Coal hopper car for the shipment of coal, ore and other bulk goods, can meet the fixed marshalling, recycling, fixed-point loading and unloading, a large number of transshipment of power stations, ports, coal preparation, iron and steel and other enterprises to use. It is mainly suitable for coal unloading ditch or high pallet with receiving pit transmission device on the ground for unloading coal on both sides at the same time. It can be automatically unloaded or manually unloaded without wind source.

1971, K18 coal hopper car was designed. By 1974, 230 coal hopper cars had been produced, which were assigned to electric power, metallurgy, coal preparation and other departments to continue to use and test. In 1977, the structure of K18 coal hopper car was redesigned in view of the weaknesses exposed in the application process, such as high door opening pressure, low rigidity of transmission parts and high resistance, and 657 coal hopper cars were mass produced in the same year. The mechanical transmission device of K18 type coal car to control the opening and closing of the bottom door adopts the structure form of single-stage transmission and wind and manual dual-purpose, and mainly adopts wind-controlled pneumatic self-unloading in application. It can stop and unload coal, or it can unload while walking; it can unload coal car by car, it can also unload coal in several cars or in rows at the same time, and it can also unload manually.

1979, after summing up the application experience of the original K18 coal hopper car, K18F coal hopper car was designed. The car is also a wind-controlled pneumatic self-unloading special railway truck, which can unload coal one by one, several cars or trains at the same time, and can also unload manually.

1980, the K18D type coal car was developed and equipped with a top lock mechanism, which solved the weaknesses of the K18 type coal car exposed during use, such as high door opening pressure, low rigidity of transmission parts and high resistance, and significantly improved the opening and closing performance of the bottom door.

In 1999, aiming at the problems existing in the daily use of the original coal hopper car in China, in order to fully meet the requirements of users, the K18DA coal hopper car was designed on the basis of the original K18D coal hopper car. The middle beam of the underframe is made of 310 B- shaped steel (09V), and the key bearing parts are strengthened. All load-bearing parts of the car body are made of 09CuPTiRE-A weather-resistant steel plates to improve the corrosion resistance of the car body and extend the maintenance cycle. The bottom door opening and closing device adopts two-stage transmission, top lock mechanism, pneumatic and manual dual-purpose. The pneumatic console and manual transmission mechanism are both arranged on the chassis at one end of the car body. The wind control pipeline device is designed as one set. The wind source comes from the train supervisor, which facilitates pneumatic unloading under the condition of no wind pressure equipment on site. The control valve adopts rotary type, which can control the opening and closing of the four bottom doors on both sides at the same time.

developed a 70t-class KM70 coal hopper car. On December 8, 2005, it passed the technical review organized by the former Ministry of Railways Transportation Bureau. In 2006, the production of coal hopper car with a load of 60t was stopped and KM70 coal hopper car was fully converted, thus upgrading the load of coal hopper car from 60t to 70t.

From July 2001 to the end of 2008, a large-scale speed-up transformation was carried out on the existing railway freight cars. During this period, the speed-up transformation of K13, K13A, K13N and other hopper cars was completed.