# US 4,391,183 A · Hydraulic blocking valve > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 4,391,183 A - Document ID: US4391183A - Status: Granted - Kind: A - Application number: 06/121,619 - Filed: 1980-02-14 - Granted: 1983-07-05 - Earliest claimed: 1979-02-22 - Assignees: Innovation Aktiebolag - Inventors: Stig Broms; Lennart Freese - Web page: https://patentgrep.com/patent/US4391183A ## CPC - F15B 13/01: Locking-valves or other detent {i.e. load-holding} devices - Y10S 137/901: Biased ball valves with operators - F15B: SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR - Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS ## Abstract The invention relates to a hydraulic blocking valve, a so-called holding valve (10), the shutting-off member of which consists of a movable ball (16) coacting with a seat (17) in an inlet chamber (24). The space (15) on the side of the ball opposite its seat forms an operating chamber (15), and both chambers are joined by a constriction passage (13) counteracting flow of hydraulic liquid between the chambers. The operating chamber (15) is in communication with valve means (32) by the aid of which the pressure in the operating chamber can be heavily reduced, e.g. by being taken to a tank (44), resulting in that the ball (16) is thrust from its seat (17) to open the valve. A throttling means (25, 26) simultaneously comes into action for reducing the flow, i.e. liquid loss through the valve means (32) from the operating chamber (15). When the valve means is subsequently closed, pressure is once again built up against the ball so that the latter is pushed towards its seat (17) for closing the valve (10). ## Claims ### Claim 1 In a hydraulic blocking or holding valve including a valve housing having a hollow interior with an inlet and an outlet and a valve body shiftable to close a main valve seat for interrupting the communication between the inlet and outlet and alternately to open said main valve seat for permitting said communication, the valve body being arranged between two chambers in said housing interior, namely one inlet chamber in communication with the inlet and located between the valve body and the valve seat, and one operating chamber located on the opposite side of the valve body from the valve seat, a throttling or constricting passage via which the inlet chamber and the operating chamber are in communication with each other for counteracting flow of hydraulic liquid between the chambers, and control valve means in normally unconstricted communication with the operating chamber and actuable for lowering the pressure in the operating chamber in relation to the pressure in the inlet chamber to thereby create a pressure difference between the two chambers causing the valve body to shift to an open position opening said main valve seat, wherein the improvement comprises a constriction means responsive to said shifting of said valve body to its open position for constricting but not stopping the outflow of hydraulic liquid from the operating chamber to said valve means, said valve body being a ball received in a movable sleeve communicating with said inlet chamber, said housing including a fixed internal spigot protruding into the housing interior and separated from said main valve seat by said ball, spring means backed with respect to said housing for urging said ball against said valve seat and away from said spigot, said sleeve being slidable over said spigot and defining with the spigot said operating chamber, a sliding gap between said sleeve and spigot forming said throttling passage between the inlet chamber and operating chamber, an orifice in said spigot providing said normally unconstricted communication of said operating chamber with said valve means, said orifice being located in said operating chamber to face said ball, said spring means being dimensioned for causing said ball, in response to said shifting of said ball and sleeve away from said main valve seat by said pressure difference, to assume an almost abutting relation with said spigot at said orifice forming said constriction means therebetween, for simultaneously constricting outflow into the orifice and maintaining the constricted outflow of hydraulic liquid from the operating chamber through the orifice to the open valve means. ### Claim 2 (depends on 1) A holding valve as claimed in claim 1, and connected into the hydraulic system of a work machine having work cylinders, such as a loading or excavating machine, to prevent hydraulic liquid leaking out of the system from one or more of the working cylinders of the machine, and thereby preventing e.g. sinking of a work implement or other load supported by the cylinder or cylinders, wherein said valve means for lowering the pressure in the operating chamber comprises a normally closed valve adapted to be opened to put, via said non-return valve and constriction means, the operating chamber in communication with an exhaust outlet, so that the holding valve is opened and lowering movement of the cylinder or cylinders is allowed. ### Claim 3 (depends on 1) A holding valve as claimed in claim 1, wherein the constriction means at the operating chamber is connected to a non-return valve permitting outflow from, bot not inflow to, the operating chamber via the constriction means. ### Claim 4 (depends on 1) A holding valve as claimed in claim 1 wherein said spring comprises a compression spring means arranged to counterbalance the pressure drop from the inlet chamber to the operating chamber, at pressures up to the maximum operating pressure of the holding valve, for resiliently holding said valve body out of closing contact with said orifice, said valve body having first and second end positions at the opposite ends of its travel, the first end position of said valve body being in closed engagement with said main valve seat, the second end position being in a range of positions all close-spaced from said orifice to limit but still permit a continuous outflow from said operating chamber through said open valve means, said second end position being resiliently adjusted in said range by said spring in response to changes in operating conditions.