In some big cities, I have seen what looked like big steel shelving. On each shelf is a row of cars. There are no ramps in evidence, and not enough room for ramps, anyway. There is some mechanical stuff in between the vertical rows, but it doesn’t look hefty enough to juggle cars.
How do these things work?
I used these at the dealership I’ve worked for and I’m pretty sure it was a combination of chains and hydraulics. With hydraulics and chains, I’m sure it’s “hefty” enough to lift a 2500 to 3000 lb. car.
We never did put the full size trucks on top of them, though.
You’d drive the top caron its “shelf”, then lift it to the next “shelf”, drive the next car on, and so forth.
In my youth I remember some parking garages where the attendant drove the car into what was essentially a large elevator. The elevator would take the car up to an open level and the attendant would then drive the car into an open space. I don’t recall the mechanics as being especially elaborate.
I haven’t seen one of those in years, but perhaps they still exist in some places.