Rotary car dumper
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A rotary car dumper is a mechanism used for unloading certain rail cars such as hopper cars or gondolas. It holds the car to a section of track and rotates the track and car together to dump out the contents. Used with gondola cars, it is making open hopper cars obsolete. Because hopper cars require sloped sides in order to direct the contents to the bottom for unloading, gondola cars can hold more volume.
Originally, individual cars would be decoupled and placed in the dumper, but now it is possible to dump an entire unit train of coal without uncoupling any of the cars. The cars used for these trains are equipped with rotary shaft tightlock couplings (AAR Type F) on one end. The end with the rotary coupler is marked with a colored stripe, typically white, red or yellow. The dumper rotates the cars on the axis of the couplers.
