While the large diesel locomotives in China usually all have electric transmission, the BJ type was created as a diesel-hydraulic mainline locomotive. The choice of hydraulic transmission for one part of the rolling stock is probably due to the consideration of saving some of the raw materials used only for diesel-electric locomotives. Experience with the use of diesel-hydraulic locomotives had already been gained with the Henschel DH 4000, 30 of which had been ordered in the 1960s. The development of the hydraulic transmission was apparently based on the Voith transmission used in these locomotives. The first prototype from 1970 was a 100 km/h two-section freight locomotive, consisting of two halves, each with a 3,000 hp diesel engine. The engine was originally supposed to have 16 cylinders, but before the production of the first two-section locomotive, it was possible to bring the same engine with only twelve cylinders to the same power without sacrificing reliability. The class was called BJ, which stands for “Beijing” and indicates the location of the manufacturer's plant.

The series production of the freight locomotive was discarded, but the first passenger locomotive was made in 1971. It consisted of only one section with two driver's cabs and was designed for 120 km/h. After tests with a few prototypes, series production began in 1975 and ended in 1990 after 342 had been built. They were mainly used in the northern and central regions of China. For cross-border traffic to the Soviet Union, 16 more locomotives were built, four of which were designed in the Soviet broad gauge of 1,520 mm. Four one-section freight locomotives with a maximum speed of 90 km/h and twelve passenger two-section locomotives were created as further variants. Shortly after the turn of the millennium, usage was nearing its end and at least 33 examples of the passenger train variant were given to North Korea free of charge as development aid, where they are or were used in freight and shunting traffic around Pyongyang.

Since new, powerful switching locomotives were needed in the seventies, which were also to be used like a road switcher, a new locomotive was developed on the basis of the DF4. Depending on the variant, the top speed is 80 or 100 km/h. With six axles and half the power compared to the DF4, it is more optimized for higher tractive forces at low speed. A V8 was made out of the V16 engine, but this was not convincing and lead to only 32 of the first generation being built. Soon the engine was developed into an inline 8-cylinder, which had better characteristics.

A member of the second generation

Shunyan Gu

Some locomotives were built in broad gauge to be used for switching in the border area with Russia. By 2006 more than 1,100 locomotives had been built, the latest generation of which has 1,800 hp instead of 1,650 and is produced by Sifang with many other improvements. Above all, it includes many innovations in the field of electronics. Today, the DF5 is the most common type of its kind in China, and North Korea also uses a few.

The DF8 is a heavy diesel locomotive for freight service, both prototypes of which were built in 1984. Series production of the actual DF8 followed in 1989. It had a sixteen-cylinder engine with an output of 3,310 kW or 4,500 hp. The same engine is also used in the DF9 and DF11 passenger locomotives. Power output was increased over the years, so that the more than 1,200 DF8Bs already had 3,680 kW or 5,000 hp. There were also experimental locomotives, such as the DF8BJ with three-phase traction motors and the DF8DJ with a 4,800 kW or 6,525 hp Caterpillar engine. The DF8 was also successful in exports, with customers found in Asia, Africa and South America.

To speed up heavy passenger trains, China Railways started development of a heavy diesel-electric locomotive in 1990. After two DF9 prototypes built for a service speed of 140 km/h, the first DF11 built for 160 km/h was completed in 1992. At a weight of 138 tonnes, it is powered by a sixteen-cylinder with a rated power of 3,860 kW (5,176 hp), calibrated for 3,630 kW in the locomotive. Six DC traction motors have 3,040 kW (4,077 hp) in total.

On test runs, these locomotives could reach a speed of 184 km/h. A normal train load when running at top speed is 640 tonnes, but even passenger trains of 1,100 tonnes can be hauled at a speed of 143 km/h. As with previous Chinese locomotives, they can't deliver head-end power to the train, so separate generator cars are needed.

There is also a special plateau type for service on the highland plains in Western China. These have special filters for running through sandstorms, a slower gear ratio for a top speed of 153 km/h and engine modifications for greater power at altitude. Up to 2005, a total of 459 DF11 have been built for service in several regions of the country. Today they are still omnipresent on many non-electrified lines.

The Chinese government's six-stage plan to speed up rail travel required a heavy-duty passenger diesel locomotive for higher speeds for the fifth stage. On the long-distance routes that were not yet electrified, this was to cover connections of more than 1,000 km (620 miles) without a stopover and not require any other crew members apart from the driver. Furthermore, it was required that the locomotive can take over the power supply of the train itself and that no generator wagons should be necessary.

In May 2003, the Ministry of Railways delegated the contract for the development directly to the locomotive factory in Qishuyan. A double locomotive was developed on the basis of the DF11, the first pair of which was delivered in November of the same year. It was the first Chinese diesel locomotive with complete microcomputer control. The streamlined head shape earned it the nickname “pig's head” in public.

Each half of the locomotive is powered by the same diesel engine as in the DF11, which has a gross output of 3,860 kW or 5,176 hp. This is sufficient to maintain a speed of 160 km/h or 99 mph with a train of 18 to 20 cars up a gradient of 0.3 percent. Here the traction is still being provided by classic DC motors. Each half of the locomotive has a separate MTU or Cummins diesel engine to power the train, with a flanged-on generator delivering up to 400 kW. The first 29 pairs had a 380 volt AC power supply and the last 63 pairs had a 600 volt DC power supply for more modern passenger cars.

During test runs, the more than 1,600 km (1,000 miles) long route between Beijing and Hangzhou was covered at an average speed of 138 km/h. In some cases, the locomotives are not used as a double unit at the front end of the train, but with one half at each end. This enables faster turning at the destination station and is jokingly called “Dōngfēng 5.5G”. On some routes that are now electrified, the DF11G has been replaced by locos such as the HXD3D.

In 2006, the Qinghai-Tibet Railway was opened, which is the highest railway line in the world at up to 5,072 meters (16.640 feet) above sea level. A variant of the GE Dash 9-44CW with an output of 5,100 hp was developed for the special requirements at this high altitude. These locomotives are mainly used there in front of passenger trains, which consist of cars with pressurized cabins. These form part of a link between Beijing and Lhasa.

EMD's four-stroke diesel, also known as the “H Engine”, was not able to gain a foothold in the USA in the 1990s because it was considered unreliable. In 2005, however, it was possible to get an export order for China for 300 heavy diesel locomotives with this engine. These had 6,300 hp and two cabs each. 30 more single-cab locomotives were built for the Lhasa Railway in Tibet, which are normally used coupled together. This line reaches an altitude of over 5,000 meters above sea level and the passenger cars used there have a pressurized cabin. Another four locomotives went to China Shenhua Energy.