One of the gifts for our almost 2 year old is a lego duplo 5608 trainset. One thing I noticed is the locomotive needs batteries to run and it cannot run free without them. There is probably a small transmission between an electromotor and the wheels. Since pressing a button for the locomotive is a bit much for the 2 year old I hoped I could set the locomotive to run free but it looks like I can't. The rest of the trainset is enjoyed anyway so it isn't much of a problem. Video with features of the Lego Duplo 5608 trainset.