Abstract: A compact support prop having a pressure limiting valve with a very high flow volume forming a prop head as a valve housing. The pressure limiting valve is integrated into the prop head. Thus, insertion speeds of more than 3 meters per second can be achieved. The drawing and filling valve consists of one or possibly two pilot-controlled check valves which can be easily attached to an outer side of the internal prop. It allows for a quick setting and drawing after removal of the released pressure medium. The released pressure medium flows off via the connection of the pilot-controlled check valve. The connection is provided as a setting gun connection and the released pressure medium can be returned to the inside by this connection.

Abstract: Pressure limiting valves intended for use in underground mining and tunnel construction are able to release the pressure medium discharged if an overload occurs without problems into the return line, since the occurring back pressure is directly neutralized in the pressure limiting valve. For this purpose a discharge of the pressure medium is provided even before the spring chamber, for which purpose the crossbores arranged there are constructed in such a way that they expand, forming a water chamber with increased volume. This water chamber is located in ring form around the valve piston that is exposed in this area and is connected via return bores to the return line. The water chamber with accordingly large volume makes it possible that the back pressure acts simultaneously on the spring and the valve piston, so that the described neutralization takes place.

Abstract: A pressure limiting valve with rates of flow of more than 8,000 l/min exhibits a valve casing comprising a control piston and valve piston. These valve casings are arranged inside the casing so as to be movable against corresponding springs, whereby the control piston and valve piston are separate units. The valve piston is arranged so as to be movable against an adjustment screw that is supported on the control piston side and has a through-bore that has a smaller diameter than the blind bore of the control piston. This special design of the valve ensures a uniform opening and reclosing of the pressure limiting valve for the described rates of flow, whereby suitable sealing rings consisting of Teflon are used in the area of the valve piston.

Abstract: A pressure limiting valve with high flow rates, but in particular with a good adaptability to the respective conditions, is constructed so that the control piston and the valve piston are coordinated with separate valve cases, whereby these valve cases are connected to each other by way of a plug-in fitting which can be screwed into the valve case of the valve piston and has on the opposite side a standardized plug connection. In the center of this plug-in fitting is provided a center bore, so that the plug-in fitting which has a corresponding opening or blind hole on both sides permits the pressure medium to flow through. The blind hole in the valve piston itself is again connected via a through-bore to the compensation chamber on the opposite side, whereby the diameter of this through-bore is smaller than that of the blind hole of the control piston.

Abstract: A pressure limiting valve having high flow rates, especially for use as a safety valve with mine props and the like, uses a tubular main valve member whose interior communicates with the valve inlet and has lateral bores opening into the valve outlet when the bores are shifted past a sealing ring in the valve housing. A pilot valve body is received in the tubular valve and the valve spring bears upon the tubular valve. The main valve is shifted by differential pressure.

Abstract: A pressure-limiting valve having high flow rates, especially for uses as a safety valve with mine props and the like, uses a tubular main-valve member whose interior communiciates with the valve inlet and has lateral bores opening into the valve outlet when the bores are shifted past a sealing ring in the valve housing. A pilot-valve body is received in the tubular valve and the valve spring bears upon the tubular valve. The main valve is shifted by differential pressure.

Abstract: A pressure-relief valve for the protection of hydraulic units in underground mining, functionable against a sudden overload in pressure, is provided including a valve housing having an upper part and a connection piece, a valve spring lodged against the upper part, a valve piston longitudinally slidable within the connection piece and engageable forceably at one end against the valve spring and having a blind bore and radial bores communicating perpendicular thereto through which a pressure medium is flowable, and at least one sealing ring against which the piston travels which is arranged in the connection piece. The sealing ring is positioned to adjoin the radial bores, consists of a very hard plastic material producing very low friction and has a rectangular cross section.