Checking Function
The chain brake is one of the most
important safety devices on the
chainsaw. Its efficiency is
measured in terms of braking time,
i.e. the time that elapses between
activating the brake and the saw
chain coming to a 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 pro-
longs the braking time. A fatigued
or stretched brake spring has the
same negative effect.
- Start the engine.
- With the chain brake activated
(locked), open throttle wide for
- brief period (max. 3 seconds) the
chain must not rotate.
- With the chain brake released,
- open throttle wide and activate
- the brake manually - the chain
- must come to an abrupt stop.
Note: The braking time is in order
if deceleration of the saw chain is
imperceptible to the eye.