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The Critical Pick: A Crane Rigging Demonstration

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2019 ASEE Annual Conference & Exposition


Tampa, Florida

Publication Date

June 15, 2019

Start Date

June 15, 2019

End Date

October 19, 2019

Conference Session

Your Best in 5 Minutes: Demonstrations of Hands-On and Virtual In-Class Teaching Aids

Tagged Division

Civil Engineering

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Paper Authors


David M. Flaherty United States Military Academy

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Major David Flaherty is an instructor in the Department of Civil and Mechanical Engineering at the United States Military Academy at West Point. He earned a M.S. in civil engineering from the University of Colorado, Boulder, in 2017. He is currently the course director for the Fundamentals of Engineering Mechanics and Design course, which is the largest course within the Civil and Mechanical Engineering Department. He can be contacted at

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This demonstration, an application of static equilibrium and geometry knowledge, depicts the importance of rigging angles during crane lift operations on a construction site. Reducing rigging angles results in a significant amplification of forces in the rigging, potentially leading to failure. By varying the connection points and sling length, students will be able to calculate the predicted forces and analyze the best combination of connection points and sling lengths to successfully complete the critical lift. The forces in rigging (sling, chain, wire rope, webbing, shackles, etc.) increase substantially as the angle formed by the sling leg and the horizontal datum becomes smaller. The key engineering principle with this demonstration is related to an understanding of statics. Students must comprehend that decreasing the angle creates a horizontal force component that increases the tension in the rigging. The demonstration takes 15-20 minutes to complete in class.

Flaherty, D. M. (2019, June), The Critical Pick: A Crane Rigging Demonstration Paper presented at 2019 ASEE Annual Conference & Exposition , Tampa, Florida. 10.18260/1-2--33377

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