Reactive Forces - Stihl MSA 120 C Instruction Manual

4 Safety Precautions
￭ Obstacles in the work area and on the escape path can
hinder the user. The user may trip and fall. This may result
in serious or fatal injuries.
► Remove all obstacles from the work area and escape
path.
￭ If you cut into or through the hinge, stabilizing strap or
holding strap too soon, the intended direction of fall
cannot be controlled or the tree can fall prematurely. This
can result in serious or fatal injuries and damage to
property.
► Do not cut into or through the hinge.
► Cut through the stabilizing strap or holding strap last.
► If the tree begins to fall too soon: Abandon the felling cut
and retreat along the escape.
￭ Kickback can occur if the rotating chain in the upper
quadrant of the bar nose makes contact with a hard felling
wedge and is suddenly braked. This can result in serious
or fatal injuries.
► Use aluminum or plastic felling wedges.
￭ If the tree does not fall all the way to the ground or gets
caught on another tree, the operator cannot finish the
operation in a controlled manner.
► Stop the felling operation and use a cable winch or
suitable vehicle to pull the tree to the ground.
0458-716-0121-B
4.8

Reactive Forces

4.8.1 Kickback
Kickback can be caused for the following reasons:
– The rotating saw chain in the upper quadrant of the bar
nose makes contact with a hard object and is suddenly
braked.
– The rotating saw chain is pinched at the bar nose.
WARNING
￭ If kickback occurs, the saw can be thrown up in the
direction of the operator. The operator can lose control of
the saw and be seriously or fatally injured.
► Hold the saw firmly with both hands.
► Operate the saw as described in this instruction manual.
► Do not cut with the upper quadrant of the bar nose.
► Always cut with a properly sharpened and tensioned
saw chain.
► Use a reduced kickback saw chain.
► Use a guide bar with a narrow radius nose.
► Always cut with the chain running at full speed.
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