Question 377 Deck General

70% to pass

You are lifting a 3 ton weight with a single whip rove on a swinging boom set at an angle of 60° to the horizontal. Use the formula for the size of a shackle with a safe working load and determine the minimum size shackle that should be used to secure the head block to the boom.

A 1 1/8 inch
B 1 1/2 inch
C 1 3/4 inch
D 2 inch
AI Explanation

The correct answer is B) 1 1/2 inch. The reasoning is as follows: To determine the minimum size shackle required, we need to calculate the maximum tension force on the shackle based on the weight being lifted and the angle of the boom. Using the formula for a single whip rove, the tension force is equal to the weight multiplied by the sine of the boom angle (3 tons x sin 60° = 2.6 tons). Referencing the safe working load charts for shackles, a 1 1/2 inch shackle has a safe working load capacity that exceeds this calculated tension force, making it the minimum size shackle that should be used. The other options are incorrect because they either undersize (1 1/8 inch) or oversize (1 3/4 inch, 2 inch) the required shackle based on the calculated tension load.

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