Gyradisk Cone Crusher. For finer size products (e.g., -6 mm), a special cone crusher known as the Gyradisc is commonly used. Operation is similar to the Standard Cone Head; however, breakage is mostly by attrition rather than impact. Reduction ratio is around 8:1. Feed size is limited to less than 50 mm with a nip angle between 25 ° and 30 °.