I think this procedure is a little difficult for most people to visualize.
Near Grodekovo, Russia, bordering Suifenhe, China, is one such station, where the wagons are uncoupled. The wheel trucks are freed from the wagons with a large key wrench (one man can do this) through floor panels inside the wagon. Huge rotary (screw) lifts beside the track then lift the cars, and the wheel trucks are rolled out onto a siding. Another set of wheel trucks are rolled underneath that match the Chinese track gauge. The large key wrench locks them in.
All passengers get off the train and waited in the yard. There were no buildings in which to wait. A thirty wagon train took about an hour to change out.
I watched this at stations on the China-Mongolia border as well.
Muchas gracias for the first-person account!
I would love to visit that part of the world.