Typically, the minimum setting on most primary crushers will be about 4 to 6 inches, as noted above. Compressionstyle jaw, cone, impact crushers, and gyratory crushers are most often appropriate as primary crushing equipment types, though there can be overlap between primary and secondary crushers as far as suitable types. 2. Secondary Crushing.
The gyratory crusher shown in Figure employs a crushing head, in the form of a truned cone, mounted on a shaft, the upper end of which is held in a flexible bearing, whilst the lower end is driven eccentrically so as to describe a circle. The crushing action takes place round the whole of the cone and, since the maximum movement is at the bottom, the characteristics of the .