NCCCO Rigger Level I key terms

The maximum load that a sling, shackle, or other rigging component is rated to lift safely under normal service conditions, as set by the manufacturer and marked on the item.

The maximum load a piece of lifting equipment is designed to handle for a given configuration, often stated in the manufacturer's charts and adjusted for hitch type and angle.

The ratio of a component's breaking strength to its working load limit, providing a safety margin against overload, wear, and dynamic forces during lifting.

The load at which a sling or fitting will fail or rupture, determined by testing or manufacturer data and always higher than the working load limit.

The angle measured between a sling leg and the horizontal load surface, which determines how much of the sling's capacity is available to carry the load.

The added force in each sling leg as the angle between the legs and the load becomes steeper or narrower, requiring reduced load per leg to avoid overloading.

One individual branch or segment of a multi-leg sling assembly that runs from the master link or hook down to the attachment point on the load.

A hitch in which a single sling leg runs straight up from the load to the hook, allowing the sling to be used at its full rated vertical capacity.

A hitch formed by passing the sling around the load and through one eye or fitting so the sling tightens on itself, reducing capacity compared with a vertical hitch.

A hitch in which the sling passes under or around the load and both ends attach to the hook, cradling the load without the sling choking on itself.

The angle at which a choker hitch grips the load; when the choke is pulled tight against the load at roughly 120 degrees, the sling retains its full choker rating.

A choker hitch in which the sling is wrapped around the load twice before passing through the eye, increasing grip and reducing the chance of slipping.

A sling assembly with two or more legs joined at a master link or ring, used to attach to multiple lifting points on a load and share the weight among them.

The large ring or link at the top of a multi-leg sling assembly that gathers the legs together and connects to the crane hook.

A U-shaped metal fitting with a pin or bolt across the opening, used to connect slings, hooks, and loads; must be rated and matched to the load.

A hook with a safety latch or other retaining device used to connect slings and hardware to the crane or load, designed so the load cannot slip off.

A spring-loaded gate on a hook that closes the throat opening to keep slings and attachments from slipping off during lifting.

The inside curve or opening of a hook where the load-bearing sling or fitting sits; its width and condition affect the hook's safe working capacity.

A flat or round sling made of woven nylon or polyester fibers, lightweight and soft on loads but vulnerable to cuts, abrasion, and ultraviolet degradation.

A sling made from strands of steel wire twisted into rope, strong and resistant to heat and abrasion but requiring inspection for broken wires and kinks.

A sling made of alloy steel chain links, durable and tolerant of abrasion and heat, but subject to wear, stretching, and cracking at the links.

The process of examining a sling before each use for damage such as cuts, broken wires, worn links, missing tags, or other defects that make it unsafe to use.

The durable label attached to a sling showing its manufacturer, working load limit, and other ratings; if missing or unreadable, the sling should not be used.

The act of taking a damaged or questionable piece of rigging out of use and tagging or destroying it so it cannot be accidentally used for lifting.

A single failed wire in a wire rope sling; a concentration of broken wires in one strand or area is a defect requiring the sling to be removed from service.

A sharp bend or twist set permanently into wire rope or chain that weakens the material and is a reason to remove that sling from service.

The point in a load where its weight is balanced in all directions; the hook must be positioned above this point for the load to hang level and stable.

The condition in which a lifted load hangs level and stable because the lifting points and sling lengths distribute the weight evenly around the center of gravity.

The use of tag lines or other means to keep a suspended load from swinging or rotating during lifting, so workers stay clear and the load lands accurately.

A rope attached to a load and handled by a worker from a safe distance to guide and steady the load without touching it directly.

A sudden, jerking application of force to rigging, such as a rapid hoist start, that can exceed the working load limit and cause failure even on a properly rated sling.

The angle at which a sling leg meets the load or the hook; steeper angles reduce the load per leg while flatter angles increase tension in each leg.

A fixed loop knot that will not slip under load and is easy to untie, sometimes used for non-critical tie-offs but not a substitute for rated rigging hardware.

A simple knot used to tie a rope to a post or rail, handy for temporary tag lines but known to slip if the load direction changes.

The rated load a two-leg sling can carry, which depends on the angle between the legs and is less than twice the single-leg capacity at any angle below vertical.

A pad or sleeve placed between a sling and a sharp or abrasive load edge to protect the sling from cuts and wear.

Any material or device, such as corner guards or wear pads, used to keep slings and rigging from being cut or damaged by load edges.