Re the car transporter trailer coming adrift:
Getting on for 20 years ago the main dealer I was working for serviced Axial vehicles. One day we had instructions issued that extra special checks were to be carried out on the couplings, some of which were of the ball and claw type, and more importantly upon the rear cross member. There had apparently been more than one occasion when vehicles which belonged to another depot had the complete rear cross member, to which the coupling was attached, ripped out of the lorry chassis; allowing the trailer to part company. I never had to do one myself, but I seem to recall seeing a vehicle having a new cross member fitted.