In gyratory crusher which part is eccentric. Gyratory Crushers - Mineral Processing Metallurgy. Essentially, the gyratory crusher consists of a heavy cast-iron, or steel, frame which includes in its lower part an actuating mechanism (eccentric and driving gears), and in its upper part a cone-shaped crushing chamber, lined.2. A gyratory crusher according to claim 1 wherein said pusher plates are disposed in direct physical contact with said piston and said drive eccentric. 3. A gyratory crusher according to claim 1 wherein said pusher plates are at least three in number and have an arcuate configuration which conforms to the curvature of the wall of the cylinder. 4.