Abstract: A coal cutter drum assembly includes a cutter drum having an inner diameter and mounted for rotation about a cutter drum shaft, along with multiple bit retainers secured to an external surface of the cutter drum, each retainer receiving a cutting bit. The coal cutter drum assembly further includes first and second bit and bearing retainer subassemblies, each of which is joined to the cutter drum and further joined to a sprocket that is used to rotate the cutter drum. A bearing supporting the cutter drum is positioned in each of the first and second bit and bearing retainer subassemblies, and each bearing has an outer diameter that exceeds the inner diameter of the cutter drum.