The picture shows a train on the Qinghai-Tibet Plateau
Although China's high-speed rail is world-class, the locomotive used in the Qinghai-Tibet Railway is imported from the United States by China, and the internal combustion locomotive uses the internal combustion engine as the driving force to drive the locomotive with wheels rotating through the transmission device. According to the fuel type of the locomotive, the vast majority of the internal combustion locomotives used on China's railways are equipped with diesel engines, but why China chooses American locomotives on the Qinghai-Tibet Plateau is actually not that China's technology is lagging behind people, but that after passing grimm station, there is no possibility of direct passage of Chinese trains on the Qinghai-Tibet Railway.
The picture shows the NJ2 diesel locomotive
Although China's high-speed rail is world-class, But China's high-speed railway train, its power structure is "based on the joint use of distributed low-load motor groups in multiple train carriages", is a pure electric train in the pure sense, itself does not carry fuel and generators, but a complete dependence on the roof or bottom of the brush, from the line near the track to obtain electricity to advance the vehicle, but after passing grimm station, the relatively severe environment, forcing China to give up the plan to deploy power supply lines around the railway. This also means that China's high-speed rail trains will completely lose their energy supply after passing through Grimm Station, so it is impossible for China's high-speed trains to continue to move forward after passing through Grimm Station.
The picture shows the HXN5 diesel locomotive
At that time, the locomotive using steam power has been completely eliminated, the only thing that can be used is the use of diesel engine as the main power system, the use of hydraulic transmission system or electric transmission of the internal combustion engine locomotive, and China also prepared the corresponding locomotive for the Qinghai-Tibet Railway, that is, Dongfeng 8B9001 and 9002 plateau diesel engine test vehicles, but at that time the Minister of Railways clearly required China to achieve leapfrog development and will be "reliable" It is listed as the most important standard for Qinghai-Tibet railway trains.
This led to the train front of the Qinghai-Tibet Railway in China becoming an NJ2 based on the american C44-9W diesel locomotive front, and subsequently, China also introduced the HXN5 train based on the C44-9W upgraded AC6000CW improvement, but due to the lack of improvement in the follow-up GM, in the end, the HXN5 based on the AC6000CW was finally inferior to the HXN3 train based on China's cooperation with EMD company, with SD90MAC as the prototype.
The picture shows the HXN3 locomotive
Why did China choose to use the NJ2 instead of the original Dongfeng 8B series trains as a dedicated train on the Tibetan Plateau route? Because at that time, the locomotive of China's internal combustion engine train was not reliable enough, and the line condition of the Lager section of the Qinghai-Tibet Plateau was not as good as people imagined, with the instability of the domestic locomotive front at that time, whether it was the 9001 locomotive or the 9002 locomotive, which was faulty, with the output of the internal combustion engine power of the Chinese diesel locomotive at that time, it was impossible to ensure that under the condition of the bicycle, the train could stick to the next station, so China will import the corresponding diesel locomotive from the United States, which is more adept at using internal combustion locomotives, instead of using the original Dongfeng 8B series locomotives.
As for today, with the gradual electrification of China's railways, the electric drive locomotive has become the mainstream structure of the Chinese train front, which has led to the fact that China's diesel locomotive front will not have a large market, so, under the premise that the current Chinese diesel locomotive market is not huge, the China Train Research Institute will naturally not focus their attention on the diesel locomotive, so as one of the few lines that cannot be electrified and upgraded, the Qinghai-Tibet Plateau can only use similar to NJ2. Diesel locomotives like HXN3 and HXN5 are off the rails.