Stihl MS 251 Manual De Instrucciones página 19

There are two mechanisms for activating
the chain brake if it is in a properly
maintained condition:
manual activation: If a kickback
–
occurs, the chain saw moves
upwards towards the user in a
rotating motion around the front
handle. The brake is designed to
engage if the left hand contacts the
front guard, which is the activation
lever for the brake, and pushes it
forward.
inertia activation: All STIHL chain
–
saws are equipped with an interia
Quickstop chain brake. If the
kickback impulse is strong enough,
this alone is sufficient to engage the
brake even without contacting the
front hand guard.
MS 251, MS 251 C
WARNING
Never operate your chain saw without a
front hand guard. In a kickback situation
this guard helps protect your left hand
and other parts of your body. In addition,
removal of the hand guard on a chain
saw equipped with a Quickstop chain
brake will disable the activation
mechanism of the chain brake.
WARNING
No Quickstop or other chain brake
device prevents kickback. These
devices are designed to reduce the risk
of kickback injury, if activated, in certain
kickback situations. In order for the
Quickstop to reduce the risk of kickback
injury, it must be properly maintained
and in good working order. See the
chapter of your instruction manual
entitled "Chain Brake" and the section
"Maintenance, Repair and Storing" at
the end of these Safety Precautions. In
addition, there must be enough distance
between the bar and the operator to
ensure that the Quickstop has sufficient
time to activate and stop the chain
before potential contact with the
operator.
WARNING
An improperly maintained chain brake
may increase the time needed to stop
the saw chain after activation, or may
not activate at all.
WARNING
Never run the chain saw above idle
speed for more than 3 seconds when the
chain brake is engaged or when the saw
chain is pinched or otherwise caught in
the cut. Clutch slippage can cause
excessive heat, leading to severe
damage of the motor housing, clutch
and oiler component and may interfere
with the operation of the chain brake. If
clutch slippage in excess of 3 seconds
has occurred, allow the motor housing to
cool before proceeding and check the
operation of your chain brake as
described in the chapter entitled "Chain
Brake" of your instruction manual. Also
make sure that the saw chain is not
turning at idle speed (see above at
"Important Adjustments").
Low Kickback Saw Chain and Reduced
Kickback Bars
STIHL offers a variety of bars and saw
chains. STIHL reduced kickback bars
and low kickback saw chains are
designed to reduce the risk of kickback
injury. Other saw chains are designed to
achieve higher cutting performance or
sharpening ease, but in turn are more
prone to kickback.
STIHL has developed a color code
system to help you identify the STIHL
reduced kickback bars and low kickback
saw chains. Cutting attachments with
green warning labels on the packaging
are designed to reduce the risk of
kickback injury. The matching of green
marked or labeled chain saws under
3.8 cubic inches (62 cm³) displacement
with green labeled bars and green
labeled saw chains gives compliance
with the computed kickback angle
requirements of the chain saw standard
when the products are in their original
condition. Products with yellow labels
are for users with extraordinary cutting
English
17