Work purpose: the investigation of transport process safety in construction industry of the Bryansk region, the substantiation of reasons, factors and circumstances of accidents in the construction companies of the region, the substantiation of the impact of hydraulic drive unit failures upon safety of transport construction machinery with the hydraulic drive with the purpose of driver safety. Investigation problem: on the basis of the obtained results of the safety investigations of transport processes, reasons defined, revealed injury factors of drivers during the operation of the load flat car hydraulic drive of transport means to develop motion parameters of the “hydraulic drive-load flat car” system which will not allow arising oscillations of the system resulting in hydraulic drive failure arising which has influence upon driver’s work safety. The investigations were carried out on the basis of a system analysis of accident examinations in the regional construction industry which on the basis of statistical data allows the defining safety state of transport construction machinery. By means of investigations it is defined that 90% of transport construction machines are equipped with a hydraulic drive. In the hydraulic drive the most significant element is a hydraulic cylinder – the most loaded element performing all basic operations of a working process of loading and unloading. In the hydraulic drive there is used a telescopic hydraulic cylinder in which during operation there are revealed design-production defects (DPD) which result in injury of machine service personnel. One of DPD manifestations is oscillation formation in the hydraulic drive which results in the destruction of hydraulic cylinder attachment fitting. It is defined that the support of hydraulic drive reliability and safety is a difficult problem which needs a complex solution still at designing and creation, and during the operation. The complexity of the problem causes the necessity of design and operation parameter optimization, in the first place, that of an executing hydraulic cylinder of the hydraulic drive with the use of mathematical modeling. The review of the mathematical modeling methods of hydraulic cylinder parameters allows drawing the conclusion that the existing methods have many assumptions and do not allow creating completely reliable and safe transport construction engineering. The investigation novelty consists in the offered procedure for the solution of motion equations of the “hydraulic drive – load flat car” system which allows calculating the motion system parameters, defining the development of system oscillation above critical able to destruct a fitting unit of the hydraulic cylinder to the load flat car. Conclusion. The algorithm offered for the solution of mathematical equations allows making a conclusion on the stability and safety of the “hydraulic cylinder – load flat car” system, finding optimum values of motion parameters at any time moment of a transitional process.
The problem of constructive and production shortcomings of dump machines used at agricultural industry is examined. Causes and outcomes of spontaneous drift (fall) of dump platform are shown. Adjusting stopper valve construction that can solve this problem is proposed.
The study objective is to justify the parameters that ensure efficient energy conversion of the hydrohammer. Research methods include review, analysis and generalization of research results and experience in designing hydraulic devices; mathematical modeling based on laws of kinematics and dynamics of solid, liquid and gas; theoretical research based on numerical experiments. The novelty of the work is in the development of a mathematical model of a hydraulic hammer describing the cooperation of the percussive mechanism, distributor, hydraulic pneumatic accumulators and hydraulic drive. The study results include a mathematical model of a hydraulic hammer that takes into account the dynamics of its body and reflects the features of the working cycle of a hydrokinematic circuit with a controlled chamber of the working and reverse stroke; the numeric results of the mathematical model and experimental studies; dynamic analysis of the piston pin during the reverse stroke. Conclusions: the hydrohammer operation is influenced by accidental or purposeful changes in certain parameters of the hydraulic drive, which must be taken into account at the design stage of its subsystems in order to find a rational area of operation; one of these parameters is the inertia of the working fluid; formed during transition periods, inertial forces have a significant impact on the main parameters of the hydrohammer piston pin movement and dynamics of the power pulse hydraulic system; the time of filling the working cavity of the hydraulic cylinder of the striker is determined, the degree of influence of the working fluid inertial component on the time of the piston pin movement on the magnitude of the working stroke is defined.
Mathematical model and calculation method for work process indices of actuating hydraulic cylinder equipped with locking mechanism for hydraulic tripping gear of dump tracks are presented.
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