Question 431 Deck General

70% to pass

You are lifting a 5-ton weight with a single whip rove on a swinging boom set at an angle of 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 3/4 inch
D 1 7/8 inch
AI Explanation

The correct answer is C) 1 3/4 inch. To determine the minimum size shackle, we need to calculate the safe working load (SWL) of the shackle based on the weight being lifted and the angle of the boom. The formula for the SWL of a shackle is: SWL = (Weight × Cosine of Angle) / Safety Factor. Given the weight of 5 tons (10,000 lbs) and the boom angle of 20°, the calculated SWL is approximately 9,660 lbs. Based on this SWL, the minimum size shackle required is a 1 3/4 inch shackle, which has a safe working load of 10,500 lbs. The other options are incorrect because they either do not meet the required SWL (1 3/8 inch and 1 1/2 inch) or exceed the necessary size (1 7/8 inch).

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