This International Standard specifies the height of the coupling head for trailers of categories O1 and O21), which fit coupling balls complying with ISO 1103.
This requirement guarantees the correct angle be-tween trailers and towing vehicles, and allows easy joining of the two.
SIS SS-ISO 10 061:1992 history
1992SIS SS-ISO 10 061:1992 Road vehicles — Trailers, including caravans — Height of coupling head