Railcar rotary dumper - GIF

[desbromilow]

Do the hitches swivel, or do they disconnect before turning them over?

2 major styles around here - both work on the principle of the coupler (hitch) swivelling...
type 1 - all couplers can swivel, allowing every single ore care to turn independent of the adjacent car. - some firms have 3 cell dumpers, AND 2 cell dumpers. The 3 cell dumpers have each cell decoupled so it can run in single, forward 2 cell, rearward 2 cell, or triple cell mode to reflect maintenance status.
type 2 - every second coupler can swivel, the alternate "coupler" is a dog-bone style solid link bar. This style means the cars are treated as "pairs", and go into 2 cell dumpers only. Rio Tinto use this style.

The couplers are expensive, so the tradeoff is lower equipment cost (couplers) vs the flexibility of being able to treat and process each car as a separate entity at all phases of processing, maintenance, etc.