Here is a vintage shot of an elevated track which would carry the hoppers up so that the coal can be gravity fed to the locomotives.
Tom
A smaller narrow-gauge version still stands on the East Broad Top in Orbisonia, PA, south of the shops. Trains pass it when they go around the wye and head forward through the yard to the station. The loading track comes from the south. A hopper car or two were pushed up and dumped into two bins. Two chutes filled tenders by gravity. Once I was there when the coal didn't flow, and the fireman had to shove it along with shovels.
The retaining wall made of logs has given way, but last I saw the concrete bins, metal chutes, and the shed on top were still there.