Hi,
DVLA specify (or did) that an "artic" (eg; A trailer with 20% of it's mass, or more, super-imposed onto the tractor unit, requires a higher class driving licence. Driving without a licence to cover the vehicle you are driving, means you are driving without a licence, so your insurance is void.
So, a trailer weighing 1 ton (2240lbs) or 1 tonne (2200lbs) may have a nose weight of 448lbs, or 440lbs, respectively. I think we can assume that if you can lift the jockey wheel off the ground, without growing another pair of Adam's apples, then it ain't an articulated trailer. But on the other hand, if you had a small trailer with a short draw-bar, and loaded four 1cwt bags of sand at the front end, it might, technicallyl, well become an articulated trailer, and your licence won't cover you to pull it, so your insurance is void. Solution? Extend the length of the draw-bar ... Principle of Levers. It's probably easier to place the bags of sand over the axle, so the trailer is better balanced, less weight on the tow-ball.
I can see no reason why a draw-bar trailer can not have a "swan-neck" draw-bar, with the tractor unit having a 50mm ball bolted to the chassis, above, or even in front of, the rear axle, so technically an articulated trailer, but not according to DVLAs definition of "20% of the trailer's mass super-imposed onto the tractor unit. PLEASE SEEK LEGAL ADVICE BEFORE DOING THIS.
Has everybody seen the DVD of a Volkswagen Beetle performing acrobatics with an articulated traler? The tow-ball was mounted in the middle of the VW's roof, so giving a full 360 degee articulation. it looked like fun.
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