Swivel Hoist Rings vs Eyebolts
Swivel Hoist Rings vs Eyebolts
(OP)
I have a general question on lifting. As I understand it, an eyebolts lifting capacity gets derated as the lifting angle leaves the [b]Normal[b]. 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 [b]Normal[b]. 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
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





RE: Swivel Hoist Rings vs Eyebolts
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
RE: Swivel Hoist Rings vs Eyebolts
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
RE: Swivel Hoist Rings vs Eyebolts
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RE: Swivel Hoist Rings vs Eyebolts
RE: Swivel Hoist Rings vs Eyebolts
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.
RE: Swivel Hoist Rings vs Eyebolts
Thanks
Bill
RE: Swivel Hoist Rings vs Eyebolts
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.
RE: Swivel Hoist Rings vs Eyebolts
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.
RE: Swivel Hoist Rings vs Eyebolts
Also see http://americandrillbushing.com/eztorque.htm for big ones - it's like a "superbolt"