What drives the carriages of the train?

The traditional train is driven by the locomotive at the front of the train, which is also called locomotive mode. One or two locomotives located at the front of the train (mainly electric locomotives, some diesel locomotives and the original steam locomotives) pull the next few to twenty cars forward.

If the locomotive power is natural enough and runs fast enough, it must have a certain weight or a special aerodynamic shape to generate enough friction, otherwise it will encounter all kinds of magical skidding when starting or climbing.

A typical example is SS8, which is the first generation 160km/h quasi-high-speed electric locomotive in China (SS8 has a record of 240km/h and is still the fastest running China railway locomotive in history). SS8 axle load is very light (power is very small, only 3600kW, in order to run fast), and as a result, all kinds of skidding on the ramp can't reach the speed.

HXD3C, a 7200kW high-power electric locomotive, can accelerate its flight like a K-prefix train (HXD3C can only run 120km/h, after all, it is only an amateur passenger plane, more like a cargo plane).

Of course, there may be more than one locomotive in some cases of steep slope or large traffic volume (for example, there will be two locomotives on the second line of Lan Xin, and there may be more 10,000-ton coal trains on the Daqin line).

Couplers are pulled between the front of the car and each car to ensure that when the locomotive in front starts, the cars in the back will also be pulled away.

Extended data:

The bogie of the train is stuck on the track and runs along the track. When turning, the bogie rotates to keep the train running along the track. The outer rail is higher than the inner rail when turning.

The original trains were drawn by ropes or horses. By the19th century, most trains were pulled by steam locomotives. After 1940s, steam locomotives were gradually replaced by diesel locomotives with cleaner and less labor, followed by electric locomotives and multiple units.

The initial investment of electrified railway is large, but the operating cost per mile is the lowest. Therefore, only high-flow lines are suitable for electrification. Electrified trains may use overhead cables or the third rail to obtain electricity.

Calculating the efficiency of the engine head by dividing the unit kilowatt (KW) power by the tractable weight metric Ton (ton) is called the tractive capacity ratio. Steam locomotive has the lowest efficiency, followed by diesel locomotive (electric transmission ratio has high hydraulic transmission efficiency). Electric locomotives or electric locomotives are relatively more economical because they don't need to consume extra kinetic energy to pull the engine that generates power.

References:

Baidu encyclopedia-train