Determining rational parameters for the impeller of a hydraulic excavator with a crowding mechanism

Introduction. The rationale for the research is conditioned by the need to improve the efficiency of hydraulic excavators which affect the prime cost of mining significantly. Research objective is to improve the design of hydraulic excavator impeller and develop the methods of determining impeller’s rational parameters ensuring its weight reduction. Methods of research. A model of hydraulic excavator with an impeller including a boom, a dipper arm, bucket, and hydraulic slewing cylinders for a boom, a dipper arm, and a bucket. For a front shovel hydraulic excavator, a new design has been developed that excludes hydraulic cylinders for a beam which are used in a base model of hydraulic excavator; a pressure rod is used for boom travel. In the developed scheme of the impeller, a superstructure is installed on the slewing ring, a crowding mechanism for the pressure rod extension is installed in the upper part of the superstructure. The pressure rod is connected to the fore boom and runs inside the saddle bearing. Such scheme allows excluding boom slewing cylinders, reduce the bending moment that has effect on the boom, which is going to reduce the boom cross section and therefore its mass. A mathematical calculation model for excavation coordinates and forces has been developed, as well as an algorithm and software on the Visual Basic language for applications, allowing to determine possible forces in the impeller elements within the limits of the working area. The force values are used when optimizing according to the mass criterion to select the cross section of a boom and dipper arm and for cylinders’ location. The mass criterion application and a restriction in a form of the required technological parameters implementation when operating in the preset mining and technological conditions will allow selecting rational parameters for the impeller’s elements. Results. Changes in the arrangement of elements (elimination of boom slewing hydraulic cylinders and the arrangement of the crowding mechanism on the rotation axis) makes it possible to improve the bucket tonnage, and therefore, the excavator’s capacity. The developed methods of determining the excavator design parameters also ensures the working zone construction and bucket teeth forces calculation within its limits in order to prove the possibility of implementing the operating functions of the new model designed.