Swivel Hoist Rings vs Eyebolts

[wchowe]

I have a general question on lifting. As I understand it, an eyebolts lifting capacity gets derated as the lifting angle leaves the Normal. Swivel Hoist rings are NOT derated and carry the same load no matter what the angle. The load on the ring, of course, gets larger on the ring at angles further from Normal. Am I correct in these statements?
The load (F)on an eyebolt is F=w/Sin 90. With 90 being a vertical lift and 90 thru 45 being some sling angle. W=weight
Thanks
Bill

 

[Barry1961]

The working load is often rated at set angles of lift. I think the standard is 30 degrees minimum for multiple lift points.

If you are using a swivel hoist ring with a single bolt connection it is easy to get it loose to the point where the bolt is being bent like when using an eye bolt. Of course once the bolt is bent all bets are off.

I would get the data from the manufacturer.

CYA!

Barry1961

 

[wchowe]

Barry,

I am refering to all the other data being as required. Bolt Torque, etc. The maximum lift angle that anyone recommends is 45 degrees. That is because the force on the eyebolt goes way up as the angle goes below 45 degrees.
Thanks
Bill

 

[unclesyd]

Take a look at the HR-1000 Swivel Hoist Ring, Look at both the catalogue and pdf.

http://catalog.thecrosbygroup.com/maininterface.htm

 

[JJPellin]

You are correct. A standard eye bolt is derated for any angle other than straight in line with the bolt. A swivel eye is not derated for any angle up to 90 degrees away from the line of the bolt. But that does not mean that the eye can lift the same weight at any angle. The eye can take the same load. If you rig with two chokers in a triangular pattern with a side angle of 60 degrees, the load on the eye bolt at the bottom of the triangle is about 15 percent greater than if the same chokers and eyes were rigged straight up. At 45 degrees the force on the eye is over 41 percent greater. The load rating of the eye does not go down, but the load does go up. We tend to use swivel eyes for things like flipping compressor cases over. In that case, the pick is always straight up and down, but the load is rotated so that the angle on the eye changes. In this case, the rating of the eye is constant and the load is constant, so no de-rating is needed. If we used a solid eye bolt in the same circumstance we would be loading the eye at an angle greater than 45 degrees away from the line of the bolt. A solid eye is not designed to take a load in this condition. We used to do this all the time, but it was not safe.

 

[ccw]

Be careful using the safety hoist rings (swivels). Always have a safety demo with your riggers to show how you can jam the swivel rotating body and apply load to in-plane to the "U", against one leg of the "U", which can pry and spread the "U" open and pull the "U" axle pins out of the rotating body. Try to keep the applied load within a 90 degree cone referenced to the axis of the grade 8 center bolt(screw).

Also, you can tighten the center grade 8 bolt (screw) to the parent material much tighter than what is specified on the tag without degradation, with units like the Crosby swivel hoist ring, acccording to Crosby.

There is a greater risk of finding swivel hoist rings grade 8 screw loose in the parent material because 1. you should not paint them (that can cause jams), and 2. since you do not paint, they rust in the weather so riggers like to take them off and keep them in their tool box.

There are 3rd party units from everybody now, since the American Drill Bushing patent ran out years ago.

 

[wchowe]

Just to be clear a solid eyebolt that is rated for 2500 lbs would be derated to (F*sin 45=) 1767 lbs should the load be lifted at a 45 degree angle? AND of course the force acting on the eyebolt goes up as well. A 1000 lb load, actually increases to 1414 lbs at the eyebolt. So with a vertical lift the safety factor is (2500/1000=)2.5 but at a 45 degree lift the safety factor is only (1767/1414=)1.25! Where as a hoist ring rated for 2500 lbs would have a safety factor of (2500/1414=)1.76 for the same 45 degree lift and load! Am I correct in this?
Thanks
Bill

 

[ccw]

wchowe,

Quoting from Crosby Group Inc. Catalog: For "shoulder nut eye bolts (properly installed) installation for angular loading IN-LINE ...Direction of Pull 45 degrees adjusted working load 30% of rated working load...Direction of Pull 90 degrees adjusted working load 25% of rated working load"

The same knock down factors are quoted for properly installed Machinery Eye Bolt IN-LINE angular loading.

For their swivel hoist ring: "When using lifting slings of two or more legs, make sure the forces in the legs are calculated using the angle from the vertical to the leg and select the proper size swivel hoist ring to allow for the angular forces. (Note: Sling angles will de-rate sling members (chain, rope, or webbing) but will not de-rate swivel hoist ring capacity.)"

I don't know how to make it any more clear. Eyebolts have knock down factors. Swivel hoist rings do not.

HOWEVER, other hazards may develop when the swivel hoist rings are in the hands of the casual user, particulary when the configuration is in extreme positions. If the configuration causes any part of the hook, thimble, shackle, cable, etc. to make contact with the adjacent parent material being lifted or some place on the swivel body, other than the bend in the "U" member of the swivel hoist ring, very bad things can happen.

 

[diamondjim]

You are right about the formula
F x Sin alpha being the max load
at each lifting bolt.
The lifting load remains constant
so the you essentially have
1767/1000 for the safety factor for
the 45 degree chain or lift angle
times the number of screws or bolts.

 

[arto]

The Swivel hoist rings need to be torqued properly to achieve their rating. Also you need to use through-bolts & nuts for most common materials [ADB sez 80ksi Su ~ HY80]to keep from stripping


Also see

http://americandrillbushing.com/eztorque.htm

for big ones - it's like a "superbolt"