Rigging, slinging, load attachment, lifting accessories and load control
Rigging and slinging
Correct rigging is essential for safe lifting. Select the right sling type (chain, wire rope, synthetic) for the load and environment. Inspect slings for damage before use. Determine the load's weight and centre of gravity. Use appropriate hitch (e.g., straight lift, choker, basket) and ensure the load is balanced. The sling angle affects capacity: wider angles reduce capacity. Use tag lines to control the load.
Lifting accessories
Shackles, hooks, and lifting points must be rated for the load. Never use damaged or modified accessories. Ensure hooks have a safety latch. The load must be attached to the crane hook securely, and the hook must be centred over the load.
Traps in questions
A common trap is ignoring the sling angle effect; a 60° angle reduces capacity to about 86% of the vertical rating. Another trap is using a sling with a damaged tag or no identification. Also, the load must not be dragged or pulled sideways.
Worked example / rule of thumb
Rule: For a two-leg sling, capacity = (single leg capacity × number of legs × cos(angle from vertical)). Example: Two legs at 30° from vertical, each 2 t capacity: total = 2 × 2 × cos30° ≈ 3.46 t.