I’ve lately picked up a modern-era working coal hopper, and I’m looking at using it on my O27 “door layout”. I could just about accommodate a coal ramp accessory, but I don’t have one and I won’t be in the US in any foreseeable future.
Anyway, I want to make things easy for little fingers (my grand-daughter) ... so I’m looking at a simple ramp, to raise the track about 40mm to fit a tray underneath. I have a K Line uncoupler Track, much lighter and simpler than the Lionel units (one button) so that can operate the hopper car.
I’ve found a German plastic kit that could easily be adapted to a simple “open top” filler design
So that seems to provide a simple operating cycle, with plenty of action. Grade on the ramp would be about 10%. Ok, let’s look at this..