Owner's Manual

MS 150 TC
English
13
Kickback
When this occurs, the energy driving the
chain can create a force that moves the
chain saw in a direction opposite to the
chain movement at the point where the
chain is slowed or stopped. This may
fling the bar up and back in a lightning
fast reaction mainly in the plane of the
bar and can cause severe or fatal injury
to the operator.
Kickback may occur, for example, when
the 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 saw. Many
factors influence the occurrence and
force of the kickback reaction. These
include chain speed, the speed at which
the bar and chain contact the object, the
angle of contact, the condition of the
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 chain types are designed
to reduce kickback forces. STIHL
recommends the use of reduced
kickback bars and low kickback chains.
ANSI B 175.1-2000 Chain Saw
Kickback Standard
§ 5.11 of ANSI standard B 175.1-2000,
sets certain performance and design
criteria related to chain saw kickback.
To comply with § 5.11 of
ANSI B 175.1-2000:
a) 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 chain, reduced
kickback bar, etc.
b) 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 chain, reduced
kickback bar, etc.
The computer-derived angles for 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 § 5.11
of ANSI B 175.1-2000 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 § 5.11 of ANSI
B 175.1-2000 does not automatically
mean that in a real life kickback the bar
and chain will rotate at most 45°.
WARNING
In order for powerheads below 3.8 cubic
inches (62 cm³) displacement to comply
with the computed kickback angle
requirements of § 5.11 of
ANSI B 175.1-2000 use only the
following cutting attachments:
Kickback may occur
when the moving saw
chain in or near the upper
quadrant of the bar nose
is suddenly and signifi-
cantly slowed or stopped
as a result of contact with
an object or is pinched.
0012BA021 KN