The question asks about the eye hook, not eye bolt(s). The minimum rating for the eye hook should be 5T since it has a 10,000 lb load. No information provided as to safety factor required, so that 5T rating will only ensure that the eye hook should not fail at the 10,000 lb load with no margin for safety.
In construction rigging most of the steel is used for a single job site and then discarded if in bad condition. They aren't in the same situation as theatrical and arena rigging where the steel needs to last 8 months or more on the road.In the hook illustration, doesn’t the side force of the two cables on the hook need to be accounted for? The hook is rated for that force in a single point vertical lift.
Todd, I’m with you, there’s no safety margin at all.
Also, does it bug anyone else that the cables are drawn without thimbles? I get that the cables are not the point, but still... If you’re going to draw the shoulders on the eyebolts, give the same detail to the cables!
Especially when there are multiple grooms.You do need to consider the bridal angle.
You do need to consider the bridal angle. If that angle approached zero (fully horizontal) the tension on the cables and hook would approach infinite. I've not checked Dagger's sling angle math, but if correct then the hook would need to support both of the 2.9T loads, which is more than any multiple choice option on the quiz.
I'm a little concerned about this thread, because there are some wrong answers to rigging questions.
How / where is the sign attached to the frame? End points of the frame? Equally distributed across the frame?
Where are the eye bolts in relation to the sign attachment points?
What are these questions from? An online exam?
The correct answer to the test question is D - none of the above. As you point out, Nick, if the 2.9 tons per leg is correct, the hoist hook is under rated for the proposed lift.You do need to consider the bridal angle. If that angle approached zero (fully horizontal) the tension on the cables and hook would approach infinite. I've not checked Dagger's sling angle math, but if correct then the hook would need to support both of the 2.9T loads, which is more than any multiple choice option on the quiz.
I'm a little concerned about this thread, because there are some wrong answers to rigging questions.
I'm going to disagree. The eye hook (assuming it is a Crosby product since it is a Crosby exam) is rated for a 5T capacity as long as the included angle of the bridle does not exceed 90 degrees. The angle of the bridle at the hook is 60 degrees (equilateral triangle = each angle is 60 degrees).
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