And it’s what a train’s wheels do as they move along the track.

这就是火车车轮沿着轨道移动时所做的事情。

There were even some non-patented drawings of train wheels and hand-drawn maps from the late 1930s.

甚至还有一些非专利的火车车轮图纸和 1930 年代后期的手绘地图。

And it's what a train's wheels do as they move along the track.

火车轮胎是什么时候做的 在轨道上移动。