Crane Anti-Two-Block Devices
Construction · Ver en español
Talking points
- Two-blocking occurs when the hook block contacts the boom tip, overloading the hoist line and potentially snapping the cable, dropping the load, or collapsing the boom.
- Anti-two-block devices sense when the hook block approaches the boom tip and automatically stop the hoist. This is a critical safety device that must be functional before any lift.
- Test the anti-two-block device at the beginning of each shift. Slowly raise the hook until the device activates — the hoist should stop automatically. If it does not, shut down the crane.
- Do not override, bypass, or disable the anti-two-block device for any reason. Doing so removes your last line of defense against a catastrophic load drop.
- Two-blocking is most common when using very short slings (which reduce the distance between the hook and boom tip) and during operations where the operator is focused on the load rather than the hook height.
Ask the crew
Was the anti-two-block device tested on our crane this morning — and did it activate properly?
Standards this talk is built on
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