The article considers the features of the kinematics of the main mechanisms of an open-pit excavator (mechanical shovel) in their joint operation. The analysis of the lever mechanism connecting the main mechanisms with the bucket was carried out, the dependences between the velocities of working movements and the position of the bucket in the working area of the excavator were established, rational values of the velocities during the operation were determined. It is shown that during the excavation of rocks, a general transmission mechanism of the drives of the main mechanisms is formed, consisting of the main mechanisms and the lever mechanism connecting the main mechanisms with the bucket. Methods of mechanism analysis, mathematical modeling and computational experiment were used. On the basis of a simulation model of the excavation process, a computational experiment was performed to calculate the operating parameters of the main mechanisms for the EKG-20A excavator manufactured by PJSC Uralmashplant when working out an excavator face. It was established that the lever mechanism has two degrees of freedom. The generalized coordinates of the lever mechanism, which determine the positions of all links of both the leverage and the main mechanisms, are the coordinates of the bucket’s cutting edge top. The rational values of the lifting and thrusting velocities were determined, at which the bucket is moved with a constant digging velocity along a given trajectory in the process of working out the face. The performed analysis of the kinematics for the joint functioning of the main mechanisms and working equipment during the excavation of rocks showed the interdependence between the operating parameters of the main mechanisms in the process of excavation. In the future, the established interdependence can serve as the basis for the development of an adaptive digital control system for the drives of the main mechanisms, which ensures, by coordinating the velocities of working movements in specific operating conditions, an increase in the efficiency of the excavator.