Problem Statement (Relevance). The paper presents the analysis of the causes for downtime of cone fine crushers. The results revealed a main cause, namely uncrushable materials entering the crushing chamber. Avoiding a crusher jamming in case of too hard rock is one of the main areas of improving cone crushers. A solution to this problem will significantly increase the machine performance by increasing the service life of the armor of the movable and fixed cones and eliminating the shutdown of the crushing process. Objectives. The study attempts to develop design solutions to increase the cone crusher performance by minimizing downtime. Methods Applied. To achieve the objective of the study, we described a mathematical model of the motion trajectory of uncrushable materials along the crushing chamber of a cone eccentric fine crusher. Originality. The authors studied the motion trajectory of an uncrushable material in the crushing chamber of the cone fine crusher, and developed a technique to identify rational parameters of the crushing chamber protection system for uncrushable materials in the operating area of the crusher. Result. The paper presents an algorithm for designing a model of the motion trajectory of the uncrushable material in the crushing chamber of the cone crusher. A hydraulic circuit diagram was developed to protect the cone crusher units against the negative impact of uncrushable materials on the chamber and clean the crushing chamber from the overflow or uncrushable materials. Practical Relevance. By introducing the development presented in this paper we can minimize the downtime of the cone crusher, increase the service life of the equipment, and reduce the machine maintenance cost.