# US 2014/0154104 A1 · Hydrostatic Positive Displacement Machine > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0154104 A1 - Document ID: US20140154104A1 - Status: Published application - Kind: A1 - Application number: 13/897,654 - Filed: 2013-05-20 - Published: 2014-06-05 - Earliest claimed: 2012-06-01 - Assignees: Linde Hydraulics GmbH & Co. KG - Applicants: Linde Hydraulics GmbH & Co. KG - Inventors: Burkhard Stuermer - Web page: https://patentgrep.com/patent/US20140154104A1 ## CPC - F04B 49/12: by varying the length of stroke of the working members - F04B 1/26: Control - F04B 17/05: driven by internal-combustion engines - F16H 61/433: Pump capacity control by fluid pressure control means - F04B: POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS (machines for liquids, or pumps, of rotary-piston or oscillating-piston type F04C; non-positive-displacement pumps F04D; pumping of fluid by direct contact of another fluid or by using inertia of fluid to be pumped F04F) - F16H: GEARING ## Abstract A hydrostatic positive displacement machine (2) is operated in a closed circuit and delivers hydraulic fluid into a working circuit. The displacement volume is varied by a control device (6) having a variable displacement piston device (7). The machine (2) has a swivel-back device (40) which, in the event of a decrease of the feed pressure from the feed pressure source (11), guarantees actuation of the machine (2) toward a reduction of the displacement volume. The swivel-back device (40) includes at least one pressure sequence valve (41), which is in communication on the input side with the working circuit of the machine (2). In the event of a decrease in the feed pressure from the feed pressure source (11) below a limit pressure, the pressure sequence valve (41) makes it possible to supply the control device (6) of the machine (2) with hydraulic fluid from the working circuit. ## Claims ### Claim 1 A hydrostatic positive displacement machine which is operable in a closed circuit and delivers hydraulic fluid into a working circuit, comprising: a control device comprising a variable displacement piston device comprising a first control pressure chamber and a second control pressure chamber, wherein the control device is in an operative connection with a displacement volume control mechanism, wherein the control pressure chambers of the variable displacement piston device are connectable by a control valve with a feed pressure source or are relieved to a reservoir, wherein the positive displacement machine and the feed pressure source are driven by a drive machine, wherein the positive displacement machine includes a swivel-back device which, in the event of a decrease of feed pressure from the feed pressure source, provides actuation of the positive displacement machine toward a reduction of a displacement volume, wherein the swivel-back device comprises at least one pressure sequence valve, which is in communication on an input side with the working circuit of the positive displacement machine, and wherein in the event of a decrease in the feed pressure from the feed pressure source below a limit pressure, the pressure sequence valve supplies the control device of the positive displacement machine with hydraulic fluid from the working circuit. ### Claim 2 (depends on 1) The hydrostatic positive displacement machine as recited in claim 1, wherein when the feed pressure from the feed pressure source is above the limit pressure, the pressure sequence valve blocks the connection between the working circuit and the control device, and the control device is supplied with hydraulic fluid from the feed pressure source. ### Claim 3 (depends on 1) The hydrostatic positive displacement machine as recited in claim 1, wherein the pressure sequence valve is actuated by the feed pressure from the feed pressure source toward a closed position in which the connection of the working circuit with the control device is blocked, and is actuated by the pressure of the working circuit toward an open position in which the working circuit is connected with the control device. ### Claim 4 (depends on 1) The hydrostatic positive displacement machine as recited in claim 1, wherein the pressure sequence valve is in communication on the output side with a feed pressure supply line that leads from the feed pressure source to the control valve. ### Claim 5 (depends on 1) The hydrostatic positive displacement machine as recited in claim 1, wherein the pressure sequence valve is in communication on the output side with a control pressure chamber of the variable displacement piston device, which acts toward a reduction of the displacement volume. ### Claim 6 (depends on 5) The hydrostatic positive displacement machine as recited in claim 5, wherein the pressure sequence valve is connected on the output side to a control pressure line which is connected with the control pressure chamber and is connected by means of the control valve with a reservoir. ### Claim 7 (depends on 5) The hydrostatic positive displacement machine as recited in claim 5, wherein the pressure sequence valve is connected on the output side to a discharge line of the control valve, which is connected with the reservoir. ### Claim 8 (depends on 5) The hydrostatic positive displacement machine as recited in claim 5, wherein a throttling device is located in a control pressure line or a discharge line of the control valve to build up a control pressure that acts toward a reduction of the displacement volume. ### Claim 9 (depends on 5) The hydrostatic positive displacement machine as recited in claim 5, wherein the pressure sequence valve is pressurized on the input side by a throttling device with the hydraulic fluid from the working circuit. ### Claim 10 (depends on 1) The hydrostatic positive displacement machine as recited in claim 1, wherein the positive displacement machine is a pump that is variable in both directions and is operated in a closed circuit, and wherein the swivel-back device is active in one direction of swiveling or both directions of swiveling of the pump. ### Claim 11 (depends on 1) A hydrostatic traction drive comprising a positive displacement machine as claimed in claim 1 in the form of a pump. ### Claim 12 (depends on 11) A mobile work machine with a hydrostatic traction drive as recited in claim 11. ### Claim 13 (depends on 1) The hydrostatic positive displacement machine as recited in claim 1, wherein the positive displacement machine is an axial piston machine with variable displacement volume. ### Claim 14 (depends on 1) The hydrostatic positive displacement machine as recited in claim 1, wherein the drive machine is an internal combustion engine. ### Claim 15 (depends on 2) The hydrostatic positive displacement machine as recited in claim 2, wherein the pressure sequence valve is actuated by the feed pressure from the feed pressure source toward a closed position in which the connection of the working circuit with the control device is blocked, and is actuated by the pressure of the working circuit toward an open position in which the working circuit is connected with the control device. ### Claim 16 (depends on 2) The hydrostatic positive displacement machine as recited in claim 2, wherein the pressure sequence valve is in communication on the output side with a feed pressure supply line that leads from the feed pressure source to the control valve. ### Claim 17 (depends on 2) The hydrostatic positive displacement machine as recited in claim 2, wherein the pressure sequence valve is in communication on the output side with a control pressure chamber of the variable displacement piston device, which acts toward a reduction of the displacement volume. ### Claim 18 (depends on 6) The hydrostatic positive displacement machine as recited in claim 6, wherein a throttling device is located in a control pressure line or a discharge line of the control valve to build up a control pressure that acts toward a reduction of the displacement volume. ### Claim 19 (depends on 7) The hydrostatic positive displacement machine as recited in claim 7, wherein a throttling device is located in a control pressure line or a discharge line of the control valve to build up a control pressure that acts toward a reduction of the displacement volume. ### Claim 20 (depends on 6) The hydrostatic positive displacement machine as recited in claim 6, wherein the pressure sequence valve is pressurized on the input side by a throttling device with the hydraulic fluid from the working circuit.