Towing capacities

As I’m sure you know, Milo, it’s a totally different towing system. 

Its still a case that the trailer has brakes controlled by the towing vehicle. the only difference is there is a (predominance / trailer control valve)   to, in effect, stop the trailer braking before the tractor. Not unlike the overrun actuation on a caravan.   You still have a trailer that when loaded weighs more the the tractor so I cant see how it can be put forward as a reason ? 

I would suggest the 85% guidelines, and that's all they are , are to allow for the misgivings of inexperienced drivers and nothing to do at all with stopping distances and   stability when taking avoiding actions.

Just my 2p's worth  

Yep,  I also used to drive 18m Artics as part of my job, and a large  tow truck towing other large vehicles.  Thats why tractor units used to have a handbrake valve with more than one function that will prevent it in an emergency but the weak link is the driver And nowadays with ABS, ESC, and other clever systems the driver has been taken out of the equation.

Suggesting you cant control an emergency stop when the caravan is more than 85% of the car is not correct. 

Far less common now though JV as explained in my other post when the human part of the problem has been taken out of the equation.

Suggesting you cant control an emergency stop when the caravan is more than 85% of the car is not correct. 

I never said it was although somebody may have. I think I said that it was not braking that was the problem

"It is not so much the braking that is the problem but the situation when braking alone is not enough and a sharp evasive manoeuvre at speed is needed to avoid a smash."

Thats how i read it 

I don't see a conflict between the two statements. Obviously as the weight ratio increases so does the degree of intervention needed to regain control an outfit that has become unstable, but that doesn't mean that it is inherently unmanageable if 85% is exceeded.

The towing characteristics of an artic are very different to a car and caravan and are of very doubtful relevance.

Basically controlling the car and caravan in an emergency stop is not the normal problem with caravans jacknifing, but if the caravan is too heavy for the car it can be a problem. The main problem, and I dealt with the accident investigation, is usually caravans traveling too fast or being caught by side winds or bow waves or a combination of these. In those cases because of the way the out fit is set up the heavier the car the better it is in controlling the situation.