OK so I know that a braked trailer manufactured after 1st October 1982 needs a breakaway cable that will activate the brakes should the main coupling separate.
Now I do have an older braked trailer (Bradley pre auto reverse hitch) where you could not use a breakaway cable, so in the case of that the best that can be done is the use of a secondary coupling as on an unbraked trailer.
Not that I'm planning on my 90's Dandy becoming unhitched at any point soon but it occurred to me that a trailer that did unhitch and have it's brakes activate it could be extremely unpleasant.
Dropping off my Dandy at 60mph in the centre lane of the M6 is not something I'd relish. I'm pretty certain the person behind me with a trailer approaching them and no warning from brake lights either would be not be happy. Think all I'd see of the Dandy from then on would be from an insurance claim.
Though Mr Plod might not be best impressed at your trailer losing it's primary coupling, I think he would be more impressed at you being able to get to the hard shoulder than parking your trailer up in the second lane?
So is there anything legally preventing you from fitting a secondary (tertiary?) coupling as on an unbraked trailer? As with all the best engineering solutions two uses from one piece of kit. If it was a substantial bit of chain attached to the bar with a lock it would provide a level of theft prevention when parked up. All be it that the level of security was less than SAS type hitchlock there would be no wories about it being disconnected before moving off.
I can't believe I've come up with an original idea what's the fatal flaw?
Having the trailer slam into you wouldn't be pleasant either,so thats one reason not to perhaps. Insurance companies will find any excuse not to pay out,so that may be another.
The third is the use of the word tertiary,which I thought was a kind of bird 'till I read this!
Re the insurance I'd ask about the adaption.
As for the trailer slamming into you. I was going to get all precious saying how you would be expected to cope with an unbraked trailer. You did make me think though. While I'm happy about my Dandy at a max 500Kg and doubt that as your both travelling at approximately the same speed I doubt there would be much slamming.
There is most probably a point where your better not remaining attached. I don't know what the maximum train weights allow as a percentage of the vehicles weight. Are there cases of 120% or even 130%? There comes a point where forget the trailer I'd want to separate.
I also motorcycle for the last few years solo motorcycles have been allowed to tow light weight trailers. If (for some strange reason) I rode one of these I'd make sure the breakaway chain they're obliged to have would be no stronger than a piece of cotton. Forget the law there is no way on this plannet I'd want a detatched trailer to revisit my bike. Not exactly a similar example but likewise there must come a point where the desire to keep the trailer attached is less than the fear of it remaining attached.
An unbraked trailer up to 750Kg should have a safety chain fitted so that in the event of the trailer becoming detatched from the ball it will remain attatched to the vehicle,the chain should be short enough to prevent the drawbar from touching the road.
Quote: Originally posted by saxo1 on 11/4/2012
An unbraked trailer up to 750Kg should have a safety chain fitted so that in the event of the trailer becoming detatched from the ball it will remain attatched to the vehicle,the chain should be short enough to prevent the drawbar from touching the road.
A single chain? I'm curious to see how that should be set up. Got any photos/know of any links I can look at?
What size chain should be used to make sure it doesn't break?
How do you attach it to the vehicle hitch?
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Quote: Originally posted by Lostdreamer on 12/4/2012
Quote: Originally posted by saxo1 on 11/4/2012An unbraked trailer up to 750Kg should have a safety chain fitted so that in the event of the trailer becoming detatched from the ball it will remain attatched to the vehicle,the chain should be short enough to prevent the drawbar from touching the road.
A single chain? I'm curious to see how that should be set up. Got any photos/know of any links I can look at?
What size chain should be used to make sure it doesn't break?
How do you attach it to the vehicle hitch?
You fit a chain, probably about 12-18 inches long, by attaching the end rings through one of the bolts that holds the hitch coupling onto the trailer. When you hitch up you slip the chain over the top of the ball before attaching the hitch.
I posted some pics a while back but can't seem to find them now, in the meantime look HERE
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Quote: You fit a chain, probably about 12-18 inches long, by attaching the end rings through one of the bolts that holds the hitch coupling onto the trailer. When you hitch up you slip the chain over the top of the ball before attaching the hitch.
Err, thanks. Now I am even more confused. I'm mostly thinking aloud now, so don't mind me too much.
You fit a chain buy inserting one of the loops under the head of the mounting bolt for the trailer coupling? Doesn't that fark up the clamping area etc for the bolt and just introduce a point of failure you didn't have before?
Doesn't it also mean you are applying your force off the centre line of the trailer and so introducing a turning moment?
Loop the breakaway chain over the towball? Isn't that just going to mean that whenever the hitch comes unseated the breakaway chain does as well?
How do you stop it fouling on the coupling & damaging the coupling/chain/hitch?
What size/rating chain should be fitted?
I'm not doubting you, I just want to understand how it works.
Much as anything else, I don't see how an 18inch chain is going to stop the drawbar kissing the dirt when it comes off a hitch that should be between 12-16inches off the deck.
------------- My opinion is worth exactly what you paid for it.
Quote: Originally posted by Lostdreamer on 12/4/2012
Quote: You fit a chain, probably about 12-18 inches long, by attaching the end rings through one of the bolts that holds the hitch coupling onto the trailer. When you hitch up you slip the chain over the top of the ball before attaching the hitch.
Err, thanks. Now I am even more confused. I'm mostly thinking aloud now, so don't mind me too much.
You fit a chain buy inserting one of the loops under the head of the mounting bolt for the trailer coupling? Doesn't that fark up the clamping area etc for the bolt and just introduce a point of failure you didn't have before?
Doesn't it also mean you are applying your force off the centre line of the trailer and so introducing a turning moment?
Loop the breakaway chain over the towball? Isn't that just going to mean that whenever the hitch comes unseated the breakaway chain does as well?
How do you stop it fouling on the coupling & damaging the coupling/chain/hitch?
What size/rating chain should be fitted?
I'm not doubting you, I just want to understand how it works.
Much as anything else, I don't see how an 18inch chain is going to stop the drawbar kissing the dirt when it comes off a hitch that should be between 12-16inches off the deck.
I probably didn't explain very well so I'll try again:
1. your tow hitch attachment will be connected to your A Frame by 2 bolts which go across the main draw bar (the tow hitch being the pressed steel part that the ball slips into)
2. you put each end of the chain through one of these bolts (meaning that the chain will be central to the trailer)
3. when you couple up you slip the chain (which is now doubled as it is connected at both ends to the underside of your tow coupling on the trailer) so it wil be about 9 inches long (I used 12-18 inches as a guide, you would need to measure the distance between the bolt on your A Frame to the tow ball)
4. as for chain gauge, as long as the breaking strain is greater than the weight of your trailer you will be OK, or at least that's how I have always done it (no more scientific than that)
As I say, without pictures its hard to explain but I have tried to add some stock pictures below to show you the 2 bolts I mean (you can make out the chain on the picture below):
To be honest, this is petty much the standard way of attaching a breakaway chain to a trailer.
------------- Give a man a fish and he'll feed his family for a day.
Teach a man to fish and he'll sit around on a boat all day drinking beer!
My trailer came with one fitted, it is a chain with 13 links app 1"x1/2" ,it is welded to the both sides of the A frame and has a large ring app 3" in diameter which which is free running along the chain and fits over the towball.When fitted it is just long enough to allow you to lift the hitch off the towball with very little spare.If the trailer became uncoupled,which by virtue of the shortness of the chain would be very difficult to imagine,then the trailer is suspended on the ring well clear of the road.
It is called a secondary coupling because that is it's purpose, to keep the trailer attatched to the towbar should the primary coupling ( the tow hitch on the trailer) becoming uncoupled.It isn't intended to cope with a catastrophic failure of the towbar or the towball mountings,
I have seen lots of reports of caravans and trailers becoming unhitched but none of the towball/towbar failing and now that they are subject to the MOT it should never happen.
Quote: I have seen lots of reports of caravans and trailers becoming unhitched but none of the towball/towbar failing and now that they are subject to the MOT it should never happen.
Saxo1
So to return to my original point.
If you have a braked trailer rather than seeing your camper unhitch and the breakaway cable deploy.
Does anyone see the advantage to,or the fatal flaw in adding a secondary coupling?
I think since you have to have a breakaway cable anything that interferes with the working of that breakaway cable would be illegal. If you fit a longer chain which allows the breakaway cable to work, then once the brakes are on the tertiary chain would be trying to drag a braked trailer. Presumably the powers that be think it is safer to use brakes where they exists. You make a good point, and I've wondered about it myself, but a breakaway cable is the law.
Quote: Originally posted by alisonme on 13/4/2012
I think since you have to have a breakaway cable anything that interferes with the working of that breakaway cable would be illegal. If you fit a longer chain which allows the breakaway cable to work, then once the brakes are on the tertiary chain would be trying to drag a braked trailer. Presumably the powers that be think it is safer to use brakes where they exists. You make a good point, and I've wondered about it myself, but a breakaway cable is the law.
Thanks ever so much Alison.
This is exactly the sort of thing I wanted.
You have made a jump in logic that I would not have made in saying that anything that interferes with the breakaway cable must be illegal. I'm not saying your wrong or right I'll look to clarification but it's something I'd not considered.
Having a cable that attached the trailer but allowed the brakes to apply would be the worst of all possible worlds.
Quote: I have seen lots of reports of caravans and trailers becoming unhitched but none of the towball/towbar failing and now that they are subject to the MOT it should never happen.Saxo1 So to return to my original point.
If you have a braked trailer rather than seeing your camper unhitch and the breakaway cable deploy.
Does anyone see the advantage to,or the fatal flaw in adding a secondary coupling?
I think that if you were to put a secondary coupling (chain) on your braked trailer then you run the risk of a possibly more serious event than if the breakaway did its job and the trailer came to a halt. The reason I say this is that braked trailers/FCs/Caravans are heavy and if the main coupling were to fail but a secondary kept the whole thing 'connected' to the pulling unit (car/motorhome/whatever) then there would be a risk that the trailer could become very unstable its forward direction. The trailer, not being directly connected to the pulling unit would probably start to snake erratically and could cause a major incident - well, this is my opinion on it at least.
I would also add that these things aren't decided arbitrarily and there has no doubt been some degree of research/anecdote which has gone in to the decision being made.
------------- Give a man a fish and he'll feed his family for a day.
Teach a man to fish and he'll sit around on a boat all day drinking beer!
If it is possible to fit a breakaway cable which applies the van trailer brakes,normally the parking brake,then a breakaway cable must be used,if you only have overrun brakes and no parking brake you should have a secondary coupling and in this case it is acceptble up to 1500 Kg gross.
I agree with Alison that to comply with the law if it is possible to have a functioning breakaway cable you must and if you fit a secondary coupling to it as well it wouldn't operate as intended as it wold be too long.
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Topic: Secondary Coupling
