A hopper car (US) or hopper wagon (UIC) is a type of railroad freight car used to transport loose bulk commodities such as coal, ore, grain, and track ballast. Two main types of hopper car exist: covered hopper cars, which are equipped with a roof, and open hopper cars, which do not have a roof.
This type of car is distinguished from a gondola car in that it has opening doors on the underside or on the sides to discharge its cargo. The development of the hopper car went along with the development of automated handling of such commodities, with automated loading and unloading facilities.
Covered hopper cars are used for bulk cargo such as grain, sugar, and fertilizer that must be protected from exposure to the weather. Open hopper cars are used for commodities such as coal, which can suffer exposure with less detrimental effect. Hopper cars have been used by railways worldwide whenever automated cargo handling has been desired. "Ore jennies" is predominantly a term for shorter open hopper cars hauling taconite by the Duluth, Missabe and Iron Range Railway on Minnesota's Iron Range.
A rotary car dumper permits the use of simpler and more compact (because sloping ends are not required) gondola cars instead of hoppers. Covered hoppers, though, are still in widespread use.
Special hopper trains
Typical American freight car weights and wheel loads
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Increase in wheel loads has important implications for the rail infrastructure needed to accommodate future grain hopper car shipments. The weight of the car is transmitted to the rails and the underlying track structure through these wheel loads. As wheel loads increase, track maintenance expenses increase and the ability of a given rail weight, ballast depth, and tie configuration to handle prolonged rail traffic decreases. Moreover, the ability of a given bridge to handle prolonged rail traffic also decreases as wheel loads increase.
The word "hopper", meaning a "container with a narrow opening at bottom", goes back to the thirteenth century, and is found in Chaucer's story "The Reeve's Tale" (written late fourteenth century) in reference to a machine for grinding grain into flour.
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- "Small Cube Open-Top Hoppers and Gondolas". GATX Corporation. Archived from the original on 16 September 2010. Retrieved 11 September 2012.
- "Covered Hopper Cars". Chicago Freight Car Leasing Company. Archived from the original on 16 April 2012. Retrieved 11 September 2012.
- Bitzan, John D.; Tolliver, Denver D. (October 2001). "The Economics of Heavy Hopper Cars". Mountain-Plains.org. Mountain Plains. Archived from the original on 23 July 2011. Retrieved 7 August 2010.
- "Hopper". Online Etymology dictionary.
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