Development and prototypes As early as 1954, the
Dalian Locomotive Works began studying 2-10-2 locomotive designs to assist
China Railways' increasing freight traffic. The first prototype 2-10-2, HP-0001, was completed by Dalian on 18 September 1956, and it was designated an HP (). In accordance with the design, the HP prototype was identical to the OR21s, as it came with all-
boxpok driving wheels (diameter of ,
flangeless center driving wheels, an all-welded boiler (diameter of , and an operating boiler pressure of , and it could generate a tractive force of . While the prototypes were being developed and tested, China Railways acquired 1,000
secondhand class FDs from the
Soviet Railways in 1958—with another 50 in 1961—as stopgap measures for their increasing freight traffic, until production on the HPs were able to begin.
Production After the final prototypes were completed, multiple modifications were made to the HP's boiler design. The boiler barrel diameter was enlarged to ; the
smokebox and
blast pipe orifice were enlarged to improve drafting; a
combustion chamber, which the prototypes lacked, was installed in the firebox to improve combustion; the number of tubes was increased, while the tube length was decreased from the firebox tube plate being extended past the grate; and the maximum cutoff was increased to 72%. The first locomotive with the design modifications, HP-101, was completed by Datong on 28 September 1964, and Datong officially began production on the rest of the HPs. In September 1966, amidst the
Cultural Revolution, the HPs were re-designated as the FD class (反帝
Fandi meaning 'anti-imperialism'), and then in 1971, the class was re-designated again as the QJ class (
Qian Jin, meaning 'march forward' or 'progress'). The 500th locomotive of the class was built in 1968, the 1,000th in 1970, the 2,000th in 1974 and the 3,000th in 1979, with production rates varying from 150 to over 300 per year between 1966 and 1985. The prototypes used eight wheel tenders, while later production models used twelve wheel tenders. After withdrawal from the Chinese national network many units were acquired by industrial railways as well as the regional
Jitong Railway in Inner Mongolia which operated ~100 units. Some remained in use on industrial lines in China in 2010. ==Preservation==