A disc saw felling head and a method of assembly for the disc saw felling head including a saw mandrel and bearing arrangement. The saw mandrel and bearing arrangement includes a housing, a mandrel, and first and second preset roller bearing packs. One of the roller bearing packs is a tapered roller double-row preset bearing pack and the other of the roller bearing packs is a cylindrical roller single row preset bearing pack. The housing includes a bore and a first and second shelf, wherein each of the shelves defines a depth of the bearings with respect to the housing to accurately locate the mandrel within the housing. The use of preset bearing packs and a housing having predetermined locations for placement of the present bearing packs provides an assembly which requires fewer adjustments.
