Figure 3. Bunker silo.
Bunker silo with three concrete wall sides and three loaders on top of the silage pile

"Loaders compacting silage, Revivim 2007" by Felagund - Own work. Licensed under CC BY-SA 3.0 via Commons - https://commons.wikimedia.org/wiki/File:Loaders_compacting_silage,_Revivim_2007.jpg#/media/File:Loaders_compacting_silage,_Revivim_2007.jpg