thumb|A gondola car built by the [[South Australian Railways in the 1920s to an American Car and Foundry design]]
In North American railroad terminology, a gondola car or gondola is typically an open-topped railroad car used for transporting loose bulk materials, although general freight was also carried in the pre-container era. Because of their low side walls, gondola cars are also suitable for the carriage of such high-density cargos as steel plates or coils, or of bulky items such as prefabricated sections of rail track. Gondola cars are distinct from hopper cars in that they do not have doors on their floor to empty cargo.
History
The first gondola cars in North America were developed in the 1830s and used primarily to carry coal. Early gondolas were little more than flatcars with wooden sides added, and were typically small – or less in length, and or less in weight. Those cars were not widely used at first, because they could only be unloaded by workers shoveling out the cargo by hand, a slow and labor-intensive process. A solution to the problem was developed around the 1860s with the drop-bottom gondola: hatches were installed in the floor which could be opened at the destination, and workers using shovels directed cargo towards the hatches. Although it was an improvement over earlier gondolas, it still required manual unloading. Starting in the 1950s and 1960s, high-sided gondolas were used for coal, thanks to stronger car construction and the invention of rotary car dumpers, which allowed those gondolas to be emptied automatically. a "double rotary" car has rotary couplers on both ends to allow it to be unloaded while it remains coupled to cars at each end. Rotary gondola cars are often nicknamed "bathtub gondolas" on account of their shape.
Coil car
The coil car is a modified gondola designed specifically for carrying coils of metal.
Track ballast gondolas
thumb|A side-dump gondola on display at the US [[National Railroad Museum]]
thumb|left|Southern Pacific air-dump car (SPMW 5121), at the [[Southern California Railway Museum. The whole body of the car is tilted up by pistons in the vertical cylinders under the car. The sides of the car tilt down to be in line with the floor, enabling the load to flow out.]]
Air-dump cars sometimes carry ballast. These gondolas are side-tipping, so they often are used to carry rock or dirt to add to an embankment, rather than dump crushed-rock ballast between the ties. Ballast is usually carried in bottom-door hopper cars, so that the ballast is dumped directly below the car, rather than to the side.
See also
- Corf
- Decauville wagon
- Mineral wagon
- Mine railway
- Quarry tub
- Railgon Company
- Well car