China Railways DFH shunting locomotives

The DFH2 was originally designed by Sifang locomotive works in 1966 as a passenger locomotive of rated power 1,470 kW (1,970 hp). The design did not enter mass production, but in 1973, the design was changed at Ziyang locomotive works to a 650 kW (870 hp) power locomotive with a top speed of 62 km/h (39 mph).[1][img 1]

The mass was 60 t (59.1 long tons; 66.1 short tons) and the starting tractive effort was 192 kN (43,000 lb_f). The locomotive used a 12V180ZL engine and SF2010 transmission.[4]

DFH5 0001

DFH5B 3030

In comparison to the DFH2 type, a number of changes were made for the DFH5: a twin-speed transmission allowing a higher top speed when running without a heavy load was included, and the mass was increased to improve traction.[3]

The DFH5 class was produced in large quantities. The engine was a 12V180ZJ and transmission ZJ2011, producing 278 kN (62,000 lb_f) of tractive effort with a mass of 86 t (84.6 long tons; 94.8 short tons) and with a top speed of 40 km/h (25 mph). A higher speed was available with a limit of 80 km/h (50 mph) and tractive effort reduced to approximately half.[2][img 2]

Variants, the DFH5B and DFH5C, were introduced in 1985, with modifications to improve reliability and performance – in both where the rated power was increased to 920 kW (1,230 hp), and the mass by 4 t (3.9 long tons; 4.4 short tons). DFH5C was produced for operations in metalworks.[3]

One example was produced for shunting in the Chinese port of Huangpu District, Shanghai.[1]

DFH7B 1009

Four units were produced for shunting in mines and industrial environments.[1]

A DF21 pulling a narrow-gauge commuter train in Kunming (2016)

Locomotives similar in design to the DFH2 type but built to meter gauge and used as universal locomotives.[1][5] The locomotives were used on the Kunming metre gauge railway, including passenger services.[6][img 3]

As of 2012, Kunming rail fans report that DFH21 locomotives are still used to haul a few passenger trains a day along the metre gauge tracks from Kunming North Railway Station to several nearby stations. As of 2014, these trains were still in operation.[7]

30 of the locomotives are also used by Vietnam Railways, where they are known as the D10H.[8] In 2005, Vietnam railways had 20 units operational.[9] In 2009, ten of the engines had Caterpillar Inc. 3512B engines fitted as replacements.[10]