Safety Manual

ManualsBrandsSTIHL ManualsChainsawsSTIHL MS 251

MS 251, MS 251 C

English

50

N Remove chain sprocket cover, saw

chain and guide bar.

N Release chain brake – pull hand

guard against the front handle

Fit new chain sprocket

– after use of two saw chains or

earlier

– if the wear marks (arrows) are

deeper than 0.02 in (0.5 mm) –

otherwise the service life of the saw

chain is reduced – use check gauge

(special accessory) to test

Using two saw chains in alternation

helps preserve the chain sprocket.

Use only STIHL original chain sprockets

to help ensure reliable functioning of the

chain brake.

N Use a screwdriver to remove the E-

clip (1)

N Remove the washer (2)

N Remove rim sprocket (3) (if so

equipped), clutch drum (4) and

needle cage (6).

N Inspect transport profile for rim

sprocket on the clutch drum (4) – if

there are also heavy signs of wear,

also replace the clutch drum

N Remove clutch drum with integrated

spur chain sprocket (5) (if so

equipped) including needle cage (6)

from the crankshaft – for

powerheads with Quickstop Plus

chain brake system, depress

throttle trigger lockout beforehand

Install spur chain sprocket / rim sprocket

N Clean crankshaft stub and needle

cage and lubricate with STIHL

lubricant (special accessory)

N Slide needle cage onto the

crankshaft stub

N After refitting, turn the clutch drum

and/or spur chain sprocket approx.

1 full turn so that the carrier for the

oil pump drive engages

N Refit the rim sprocket – cavities

toward the outside

N Refit washer and E-clip on the

crankshaft

Checking and Replacing the

Chain Sprocket

001BA121 KN

001BA122 KN

1

2

4

5

6

1

2

3

6