A more literal "ball train" was an experimental Soviet project in the 1930s designed by Nikolai Yarmolchuk.

The term is most commonly a direct translation of the English "bullet train," referring to high-speed rail systems characterized by aerodynamic "bullet-shaped" locomotives.

: These systems are designed to minimize "play" between the tractor and the trailer, reducing wear and improving safety during transport. 3. Historical Curiosity: Yarmolchuk’s Ball Train

: Instead of traditional wheels, the train cars sat on massive motorized spheres that ran in a semi-circular concrete trough.

: The nose of these trains is engineered to reduce air resistance and prevent the "tunnel boom" effect caused by rapid air displacement.

: A prominent manufacturer (like Scharmüller ) that provides these hitches for tractors.