Echo X7522340000 Safety Manual page 34

OPERATION
• ALWAYS use blade only for application for which it was intended
• ALWAYS use the correct front handle for the type of blade being used.
ECHO Inc. recommends using a U-Handle for all blade use.
REACTION FORCES - Push/Pull - Kickback/Kickout
During normal use, operating a brushcutter with a
circular metal blade can produce sudden strong
reaction forces that are difficult to control. Strong
reaction forces can cause a loss of balance or loss
of control of the unit, resulting in serious injury to
operator and bystanders.
Understanding what causes these reactive forces
may help you to avoid them, and can help you
to maintain control of the unit if you experience a
sudden reaction during cutting. Reactive forces
occur when the force being applied by the cutting
teeth of a blade meet resistance, and some of
the cutting force is directed back toward the unit.
The greater the cutting force or the amount of
resistance, the greater the reactive force.
Push and Pull Forces
Push and pull forces are reactive forces that push
the unit directly toward the operator, or that pull the
unit directly away from the operator. These forces
are the result of cutting on the sides of the blade.
The direction of the force depends on the side of
the blade being used, and the direction of blade
rotation at the point of contact. The reactive force
is in the opposite direction of blade rotation at the
contact point, regardless of where the contact is
being made. These types of reactive forces are
also called "Blade Thrust."
As shown in the illustration, a blade turning
counterclockwise will cause the unit to pull away
from the operator if the point of cutting resistance
is on the left side of the blade. If the point of
cutting resistance is on the right side of the blade,
the unit will push back toward the operator. In
both examples, the reactive force is in the opposite
direction of blade rotation at the contact point
where resistance occurs.
34
PULL
Contact
Point
PUSH
Contact
Point