Rigging and load assessment
To assess the load correctly before the lift begins
Rigging is the link between the crane and the load. A lift cannot be safer than the rigging that bears it. Therefore, every crane lift begins with an assessment of what is to be lifted, how heavy it is, where the center of gravity lies, and what equipment is suited to the task.
§Assessment of weight and center of gravity
Before the machine is driven in
§Selection of lifting gear
Rigging equipment includes, among other things, chains, wire slings, fiber slings (round slings and straps) as well as shackles, hooks, and lifting eyes. Each piece of equipment has a marked working load (WLL – Working Load Limit) which must never be exceeded. The equipment is chosen based on the load's weight, shape, suspension angle, and surface – sharp edges require edge protection so the sling is not cut.
- 01Chains: robust, withstand high temperature and sharp edges better than fibre
- 02Wire straps: strong and flexible, but can get breaks on the individual wires
- 03Fiber slings: lightweight and gentle on the surface, but vulnerable to sharp edges and chemicals
§Sling angle and number of legs
When a load hangs from multiple straps, the weight is not distributed equally if the angle between the straps is large. The greater the angle from vertical, the greater the force in each strap. This is why the allowable load decreases when the straps spread out. The equipment's marking and tables show how capacity is reduced at different angles—and you stay within the marked limits rather than guessing.
§Inspection of equipment.
Rigging equipment must be inspected before use. Equipment with visible damage is discarded: broken wires in cable, deformed links or stretched chains, cuts, heat damage, or heavy wear in fiber slings, and shackles with worn or deformed bolts. Damaged equipment is immediately taken out of service.
§Communication during the lift
Rigging and crane operation are often two people. Clear signals are arranged – hand signals or radio – and only one person directs at a time. The stop signal must be given and understood by everyone. No one stays under a suspended load.