NCCER Rigger key terms

The maximum load a rigging component or assembly is rated to lift under normal service conditions, stamped or tagged by the manufacturer and never exceeded during a lift.

The ratio of a component's breaking strength to its working load limit. Higher factors give more safety margin and vary by component type and sling material.

The load at which a sling, shackle, or other rigging component will fail or rupture. It is always greater than the working load limit by the design factor.

A test load applied to rigging hardware to verify it performs without permanent deformation. It is greater than the working load limit but below the breaking strength.

A U-shaped metal connector with a pin or bolt used to join slings to loads or lifting points. Body, pin, and load-bearing faces must be rated and free of wear.

A threaded fastener with a ring or loop used as a lifting point. Only shoulder-type eyebolts should be loaded at an angle; plain eyebolts are for straight vertical pulls.

An assembly of chain, wire rope, synthetic webbing, or rope used to connect a lifting hook to a load. Each type has its own capacity, wear limits, and inspection rules.

A sling made of alloy steel chain with hooks or master links. It resists abrasion and heat but must be inspected for stretch, nicks, cracks, and worn links.

A sling made from strands of steel wire twisted into rope, usually with thimbles and eyes. It is strong and abrasion-resistant but must be checked for broken wires and kinks.

A flat or round sling woven from nylon or polyester fibers. It is light and soft on loads but vulnerable to cuts, UV damage, and heat, so its tag and condition must be checked.

The angle measured between a sling leg and the horizontal load surface. As this angle decreases, tension in each leg increases sharply, reducing the assembly's capacity.

A multiplier used to calculate sling tension from the vertical share of the load. It equals sling length divided by lift height and grows as the sling angle becomes shallower.

The force carried by each sling leg during a lift. It depends on the load weight, the number of legs sharing the load, and the angle of each leg.

The point where a load's weight is balanced in all directions. The hook must be positioned directly above this point so the load hangs level and does not shift.

The condition in which a suspended load hangs level because the hook is over the center of gravity and sling legs share weight evenly. Poor balance causes tilting and uneven tension.

A hitch in which a single sling leg runs straight down from the hook to the load. It uses the full rated capacity of the sling with no angle reduction.

A hitch where the sling passes around the load and back through its own eye, tightening as load is applied. It grips the load but reduces capacity, often to about three-quarters of vertical rating.

A hitch in which the sling cradles the load and both ends attach to the hook, forming a U shape. It supports the load from below and typically provides about twice the vertical capacity.

A hitch using two or more slings joined at a common point to support a load from multiple lifting points. Leg tension depends on attachment geometry and load balance.

A choker hitch in which the sling is wrapped around the load twice before passing through the eye. The extra wrap increases grip and reduces the capacity loss of a single choker.

A sudden increase in force caused by jerking, snatching, or rapidly starting a lift. It can far exceed the static load weight and overload rigging that was properly rated.

Additional force on rigging caused by movement, acceleration, or deceleration of the load during a lift. It requires extra capacity margin beyond the static weight.

A written or drawn outline of how a lift will be performed, covering load weight, rigging selection, hitch type, crane position, travel path, and roles of crew members.

A documented plan prepared for a specific lift that identifies hazards, capacities, rigging, and step-by-step procedures. It must be reviewed with the crew before work begins.

A lift that requires special planning and approval because of high risk, such as lifting over occupied areas, near power lines, or at or near crane capacity.

A person who by training and experience can select rigging, calculate loads, and direct lifts safely. Qualification requirements are set by the employer and applicable standards.

The crew member who relays hand, voice, or radio signals between the rigger and the crane operator. Only one signal person directs the operator at a time.

A rope attached to a load to control rotation and swing from a safe distance. It keeps workers from having to touch or stand under a suspended load.

The manufacturer's table showing a crane's capacity at various boom lengths, radii, and configurations. The operator must stay within these limits for every lift.

The horizontal distance from the crane's rotation center to the center of the load. As radius increases, lifting capacity generally decreases.

The angle of the crane boom measured from horizontal. It affects both the radius and the rated capacity shown on the load chart.

A designated attachment on a load, such as an eyebolt, lug, or pad eye, intended to receive rigging. It must be rated for the load and inspected before use.

A knot that forms a fixed loop at the end of a rope and unties easily after loading. It is useful for securing tag lines but is not a substitute for rated rigging hardware.

The tendency of a load to rotate or fall over when its center of gravity moves outside its base of support. Proper hitch placement and balance prevent it.

A lift in which sling legs spread outward to attachment points rather than hanging vertically. The wider the spread, the greater the tension in each leg.

The systematic examination of slings, hardware, and lifting points for wear, damage, and missing tags before each use. Defective components are removed from service immediately.