Warning!
Some STIHL power tools are equipped with a catalytic converter, which is
designed to reduce the exhaust emissions of the engine by a chemical
process in the muffler. Due to this proc- ess, the muffler does not cool down as rapidly as conventional mufflers when the engine returns to idle or is shut off. To reduce the risk of fire and burn injuries when using a catalytic converter, always set your power tool down in the upright position and never locate it where the muffler is near dry brush, grass, wood chips or other combustible materials while it is still hot.
Reactive Forces Including Kickback
Warning!
Reactive forces may occur any time the chain is rotating. Reactive forces can cause serious personal injury.
001BA093 LÄ
The powerful force used to cut wood can be reversed and work against the operator. If the rotating chain is suddenly stopped by contact with any solid object such as a log or branch or is pinched, the reactive forces may occur instantly. These reactive forces may result in loss
MS 192 T, MS 192 TC
of control, which, in turn, may cause serious or fatal injury. An understanding of the causes of these reactive forces may help you avoid the element of surprise and loss of control. Surprise contributes to accidents.
The most common reactive forces are:
–kickback,
–pushback,
–
Kickback
Kickback may occur when the moving saw chain near the upper quadrant of the bar nose contacts a solid object or is pinched.
0012BA021 KN
The reaction of the cutting force of the chain causes a rotational force on the chain saw in the direction opposite to the chain movement. This may fling the bar
English
up and back in a lightning fast reaction in an uncontrolled arc mainly in the plane of the bar. Under some cutting circumstances the bar moves towards the operator, who may suffer severe or fatal injury.
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
Kickback Standard
§5.11 of ANSI standard B
To comply with § 5.11 of
ANSI B
a)Saws with a displacement of less than 3.8 cubic inches (62 cm³)
13