Abstract: A gyratory crushing apparatus for frangible or friable material comprises: a bowl having a chamber for receiving the material and a discharge opening disposed at the base with a central axis and a gyratory axis extending at an angle to the central axis; a crushing head and a drive assembly. The discharge opening defines a throat with a circumferential wall and the crushing head is disposed within the discharge opening. The crushing head has a crushing face in spaced relation to the circumferential wall of the throat defining a nip between the circumferential wall and the crushing face. The drive assembly includes a transmission and a rotatable eccentric shaft for driving the crushing head within the bowl and about the gyratory axis in a notating motion. The bowl also comprises a feed section and a discharge section, each defined by a wall and spaced by a mid-section, wherein thickness of a wall defining the mid-section is greater than a thickness of the discharge section wall.