Stability & Equilibrium in Rigging Engineering & Lift Planning
Stability & Equilibrium is vitally important for rigging engineers and lift planners to understand. How to determine whether a rigging arrangement is stable or not, and how unstable arrangements can be stabilized are skills every rigging engineer and lift planner should have. "Stability & Equilibrium" is a Lesson in the Fundamentals of Rigging Engineering Program taught by Keith Anderson, Chief Rigging Engineer for Bechtel Corporation. To begin the Lesson, Anderson addresses several questions that must be asked in order to determine a rigging arrangement, and thus, the stability:- Does the load need to be upended, flipped, or rotated?
- Is there a required rigging arrangement?
- Are lifting points provided?
- What loads are involved and how accurately are the weights known?
- What rigging gear is available and is it rated adequately?
- Is the load strong enough to lift in the recommended arrangement?
- Are spreader bars required?
- Are there headroom restrictions?
Anderson then leads students into a discussion regarding stability. In short, the load being handled must remain controlled, secure and stable throughout the duration of the lift/move. Uncontrolled movements can result in a loss of the load, loss of the load handling device (e.g. the crane), collateral damage to property and person. So, the potential consequences of instability are serious, but the causes are not always well understood. Furthermore, establishing whether a proposed rigging arrangement is stable, is not always straightforward.
Prior to delving into analyzing stability, Anderson ensures students understand the definition of static equilibrium - when all forces and all moments acting are in balance. Afterwords, a lengthly discussion ensues where Anderson peppers students with examples of stable and unstable arrangements, testing their knowledge about what makes a load stable.
A major consideration regarding a two-sling arrangement is that the center of gravity must be contained within the angle of the two slings or else the load will roll out of the slings. Also, the point at which the two inclined slings meet at the shackle is the point from which the load is suspended and can act as a hinge. That point will align itself on the vertical line through the center of gravity and the crane head sheaves. If the center of gravity is below that hinge point, the load acts as a plum bob and is stable.
Anderson presents this 1.5-hour Lesson in the Rigging, Equipment, and Applications Course which is one of five required courses to complete the
Rigging Engineering Program.
Rigging Engineering Program.About The Fundamentals of Rigging Engineering Program
Fundamentals of Rigging Engineering is ideal for lift planners, rigging engineers, and other key personnel who strategize and plan crane and rigging activities.To better understand the breadth and depth of this cutting-edge new program, download the Program eBookwhich outlines:
- Program Outline by Course
- Instructor Profiles
- Pricing Options
- Customers
- Supporters
To learn more, visit riggingengineering.com or call Christina Lanham, ITI Manager of E-Learning at 800-727-6355.
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