This Japanese tin toy consists of a horse and rider, with a gyroscope below. Below the gyroscope there is a tiny metal wheel with a slot in it, which allows the horse and rider to balance on the track.
The gryroscope is fired up in time honoured fashion - by pulling on a length of string. The horse and rider can then be placed on the circular track, and they proceed to whizz around the track at great speed, at least until the gyroscope starts to run down. Then the horse and rider start to sway, as if through exhaustion, until finally they fall off the track.
Not immediately apparent until you inspect the mechanism closely is why the horse and rider go round the track - normally a gyroscope stays in one place.
The reason is as follows. The gyroscope can slide up and down a little bit within its mounting, and the bottom of the spindle makes contact with the little metal wheel that sits on the track. The wheel has a groove in the middle, and one side of the wheel is slightly bigger than the other. This does not affect the way it sits in the groove, but it means that the gyroscope spindle is only making contact with one side of the wheel. As the spindle turns, some of its energy is used to turn the wheel at the bottom, via a slipping contact.