NCCCO Sling Types and Load Distribution 2

Question 1

What is the D/d ratio for a wire rope sling and why is it important?

Accepted Answer

It is the ratio of the bend radius (D) around a hook, shackle, or fitting to the rope diameter (d), which determines the efficiency loss — smaller D/d ratios cause greater bending stress and capacity reduction

Answer

It is the ratio of drum diameter to rope diameter, used for hoist drum sizing

Answer

It is a quality control ratio used in wire rope manufacturing

Answer

It applies only to synthetic web slings, not wire rope

Question 2

A rigging crew is using a two-leg bridle sling to lift a horizontal beam. The horizontal angle of each sling leg from vertical is 30 degrees. What effect does this angle have on the tension in each sling leg?

Accepted Answer

The tension in each sling leg is greater than half the load weight — the more horizontal the angle, the greater the tension in each leg

Answer

Each sling leg carries exactly half the load weight regardless of angle

Answer

Sling tension decreases as the horizontal angle increases

Answer

Angle has no effect on sling tension as long as the load is level

Question 3

Under ASME B30.9, what is the minimum allowable horizontal sling angle for a wire rope sling in a two-leg bridle configuration?

Accepted Answer

30 degrees from horizontal

Answer

15 degrees from horizontal

Answer

45 degrees from horizontal

Answer

60 degrees from horizontal

Question 4

What is the difference between a vertical hitch, a choker hitch, and a basket hitch for a single sling?

Accepted Answer

Vertical hitch suspends the load from the end of the sling; choker hitch wraps around the load and passes through itself, reducing capacity; basket hitch wraps under the load with both ends attached to the hook, increasing capacity

Answer

They are three different names for the same rigging configuration

Answer

Choker hitches are the strongest; basket hitches are the weakest

Answer

Vertical hitches are only used with chain slings; choker and basket are for synthetic slings

Question 5

A synthetic web sling has a working load limit (WLL) of 10,000 lbs in a vertical hitch. What is the approximate WLL in a basket hitch with a 45-degree horizontal sling angle?

Accepted Answer

14,140 lbs

Answer

10,000 lbs

Answer

20,000 lbs

Answer

7,070 lbs

Question 6

What is the concern with side loading on a shackle pin, and how does it affect the shackle's working load limit?

Accepted Answer

Side loading on the pin can reduce shackle capacity by up to 30% or more because it creates a bending moment the pin is not designed to resist

Answer

Both bow and pin have the same capacity — they are rated as a unit

Answer

The bow is always the weakest part of any shackle

Answer

Pin capacity is always higher than bow capacity, making pin selection irrelevant