# Hold My Beer and Watch This



## SeniorSitizen (Sep 10, 2012)

but first I need to know if there is an engineer in the house.

If I have a object on the floor xx feet long, and I'm going to lift one end with a hoist, as the end is lifted the load on the hoist lessens as the lift angle increases.

Here is where I need a graph, if possible, that shows the load change at degree angles. 

Thank you for your time.

SeniorSitizen


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## dgparks (Dec 5, 2015)

SeniorSitizen said:


> but first I need to know if there is an engineer in the house.
> 
> If I have a object on the floor xx feet long, and I'm going to lift one end with a hoist, as the end is lifted the load on the hoist lessens as the lift angle increases.
> 
> ...


here's your graph ________ no engineering here...  :vs_cool:


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## ddawg16 (Aug 15, 2011)

Important point....

Does the hoist on the one end have captive hold of the object? In other words, can XX slide off the hoist?

If the hoist is not captive, then you can assume that the hoist holds 1/2 the weight, and as you go vertical, the weight proportionally shifts to the other end.


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## dgparks (Dec 5, 2015)

ddawg16 said:


> Important point....
> 
> Does the hoist on the one end have captive hold of the object? In other words, can XX slide off the hoist?
> 
> If the hoist is not captive, then you can assume that the hoist holds 1/2 the weight, and as you go vertical, the weight proportionally shifts to the other end.


i agree to disagree... Your math is wrong my friend...


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## ddawg16 (Aug 15, 2011)

dgparks said:


> i agree to disagree... Your math is wrong my friend...


So, show us............


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## ddawg16 (Aug 15, 2011)

I need to get to bed...so I'll explain it to you....

If we assume beam xx is of consistent weight across it's length.....for the below topic lets assume 1000 lbs.

Floor has 500lbs....hoist 500lbs.

We also assume the hoist will move towards the other end as it lifts.

As the hoist lifts, the CG (Center of Gravity) moves towards the floor end, thus the weight on the floor increases. 

Simple trig will tell you the exact weight at each point. This is high school stuff.

When that beam gets vertical, you have 1000 lbs on the floor and 0 lbs on the hoist. Anything in between is proportional.


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## Nik333 (Mar 1, 2015)

This may explain it, although they don't recommend only one sling ( stated further on down).
http://www.lift-it.com/info_hitches_all.asp If I'm totally out to lunch, let me know.


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## Nik333 (Mar 1, 2015)

I didn't mean that post as a counter to what ddawg16 wrote. I just tried to find a "graph" like reference.


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## ddawg16 (Aug 15, 2011)

Nik333 said:


> I didn't mean that post as a counter to what ddawg16 wrote. I just tried to find a "graph" like reference.


Nothing there to be offended to...good info.

If I have time I'll draw a graph.


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## SPS-1 (Oct 21, 2008)

A lot of variables that are not specified. 

If the hoist is directly over the lifted end, you will start with half the load on the hoist.

If the other end is blocked from sliding, and you are lifting the beam like a framed wall is put up, then, when the beam approaches vertical, load on the hoist can very little. But you pretty much need the hoist to be able to move laterally as the beam is lifted.

If your hoist is fixed, and you expecting the bottom of the beam to slide towards the hoist, the entire weight of the beam is on the hoist as it approaches vertical.


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## Daniel Holzman (Mar 10, 2009)

SPS-1 makes a number of good points. This problem is actually more complicated than it seems at first. In an ideal case, where the hitch is firmly attached to the end of the beam, and the hitch lifts perfectly vertically (example there is a horizontal pin through the end of the beam), then for any given amount of lift, the beam will settle into a static position, and half the weight of the beam will be carried by the hitch, and half by the floor, and all the loads will be vertical.

However, the beam has to achieve the static condition, which means that as the beam rotates during the lift, either the floor end slides, the hitch moves, or both the hitch moves and the floor end moves. Exactly what movement occurs depends on the friction angle between the floor and the beam, and also the rate at which the beam is lifted. I read a recent fatal incident report where the sudden, unexpected movement of a large steel beam during a lift caused one fatality and a serious injury. The mathematics are complicated because the beam is not static, so the forces are subject to rapid variation during the lifting process.

There is also a statically undefined point when the beam gets vertical. In the vertical state, the beam could be entirely supported by the floor, or entirely supported by the hitch (if the hitch lifts the beam off the floor), or somewhere in between. The load on the hitch and the floor in the vertical position depends on the exact details of the lift.


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## Nik333 (Mar 1, 2015)

Daniel Holzman - so what would you recommend for safety?


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