Load Handling, Stability, Capacity Charts and Attachments
This is the heart of the assessment. Understand stability: the machine's centre of gravity shifts with boom extension, load weight, ground conditions and slope. Capacity is defined by a load chart that gives maximum load at a given radius and boom configuration - and often at a stated attachment. Attachments change capacity: a bucket, jib, or man-riding platform has its own chart or restriction.
Know the terms: rated capacity, radius (horizontal distance from the machine's tipping line to the load's centre of gravity), load centre, and derating for attachments. Understand that a load's centre of gravity and any wind area (large flat loads) affect stability.
Traps:
- Reading the chart at the wrong radius - always measure the actual radius, not the boom length.
- Forgetting to add the weight of the attachment or slinging gear to the load.
- Assuming the chart applies to all attachments.
- Believing a heavier machine can always lift more - the chart rules.
- Overlooking ground bearing capacity and slope.
Rule of thumb: Total load = payload + attachment + slinging gear. If the total exceeds the chart at the measured radius, do not lift.
Worked example: Chart shows 2,000 kg at 4 m radius with a standard carriage. Your pallet weighs 1,850 kg, the slinging gear 60 kg, and you fit a heavier attachment rated 150 kg. Total = 2,060 kg at 4 m - over capacity. Reduce the load or move closer.