Читать книгу Chainsaw Manual for Homeowners - Brian J. Ruth - Страница 16

To learn how to control the chainsaw, consider the forces involved.

■ The chain on the top of the bar races away from the operator.

■ The chain on the bottom of the bar speeds toward the operator.

■ The chain travels downward as it changes direction around the nose of the saw bar.

Remembering high-school physics, for every action there is an equal but opposite reaction. As a result:

■ When you are cutting downward using the chain on the bottom of the guide bar, the forces pull the saw in toward the wood, and/or the wood toward the operator.

■ When you are cutting upward using the chain on the top of the bar, the forces push the wood and the saw engine away from one another.

■ You don’t cut with the nose of the bar. If you did, the forces would tend to rotate the saw upward—that’s kickback.

Controlling the chainsaw requires planting both feet on the ground in a sturdy marching stance and keeping both hands on the saw handles. Whether cutting downward or upward, keeping the saw engine close to the wood helps you control the forces of pull-in and push-back.

As the chain rounds the nose of the guide bar, its motion suddenly acquires a downward component. As a result, when the upper quadrant of the bar nose contacts the wood, it’s liable to be thrown upward. The saw abruptly pivots in your hands in a direction you weren’t braced to resist—that’s kickback as well.