DF4

DF4 is a class of diesel‑electric locomotive produced by China’s Dalian Locomotive & Rolling Stock Works for the national railway network. Designed in the late 1960s to replace aging steam traction, the first DF4 units entered service in 1970. The designation “DF” stands for “Dong Feng” (East Wind) and the numeral 4 indicates the fourth generation of Chinese diesel locomotives.

The original DF4 was built around a 12‑cylinder V12 16V240ZJ diesel engine delivering approximately 2,650 kW (3,600 hp) at the crank. Power is transmitted to the wheels via a generator‑driven electric traction system, a configuration that provides reliable performance across the varied terrain of China’s rail lines. The locomotive’s Co′Co′ wheel arrangement distributes weight evenly, allowing operation on both main‑line and secondary routes.

Throughout the 1970s and 1980s, several variants were produced to meet specific operational requirements. The DF4B (introduced in 1985) incorporated an upgraded 16V240ZJ engine with improved fuel efficiency and a revised cab layout for better ergonomics. The DF4C, which appeared in the early 1990s, featured a more powerful 16V240ZJ‑K engine and enhancements to the cooling system, enabling higher sustained speeds. A limited number of DF4D units were built for heavy freight service, featuring reinforced frames and higher tractive effort.

By the 2000s, the DF4 series had become one of the most numerous locomotive classes in China, with over 7,000 units built. Although newer models such as the HXD series have begun to replace it on main‑line duties, DF4 locomotives remain in use on regional and industrial lines, where their durability and ease of maintenance continue to be valued. The DF4’s long service life reflects its role in modernizing China’s railway freight and passenger operations during the latter half of the 20th century.