Thank you very much for your answer, Bert.
But I think that the trailer of my photo does not match exactly with any of these types. Pf.10 Bockwagen, Pf.11 Pontonwagen and Pf.12 Rampenwagen: all these trailers had dual tires on both axles, while the trailer of my photo has single tires.
Uferbalkenwagen, What does it mean?
On the other hand, the Pf.10 and Pf.12 trailers are very difficult to differentiate.
Regards Sturm78.