Sign hung issue

In a situation like this ( see drawing)

Can those #4 bolts hold the 8ft section?
( is it better to make a bridle with motor 1 (M1)?

Dagger said:

In a situation like this ( see drawing)

Can those #4 bolts hold the 8ft section?
( is it better to make a bridle with motor 1 (M1)?

Click to expand...

If you have a new question, please start a new thread. this one is confusing enough.

Yeah I think all the Dagger threads need to be merged and retitled Dagger Asks.

Dagger said:

In a situation like this ( see drawing)

Can those #4 bolts hold the 8ft section?
( is it better to make a bridle with motor 1 (M1)?

Click to expand...

"#4 bolts" Huh? #4 as in 4-40 machine screws??
Toodleoo!
Ron Hebbard

tdrga said:

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).

The eye bolts do need to take into account the additional load due to sling angle, but the eye hook is already rated for the sling angle given in the example.
See the Crosbly application note for hooks attached.
-Todd

Click to expand...

I'm not disputing the angle, but read exactly what I wrote: "As you point out, Nick, if the 2.9 tons per leg is correct..." 2.9+2.9=5.8 tons. Or has addition changed in the decades since I was in first grade?

Grade 8 bolts

TimMc said:

I'm not disputing the angle, but read exactly what I wrote: "As you point out, Nick, if the 2.9 tons per leg is correct..." 2.9+2.9=5.8 tons. Or has addition changed in the decades since I was in first grade?

Click to expand...

No, addition is still the same- you are just adding the wrong things.

There are two ways to look at this problem.
One- given that the load and all rigging weighs 10,000 lbs. and the hook is rated to lift that weight at that bridle angle- does the angle of the bridle at the hook increase the weight that is lifted? No it doesn't.
Two- add the vector forces. The side pull from the left bridle is canceled out at the hook by the side pull from the right bridle, leaving only a vertical downward force of 10,000 lbs (the weight of the load and all rigging) at the hook.

You are confusing the loads present at the eye bolts with the loads present at the hook.

Does your line of thinking allow for a safety margin, yes - but given the manufacturer's instructions, the 5T hook is the minimum needed to lift the load (which is the original question). I would probably go up a size to be safe in the real world.
-Todd

In rigging trianlge the sum of tension in legs does NOT equal to the loading seen at top .

Dagger said:

In rigging trianlge the sum of tension in legs does NOT equal to the loading seen at top .

Click to expand...

Calling @What Rigger? and @egilson1
Toodleoo!
Ron Hebbard

tdrga said:

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

Click to expand...

Ah. Didn't know that. Makes sense.

I'm not even touchin' this one. This thread is going down a weird rabbit hole I can barely follow.