Question 595 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 20° 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 3/8 inch

B 1 1/2 inch

C 1 5/8 inch

D 1 3/4 inch

AI Explanation

The correct answer is A) 1 3/8 inch. To determine the minimum size shackle, we need to calculate the safe working load (SWL) of the shackle. The formula for the SWL of a shackle is: SWL = (Weight x Safety Factor) / Sine(Angle). Given that the weight is 3 tons and the angle is 20° to the horizontal, the minimum size shackle required is 1 3/8 inch. The other options are incorrect because they do not meet the SWL requirement based on the given weight and angle. A smaller shackle size would be unsafe, while a larger size would be unnecessarily large and expensive.

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