Rigging, Hoisting and Material Handling Flashcards

A 2,000 lb load is lifted with a two-leg bridle sling. Each leg is at 60° from horizontal. About how much tension is on each leg?

Answer: 1,155 lb

Each leg carries half the load (1,000 lb) times the sling angle factor. At 60°, that factor is 1/sin(60°) ≈ 1.155, so each leg carries about 1,155 lb. Leg tension rises as the angle gets flatter.

Why should sling angles below 30° from horizontal generally be avoided?

Answer: Leg tension rises sharply and can exceed the sling's rated capacity

As a sling angle flattens, the tension in each leg climbs quickly. At 30°, each leg carries the full load weight, and below that it carries even more. This makes overload very likely.

Compared with a vertical hitch, roughly what share of the vertical rated capacity does a sling typically have in a choker hitch?

Answer: 75%

The choke point bends and stresses the sling, so a choker hitch is commonly rated at about 75% of the vertical capacity at standard choke angles. A basket hitch, by contrast, can be rated up to 200%.

Which wire rope condition requires removing the rope from service?

Answer: Birdcaging or kinking

Birdcaging (strands spreading apart) and kinking are permanent structural damage that greatly reduce the rope's strength. Either one means the rope must be removed from service.

What is the main purpose of a tag line during a lift?

Answer: To control rotation and swing of the load from a safe distance

A tag line is a rope attached to the load. It lets a worker guide the load and stop it from spinning or swinging, without standing under it or touching it directly.

What does the Working Load Limit (WLL) marked on rigging hardware mean?

Answer: The maximum load the hardware is rated to handle in normal service

WLL is the maximum load the manufacturer allows in normal use. It is set well below the breaking strength by a design factor (often 5:1 for shackles and slings), so it must never be exceeded.