Debate on the necessary limitation of the angle of the 5th wheel of a dolly
Debate on the parking brake and the current text of UN R13. Semi-trailer must take over its total weight on a slope of 18%. All vehicles must be able to take over their full load on a 18% slope. In case of a combination, the slope is 12% performed by the motor vehicle alone.
Stability system: the vehicle is not able to measure its COG (which is varying with load and type of goods), hence automatic adjustment is not possible. Some manufacturers provide manual adjustment within a certain limited margin.