Craig Miller
Posts:11799
 | | 19 Jan 2011 11:30 PM |
| Anyone know how hard it would be to fabricate one of these and have it rated to at least 15,000lbs WLL? It looks simple enough from a design perspective, but the WLL seems more difficult to achieve for the amateur. Craig | | |
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Dan Cronin
Veteran Member
Posts:2844
| | 20 Jan 2011 07:33 AM |
| 15K lbs?!?! :-) What are you pulling with that? A Sportsmobile? | | | |
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Benny Benson
Veteran Member
Posts:1681
| | 20 Jan 2011 07:38 AM |
| I would think that materials and labor would come close to what that site wants minus the shipping. Not sure about how to go about getting it tested for the WLL. But if you trust the welder and or fab shop I don'y see the real need to have the WLL stamped on it. | | | |
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Craig Miller
Posts:11799
| | 20 Jan 2011 07:55 AM |
| Posted By Dan Cronin on 01/20/2011 7:33 AM
15K lbs?!?! :-) What are you pulling with that? A Sportsmobile?
Possibly. ;-) All of the receiver shackle items I've found state, "Do not exceed your to receivers capacity" indicating to me that they are *way* stronger than any other item in the recovery WLL chain. So I asked for 15k.
What I need is a true WLL around 8-10k as my recovery WLL chain consists of:
Bow shackles with a green pin - WLL 9.5k :-)
ARB bumper hitch receiver - WLL 8k
Dixon Bate tow jaw - WLL 7.5k
Receiver mount for tow jaw - WLL??? | | | |
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Craig Miller
Posts:11799
| | 20 Jan 2011 07:57 AM |
| Posted By Benny Benson on 01/20/2011 7:38 AM I would think that materials and labor would come close to what that site wants minus the shipping. Not sure about how to go about getting it tested for the WLL. But if you trust the welder and or fab shop I don'y see the real need to have the WLL stamped on it. I guess the real question is whether or not you trust it. If it comes flying off of there when I'm pulling you (or someone else) out of the ditch it's going to come flying at your windshield with all of the energy stored in a recovery strap.  | | | |
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Benny Benson
Veteran Member
Posts:1681
| | 20 Jan 2011 08:11 AM |
| I have faith you will choose a reputable welder to have this made.  lol. It's kinda like the same trust/faith that I have that everyone I wheel with has chosen their gear correctly/smartly. | | | |
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Craig Miller
Posts:11799
| | 20 Jan 2011 08:13 AM |
| I think I'll probably just buy one. LOL. | | | |
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Alex Kogan
Basic Member
Posts:421
| | 20 Jan 2011 08:21 AM |
| I wouldn't blow all that WLL rating out of proportion. Is your receiver WLL rated? No! Is receiver pin rated? No. Are Bolts attaching tow jaw to adaptor WLL rated? No. Are the frame/frame attachment points rated? No. Etc... But common sense tell you they are strong enough. Use your common sense | | | |
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Craig Miller
Posts:11799
| | 20 Jan 2011 08:43 AM |
| Actually Alex the answer to all of those questions is Yes and/or the sheer strength is known.
Receiver is WLL to 8k
Receiver Pin is from Curt Manufacturing and has a sheer strength of 30k
Attachment hardware - Dixon Bate recommends Metric 8.8 to achieve their specified WLL. I'll be using metric blue 12.9
Receiver WLL is based on frame strength and was tested by ARB engineers.
I am using my common sense. My common sense tells me to pay attention to the numbers and not trust my layman's perception of what is or isn't strong enough. The latter is what gets people in trouble.
Craig | | | |
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Curtis Bray
Basic Member
Posts:189
| | 20 Jan 2011 09:13 AM |
| This is super easy to fabricate. It will hold to your desired specification.
That said, though a high school metal shop student probably should not build it for you. A weld like this with differing thickness is not easy to do well for a novice. But simple enough for somone with modest experience. | | | |
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Peter Schuldt
Basic Member
Posts:229
| | 20 Jan 2011 09:51 AM |
| In the long run I think it would be better just to buy one of those. If it were exotic then maybe but if it is ready off the shelf just buy it. | | | |
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Alex Kogan
Basic Member
Posts:421
| | 20 Jan 2011 03:34 PM |
| We shouldn't confuse WLL with SWL (which used to imply certain safety factor say *5) WLL just specifies maximum working load for particular device in particular application, in particular settings. In one case say shackle it might indeed be same as SWL (overhead dead load), in other could be totally different. In case of towing receiver hitch it definitely does not mean there is 5*dead load safety built into it. It just mean you can safely tow 8000lb trailer. It's certainly not tested for some odd angle dynamic recovery. It doesn't mean you can hang 40000lb at 90 degree angle. Yet I'm pretty sure we are not talking about towing here. Yes of course there is inherent overbuild in all towing device and surely they can handle much larger loads but there is no deterministic way to find out true breaking strength by looking at WLL. Same goes for bolts. Even super airspace age bolt will snap if one overtightens it without even applying any load. Don't get me started on welds.
None the less just buy one ready made. I really doubt that you can have one made for less (cutting, marking out holes, drilling, welding, painting...). Throw in WLL testing it will be $59k not $59 | | | |
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Craig Miller
Posts:11799
| | 20 Jan 2011 05:04 PM |
| Posted By Alex Kogan on 01/20/2011 3:34 PM
None the less just buy one ready made.
Yep, that's the plan.
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Tom Thomas
Basic Member
Posts:192
| | 20 Jan 2011 05:22 PM |
| The reciever would be easier to fab than tell you how to do it, and cost around $25. 1st, while it could be done with a 110v mig, that would not be suggested. The problem with any mig is it will "always" make a good looking weld, not necessarily a good weld. So my suggestion would be a DC+ arc, with maybe 11018 electrode for piece of mind. The thing about arc welding, if it looks bad, it is. Grind it and re-weld. For even added piece of mind, pre and post heat. And for the most secure mind, add gussets. ;) | | | |
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John Anderson
Basic Member
Posts:253
| | 16 Feb 2011 08:50 PM |
| As long as the steel was pre-bevelled and pre-heated and clean as well as welded with the proper stick/wire 15,000 may be possible by the do-it-yourselfer. Another alternative is to purchase this same piece by different brand/model name from an industrial trailer and hitch supply house like "Six Robblees." The are located next to Horizon Ford in Tukwila. My company has been purchasing all kinds of towing, hitch and trailer accessories for years at reasonable prices. | | | |
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Craig Miller
Posts:11799
| | 16 Feb 2011 10:46 PM |
| Thanks John. I think I'm going to have to have it fabricated, go with a 5ton Tow Jaw on the bumper, or go with a traditional receiver bow shackle.
I ordered the mount linked above for the Dixon Bate, but it isn't long enough to reach the hole where the receiver pin slides through in my ARB bumper. I can't find anything similar.
Craig | | | |
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Tony Sims
Veteran Member
Posts:1231
| | 17 Feb 2011 12:08 AM |
| My concern with using a receiver vs. a solid mount would be snatch recovery. Any movement in the receiver creates a risk, at least in my simple mind, because then you are dealing not just with the pull but a shock as parts move and stop. The pin may have a shear strength of 30k lb, but is how is that tested, by incremental increase of force, and is it single or double shear? I would bet that you could cut one with less than 30k force if the mandrel was moving before it contacts the material. And 30k may sound like a lot, but when you take 7k of truck on one end of a snatch strap and 7k on the other and accelerate them apart, 30k of force isn't out of the realm of possibility. OK, maybe I worry a bit too much about snatch recovery, but it is more dangerous than a controlled pull. | | | |
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Craig Miller
Posts:11799
| | 17 Feb 2011 12:52 PM |
| I've thought about that before too Tony. Pragmatically, I don't think I've ever heard of a receiver shackle failing in the field despite their abundant use. Theoretically, the stretch in a recovery straps gradually applies the force. | | | |
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Peter Schuldt
Basic Member
Posts:229
| | 17 Feb 2011 02:58 PM |
| I was discussing this with a co worker who has seen yank recoverys distroy turcks. It was always with a chain. The dynamic starp is the key. | | | |
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Jay Erickson
Advanced Member
Posts:811
| | 17 Feb 2011 03:14 PM |
| Very true, all the damaged vehicles that I can think of from yanking were all due to using some sort of chain, tow strap or cable. I think from a purely safety oriented aspect using a winch is safer as you have more control of the load forces however a lot of times our rigs just aren't that stuck. In that respect its better to hook up the yank strap and give a rig a tug than to have 2 or 3 people pushing or trying to rock the vehicle to get some traction. A yank strap is also a whole lot faster than most people winching.
It's just a tool, it can be used very successfully so long as you respect it's limitations. | | | |
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