Open hopper
An open hopper unloads through bottom gates. Coal, stone, and ore are the classic loads.
Gates underneath
An open hopper has no roof. The floor slopes into bays, and each bay has a gate so the load can drop between the rails or to the side of them. Two-bay, three-bay, and four-bay cars are all common. The bay count is something you can see.
Coal, ballast, stone, and taconite are typical loads. The car is open because the commodity can get wet, or because it is loaded from above by a flood loader. A covered hopper is the closed version of the same idea, for freight that has to stay dry.
The code and the weight
The type letter is H for a plain open hopper and K when the car is specially equipped. Older cars marked HT are the three- and four-bay hoppers. HM is the older two-bay designation.
These cars live and die by the load limit. A hopper full of ore and a hopper full of coal are very different weights in the same volume. The cubic figure and the load limit together tell you which job the car was sized for. The placard is rare on a coal hopper. If you do see a diamond, read it as a hazardous load, not as the car type.
Common questions
- What does the number of bays tell me?
- It is the number of discharge compartments under the car. More bays usually means a longer car. It does not tell you the commodity by itself.
- Is a rotary-dump coal car an open hopper?
- Usually it is a high-side gondola. Hoppers unload through gates. Rotary cars are picked up and turned over.