The analysis of the work of a hydraulic manipulator of a forest machine with a cyclic control system

Logging is one of the most dynamic economic sectors in our country. At the moment, the methods of timber harvesting have undergone significant changes. Instead of manual labor, various devices and devices are used, including hydraulic manipulators for the forest. The manipulator-type equipment (hydraulic manipulator) is a mechanism that is installed on cars, tractors, specialized vehicles, as well as stationary. The efficiency of using machines and equipment is directly dependent on their technical condition, readiness to reliably, efficiently and safely carry out the processes of logging production. The condition of machines and equipment depends not only on their technical level and compliance with operating rules, but also on the quality of their design. Dynamic research of volumetric hydraulic drives of forest machines occupies an important place in the process of their design. In engineering practice, at the stage of both preliminary analysis of the dynamic characteristics of volumetric hydraulic drives, and at the stage of preliminary design, their linearized mathematical models are widely used. The article considers linearized models: a cyclic hydraulic drive with throttle control, an actuator for a hydraulic servo drive of a forest machine manipulator, a hydraulic servo drive with mechanical control. The results of a study of the stability of a servo hydraulic drive with mechanical control are presented. An expression is derived that determines the stability of a hydraulic servo drive with mechanical control, including the slip coefficient of the generalized hydraulic characteristics of the spool and the flow rate gain, which makes it possible to find their values corresponding to the steady state of a hydraulic drive with mechanical control. The results obtained can be used in the process of designing hydraulic manipulators of forest machines, both at the stage of preliminary design and at the stage of technical design and obtaining the amplitude-phase frequency characteristics of the hydraulic drive of forest machines.

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