A rotary machine includes a vessel that defines an interior for receiving materials. The vessel is mounted to rotate about an axis of rotation that extends through the vessel. The rotary machine also includes a sprocket mounted circumferentially about an exterior of the vessel so as to encircle the axis of rotation of the vessel. The sprocket includes a plurality of sprocket teeth. The sprocket defines a sprocket pitch diameter and a sprocket addendum diameter. The rotary machine also includes a drive wheel that intermeshes with the sprocket for driving rotation of the vessel about the axis of rotation of the vessel. The drive wheel includes a plurality of rollers that are received between the sprocket teeth of the sprocket. The rollers each have a roller diameter and a roller axis. The rollers are rotatable about their respective roller axes. The drive wheel has a drive wheel pitch diameter defined by the roller axes. The sprocket addendum diameter is equal to the sprocket pitch diameter plus a distance equal to at least 1.0 times the roller diameter.