Abstract: In the case of overloading of a gyratory crusher the manometer 14 detects a mean effective pressure of the hydraulic fluid in the cylinder 7 greater than a first limiting value, which causes the opening of the maximum pressure valve 18. The hydraulic fluid then flows into the hydraulic accumulator 22, previously filled with a gas at a pressure substantially equal to the said first limiting value. When the overloading is terminated, the maximum pressure valve 18 re-closes and the hydraulic fluid returns by the return branch 24 into the pressure chamber of the cylinder 7. In the case of very substantial overloading capable of damaging the apparatus, the manometer 26 causes the opening of the safety valve 29.