Quote:
Originally Posted by Peter_C
Interesting failure. Something wasn't fully engaged and as suggested the key could be part of the equation
In the USA we use safety chains or cables should the ball disconnect. Safety chains work! If it is a braked trailer there will often be a breakaway leash to engage the brakes too. Our receivers are held in with "pins" which won't fail, but could fall out should the secondary clip come loose. Often though the ball mount latch has a spot for a secondary pin which is not utilized. Either a lock or a tractor pin is recommended.
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North America uses a completely different system for tow bars though, and arguably it's one of the very few things they do better than Europe. Standardised receivers and a simple, but very robust mechanism for securing the hitch in the receiver with a big pin which is itself secured by a cotter pin or R clip.
Europe on the other hand has no standard, and instead has a multitude of tow bar manufacturers that all make proprietary systems with fancy detachable hitches, none of which are compatible with each other. I think the reason why we like these is because the majority of them have the receiver mounted vertically rather than horizontally, meaning it's much easier to have a completely invisible system when the hitch is not inserted, without needing to cut the bumper etc. The problem with this is it would be extremely difficult to use the pin system that NA uses, because you can't see or reach in to the receiver to put the pin in it.
Detachable hitches here tend to have a spring loaded locking pin, which you "arm" by twisting something on the neck of the hitch. Then, when inserted fully into the receiver, a small catch is depressed and the spring pressure is released, forcing the locking pin outwards on the inside of the hitch, usually into a hole, which locks the hitch in place. There is usually a key slot too allowing you to lock the arming handle, preventing anyone from inadvertently disconnecting the hitch.
This system is great because it's simple to use but not infallible. In fact, some manufacturers (e.g. Land Rover) that offer either a fixed or detachable tow bar as a factory option on their vehicles, specifically recommend against towing regularly with detachable systems and instead advise using a fixed tow bar instead. They market the detachable system for occasional use only. I have heard many horror stories about especially Land Rover owners who have had the genuine LR detachable tow bars fail in exactly the above way while towing horse boxes etc.
As for the breakaway cable / chains, we only have chains (actually it's usually a steel cable) on unbraked trailers - up to 750kg max gross weight, designed to keep the trailer attached to the towing vehicle should the coupling fail. The vast majority of light braked trailers (750kg to 3500kg) instead have a breakaway cable which is a small steel cable which you connect to the tow vehicle, and it is attached to the trailer parking brake in such a way that if the coupling fails, the cable will pull and apply the trailer parking brake before the cable itself snaps. Thus the trailer breaks away from the tow vehicle and rapidly brings itself to a stop.
The breakaway cable SHOULD be attached to some strong point on the tow vehicle separate to the hitch itself, but many people (especially those who have not had any training in towing) just loop it around the neck of the hitch. Clearly this is going to do nothing when the hitch comes away from the tow vehicle. Astonishingly, the UK government have recently removed the requirement for any extra training before towing trailers >750kg.
Sula
BLACK PIG
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