Safety Manual

ENGLISH

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 difcult 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.

PULL

PUSH

Contact

Point

Contact

Point

OPERATION