Wind, Load and Fatigue on a Live Lift
A combined personnel/materials hoist rated 1000 kg or 12 persons serves a nine-level project. At 10:00 the wind is 14 m/s gusting 21 m/s; the manual's operating limit is 20 m/s. A tiler loads a shrink-wrapped pallet of tiles weighing about 780 kg onto the cage and three workers (about 85 kg each) step in behind it for the ride to level 8, saying the pallet is wrapped so it won't move. The cage has no load display. The operator is in the eleventh hour of a shift that started at 05:30, with no break. The pallet is not restrained to the cage, and the gate is a short bar-and-mesh type.
1. Do the load numbers, and state what you would allow on that cage.
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Numbers:
- Pallet: 780 kg
- Three persons at ~85 kg: 3 × 85 = 255 kg
- Total: 1035 kg against a 1000 kg rating - over by 35 kg (about 3.5%).
That is the arithmetic. The judgement is worse than the arithmetic:
- The tile weight is an estimate ('about 780 kg'). Tiles are dense and pallets vary; without a load display or a calibrated check, the true figure could be 850 kg, which puts the total near 1100 kg.
- The pallet is unrestrained in a cage with a short bar-and-mesh gate. On a stop, 780 kg of tiles slides forward against a gate designed to keep a person in, not to arrest a pallet. A person standing between the pallet and the gate has nowhere to go.
- Mixed personnel/material loads are only acceptable where the load is secured and the manual permits it; the persons are also standing beside an unrestrained mass.
What I would allow: the pallet alone, secured to the cage (banded to the frame, not the gate), or the three persons alone - not both. Better still, split the pallet across two lifts. Never persons with an unrestrained load.
2. Which of the other conditions would independently stop the lift?
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Two of them, either on its own.
Wind: gusting 21 m/s against a 20 m/s operating limit. A limit is set for the gust, not the average - 14 m/s steady would be fine, the 21 m/s gust is what loads the mast, the ties and the landing gates, and what swings the cage against the structure. The cage and mast present a large sail area, and the cage is at the top of the mast where displacement is greatest. Park the cage at the bottom landing, close and latch the gates, and wait for the gust to drop and stay down - not for the next gap between gusts.
Operator fatigue: eleventh hour, no break. Reaction time, judgement and risk perception are all degraded, and this is precisely the moment someone accepts a 1035 kg lift with an unrestrained pallet because it's easier than splitting it. Fatigue is a hazard the operator must act on, not push through. The lift should not proceed: hand over, take a break, restart with a fresh operator and an entry in the logbook.
Also relevant (but second-order): no load display means nobody can verify the load; the unrestrained pallet is a load-security failure; and the short gate means the load restraint matters more, not less.
3. How do you deal with capacity verification and the end-of-shift, given the job 'has to finish today'?
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Capacity verification: the rated capacity must be marked on the cage, and the manual's load chart governs. With no load display, verify by calculation and by known weight - a calibrated load cell, or a unit count of pallets from the supplier's docket - and record the figure and method in the logbook. Do not accept 'it's about 780'. If the load can't be verified, it doesn't fly.
Shift: the operator is unfit to continue as things stand. Insist on a break and a handover to a fresh operator with the logbook signed, and tell the supervisor why - an overloaded, unrestrained lift in a 21 m/s gust is the combination that kills people, and fatigue is the reason it gets accepted. Offer to complete the tiling lifts first thing when the wind forecast is below the limit, and confirm with the PM in writing.
Before leaving the machine unattended: cage at the bottom landing, gates closed and latched, isolator off and locked where the site procedure requires it, landing gates closed, exclusion zone maintained, and a logbook entry covering the load, the wind at the time of the stop and the handover.