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Question:

# What is the equation and answer for this lifting questionAny rigging experts out there?

If I have a 10 foot board that weighs 100 pounds and lifted one end with a weight scale and left the other end on the ground, what would the scale meausurement read in pounds at the first point of lift and how might it change as it is liftedLink suggestions to answer are welcomeThank's

## Answer:

easy stuff think of the board as if it were a peice of string 10 Ft long with 50 Lbs at each endthe scale would read 50 Lbs when first liftedbut because its a board the same applies iethere is 50 Lbs supported by the ground 50 Lbs on the spring balanceas you lift the board more weight is transfered to the end on the ground ie at 45 degrees then half the weight from the spring balance end is transfered to the end on the groundmaking that end weigh 75Lbs so the spring balance is only holding 25 Lbsthe weight on the spring balance continues to fall untill the board is verticalthen the spring balance holds no weightany further lifting will put 100% on the balance making the reading 100LBS Weight Vs Angle The angle at which a sling holds a given load influences the effective weight of the loadStresses are minimal for loads with slings held perpendicular to the load, as shown in Figure AFor distributing the load vertically among more than a single leg of a sling, a spreader bar may be usedAs shown in figures B-D, increasing the angle of the sling to the hook from 30 to 60 degrees increases the effective mass of the load from 1154 lbs to 2000 lbs, essentially doubling the weight on each leg of the sling at 60 degreesThe chart in the middle offers a handy guide for assessing the effective angle of the sling to the relative weightThus, it is always better to limit the angle of the slingFurther, such changes in sling angle must be accounted for in lifts that are close to the sling weight limit and/or for critical lifts (greater than 90% of the crane limit)Crane operators should download a copy of this chart and carry it with them during crane operations.

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