What is the maximum vertical play permitted for a coupling pin?

In German traffic regulations, the maximum vertical play allowed for a coupling pin is 4 mm. This limit ensures that the trailer connection is secure and stable during driving, preventing excessive movement that could lead to accidents or damage. The coupling pin must fit tightly enough to avoid dangerous wobbling, but still allow for necessary articulation. So, when checking coupling pins, a vertical play exceeding 4 mm is considered unsafe and not roadworthy. This helps maintain safe towing conditions on German roads.