Pressure control valve for mine props hydraulic

摘要

A valve device for pressure-relief of, e.g., hydraulic props of mine equipment, has a main hollow housing into which a guide is in screw threaded engagement for adjustment purposes. The guide has a through bore which slidably receives the cylindrical stem of a valve member. The valve member has a domed head with a stop face held against an inner end face of the guide by means of a compression spring located in the housing and bearing on a thrust bushing guided and located on the head of the valve member. The stem of the valve member has a blind axial bore leading to frusto-conical outlets at its periphery via radial borings. The axial bore in the stem receives pressure fluid to be controlled via the guide bore. A sealing ring held in a groove in the guide bore engages on the periphery of the stem of the valve member. As defined hereinafter, the material of the sealing ring has a certain composition and certain other characteristics of the valve device components have a specific relationship to provide an improved performance. Excess pressure moves the valve member to raise the head off the guide end face against the restoring force of the spring to thereby allow pressure fluid to discharge from the outlets of the valve member, moved beyond the sealing ring.