Trailer for transportation train

The trailer (3) load bearing structure (30) comprises a chassis (7) with wheels and hitching means (6) and a platform (8) for the load (4) coupled the chassis. The platform comprises auxiliary wheels (9) so as to be able to be displaced relative to the chassis. The chassis has a central rail (77) able to receive a complementary guard rail (83) on the platform so as to create a linking connection between the platform and the chassis.