Power tool

Chainsaws

Every safety device on a saw has a daily test, and every injury pattern traces back to reactive forces or a bad body position.

Safety features explained

Chain brake / hand guard

Stops the chain in milliseconds when pushed forward by the hand or by inertia during a kickback rotation.

Throttle interlock

The trigger cannot be pulled unless the interlock is depressed, so a snagged branch can't run the chain.

Chain catcher pin

Traps a thrown or broken chain before it reaches the operator's hand and forearm.

Anti-vibration mounts & rear hand guard

Isolation mounts reduce HAVS exposure; the rear guard shields the right hand from a whipping chain.

Low-kickback bar tip & reduced-kickback chain

Narrow-radius tips and bumper drive links lessen the energy available in the upper-quadrant kickback zone.

1Chain brake: engage and disengage, then bench-test that the running chain stops instantly.
2Throttle: springs back to idle, interlock blocks the trigger, no sticking at any position.
3Chain catcher present and intact; rear hand guard not broken.
4Bar: straight, rails not burred or spread, groove clean, oil holes clear, sprocket nose turning freely.
5Chain: correct tension (snaps back, drivers stay in the groove), sharp uniform cutters, no cracked links, depth gauges filed correctly.
6Bar and chain oil full, fuel fresh and capped, no fuel or oil leaks.
7Air filter, spark arrestor screen, starter cord, AV mounts, and all fasteners tight.
8Dogs/bumper spikes intact; muffler tight and shielded.

Chain brake that does not stop the chain, or a disabled/wired-open safety device.
Fuel leak, cracked fuel line, or damaged muffler.
Missing chain catcher, hand guard or bar nuts.
Cracked chassis or bar, spread bar rails, cracked chain link.
Chain that keeps turning at idle — carburetor out of adjustment.

Cold start on the ground: brake on, saw pinned by foot and hand, or start between the knees when supported. Never drop-start.
Warm restart: brake on, saw supported, throttle off choke — restart with the same discipline as a cold start.
Know the kickback zone: the upper quadrant of the bar tip. Cut with the lower edge of the bar when you can.
Pushback happens when the top of the bar pinches — the saw drives back toward you; pull-in happens when the bottom pinches.
Set your body outside the plane of the bar, thumbs wrapped, elbow locked on the rear handle, feet planted on stable ground.
Directional felling: plan the escape route, make a face notch matched to the lean, leave hinge wood to steer the tree, and use a back cut above the notch corner with a holding strap or wedges.
Brake on and chain stopped for every step you take, every hand-off and every climb move.
Fuel cold, 10 ft from the cut, and wipe spills before starting.

ANSI Z133: chainsaw operators wear head, eye, hearing and leg protection; saws are started on the ground or otherwise firmly supported, never drop-started.
ANSI Z133: two hands on the saw whenever the chain is moving, and the chain brake is engaged before any move.
OSHA 1910.266(e) for chainsaw operation, fueling and safety-device requirements.

Summarised for field use. The current ANSI Z133 standard, OSHA rules and the manufacturer's manual are the controlling documents.

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chain brake bench test

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pre-operation chainsaw checklist

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kickback zone and body positioning

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ground start method

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