Theoretical studies of the safety of agricultural machinery equipped with hydraulics

The article substantiates a mathematical model for calculating the parameters of supports with a hydraulic drive, considers cases of operation of a hydraulic cylinder with a hydraulic lock when the rod is extended without load until the heel of the hydraulic support contacts the supporting surface and the machine is lowered on the supports, retracting the rod under load. There has been substantiated a method for checking the calculation of hydraulic cylinder parts for strength, with which one can determine the stresses that occur in dangerous sections of parts at the highest acting loads, which are then compared with the allowable stresses for the selected material, while hydraulic cylinder parts are calculated for static loads. The calculation of the hydraulic cylinder for strength is carried out after the design is completed, when the design, dimensions of parts and tolerances for their manufacture are already known, as well as materials and their heat treatment are selected. Hydraulic cylinder parts are usually calculated for static loads; hydraulic cylinder parts are not calculated for fatigue. The design loads are the highest working or limit loads acting on the part during the operation of the hydraulic cylinder, with a given adjustment of the hydraulic safety valves. The working load refers to the loads that occur during normal operation, while the limit load refers to the maximum loads under which the strength of the hydraulic cylinder parts must be ensured. To simplify the calculations, we can neglect the values that have small values: the forces of the springs of the check valves and the friction forces of the moving parts of the hydraulic lock. With sufficient accuracy, it can be assumed that the weight of the rod with the bearing heel is balanced by the friction forces of the sealing elements. The above method of calculation makes it possible to eliminate these harmful phenomena and determine the maximum allowable rod diameter for this case, for one of the given payload conditions, the hydraulic cylinder diameter.