Basic Rigging (RB) key terms

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

The ratio of a component's breaking strength to its working load limit. A higher factor means more safety margin built into the equipment rating.

The load at which a sling or fitting fails and pulls apart. It is always greater than the working load limit and is used to calculate safety margins.

A test load applied to hardware to confirm it holds without permanent deformation. It is above the working load limit but below the breaking strength.

A written outline of how a load will be lifted, including equipment, hitch type, rigging positions, travel path, and hazard controls. It is reviewed before the lift begins.

A lift that is unusually hazardous because of load weight, configuration, location, or public exposure. It requires extra planning, engineering review, and often a dedicated supervisor.

A worker who can identify hazards and has the training and authority to correct them. For rigging, this person inspects gear and approves safe lift setups.

A person with recognized training and experience who selects and configures rigging equipment. This individual understands load limits, sling angles, and hitch behavior.

A U-shaped metal fitting with a pin or bolt used to connect slings to loads or lifting points. Shackles are rated and marked with their working load limit.

A large oval link at the top of a multi-leg sling assembly. It gathers the legs and connects the assembly to the crane hook or lifting device.

Lifting hooks fitted with a spring-loaded latch that closes the throat. The latch prevents slings and rings from slipping out during lifting or slack conditions.

The clear gap inside a hook where slings or fittings sit. Loads must bear on the saddle, not the tip, and the opening must fit the hardware.

A sling made of steel wire strands wound into rope and fitted with eyes or fittings. It is strong and abrasion resistant but must be inspected for broken wires.

A flat or round sling woven from nylon, polyester, or similar fibers. It is light and soft on loads but vulnerable to cuts, heat, and chemical damage.

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

A durable label attached to a sling showing its capacity, material, and manufacturer. If the tag is missing or unreadable, the sling must be taken out of service.

A multi-leg sling assembly where each leg attaches to a separate point on the load. The legs share the load and pull inward as they rise.

A hitch where the sling wraps around the load and passes through its own eye. It grips the load but reduces capacity compared with a vertical hitch.

A hitch where the sling passes under the load and both eyes connect to the hook. It cradles the load and preserves most of the sling's capacity.

A hitch where a single sling leg hangs straight from hook to load. It gives the full rated capacity of the sling leg.

The angle between a sling leg and the horizontal load surface. As this angle decreases, tension in each leg rises sharply and capacity drops.

The pulling force carried by each sling leg. It increases as the sling angle becomes shallower, even when the total load stays the same.

A multiplier used to find tension in a sling leg from the share of load it carries. It grows as the sling angle flattens toward horizontal.

A fixed loop knot that will not slip under steady load and unties easily after unloading. Riggers use it for temporary loops, though knots reduce sling strength.

Padding, softeners, or edge guards placed between a sling and sharp or rough load surfaces. Protection prevents cuts and abrasion that weaken slings.

The point where the load's weight is balanced in all directions. The hook must sit directly above it to keep the load level and stable.

The process of calculating or looking up a load's weight before lifting. It uses shipping papers, material density, and measured dimensions to avoid overload.

Distributing weight evenly among sling legs and lifting points so the load stays level. Uneven sharing can overload one leg even when total weight is within limits.

A manufacturer's table showing the capacity of a crane or lifting device at various radii and configurations. Riggers check it to confirm the lift is within capacity.

The triangle formed by two sling legs and the load span between their attachment points. Its shape determines sling angle and leg tension.

Sideways movement of a load caused by wind, off-center weight, or uneven lifting. It can swing the load out of control and increase tension on slings.

A rope tied to a load and held by a worker to control rotation and swing. It keeps the load from drifting while staying clear of the lift path.

The person who coordinates a lift and directs the crane operator and riggers. This individual confirms the rigging plan and gives the final go-ahead.

Agreed gestures used to direct crane operators when voice or radio contact is unreliable. They must be understood by the operator and the signal person.

The designated worker who relays hand signals or radio commands from riggers to the crane operator. Only one person should signal at a time.

A dangerous condition where the load block is pulled up against the boom tip. It can snap the hoist rope or damage the crane.