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• CHAIN SAW - A tool designed to cut wood with a saw chain. A chain saw is an integrated unit comprised of a power source, saw chain,
guide bar, and handles that are designed to be held by two hands during operation.
• CHAIN SAW POWERHEAD - A chain saw without the saw chain and guide bar.
• DRIVE SPROCKET - A toothed wheel that drives the saw chain.
• FRONT HANDLE - A support handle located toward the front of the chain saw.
• REAR HANDLE - A support handle located toward the rear of the chain saw.
• CHAIN BRAKE LEVER / FRONT HAND GUARD - A structural barrier between the front handle and the guide bar. The front hand guard
helps protect the operator’s left hand if it slips off the front handle while the unit is running. The chain brake lever is also used to manually
engage the chain brake.
• CHAIN BRAKE - A device that reduces the chance of injury if kickback occurs, by stopping the saw chain in milliseconds. The chain brake
is designed to engage automatically in response to kickback. The chain brake can also be activated by pushing the chain brake lever
forward, either intentionally or if the operator’s hand strikes the lever during kickback.
• REAR HAND GUARD - A structural barrier below the rear handle. The rear hand guard helps protect the operator’s right hand if the saw
chain breaks or disengages from the guide bar during operation.
• GUIDE BAR - A solid railed structure that supports and guides the saw chain.
• GUIDE BAR TIP - The tip or end of the guide bar.
• REDUCED-KICKBACK GUIDE BAR - A guide bar that has been demonstrated to reduce kickback significantly.
• SAW CHAIN - A loop of chain with teeth designed to cut wood, which is driven by the engine and is supported by the guide bar. The saw
chain is composed of drive links, cutters and side links, held together by rivets.
• LOW-KICKBACK SAW CHAIN - A saw chain that complies with the kickback performance requirements of ANSI/OPEI B175.1-2012 when
tested on a representative sample of chain saws. Low-kickback saw chain significantly reduces the chance of kickback and the intensity of
kickback, due to specially designed depth gauges and guard links.
• REPLACEMENT SAW CHAIN - A saw chain that complies with the kickback performance requirements of ANSI/OPEI B175.1-2012 when
tested with specific chain saws. It may not meet the ANSI/OPEI performance standards when used with other chain saws.
• SPIKED BUMPER - The pointed tooth (or teeth), at the front of the chain saw, used during felling and bucking to help pivot the saw and
maintain a stable position while cutting.
• CHAIN CATCHER - A device designed to intercept a whipping chain. The chain catcher reduces the chance of injury if the saw chain
breaks or disengages from the guide bar during operation.
• OILER CONTROL - A system for oiling the saw chain and guide bar.
• ON/OFF SWITCH - A device that immediately stops the engine when moved to the OFF position. The saw chain will then coast to a stop.
The On/Off switch must be moved to the On position to start the engine.
• THROTTLE CONTROL - A device used in conjunction with the throttle lockout to accelerate the engine. Releasing the throttle control
returns the engine to idle.
• THROTTLE LOCKOUT - A device that prevents accidental acceleration of the engine. The throttle control cannot be squeezed unless the
throttle lockout is engaged.
• SPARK ARRESTER SCREEN - A device that retains carbon and other flammable particles over 0.023 inches (0.6mm) in size from the
engine exhaust flow. Compliance with local, state and federal laws and/or regulations governing the use of a spark arrester screen is the
user’s responsibility. Refer to Spark Arrestor Note in the Safety section for additional information.
• KICKBACK - A sudden backward and/or upward motion of the guide bar and saw chain. Kickback can occur if the upper portion of the
guide bar tip touches an object while the saw chain is spinning (rotational kickback). Kickback can also occur if the wood closes in and
pinches the saw chain inside the cut (linear kickback).
• ROTATIONAL KICKBACK - A sudden backward and upward motion of the guide bar and saw chain. Rotational kickback can occur if the
upper portion of the guide bar tip touches an object while the saw chain is spinning. The guide bar and saw chain are then kicked up and
back toward the operator in a lightning-fast reverse reaction.
• LINEAR KICKBACK (PINCH KICKBACK) - A sudden backward motion of the guide bar and saw chain. Linear (pinch) kickback can occur if
the wood closes in and pinches the saw chain inside a cut. The saw is then sent straight back toward the operator.
• NORMAL CUTTING POSITION - The positions assumed while making bucking and felling cuts.
• FELLING - The process of cutting down a tree.
• NOTCHED UNDERCUT - The first cutting procedure in the tree felling process. A notch is cut on one side of the tree to direct its fall.
• FELLING BACK CUT - The final cut in the tree felling process. The felling back cut is made on the opposite side of the tree from the
notched undercut.
• BUCKING - The process of cutting a felled tree or log into lengths.
• LIMBING - The process of removing branches from a fallen tree.
• PRUNING - The process of cutting limbs from a living tree.
ESSENTIAL TERMS AND DEFINITIONS