A covered hopper car that uses differential air pressure to unload fine dry bulk commodities such as cement, flour, or fly ash through a pneumatic conveyor system. Air is introduced beneath the fluidized bed of material and carries it through discharge pipes to receiving silos. Pressure differential cars eliminate the need for mechanical unloading equipment at the destination.
A closed-top hopper car with roof hatches for top loading and bottom discharge gates for gravity unloading, designed for dry bulk commodities such as grain, fertilizer, plastic pellets, and cement. Covered hoppers protect lading from moisture and contamination. They are the most numerous car type on North American railroads.
A covered hopper car designed for a wide range of dry bulk commodities without the specialized features of cars built for a single commodity. General purpose cars typically have multiple roof hatches and bottom gates configurable for different discharge angles. They provide operational flexibility for shippers with diverse bulk commodity needs.