China Railway DF11G

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 On some routes that are now electrified, the DF11G has been replaced by locos such as the HXD3D.