This is what you see when you take off the top of a toy trail (a rovex triang-hornby, 262 side tank.). Prairie wheel arrangement. My hubby decided to fix it, it’s about 60 years old and hasn’t been working for most of that time, though it is now. After taking the top off by unscrewing the top of the model, you can see the workings of the engine. After cleaning and oiling the toy train is now in working order. Ignore the batteries in the photo, my hubby thinks you can never have enough of them for use in his torches!