The present disclosure relates to a method for operating a gyratory cone crusher as well as a hydraulic circuit suitable for carrying out the method. A crusher comprises an inner crusher shell and an outer crusher shell, which define a crusher gap, and the crusher gap size is maintained by means of a hydraulic cylinder, and, in case the hydraulic liquid pressure exceeds a pressure threshold, hydraulic liquid is evacuated from the cylinder to increase the crusher gap size. The method involves carrying out detection of a tramp iron processing condition, implying that matter which the crusher cannot process has enter the gap. If such a condition is detected, the pressure threshold is lowered during a period of time. This means that the crusher gap is opened quicker, such that the matter that cannot be crushed is removed from the crusher, which is thereby protected from potentially detrimental impacts.