Abstract: The invented fixed-angle roller mechanism comprises: a frame providing two bearings; a roller shaft supported by said bearings such to rotate along the axis of said roller shaft, which roller shaft is connected to a rotation element; an angle regulator provided on said roller shaft to limit rotation angle of said roller shaft; and an angle fixing means provided on said frame to couple with said angle regulator such that rolling angle of said roller shaft may be limited by said angle fixing means loosely; wherein said angle regulator regulates at least two rotation angles of said roller shaft.