Make one gameobject always touch another gameobject

I am trying to make a game involving trains, and I wanted to be able to make the train wheels always be on the track.
Is there a way that I can make the wheels be permanently on the track?
Thanks in advance,

Take a look at the spline controller. I’ve not used it myself but appears to do what you want.

[Hermite Spline Controller][1]

It maps a path for your train to follow.