Metal roof beam hinged roof timber roof beam cross word double-wedge top beam top beam of good quality and reasonable price, this type of articulated roof beam is a top beam, which can be used with all types of single component metal pillars with metal stents for coal mining in the horizontal and gently inclined face support a roof beam high intensity. Because of this the top of the cantilever support beam to the front face of the transport channel coal wall above the roof, the pillars of coal between the wall and no greater support space. Therefore, for the introduction of new mining machinery and transport can be bent to achieve the general mechanization coal mining conditions is a high grade conventional mining and mining technology in the new high-end equipment necessary