Hi Musky your blessed with the eyesight of a shit house rat LOL
It looks like they've attached a piece of thread to the bottom of her dress so it can be pulled to make it appear she is moving 🤔
Speculating on the details of this motorized pram is not necessary, I think. Google "vintage motorized pram" or "Dunkley Pramotor." Many more, and sharper, puctures.Richard L.