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I need to fit some rope hooks to my trailer. I looking at bolt-on as I can't weld and would like to avoid the cost of paying someone My concern is I make them as secure as I can I could use a spreader plate to go between the trailer and the fixings but what about the the nuts, bolts and washers? I'm familiar with the phrase 'high tensile' but I don't know if that is a technical term or just generic for 'stronger than most' Is there a particular design of washer best for this sort of application? This is a diagram of the hooks I'm looking at  |
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vanpeebles
Part of things
I am eastbound in pursuit of a white Lamborghini, this is not a recording.
Posts: 978
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Just good quality ones would do, rather than chinese pot metal specials. With a nyloc nut and some big washers. Would you put the plate on the back?
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Yes I was going to put the plate behind the trailer part so it goes hook - trailer - plate - washers - nuts The trouble with looking for 'good quality' bolts is everyone describes their's like that Even the curse word ones  |
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I've ordered the hooks. The bolt holes are 8.5mm
I've found out bolts rated at 10.9 are strong
Once they've arrived I'll work out how long they need to be
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What are you carrying on the trailer? What's the impact if the tie downs fail? Also, how big are the bolts (dia E in the diagram)?
If 'E' is 8 or 10mm, then as Vanpeebles says use M8/M10 with 'penny' washers on the back and nyloc nuts. The bolts from Toolstation or Screwfix would be fine. The need for a spreader plate on the front will depend on the thickness of the trailer body. Most of the stress will be either 'tension' (pulling the bolts through from the back - hence the penny washers) or 'sheer' (effectively elongating the holes).
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May 20, 2019 10:34:56 GMT
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I carry part dismantled cars on the back so result of failure could be bad
I feel quite happy with my options now
Thanks
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May 20, 2019 19:57:17 GMT
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even with heavy duty ratchet straps , i doubt you would unduly worry decent quality fixings. you will probably break/straighten the hook first!
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'80 s1 924 turbo..hibernating
'80 golf gli cabriolet...doing impression of a skip
'97 pug 106 commuter...continuing cheapness making me smile!
firm believer in the k.i.s.s and f.i.s.h principles.
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May 23, 2019 10:29:24 GMT
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The actual topic re load restraints is quite interesting. What many forget is that the angle at which the restraining strap/chain pulls has a dramatic effect on the load that a particular hook or tethering fixture can take. I spent a long time on the Internet trying to establish which fittings would suit a recent project to rebuild a second-hand trailer, and load restraint was one of the more complicated aspects to unravel. In the end I bought specific anchor points, which are rated in excess of the load weight that I know that I shall be carrying. Being rated/certificated adds to the price considerably, but at least I can wave a piece of paper at anyone who wishes to challenge their integrity. Re bolts there are in fact an additional strength of bolt, namely 12.9. Again though the direction of pull by the load alters ratings. Effectively suck and see; pray that nothing goes wrong. I have the orange coloured lashing points fitted to a small crawler tractor; they are made in Luxembourg and should come gold-plated. The yellow versions are considerably cheaper, but still certificated, and these are actually bolted to the load-bed of the trailer. Both versions come complete including bolts to fasten them down.   |
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pow
Part of things
Posts: 110 
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May 23, 2019 10:40:45 GMT
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May 23, 2019 11:42:48 GMT
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I have worked with lifting equipment for a few years and those eye bolts you are using are officially only suitable untill 45 deg and should not be treated with side loads. You can see it on more professional eye bolt suppliers like RS (https://nl.rs-online.com/web/p/eye-bolts/0673658/) One of the big disadvantages is that these can become loose due to the loads and once it is a bit loose, it looses a lot of its strength as the thread gets a shear load which is not good.The strenghts threaded connections get is that a pull load is created in the bolt and this causes a friction between headbolt and the to clamp items so even with side loads, a good bolt connection does not see shear loads. In practice a 16mm eye bolt will handle a fair bit of load but you cannot rate and in the lifting world it is forbidden except for positioning heavy equipment during installation. The items Norfolkshire shows are the only and best eye type bolts for side loads. Due to the no shear - friction between bolt head issue, it is very important that the eye bolts and every botl nut structure, are torqued properly in order to handle their specified loads
The hooks Jim shows are worse then pows eyebolts
Peter
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pow
Part of things
Posts: 110
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May 23, 2019 15:31:43 GMT
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Interesting read, I'll post a couple of what I have on my trailer and the angles.
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May 24, 2019 18:51:31 GMT
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Petervdv, being involved with lifting equipment as stated, has well and truly hit the nail on the head. During my searches on the Internet I came across many individuals who in age old parlance would be classed as 'Barrack Room Lawyers', expounding their knowledge on this subject.
It was blatantly clear that the majority of advice being given was completely wrong, and only perpetuating complete rubbish.
My criteria was that should I unfortunately become involved in an incident where the load carried on my trailer was the cause of injury, etc... to a third party, would I be taken to the cleaners for injury/damage; would my insurance company quickly do a runner and leave me to face any bill for damages.
Again as Petervdv states "The items Norfolkshire shows are the only and best eye type bolts for side loads".
That is fact and virtually no other style of fixing, no matter if it claims to be as strong as the Forth Bridge, is guaranteed to withstand side-loads, up to the level the lashing point is certified to.
My own lashing points are certified at 1 tonne each, and there are in fact six of these lashing points bolted into the load-bed of the trailer; my ratchet straps/shackles/short length of chains are all rated at 2 tonnes. My two horticultural tractors each weigh 800kgs; the trailer can only carry one of them at a time.
My towing hitch is rated at 5 tonnes, but the towing vehicle can only tow 3.5 tonnes because the trailers are fitted with over-run brakes; the trailer has a plated GVW of 1.8tonnes.
I believe that it is these figures which we should all be aware of when towing loaded trailers around.
Sorry to throw cold water on commonly held theories.
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