China Railway DFH shunting locomotives

DFH2

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. 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]

In 1976, CRRC Sifang produced several DFH and DFH2 locomotives for use on the Chinese funded Tanzania-Zambia Railway (TAZARA Railway), becoming the first locomotive to be exported from China.^[5]

DFH5

To compensate to the growing needs of growing railway traffic for industrial and mining operations, the Ziyang Diesel Locomotive Factory redesigned the DFH2, addressing technical issues in the manufacturing process and operations, to create the DFH5. The locomotive's pushing capacity was increased to 3300 tons. Between 1975 and 1993, 450 units were manufactured.

Early models of the DFH2 and DFH5 locomotives suffered from high oil temperatures in warm environments. To address this issue, in August 1976, the Ziyang Diesel Locomotive Factory improved the lubrication oil pipeline on the DFH5 locomotive No. 0001 to reduce oil temperatures, a change that was further implemented on later units of the DFH5. In 1986, the Ziyang Diesel Locomotive Factory then made improvements to the torque converter in the hydraulic transmission box, adding a new turning mechanism and module axle gears. Improvements were also made to the axle gearbox and bogie frame. To meet the high-temperature and corrosion-resistant requirements of metallurgical and chemical systems, the locomotive uses fire-resistant, heat-insulating, and corrosion-resistant materials, enabling it to operate in external temperatures of 50°C. These improvements led to the widespread use of the DFH5 diesel locomotive in local railways and industrial and mining enterprises.^[6]

The DFH5 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]

DFH6

In 1981, CRRC Ziyang designed and trial-produced the 2,000 horsepower hydraulic transmission shunting locomotive, the DFH 6.^[7] One example was produced for shunting in the Chinese port of Huangpu District, Shanghai.^[1]

DFH7

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

DFH21

CRRC Sifang designed and developed the DFH 21 diesel shunting locomotive in 1977 for use on Yunnan’s metre-gauge railway, upgrading the line from steam to modern diesel powered engines.^[8] The DFH 21 locomotive was similar in design to the DFH2 type but was built to meter gauge and used as universal locomotives.^[1][9] The locomotives were used on the Kunming metre gauge railway, including passenger services.^{[10][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^[update], these trains were still in operation.^[11]

30 of the locomotives are also used by Vietnam Railways, where they are known as the D10H.^[12] In 2005, Vietnam railways had 20 units operational.^[13] In 2009, ten of the engines had Caterpillar Inc. 3512B engines fitted as replacements.^[14]