Hopper cars are widespread for the transport of various bulk cargoes: grain, cement, ore, coal, ballast, and more. The shape of the body of the hopper forms a certain funnel, at the bottom of which there are special hatches used to empty the cargo under its own gravity. Therefore, the transport of hoppers is characterized not only by practicality, but also by the speed of unloading.
Open hoppers are used to transport hot sinter and pellets, coal, peat, coke. The body covering of the hopper for hot pellets, sinter and coke, unlike other types of cars, does not rigidly connect with the supporting frame of the side and end walls, which eliminates the body warping under the action of high temperatures and provides an easy replacement for damages. Open hoppers, as a rule, have a remote automated system for unloading cargo on both sides of a railway track, controlled by compressed air coming from a power plant of a locomotive. The wider use of rotary car dumpers reduces the use of open hoppers.
Closed hoppers are used to transport grain, cement, carbon black (soot). The cargo is unloaded into the inter-rail space, the covers of the unloading hatches are opened manually. For the transportation of mineral fertilizers used covered hoppers with unloading on the side of the railway track with compressed air.
Hoppers have standard biaxial trolleys, coupler and auto brake equipment. The mechanism for opening the covers of the unloading hatches is pneumatic or manual.