Heavily block backrest skeleton

The utility model belongs to the technical field of heavily block the chair framework, a heavily block backrest skeleton is disclosed, including back frame, the back frame top is equipped with back headrest pipe, back frame upper end both sides are equipped with the shoulder reinforcing bar, the back frame both sides are equipped with the waist support reinforcing bar, the back frame inboard is connected with the stay tube that the level set up, be equipped with criss -cross back arm -tie anyhow between the stay tube, back frame is set up to the upper end hypsokinesis by the lower extreme, back frame lower extreme both sides are provided with the yoke plate, it is dentate structure to go up the yoke plate bottom, first line of a couplet inboard face down bonding has connect the yoke plateto strengthen the pinion rack, the tooth portion shape that goes up yoke plate enhancement pinion rack and last yoke plate is the same, upward be equipped with locating hole no. 1 on the yoke plate, upward the corresponding d