14
English / USA
MS 170, MS 180, MS 180 C
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 chainsaw
kickback standard
Section 5.11 of ANSI standard
B 175.1-2000, sets certain performance
and design criteria related to chainsaw
kickback.
To comply with section 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 inch (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
inch (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:
– bar and chain combinations listed
as complying in the "Specifications"
section of the instruction manual or
– other replacement bar and chain
combinations marked in
accordance with the standard for
use on the powerhead or
– replacement chain designated
"low kickback saw chain.“
See the section on "Low kickback saw
chain and reduced kickback bars."
