Disc saw felling head housing improvements

In a disc saw felling head having a disc saw blade which is rotated about a generally vertical axis to fell a tree, said disc saw blade extending axially for a certain thickness within a housing, said housing including a top wall which is part of an upper portion of said head, the improvement wherein said housing includes a generally vertical wall which spans the thickness of said disc saw blade and wherein said wall which spans the thickness of said disc saw blade is removably fastened to said upper portion of said head.