Planning a Lift with a Blind Landing
A rigger must lift a 2,500 lb HVAC unit onto a roof. The crane operator cannot see the roof landing area from the cab. The rigger will be on the roof with a radio. The roof has a parapet that blocks the rigger's view of the unit as it comes over the edge. The unit must be set within 6 inches of a curb. Wind is calm. The rigger has a tag line but no spotter on the ground. The crane's load chart shows 4,000 lb capacity at the planned radius.
1. What communication and signal plan should the rigger establish before the lift?
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The rigger should establish a dedicated radio channel and test it before the lift, with the operator and the rigger both confirming. Because the parapet blocks the rigger's view of the unit as it comes over the edge, the rigger should position a second signal person or use a mirror or camera to maintain line of sight, or have the operator stop the load at a prearranged point above the parapet where the rigger can see it. The rigger should agree on standard signals and a clear stop signal. The rigger should not rely on a single radio with no backup; hand signals should be agreed in case the radio fails.
2. How should the rigger control the load for a 6-inch placement?
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The rigger should use tag lines to control rotation and swing, and should plan the approach so the unit comes over the parapet at a controlled speed and stops at a prearranged height. For a 6-inch placement, the rigger should use a slow, controlled lowering with the operator responding to the rigger's signals, and should have a spotter or a marked reference on the curb to judge the distance. The rigger should not stand under the load or between the load and the parapet. The rigger should also check that the unit's rigging does not shift during the lift, which would change the landing position.
3. What capacity and load-weight checks are needed?
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The crane capacity at the planned radius is 4,000 lb, and the unit is 2,500 lb. The rigger must add the weight of the rigging, including slings, shackles, and spreader if used, and confirm the total is below 4,000 lb with margin. The rigger should also confirm the radius is the actual radius, not an estimate, because capacity drops quickly as radius increases. The rigger should check the unit's weight from the nameplate or shipping documents rather than estimating, and should verify the rigging's WLL for the hitch and angle used. If the total approaches the capacity, the rigger should reduce the radius or use a larger crane.