To promptly stop a backside dolly device released by a towing means and a backside connecting means.

A backside braking device B1 is constructed so that each rubber buffer body 26 attached between a slide body 25a and another slide body 25b is compressed and deformed and kinetic energy is absorbed by allowing a collision member 23 provided on the backside dolly device Db to collide with the slide body 25a and sliding the slide body 25a. The backside braking device B1 is attached to an internal surface 5b of a single guide rail 5 constructing guide rails G at an immediate downstream side of a striker S in the guide rails G.