Bell on NJ2 locomotive of Qinghai-Tibet Railway

This is the tradition of American cars.

Traditionally, American locomotives have a bell besides a whistle (changed to bagpipes after the internal combustion era). The hammer of this bell is linked with the whistle rod, and when the whistle rings, it will also ring.

As for how this tradition came into being, I have not found any textual research for the time being, except that this clock was found on an American locomotive.

NJ2 was originally imported from America, so we brought this tradition in. However, at the time of import, Americans cancelled the linkage mechanism of the clock because they knew that China people didn't use it, so the clock now has no function except decoration.

Similarly, ND5 is an American locomotive. It also has a clock, but the position of that clock is hidden and ordinary people can't find it.