Why must the power transmission of the internal combustion engine locomotive use electric or hydraulic transmission instead of bearing transmission like automobile?

Because there is only one direction of rotation of the main shaft of the internal combustion engine

And the locomotive must change the direction of traction at any time, so if you use a mechanical gearbox, the speed change mechanism will be very complex, and the use of maintenance is very inconvenient.

Electric transmission or hydraulic transmission is simple, according to the need only need to reverse the motor wiring or fluid lines can be

Secondly

The locomotive's traction is very large, especially when the start of the car has a low-speed under the need for high power, if you use a mechanical transmission, it is very easy to suffocate the internal combustion engine or wear out the clutch plate at this time (you know if you have driven, if you have started with gears, it is difficult to start or to start with a gear, then it will be very difficult to start or to start with a gear, and it is very difficult to start or to start with a gear.

Unlike an electric motor, which can start under very high loads, the starting speed is at best a bit lower.

Finally, an internal combustion engine has to be at a relatively high constant RPM to maximize torque, and locomotives often don't reach that RPM if they are mechanically driven, resulting in wasted power, which doesn't matter with electric motors.

In fact, some high-power mining machinery, is also used to drive the traveling parts of the electric drive

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