US3817153A - Hydraulic control circuit - Google Patents

Hydraulic control circuit Download PDF

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Publication number
US3817153A
US3817153A US00292696A US29269672A US3817153A US 3817153 A US3817153 A US 3817153A US 00292696 A US00292696 A US 00292696A US 29269672 A US29269672 A US 29269672A US 3817153 A US3817153 A US 3817153A
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United States
Prior art keywords
pressure
valve
idling
conduit
hydraulic
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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US00292696A
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English (en)
Inventor
E Zunzer
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Bosch Rexroth AG
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GL Rexroth GmbH
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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
    • F15B11/16—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors
    • F15B11/17—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors using two or more pumps
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B1/00—Installations or systems with accumulators; Supply reservoir or sump assemblies
    • F15B1/02—Installations or systems with accumulators
    • F15B1/027—Installations or systems with accumulators having accumulator charging devices
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
    • F15B2211/205—Systems with pumps
    • F15B2211/2053—Type of pump
    • F15B2211/20546—Type of pump variable capacity
    • F15B2211/20553—Type of pump variable capacity with pilot circuit, e.g. for controlling a swash plate
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
    • F15B2211/205—Systems with pumps
    • F15B2211/20576—Systems with pumps with multiple pumps
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
    • F15B2211/25—Pressure control functions
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/31—Directional control characterised by the positions of the valve element
    • F15B2211/3105—Neutral or centre positions
    • F15B2211/3116—Neutral or centre positions the pump port being open in the centre position, e.g. so-called open centre
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/30—Directional control
    • F15B2211/32—Directional control characterised by the type of actuation
    • F15B2211/329—Directional control characterised by the type of actuation actuated by fluid pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/635—Circuits providing pilot pressure to pilot pressure-controlled fluid circuit elements
    • F15B2211/6355—Circuits providing pilot pressure to pilot pressure-controlled fluid circuit elements having valve means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/67—Methods for controlling pilot pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/71—Multiple output members, e.g. multiple hydraulic motors or cylinders
    • F15B2211/7142—Multiple output members, e.g. multiple hydraulic motors or cylinders the output members being arranged in multiple groups

Definitions

  • a plurality of valve units each including a plurality of [4 June 18, 1974 main valves connected in series in an idling conduit connecting the outlet of a control pump with a discharge space, is used for supplying hydraulic consumer motors with pressure fluid.
  • Each main valve has an idling position for connecting the outlet of the pump with the discharge space through the idling conduit, and two operative positions for supplying and discharging fluid from the respective consumer motor, and for closing the idling circuit.
  • Each main valve includes hydraulic operating means for shifting the main valve between idling and operative positions.
  • a plurality of control valves supplies fluids to and discharge fluids from the hydraulic operating means, and a pressure control unit connects the idling conduit with the control valves.
  • the pressure control unit includes a pressure reducing valve, a pressure fluid accumulator, a check valve between the accumulator and the pressure reducing valve so that a selected pressure is maintained in the hydraulic operating means when the respective main valve is in one of the operating positions.
  • a pressure limiting valve is arranged downstream of the pressure reducing valve, and has a higher pressure than the same.
  • a pressurizing valve is provided between the idling conduit and the discharge space for maintaining a pressure in the idling conduit by which the operation of the operating means is started.
  • the present invention relates a hydraulic control circuit for hydraulic operation of the type in which the pressure fluid flows back to a low pressure container in the position of rest of control valves. Hydraulic control circuits of this type are advantageously used for movable hydraulic apparatus, such as dredging apparatus.
  • the pressure fluid for the control valves which control the main valves is supplied by a gear pump which is independent of a main pump. It is also known to operate the control valves directly by pressure fluid taken from the main pump, eliminating a separate control pump.
  • the control pressure fluid is taken from the main operating fluid between the pump for the operating fluid and a control valve by means of an adjustable throttle together with a pressure limiting valve which is adjusted to a position corresponding to the maximum control pressure. If there is no control fluid required, the control fluid is returned through the pressure limiting valve to the low pressure discharge container.
  • a pressure controlled check valve with a throttle is disposed in the conduit leading to the discharge container.
  • the flow of working fluid is throttled by the throttle to such an extent that the pressure required for the operation of the main valve, is obtained.
  • the prior art apparatus of the type in which the control fluid for operating the main valves is influenced by the main flow of working fluid detrimentally affects the total efficiency of the hydraulic apparatus, since part of the control pressure fluid flows back to the low pressure container without being used, while in another case the pressure level downstream of the main valve must be maintained at a high level. In addition to this loss of efficiency, the developed heat loss must be compensated by the control pressure fluid.
  • control valves by which the positions of the main valves are controlled include a pressure reducing valve and a pressure fluid accumulator, a check valve being provided between the pressure fluid accumulator and the pressure reducingvalve. Due to the fact that the pressure of the circulating fluid, and the initial control pressure for operating the main valves correspond to each other, it is assured that the main valves can be operated starting with the initial position.
  • the higher control pressure required after starting of the shifting of the main valves is obtained by throttling the circulating working fluid which causes a higher pressure in the sure is sufficient to move the main valves to the desired position.
  • the pressure-reducing valve limits the pressure of the control fluid, and the additionally provided pressure fluid accumulator assures an operation of the main valves, for example for lowering a load to the ground, even if the pump fails.
  • the pressure fluid is taken from the main flow through each of the pumps, and supplied to the pressure reducing valve by a double check valve having two inlets and an outlet connected with the pressure reducing valve.
  • a double check valve having two inlets and an outlet connected with the pressure reducing valve.
  • FIG. 1 is a diagramatic view schematically illustrating a hydraulic control circuit in accordance with an embodiment of the invention, serving for operating a dredging apparatus;
  • FIG. 2 is a sectional view taken on line Il--II in FIG. 3, and illustrating a pressure control unit in accordance with the invention.
  • FIG. 3 is a sectional view taken on line III-Ill in FIG. 2.
  • a pump unit 1 includes two hydraulic pumps 3 and 4 whose displaced volume can be adjusted by operation of a setting cylinder and piston means 5.
  • An electric motor 6 drives the two pumps 3 and 4.
  • Pumps 3 and 4 pump pressure fluid through conduits 7 and 12 to the inlets P1 and P2, respectively, of two valve units 11 and 16.
  • the pressure conduit 7 flows through an idling conduit 23, 24, 25, 26 through three main valves 8, 9 and 10, when the main valves 8, 9 and 10 are in the illustrated idling position. From the point T the fluid flows through conduit 27 and discharge conduit 27a, and through pressurizing valves 55 and a check valve 55a into the low pressure discharge container T from which pumps 3 and 4 suck fluid.
  • Conduit 12 is connected at the point P of valve unit 16, with pressure fluid flowing through the idling conduit 28, 29,. 30, 31 and through the main valves 13, 14, 15 in the illustrated idling position to the point T which is connected by conduit 32 and discharge conduit 27a with the above-described pressurizing valve means 55 and 55a.
  • Each of the main valves 8 to 10 and 13 to 15 has, in addition to the illustrated idling position, two operative positions for supplying and discharging pressure fluid to associated hydraulic consumer apparatus 17 to 19 and 20 to 22, the flow being reversed in the two operative positions of the respective main valve.
  • the working conduits A8 and B8 are connected with the vehicle drive means 17 on the left side of the vehicle, and the conduits A13 and B13 are connected with the vehicle drive means 20 on the right side of the vehicle.
  • the working conduits A9 and B9 of the main valve 9 are connected with an hydraulic cylinder and piston motor 18 which operates the arm of the dredging apparatus, and the working conduits A10 and B10 of the main valve are connected with a hydraulic cylinder and piston motor 19 which operates the scoop of the dredging apparatus.
  • the working conduits A14 and B14 of main valve 14 are connected with a rotary hydraulic motor 21, and the working conduits A15 and B15 of main valve 15 are connected with the hydraulic cylinder and piston motor 22 by which the boom is operated.
  • the conduit sections 23, 24, 25 and 26 are connected with each other by the main valves in the idling position, so that the fluid from pumps 3 and 4 can flow through idling conduits 7, 23, 24, 25, 26, 27 and 12, 28, 29, 30, 31, and 32 between the pump and the low pressure discharge conduit 27a and discharge container T.
  • the pressurizing valves 55 maintain certain pressure in the idling conduits, and the check valve 55a prevents return flow from the tank.
  • a pressure conduit 70 branches off the pump conduit 7, and a pressure conduit 120 branches off the pump conduit 12.
  • Conduits 7a and 12a are connected to inlets of a pressure control unit 2, which is shown schematically in FIG. 1 and in detail in FIGS. 2 and 3. As best seen in FIG. 3, the two inlets 7a and 12a cause the ball of the double check valve 33 to assume such a position that flow into the pressure control unit 2 is possible only from the one of the conduits 7a and 12a in which the greater pressure prevails.
  • the outlet 33a of the double check valve 33 is connected with a pressure reducing valve 34, and the fluid at reduced pressure flows through a conduit 35 and the check valve 36 to three control valve units 37, 38, and 39, each of which contains four control valves 40 to 43, 44 to 47, and 48 to 51.
  • Control valves 40 and 43 are connected by control conduits 40a and 43a to pressure chambers 9a and 9b of the main valve 9 so that the valve slide piston, not shown, of main valve 9 is shifted, as desired, between the illustrated idiing position, and two operative positions in which the respective hydrauilc consumer motor 18 is operated in forward or rearward direction, respectively.
  • control valves 41 and 42 of the control valve unit 37 are connected by control conduits 41a, 42a to the control chambers 10a, 10b of the main valve 10 cooperating with the hydraulic consumer motor 19.
  • the control valves 44 and 45 of the control valve unit 38 are connected by control conduits 44a, 450 with the control chambers 8a, 8b of the hydraulic consumer motor 17 which drives the left drive means of the vehicle, while the control valves 46 and 47 of the same control valve unit 38 are connected by control conduits 46a, 47a with the control chambers 13a, 13b of the main valve 13 which is associated with the hydraulic motor 20 by which the drive means on the right side of the vehicle are operated.
  • control valves 48, 51 of the control valve unit 39 are connected by control conduits 48a, 51a with the control chambers 15a, 15b of the hydraulic motor 22 for operating the boom of the dredging apparatus under the control of main valve 15, and the control valves 49 and 50 are connected by control conduits 49a, 50a with the control chambers 14a, 14b of the main valve 14 operating the rotary hydraulic apparatus 21 by which a support of a dredging apparatus is rotated.
  • the predetermined pressure produced and maintained in this manner in the idling conduit corresponds to the control pressure required in the initial operation of the main valves out of the illustrated circulation position toward one of the two operative positions.
  • a throttling of the flow cross section takes place which causes a further pressure increase in the respective pressure conduit 7 or 12 of the pumps 3 or 4.
  • This pressure increase is sufiicient for operating a respective main valve toward one or the other selected operative end position.
  • the hydraulic motors 17, 20, 21 and 18, 19, 22 are operated by pressure fluid, resulting in an average pressure corresponding to the power load of the hydraulic consumer motors 17 to 19 and 20 to 22.
  • the pressure reducing valve 34 in the pressure control unit 2 maintains the fluid pressure independently of the magnitude of the pressure of the fluid in the working conduits and in the consumer apparatus.
  • the fluid pressure accumulator 52 is charged.
  • the check valve 36 prevents a discharge of the fluid from pressure fluid accumulator 52 into the pressure conduits 7 and 12, so that an amount of pressure fluid is maintained in the accumulator for an emergency operation of the main valves 8 to 10 and 13 to 15.
  • a pressure limiting valve 53 which is arranged downstream of the pressure reducing valve 34, is set to a slightly higher pressure than the pressure reducing valve 34. Due to this arrangement, the supply of control fluid to the control valves 40 to 51 is assured, while at the same time during normal operations, a discharge of fluid is effectively prevented.
  • FIGS. 2 and 3 illustrate the pressure control unit 2 in detail, and it will be seen that a block 54 is provided with threaded bores 54a, 54b in which threaded plugs 12a and 12b are mounted which form the inlet conduits 7a and 12a of the double check valve 33 whose outlet is connected with the pressure reducing valve 34, which includes a spring 34a, as best seen in FIG. 2. Downstream of the pressure reducing valve 34, the pressure limiting valve 53 includes a spring 53a acting on a pointed valve member cooperating with a valve seat 53b. A discharge conduit 530 communicates with a low pressure discharge container T.
  • the pressure control unit illustrated in FIG. 2 and 3 requires only connectors for the branch conduits 12a and 7a, and for the conduit 35 which is connected with the control valves 40 to 51.
  • the pressure fluid accumu lator 52 has a threaded portion secured in a threaded bore 52a of the block 54.
  • the accumulator is connected with the conduit 35 via the valve body 36 which is provided with a (not visible) blind bore.
  • the latter communicates via bores 36a and via bores 360 of the member 36b with a space 35d, which in turn communicates with outlet 35c (FIG. 3) leading to conduit 35.
  • the threaded connectors permit a very quick connection of the pressure control unit 2 with the respective conduits.
  • valve units 11 and 16 Only two valve units 11 and 16 have been shown, but it is understood that a greater number could be provided. If more than two pumps 3 and 4 are provided, the check valve means 33 have to be accordingly constructed to permit flow into the pressure control unit 2 only from the pump operating at the highest pressure.
  • Hydraulic control circuit comprising a control pump having an outlet for pressure fluid; a discharge space; idling conduit means between said outlet of said pump and said discharge space; at least one valve unit including a plurality of main valve means connected in series in said idling conduit, and being respectively associated with hydraulic consumer motors, each main valve means having an idling position for connecting said outlet of said pump with said discharge space through said idling conduit, and at least one operative position for supplying fluid to, and discharging fluid from the respective consumer motor, and for closing said idling conduit, each main valve means including hydraulic operating means for shifting said main valve means between said idling and operative positions; a plurality of control valve means for supplying fluid to, and for discharging fluid from said hydraulic operating means, respectively; and a pressure control unit connecting said outlet of said pump and idling circuit with said control valve means so that in said idling position the initial pressure in said idling conduit starts said operating means, said pressure control unit including pressure reducing valve means, a pressure
  • Hydraulic control circuit as claimed in claim 1 comprising pressurizing valve means between said idling conduit and said discharge space for maintaining a pressure in said idling conduit in said idling position of said control valve means.
  • Hydraulic control circuit as claimed in claim 2 wherein said pressurizing valve means includes a check valve opening towards said discharge space.
  • Hydraulic control circuit as claimed in claim 1 wherein said pressure control unit includes a pressure limiting valve downstream of said pressure reducing valve, said pressure limiting valve being set to a higher pressure than said pressure reducing valve.
  • Hydraulic control circuit as claimed in claim 1 comprising two control pumps; two idling conduits; two valve units; and wherein said pressure control unit includes a shiftable double check valve having two inlets connected near outlets of said pumps with said idling conduits, respectively, and one outlet connected with said pressure reducing valve means.
  • Hydraulic control circuit as claimed in claim 5 wherein said pressure control unit includes a pressure limiting valve downstream of said pressure reducing valve, said pressure limiting valve being set to a higher pressure than said pressure reducing valve means; and wherein said pressure control unit includes a valve block formed with bores in which said pressure reducing valve means, said pressure limiting valve means, and said double check valve are located, and having a threaded bore into which said accumulator is threaded.
  • each main valve means has two operative positions and said idling position; and wherein said consumer motors are reversed in said two operative positions.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Fluid-Pressure Circuits (AREA)
  • Operation Control Of Excavators (AREA)
US00292696A 1971-09-29 1972-09-27 Hydraulic control circuit Expired - Lifetime US3817153A (en)

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DE2148502A DE2148502B2 (de) 1971-09-29 1971-09-29 Ein- oder mehrkreisiges Hydrauliksystem

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Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4024797A (en) * 1975-10-28 1977-05-24 Caterpillar Tractor Co. Spring centered balanced resolver valve
US4306413A (en) * 1975-06-30 1981-12-22 The United States Of America As Represented By The Secretary Of The Navy Hydraulic power and control system
EP0056024A1 (de) * 1980-06-16 1982-07-21 Caterpillar Tractor Co Druckminderventil mit frei beweglichem stössel für die nachfüllung.
US4341243A (en) * 1980-06-16 1982-07-27 Caterpillar Tractor Co. Pressure reducing valve with floating stem for make-up vent
US4367624A (en) * 1979-02-20 1983-01-11 Kabushiki Kaisha Komatsu Seisakusho Control system for hydraulic actuator
US4498370A (en) * 1982-02-22 1985-02-12 Vickers, Incorporated Power transmission
US4535681A (en) * 1983-05-31 1985-08-20 Kabushiki Kaisha Komatsu Seisakusho Fluid operated transmission control system
US4638720A (en) * 1980-12-01 1987-01-27 Deere & Company Electro-hydraulic control system
US4738103A (en) * 1986-02-04 1988-04-19 Chs Vickers S.P.A. Hydraulic control circuit for working members of earth-moving machines with centralized braking of the actuators
US4986165A (en) * 1989-08-29 1991-01-22 Kabushiki Kaisha Kobe Seiko Sho Hydraulic shovel control circuit with operating pattern switching valve
US20050229594A1 (en) * 2004-03-31 2005-10-20 Kobelco Construction Machinery Co., Ltd. Hydraulic control system and construction machine
CN107075823A (zh) * 2014-09-25 2017-08-18 D·巴特尔特 人工侵蚀储水水域的方法
US20230193931A1 (en) * 2020-05-22 2023-06-22 Volvo Construction Equipment Ab Hydraulic machine

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3271311D1 (en) * 1981-03-03 1986-07-03 Hitachi Construction Machinery Hydrostatic drive system for civil engineering and construction machinery
JPS58146630A (ja) * 1982-02-25 1983-09-01 Hitachi Constr Mach Co Ltd 油圧作業機械の油圧回路
DE3420674C2 (de) * 1984-06-02 1986-10-02 Danfoss A/S, Nordborg Druckversorgungseinrichtung für ein Hydrauliksystem
DE3901207C2 (de) * 1989-01-17 1994-06-23 Rexroth Mannesmann Gmbh Ventilanordnung für mehrere hydraulische Antriebe, insbesondere für die Antriebe eines Krans
DE3901349A1 (de) * 1989-01-18 1990-07-19 Rexroth Mannesmann Gmbh Ventilanordnung fuer mehrere hydraulische verbraucher
DE19526909A1 (de) * 1995-07-22 1997-01-23 Rexroth Mannesmann Gmbh Hydraulische Antriebseinrichtung
CN105443480B (zh) 2014-08-12 2017-09-08 徐工集团工程机械股份有限公司 工作联阀体结构及比例多路阀

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Publication number Priority date Publication date Assignee Title
US2669842A (en) * 1951-03-31 1954-02-23 Goodman Mfg Co Emergency operated dual pressure hydraulic system
US3620129A (en) * 1970-07-15 1971-11-16 Gen Signal Corp Hydraulic power circuit with emergency lowering provisions
US3693350A (en) * 1971-01-11 1972-09-26 Commercial Shearing Hydraulic control circuits and apparatus
US3720059A (en) * 1969-10-15 1973-03-13 Linde Ag Hydraulic system and valve therefor

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2669842A (en) * 1951-03-31 1954-02-23 Goodman Mfg Co Emergency operated dual pressure hydraulic system
US3720059A (en) * 1969-10-15 1973-03-13 Linde Ag Hydraulic system and valve therefor
US3620129A (en) * 1970-07-15 1971-11-16 Gen Signal Corp Hydraulic power circuit with emergency lowering provisions
US3693350A (en) * 1971-01-11 1972-09-26 Commercial Shearing Hydraulic control circuits and apparatus

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4306413A (en) * 1975-06-30 1981-12-22 The United States Of America As Represented By The Secretary Of The Navy Hydraulic power and control system
US4024797A (en) * 1975-10-28 1977-05-24 Caterpillar Tractor Co. Spring centered balanced resolver valve
US4367624A (en) * 1979-02-20 1983-01-11 Kabushiki Kaisha Komatsu Seisakusho Control system for hydraulic actuator
EP0056024A1 (de) * 1980-06-16 1982-07-21 Caterpillar Tractor Co Druckminderventil mit frei beweglichem stössel für die nachfüllung.
US4341243A (en) * 1980-06-16 1982-07-27 Caterpillar Tractor Co. Pressure reducing valve with floating stem for make-up vent
EP0056024A4 (de) * 1980-06-16 1983-10-06 Caterpillar Tractor Co Druckminderventil mit frei beweglichem stössel für die nachfüllung.
US4638720A (en) * 1980-12-01 1987-01-27 Deere & Company Electro-hydraulic control system
US4498370A (en) * 1982-02-22 1985-02-12 Vickers, Incorporated Power transmission
US4535681A (en) * 1983-05-31 1985-08-20 Kabushiki Kaisha Komatsu Seisakusho Fluid operated transmission control system
US4738103A (en) * 1986-02-04 1988-04-19 Chs Vickers S.P.A. Hydraulic control circuit for working members of earth-moving machines with centralized braking of the actuators
US4986165A (en) * 1989-08-29 1991-01-22 Kabushiki Kaisha Kobe Seiko Sho Hydraulic shovel control circuit with operating pattern switching valve
US20050229594A1 (en) * 2004-03-31 2005-10-20 Kobelco Construction Machinery Co., Ltd. Hydraulic control system and construction machine
US7174711B2 (en) * 2004-03-31 2007-02-13 Kobelco Construction Machinery Co., Ltd. Hydraulic control system and construction machine
CN107075823A (zh) * 2014-09-25 2017-08-18 D·巴特尔特 人工侵蚀储水水域的方法
US10450711B2 (en) * 2014-09-25 2019-10-22 Dietrich Bartelt Method for artificially eroding dammed bodies of water
US20230193931A1 (en) * 2020-05-22 2023-06-22 Volvo Construction Equipment Ab Hydraulic machine

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DE2148502A1 (de) 1973-04-05
DE2148502B2 (de) 1978-11-02

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