The process of using the sand house is pretty straight forward. The sand is located in the underground hopper, which is then closed and pressurized with compressed air. The air lifts the sand to the upper sand hopper until it is full. The locomotive pulls up, removes the sand dome lid, and then located the hose/or pipe from the upper hopper into the dome. He opens a simple gate valve and the sand flows by gravity from the upper hopper into the locomotives sand dome. Lifting the sand from lower to upper depends on the need to fill the upper hopper based on how much is used from day to day. Back in the day, railroad laborers would dry and shovel the sand and make sure the upper hopper was always full. All the hostlers and engine crews had to do was pull up and "fill er up!"
I spent a lot of "quality time" going through the motions of shoveling, drying and lifting sand at the old Durango sand house in my younger days....it was loads of fun!
Mike Ramsey