Hoist Overload and Load Chart Interpretation

The effective load must account for the off-center moment. The hoist capacity is based on a centered load. When the load is off-center, it creates a moment that reduces the effective capacity. Assume the platform width is 2 m, so the load is at 1 m from the center. The moment due to off-center load is 750 kg × 1 m = 750 kg·m. The hoist's moment capacity at 20 m height and 10 m jib is 800 kg × 1 m (centered) = 800 kg·m? Actually, the capacity is given for centered load, so the allowable moment is 800 kg × 1 m = 800 kg·m. But the actual moment is 750 kg × 1 m = 750 kg·m, which is less than 800 kg·m, so it might seem safe. However, the load chart capacity of 800 kg is the maximum total load for centered. With off-center, the effective load is increased due to the moment. A common method is to use the formula: effective load = actual load × (1 + (e / (L/2))), where e is eccentricity and L is platform length? Not exactly. Better to use the concept of load moment: the hoist's structural capacity is based on a maximum load moment. The rated capacity of 800 kg is for a centered load at a certain radius. If the load is off-center, the moment arm increases. For simplicity, assume the hoist's capacity is based on a maximum moment of 800 kg × 1 m = 800 kg·m (if the load is centered at 1 m from the mast). With the load at 1 m off-center, the moment arm becomes 1 m + 1 m = 2 m, so the allowable load would be 800 kg·m / 2 m = 400 kg. Since the actual load is 750 kg, it exceeds the allowable 400 kg, so the lift is unsafe. Alternatively, using the formula: effective load = actual load × (1 + (2e / L)) where L is the platform length? Not standard. I'll stick with the moment approach. The key is that off-center loading reduces capacity significantly. Therefore, the lift should not proceed. The load must be centered, or a smaller load used. Also, wind speed of 15 km/h is within typical limits (often 20 km/h for hoists), so wind is not the issue. The main issue is off-center loading. So answer: The lift is unsafe due to off-center loading; effective capacity is reduced to approximately 400 kg, which is less than 750 kg. Do not proceed.

First, I would stop the operation and explain to the supervisor that the load is off-center and exceeds the reduced capacity. I would show the load chart and explain the calculation. Then, I would suggest centering the load on the platform. If the pallet cannot be centered due to its size or shape, I would recommend splitting the load into smaller quantities that can be centered and are within capacity. For example, lift half the bricks at a time (375 kg each), ensuring each load is centered. I would also check that the platform is clear and that the load is secured. Before proceeding, I would perform a trial lift to ensure stability. I would document the incident and the corrective action in the hoist logbook. Communication with the supervisor should be clear and assertive, emphasizing safety over schedule. If the supervisor insists on proceeding, I would refuse and escalate to the site safety manager, as it is my duty to operate safely.