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DYNAMIC RESISTANCE TEST FOR SAFETY VALVE IN ELECTRO-HYDRAULIC CONTROL SYSTEM FOR POWERED ROOF SUPPORTS

D. Szurgacz, J. Brodny
Thursday 11 October 2018 by Libadmin2018

ABSTRACT

An electrohydraulic control system as a part of powered roof support is required to be equipped with a safety valve. The aim of the valve is to protect the roof support against overloads that may damage hydraulic legs, and subsequently lead to loss of stability of the whole support unit. In order to select optimal operating parameters of the safety valve it is necessary to carry out tests in conditions similar to those in the mine. The tests should reflect the actual load condition of the support as much as possible. The tested safety valves were impacted by dynamic loads as they pose the biggest threat. Such a load condition occurs in the case of dynamic impact of rock mass on the support. The test that included the dynamic load was carried out using a drop weight tester. Here, the source of the load is impact mass falling from a certain height. The tests included hydraulic legs equipped with safety valves. The article presents the results of the tests. Their purpose is to determine the value of the operating pressure at which the valve will open and close These values are extremely important for the correct operation of the valve, and subsequently for ensuring the safety of the roof support and the stability of protected workings. The paper also analyses the construction and operation principle of the safety valve as one of the key elements of the control system of the powered roof support. The Authors believe that the presented research results will contribute to the improvement of safety in underground mining.

Keywords: safety valve, dynamic tests, control efficiency, mining machinery.


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