Mobility Scooter & Trains

Hi. We’re planning a trip to Spain for 3 weeks in October. We have been to Europe many times over the years, but never Spain until now. We’re also usually drivers wherever we go, but have decided on public transport for this entire trip. What I’m trying to figure out is how train travel works with my mobility scooter. It’s a rather large and heavy scooter (1200mm x 635mm). It doesn’t fold up. I can’t seem to find what happens to it on a train trip say from Madrid to Barcelona. I want to sit in a train seat and can easily transfer to one. (I am unable to walk long distances.) So where does the scooter go during the trip? Thanks for your help!