DCHP-1 Online
dump car 
n. a self-unloading gondola railway car; also, in mining, a smaller car made to drop its load by levers or by tipping.
- 1912 As the train was a mixed passenger and freight, we were constantly stopping at various places to take on or put off "flat-cars" full of gravel, or "dump-cars" full of "dirt" deposited there by the steam shovel, trucks loaded with rails or ties, "box-cars" full of provisions, coal or lumber.
- 1956 They were using a 1½-ton Manchu battery-operated electric trammer with five 1-ton end dump cars.
- 1912 As the train was a mixed passenger and freight, we were constantly stopping at various places to take on or put off "flat-cars" full of gravel, or "dump-cars" full of "dirt" deposited there by the steam shovel, trucks loaded with rails or ties, "box-cars" full of provisions, coal or lumber.