NCCCO Rigger key terms

The visual and hands-on check a rigger makes of slings, shackles, hooks, and other gear before every lift, to catch damage, missing tags, or anything that makes the equipment unsafe.

Published limits or defects, such as a broken wire, a stretched hook, or excessive chain wear, that require a rigger to stop using the item, tag it, and turn it in for repair or disposal.

The manufacturer's label permanently attached to a sling or piece of hardware showing its rated capacity, type, material, and length; gear with a missing or unreadable tag must not be used.

The inside measurement across a hook's opening. Any increase beyond the manufacturer's limit shows the hook has been overloaded or bent and must be removed from service.

A spring-loaded gate that closes the hook throat so slings, chains, and ropes cannot slip out. A missing, bent, or weak latch takes the hook out of service.

The number of fractured individual wires found within a set length of wire rope; it is counted during inspection and compared with a published limit that decides whether the rope stays in use.

A defect in which the outer strands of wire rope balloon away from the core, usually after shock loading or twisting. The rope is permanently damaged and must be removed from service.

A sharp bend or permanent loop set into rope by slack, back-twisting, or sudden release. Kinks cannot be straightened out and the rope must be removed from service.

Stretching or link wear greater than the manufacturer's limit, checked by measuring across several links. Worn or stretched chain has lost strength and is removed from service.

Damage to webbing or roundslings from sunlight, chemicals, heat, or abrasion, seen as fading, stiffness, melting, or frayed fibers. It weakens the sling and is grounds for removal.

A controlled test load applied above a component's working load limit, by the manufacturer or a qualified tester, to confirm the item's strength before it is placed in service.

The maximum mass a sling, shackle, or other component may support in a particular configuration, as set by the manufacturer. It already includes the design factor and appears on the tag.

The ratio of a component's breaking strength to its working load limit. Rigging slings and hardware typically use factors of about four to five to cover wear, dynamic forces, and unknown load weights.

A single leg hanging straight from the hook to the load with the eyes in line. It carries the sling's full vertical rated capacity and puts no sideways pull on the hook.

The sling passes around the load and back through its own eye or choker, tightening as the load is lifted. It grips the load but reduces the sling's rated capacity.

The sling passes under or around the load with both eyes on the hook, cradling the load. A double-wrap version grips loose or round loads and keeps them from spreading.

Two or more slings run from a common hook to separate attachment points on the load. Load in each leg depends on the sling angles, so the legs are rarely equally loaded.

The angle between a sling leg and the horizontal. As the angle flattens, tension in the leg and the force pushing the load's attachment points together rise steeply.

A multiplier that converts load weight into tension in each sling leg for bridle and basket hitches. It equals the sling length divided by the vertical height from hook to load.

The loss of rated capacity when a sling is used in a choker or angled hitch instead of a straight vertical pull. Manufacturer charts give the reduced capacity for each hitch and angle.

The diameter a sling bends around (pin, hook, or load edge) divided by the sling's own diameter. A small ratio squeezes wire rope and reduces its strength.

The balance point of a load's weight. The hook must sit directly above it, or the load will tilt when lifted and may shift or spill.

The share of a rope's strength that remains after a knot is tied. Bending and compression at the knot can cut strength by half, so knotted rope is not used as a rated sling.

A knot that forms a fixed loop which will not slip or tighten under load and unties easily afterward. Used for tag lines and utility rope work, not as a rated lifting sling.

Two crossing turns that grip a rail or post from either direction but can slip when the load changes. Useful for temporary tie-offs and for starting lashings.

A hitch that wraps a rope around a log and tucks the tail under its own turns so the load tightens the grip. It is used for dragging or lifting poles and round sections.

A sudden application or release of force, such as a jerking hoist or a load dropping into a slack sling, that can create forces several times the static weight.

Pulling across a hook, shackle, or sling in a direction it was not designed for. It bends hooks, unseats pins, and sharply reduces the component's capacity.

Loading gear or a crane beyond its rated capacity. Unlike a warning, overload causes permanent damage or sudden failure, often with no visible sign beforehand.

The ground area beneath and around a suspended load where it would land if dropped or swung. Only essential rigging crew stay in it, and never directly under the load.

The closest a crane, boom, load, or rigging may come to an energized power line under OSHA and utility rules. Coming inside it can cause arcing and fatal shock, even without contact.

Any place where a hand, foot, or body part can be caught between the load, sling, hook, or structure as the rigging tightens or the load moves.

A written or worked-out outline of a lift covering load weight, rigging arrangement, capacity checks, crane setup, travel path, and the hazards to be controlled before the lift starts.

A rope tied to the load and handled from outside the fall zone so the load does not spin or swing while it is hoisted and landed.

Padding, sleeving, or corner protectors placed between a sling and sharp edges, abrasive surfaces, or hot metal to keep the sling from being cut, worn, or burned.

A rigid beam hung between the hook and two or more sling legs to hold the legs vertical. It keeps the load from being squeezed and lets the slings keep full capacity.

Rigging a shackle so the load is taken in the bow with the pin fully seated and unable to roll loose. Side-loading or loading the pin incorrectly can deform it and cut capacity.

A threaded fitting with a looped head used as a lifting point. It must be screwed in fully, seated against the surface, and pulled in line with its designed direction.

A U-bolt clamp used to make an eye in wire rope. The correct number, spacing, and orientation of clips decide whether the termination keeps most of the rope's strength.