Determining the maximum turning force of the hydraulic backhoe excavator bucket

Introduction. Single-bucket excavators with both flexible and rigid suspension of work equipment are actively engaged in construction, stripping work and production mining. Excavators with rigid suspension are commonly used in construction, while excavators with flexible suspension are used in mining practice. This work considers the process of excavating rock with a single-bucket hydraulic backhoe excavator. The reliability and durability of excavators depend on the correct choice of the parameters of work equipment elements. Research objective is to determine the maximum turning force of the bucket of a hydraulic backhoe excavator, taking into account soil friction against the bucket bottom and side plates during rock excavation. Methods of research. When the maximum force on the bucket turning hydraulic-cylinder rods in the course of rock excavation is analytically defined, it is advisable to consider digging a trench in plain surface or in the open-pit in plain surface of a stope face provided that per one turn the bucket is filled to capacity. In this case, a segment of soil cut from the rock mass has maximum depth of cut as compared to other excavation methods. Total excavation resistance includes: resistance arising from cutting rock with a bucket with maximum depth of cut; resistance associated with the impact of gravity of the rock mass on the bucket; resistance associated with rock mass friction against the bucket bottom; resistance associated with rock mass friction against the inner surfaces of the bucket side plates. Results. The dependence has been determined between the maximum force on the bucket turning hydraulic-cylinder rods and bucket design parameters as well as the physical and mechanical characteristics of the face rock. The results analysis showed that both excavation process flow scheme and rock characteristics have a significant influence on the total bucket excavation resistance. Conclusions. The developed method of calculating the excavation resistance takes into account the internal forces of bucket interaction with rock and makes it possible to increase the accuracy of maximum digging force calculation. It therefore becomes possible to more reasonably approach the choice of the excavator bucket turning hydraulic cylinder parameters and thereby increase the reliability and durability of the machine as a whole.