The China Railways JF4 (解放4, ''Jiěfàng'', "liberation") class steam locomotive was a class of

superheated A superheater is a device used to convert saturated steam or wet steam into superheated steam or dry steam. Superheated steam is used in steam turbines for electricity generation, steam engines, and in processes such as steam reforming. There are ...

2-8-2 steam locomotives for goods trains operated by the China Railway. They were originally built for the

South Manchuria Railway The South Manchuria Railway ( ja, 南満州鉄道, translit=Minamimanshū Tetsudō; ), officially , Mantetsu ( ja, 満鉄, translit=Mantetsu) or Mantie () for short, was a large of the Empire of Japan whose primary function was the operatio ...

(''Mantetsu'') in Japan in 1935.

History

After a number of incidents involving broken crankshafts in the Mikani class locomotives, as well as needing more motive power to meet the increase in goods traffic following the establishment of Manchukuo, the Mikashi class was designed in 1933 and put into production in 1935, with fifteen built in Japan that year, four by Kisha Seizō and eleven by Kawasaki. As the three-cylinder design of the Mikani class was deemed too complex, the Mikashi class returned to the proven two-cylinder layout. In order to achieve a

tractive effort As used in mechanical engineering, the term tractive force can either refer to the total traction a vehicle exerts on a surface, or the amount of the total traction that is parallel to the direction of motion. In railway engineering, the term t ...

equal to or greater than that of the three-cylinder locomotives with a two-cylinder engine, it is necessary to increase the

adhesive weight Adhesive weight is the weight on the driving wheels of a locomotive, which determines the frictional grip between wheels and rail, and hence the drawbar pull which a locomotive can exert. See also *Factor of adhesion An adhesion railway relie ...

of the locomotive; however, this would make the

axle load An axle or axletree is a central shaft for a rotating wheel or gear. On wheeled vehicles, the axle may be fixed to the wheels, rotating with them, or fixed to the vehicle, with the wheels rotating around the axle. In the former case, bearin ...

unacceptably high - between and . To overcome this, a limited cutoff system was adopted with a maximum cutoff of 50%; by balancing the rotational forces of the left and right cylinders, the axle load was successfully limited to . Boiler pressure was increased from , whilst other new features included a Schmidt type E superheater, a

feedwater heater A feedwater heater is a power plant component used to pre-heat water delivered to a steam generating boiler. Preheating the feedwater reduces the irreversibilities involved in steam generation and therefore improves the thermodynamic efficiency of ...

and a combustion chamber firebox. Fuel consumption was also improved, with the Mikashi class using from 10% to up to 22.6% less coal than the Mikani class. The wheel diameter was also increased from in order to increase the speed of goods trains, however as this could result in wheel slippage on steeper sections due to the reduction in piston speed, so the timetables of goods trains were adjusted accordingly. Used primarily on heavy goods trains between Fengtian and Dalian to transport coal from the Fushun Coal Mine to port, they could pull up to sixty coal hoppers.

Postwar

At the end of the Pacific War, the 15 Mikashi class locomotives were divided between the Dalian (13) and the Fengtian (2) depots, and all were taken over by the Republic of China Railway. Following the establishment of the

People's Republic People's republic is an official title, usually used by some currently or formerly communist or left-wing states. It is mainly associated with soviet republics, socialist states following people's democracy, sovereign states with a democratic- ...

and the subsequent creation of the current China Railway, they became class ㄇㄎ肆 (MK4) in 1951, and class 解放4 (JF4, ''jiěfàng'', "liberation") in 1959 and numbered 2701–2715. As during the Mantetsu times, they were primarily used around Dalian and Shenyang (formerly Fengtian).

References

{{Mantetsu rolling stock 2-8-2 locomotives Kawasaki locomotives Kisha Seizo locomotives Railway locomotives introduced in 1935 Steam locomotives of China Standard gauge locomotives of China Rolling stock of Manchukuo Freight locomotives