9.8 KICKBACK (FIG.13)
Definition: Kickback –
Rapid upward and/or backward motion of the
chainsaw which can occur when the moving saw
chain near the tip of the guide bar contacts an
object such as a log or branch.
Kickback is the most common hazard associated with
chainsaws and can result in serious injuries even
fatality. This chainsaw features an Inertia activated
chain brake and a manually triggered chain brake. In
the event of a particularly strong kickback, the brake
lever will trigger the chain brake. If the kickback is less
the chain brake lever will activate on the operator’s
left hand (hence the necessity to always operate the saw two handed). There are different
types of kickback and a couple of other associated risks.
– Because the chainsaw is driven along the top of the guide bar away from the power head
contact with the kickback zone cam translate the saw chain movement in the opposing
direction on the guide bar. This is particularly the case if the saw chain becomes pinched
or snags in the kickback zone of the guide bar.
– Another kickback danger can result in the chainsaw being forced horizontally back
toward the user. Kick back of this nature is the result of the saw chain along the top of
the guide bar being pinched, translating the force backward through the guide bar.
– The opposite to kickback is having the chainsaw pulled away. Pull-in can be a result of
the saw chain pinching along the bottom of the guide bar. As the saw chain along the
bottom of the guide bar is returning to the power head, the transiting force pulls the
chainsaw from the operators hands.
– In addition to these risks are skatting and bouncing which can lead to a loss of control of
the chainsaw.
– If the saw chain fails to make an initial incision it can move sideways along the timber
‘skatting’ and ‘bouncing’. This sideways movement can result in off balancing or
overstretch and further loss of control or contact with the guide bar tip on another limb
causing a ‘kickback’.
– To avoid kickback occurring, do not use the tip of the guide bar. Take note of foreign
objects and other branches/limbs close to the area being cut. Note: They may not be in
your line of sight. Always make the initial cut on the tension surface of the timber and
use non-metal spreading wedges to avoid the timber pinching the saw chain. Always
begin cutting at full speed and ensure the body of the saw, in particular, the spiked
bumper is against the timber. Cut only one piece of timber at any time and observe the
timber while making the cut to ensure the tension was assessed correctly. Hold the
chainsaw firmly as described. Maintain a good firm stance and do not over reach.
– Do not cut over head height.
– The use of low kickback saw chain is also advised. These are designed specifically to help
reduce the factors leading to kickback.
– Do not solely rely on the chain brake to stop an accident occurring or chainsaw PPE to
avoid injury.
9. OPERATION AND USE
17
FIG.13
KICKBACK
ZONE
