Intermediate Rigging (RI) flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Working Load Limit

The maximum load a rigging component is designed to support in a specific configuration. It equals minimum breaking strength divided by the design factor and is marked on rated hardware.

Design Factor

The ratio of minimum breaking strength to working load limit. Common values are 5:1 for slings and 4:1 to 5:1 for hardware, providing a safety margin.

Sling Angle Factor

A multiplier applied to a leg's share of the load based on its angle from horizontal. It is 1.000 at 90 degrees, 1.414 at 45 degrees, and 2.000 at 30 degrees.

Center of Gravity

The point where the load's weight is balanced. The hook must be directly above it for a level lift; otherwise load shifts between sling legs.

Two-Leg Bridle Tension

Tension per leg equals load divided by twice the cosine of the angle from vertical. Steeper angles from vertical produce higher tension in each leg.

Gross Load

The total weight being lifted, including the payload plus all rigging below the boom tip such as hook block, slings, and spreader beams.

Shock Loading

A dynamic force from sudden acceleration, jerking, or stopping that can multiply static tension several times and overload rigging that is adequate for static load.

Load Angle Multiplier

A factor applied to a sling leg's load share when legs are not vertical. Values include 1.155 at 60 degrees, 1.414 at 45 degrees, and 2.000 at 30 degrees from horizontal.

Grade 80 Chain

Alloy steel chain grade commonly used for overhead lifting slings. Grades below alloy, such as proof coil or transport chain, are not acceptable for lifting.

Choker Hitch Capacity

A hitch where the sling passes around the load and through itself. Rated capacity is typically about 80 percent of the vertical rating.

Basket Hitch Capacity

A hitch where the sling cradles the load with both ends attached to the hook. Rated capacity is typically about 200 percent of the vertical rating.

Web Sling Rejection

Remove a synthetic web sling for holes, burns, charring, ultraviolet damage, exposed red core yarn, or missing tags. Cut or tag it out of service.

Wire Rope Sling Defects

Reject wire rope slings with broken wires beyond criteria, kinks, bird-caging, crushed sections, severe corrosion, or cracked and damaged end fittings.

Sling Protection

Softeners and corner protectors shield slings from sharp edges, heat, and abrasion. Protect synthetic slings from chemicals and sunlight and avoid tight bends.

Knot in a Sling

A knot greatly reduces sling strength and is never permitted. A sling found with a knot is removed from service.

Screw-Pin Shackle

A shackle whose pin is threaded and screwed into the bow. The pin must be fully seated and never replaced with an unrated bolt.

Hook Safety Latch

A device that closes the hook throat to prevent slings or lines from slipping off. A missing, broken, or distorted latch requires removal from service.

Shoulder Eyebolt

An eyebolt with a collar that allows angular loading within rated limits. Plain eyebolts without a shoulder are limited to vertical lifts.

Wire Rope Clips

Fittings that form an eye in wire rope. Use the correct count and spacing for the diameter, place the U-bolt on the dead end, and retorque after loading.

Master Link Rating

A rated alloy fitting that connects slings to the hook. Assembly capacity is limited by the weakest component, not by the strongest one.

Side Loading

Loading a shackle or hook perpendicular to its designed axis. Side loading reduces capacity and is not permitted beyond the rated design.

Net Crane Capacity

Chart capacity minus the weight of all lifting attachments below the boom tip. The payload must fit within the remaining net capacity.

Operating Radius

The horizontal distance from the crane's center of rotation to the center of the load. Increasing radius reduces chart capacity.

Ground Bearing Pressure

The force per unit area under outrigger floats or tracks. Mats and cribbing spread the load to keep pressure within soil capacity.

Lift Plan

A document listing load weight, rigging, crane position, radius, chart used, ground conditions, power line clearance, and the load path.

Critical Lift

A lift near chart capacity, with multiple cranes, unusual configuration, or personnel exposure. It requires engineered planning and a pre-lift meeting.

Boom Configuration

Boom length, angle, jib status, outrigger extension, and counterweight. Each combination changes the load chart capacity for a given radius.

Designated Signal Person

The single person authorized to direct the crane operator. Anyone may give a stop signal, which the operator must always obey.

Emergency Stop Signal

Both arms extended with palms out. It must be obeyed immediately by the operator regardless of who gives it.

Tag Line Use

A rope used to control load rotation and swing. Keep it long enough to stay clear of the load and never wrap it around hands or body.

Test Lift

A slight lift of a few inches to confirm load balance, rigging security, and crane stability before committing to the full lift.

Power Line Clearance

The minimum required distance between crane, load, and energized lines. Use a spotter and treat any contact as energized.