The identification of the damage causes of the hydraulic control system components in powered roof support by means of tests and calculations

摘要

The article discusses a case of hazards in a longwall equipped with a technically efficient, properly selected two-legs powered shield support. The support was introduced to the market and for operation in compliance with the requirements covering Polish hard coal mining. As a cause of the hazard, an accidental coincidence was indicated, such as the occurrence of a tremor at an area with unfavorable geometry for the operation of the support at the time of the mining process. Immediate safety measures were applied successfully. They were aimed at minimizing the conditions dangerous to the crew. The support was yielded and set again. As a result, the leg operated in full extension mode of the 1st hydraulic stage, obtaining the required strength and geometry of the support and its leg. The presented case study is additionally supplemented with selected analytical and bench tests. Analytical and bench tests contain the analysis of flows and the occurrence of strokes in the hydraulic system of the powered support leg. The article also presents research using mass impact and is a complement to previous analyzes [27].