Stihl MS 193 Instruction Manual page 16

English
Kickback may occur, for example, when
the saw chain near the upper quadrant
of the bar nose contacts the wood or is
pinched during limbing or when it is
incorrectly used to begin a plunge or
boring cut.
The greater the force of the kickback
reaction, the more difficult it becomes for
the operator to control the chain saw.
Many factors influence the occurrence
and force of the kickback reaction.
These include saw chain speed, the
speed at which the bar and saw chain
contact the object, the angle of contact,
the condition of the saw chain and other
factors.
The type of bar and saw chain you use
is an important factor in the occurrence
and force of the kickback reaction. Some
STIHL bar and saw chain types are
designed to reduce kickback forces.
STIHL recommends the use of reduced
kickback bars and low kickback chains.
14
Chain Saw Kickback Standard
The following standard apply with
respect to kickback:
§ 5.11 of ANSI/OPEI B175.1-2012
–
This standard, in the following referred
to as "the chain saw kickback standard"
sets certain performance and design
criteria related to chain saw kickback.
To comply with the chain saw kickback
standard:
a) Chain saws with a displacement of
less than 3.8 cubic inches (62 cm³)
must, in their original condition,
–
meet a 45° computer derived
kickback angle when equipped with
certain cutting attachments,
and must be equipped with at least
–
two devices to reduce the risk of
kickback injury, such as a chain
brake, low kickback saw chain,
reduced kickback bar, etc.
b) Chain saws with a displacement of
3.8 cubic inches (62 cm³) and
above
must be equipped with at least one
–
device designed to reduce the risk
of kickback injury, such as a chain
brake, low kickback saw chain,
reduced kickback bar, etc.
The computer derived angles for chain
saws below 3.8 cubic inches (62 cm³)
displacement are measured by applying
a computer program to test results from
a kickback test machine.
WARNING
The computer derived angles of the
chain saw kickback standard may bear
no relationship to actual kickback bar
rotation angles that may occur in real life
cutting situations.
In addition, features designed to reduce
kickback injuries may lose some of their
effectiveness when they are no longer in
their original condition, especially if they
have been improperly maintained.
Compliance with the chain saw kickback
standard does not automatically mean
that in a real life kickback the bar and
saw chain will rotate at most 45°.
WARNING
In order for chain saws below 3.8 cubic
inches (62 cm³) displacement to comply
with the computed kickback angle
requirements of the chain saw kickback
standard use only the following cutting
attachments:
bar and saw chain combinations
–
listed as complying in the
"Specifications" section of the
instruction manual or
other replacement bar and saw
–
chain combinations marked in
accordance with the standard for
use on the chain saw or
replacement saw chain designated
–
"low kickback saw chain."
See the section on "Low Kickback Saw
Chain and Reduced Kickback Bars."
MS 193 C