Reactive Forces During The Cut, Including Kickback; Kickback - Stihl 015 Instruction Manual / Owners Manual

Reactive forces during the cut, including kickback
Warnlngl
Reactive forces, that may occur during any cut are kick-
back, pushback and pull-in. Reactive forces can be
dangerous! In any chain saw, 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 like a log or branch or is pinched, the
reactive forces instantly occur. These reactive forces may
result in loss of control which may, in turn, cause serious
or fatal injury. An understanding of the causes of these
reactive forces may help you avoid loss of control.
The most common reactive forces are
- kickback,
- pushback,
- pull-in.
Kickback:
Kickback occurs when the upper quadrant of the bar nose
contacts a solid object in the wood or is pinched (ill. 12).
The reaction of the cutting force of the chain causes a
rotational force of the chain saw in the direction opposite
to the chain movement, flinging the bar in a uncontrolled
arc mainly in the plane of the bar. Under some circumstan-
ces the bar moves towards the operator who may suffer
severe or fatal injury.
It
may also occur during limbing.
It also occurs when the nose of the guide bar is pinched
unexpectedly, unintentionally contacts solid material in the
wood (ill. 13) or is incorrectly used to begin a p'lunge or
10
boring cut.