US3916624A - Hydraulic controls - Google Patents

Hydraulic controls Download PDF

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Publication number
US3916624A
US3916624A US523378A US52337874A US3916624A US 3916624 A US3916624 A US 3916624A US 523378 A US523378 A US 523378A US 52337874 A US52337874 A US 52337874A US 3916624 A US3916624 A US 3916624A
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US
United States
Prior art keywords
pressure
valve
hydraulic
circuit
auxiliary
Prior art date
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
Application number
US523378A
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English (en)
Inventor
Karl-Heinz Machens
Erich Reupke
Gerhard Isensee
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
HANOMAG A CORP OF GERMAY GmbH
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Massey Ferguson Services NV
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Filing date
Publication date
Priority claimed from DE19732356809 external-priority patent/DE2356809C3/de
Application filed by Massey Ferguson Services NV filed Critical Massey Ferguson Services NV
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Publication of US3916624A publication Critical patent/US3916624A/en
Assigned to HANOMAG GESELLSCHAFT MIT BESCHRAENKTER HAFTUNG, A CORP. OF GERMAY reassignment HANOMAG GESELLSCHAFT MIT BESCHRAENKTER HAFTUNG, A CORP. OF GERMAY ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: MASSEY-FERGUSON SERVICES N.V.
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Expired - Lifetime legal-status Critical Current

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Classifications

    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/08—Superstructures; Supports for superstructures
    • E02F9/0841—Articulated frame, i.e. having at least one pivot point between two travelling gear units
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/22—Hydraulic or pneumatic drives
    • E02F9/2203—Arrangements for controlling the attitude of actuators, e.g. speed, floating function
    • E02F9/2207—Arrangements for controlling the attitude of actuators, e.g. speed, floating function for reducing or compensating oscillations
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/22—Hydraulic or pneumatic drives
    • E02F9/2221—Control of flow rate; Load sensing arrangements
    • E02F9/2239—Control of flow rate; Load sensing arrangements using two or more pumps with cross-assistance
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/22—Hydraulic or pneumatic drives
    • E02F9/2278—Hydraulic circuits
    • E02F9/2292—Systems with 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
    • 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
    • F15B21/00—Common features of fluid actuator systems; Fluid-pressure actuator systems or details thereof, not covered by any other group of this subclass
    • F15B21/08—Servomotor systems incorporating electrically operated control 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
    • F15B2211/20—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
    • F15B2211/30—Directional control
    • F15B2211/305—Directional control characterised by the type of valves
    • F15B2211/30505—Non-return valves, i.e. check valves
    • 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
    • F15B2211/50—Pressure control
    • F15B2211/505—Pressure control characterised by the type of pressure control means
    • F15B2211/50509—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means
    • F15B2211/50536—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means using unloading valves controlling the supply pressure by diverting fluid to the return line
    • 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
    • F15B2211/50—Pressure control
    • F15B2211/52—Pressure control characterised by the type of actuation
    • F15B2211/528—Pressure 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
    • F15B2211/63—Electronic controllers
    • F15B2211/6303—Electronic controllers using input signals
    • F15B2211/6306—Electronic controllers using input signals representing a pressure
    • F15B2211/6313—Electronic controllers using input signals representing a pressure the pressure being a load 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
    • F15B2211/63—Electronic controllers
    • F15B2211/6303—Electronic controllers using input signals
    • F15B2211/634—Electronic controllers using input signals representing a state of a valve
    • 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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S60/00—Power plants
    • Y10S60/911—Fluid motor system incorporating electrical system

Definitions

  • ABSTRACT [30] Foreign Application Priority Data Nov. 14 1973 Germany 2356809
  • a hydraulic circuit Particularly useful for a loader hicle is provided with a main pump and an auxiliary 52 us. c1. 60/394; 60/428; 60/468; P The flew of the euxlhery m may he e e' 60/486. 60/1316. 2 tively added to the flow of the mam pump but 18 di- 51 lm. cl. i151; 11/16 verted to the reservoir if the system Pressure rises [58] Field of Search 60/394 421 428 430 above a predetermined level. A delay device is incor- 60/468 4 porated in the control to prevent rapid switches of the v auxiliary pump into and out of the main circuit and so [56] References Cited prevent undesirable vibrations in the loader vehicle.
  • Sheet 3 of 4 U.S. Patent Nov. 4, 1975 nvnmuuc contracts The invention relates to hydraulic controls especially those used for heavy construction vehicles which are equipped with hydraulically operated ancillary implements such as buckets, blades or forks.
  • German Offenlegungschrifft No. 2,012,752 for such vehicles to be equipped with an engine-driven hydraulic pump for supplying an implement circuit and a standby pump the flow from which can be added or cut-in to the hydraulic system for the purpose of providing additional capacity for special circumstances of operation.
  • the cut-in of the standby pump ensures that for each operating condition there is a sufficient but not excessive machine capacity available to deal with it.
  • the pressure in, for instance, the implement circuit reaches a certain predetermined value the standby pump flow is cut-out and is returned directly to the tank.
  • the object of the present invention is to obviate or mitigate the above disadvantages.
  • a hydraulic control system comprising a reservoir for hydraulic fluid, a main pump, a fluid pressure actuator and a control valve for control of pressure fluid therebetween, an auxiliary pump and an auxiliary valve means adapted to channel pressure fluid from said auxiliary puinp alternatively into said circuit or to the reservoir, control means for conditioning said auxiliary valve means in response to the presence or absence of a pressure level of predetermined value in said actuator wherein said control means incorporates a time delay device which is operative to delay the change in condition of said auxiliary valve means when the pressure level reaches said predetermined value.
  • FIG. 1 is a side elevation of a typical machine to which the present invention would be applicable.
  • FIG. 2 is a plan view of the machine of FIG. 1 and illustrates the disposition of the hydraulic cylinders that are involved.
  • FIG. 3 is a diagrammatic illustration of a first hydraulic circuit.
  • FIGS. 4 and 5 are diagrammatic native hydraulic circuits.
  • FIGS. 1 and 2 show an articulated wheeled loader 30 having two pairs of driving wheels 31 supporting the illustrations of alterfront body 32 and the rear body 33.
  • the two bodies are joined together at the pivot 34.
  • the front body 32 carries a drivers cab 35, a pair of lift arms 36, a bucket 37 pivotted on the end of the lift arms 36, a bucket tilt linkage 38 mounted on the lift arms and connected to the bucket 37, hydraulic bucket cylinders 9 for moving the tilt linkage 38 and bucket 37, and hydraulic lift cylinders 10 for raising and lowering the lift arms.
  • the rear body 33 supports the engine and transmission assembly which is hidden beneath the hood 41.
  • the engine also drives the hydraulic pumps.
  • the front and rear bodies are pivotable with respect to each other to effect steering by means of a pair of steering cylinders 42 disposed on opposite sides of pivot 34.
  • the bucket In use the bucket is loaded by driving it into a pile of material, tilting the bucket back by extending bucket cylinder 9 followed by reversing out of the pile. Simultaneously with reversing or other movement of the loader 30 the cylinders 10 are used to raise the load to a sufficient height for dumping e.g. into a truck. If the bucket is carrying its maximum load the bouncing movement along uneven terrain may cause high pressure peaks in the hydraulic circuit. These pressure peaks cause the undesirable vibration and oil heating effects which have been previously referred to and which are now mitigated by the present invention. This condition can be met if an unusually high load is applied suddenly to the bucket e.g. if a large rock falls on to the bucket whilst the loader is working at the rockface.
  • FIGS. 3, 4 and 5 the symbols used are in accordance with International Standards Office Publication No. R 2917. All controls are shown in their inactive positions.
  • the arrangement shown in FIG. 3 comprises an engine-driven hydraulic pump P1 which draws hydraulic flud from tank 19 via line 1 and delivers it via lines 2 and 3 to a control unit 4.
  • Control spool-valve 4a is contained within the unit 4 and this is adapted to supply pressure fluid to one of lines 5 and 5a.
  • Control spool valve 4b serves a similar purpose for lines 6 and 6a.
  • Lines 5 and 5a serve a hydraulic actuator 9 and lines 6 and 6a serve actuator 10.
  • the actuator 9 is the bucket cylinder and the actuator 10 is the boom lift cylinder of the machine shown in FIGS. 1 and 2.
  • the control unit 4 also includes a pressure relief valve 41: which is adapted to protect the circuit.
  • An engine driven standby pump P2 is also provided. This delivers into a pressure line 17 and through a nonreturn valve 15 into line 3. Pressure line 17 and return line 18 are connected together by a normally open pressure control valve 14.
  • This valve 14 is a pilot operated valve which is spring loaded to the open position and on receipt of a pressure signal it closes. The signal is provided by means of a three port two position valve 16 which is connected to pressure line 3, to return line 18, and to valve 14 and is spring loaded in a direction such that in its normal condition zero pressure is applied to valve 14.
  • a solenoid 16a is employed to alter the valve 16 against the spring so that pressure from line 3 is applied to valve 14.
  • Pressure in cylinder 10 is constantly applied to a valve actuator 11a which, at a predermined pressure level, is adapted to close an electrical switch 11.
  • the pressure level at which the electrical switch 11 closes is pre-set at the factory.
  • the switch 11 is in an electrical circuit 12 which begins at the electric battery 50 and includes in series a time delay device 13a and a solenoid 13c which operates on being energized to open an electric switch 13d.
  • a second electrical circuit 13b includes in series the switch 13d and solenoid 16a.
  • a master switch 51 which is closed when the engine is started also makes the circuit 13b live and energizes solenoid 16a to change valve 16 so that pressure from line 3 is adapted to close control valve 14.
  • the open centre spool valve 4a is manually operated and spring centred and is in series flow connection with a similar valve 4b.
  • valve 14 In operation let it be assumed that the bucket has been filled and is being lifted by cylinder 10. The pressure in cylinder is applied to the pressure control valve 14 via valve 16 and accordingly valve 14 is in a condition where it prevents flow from pump P2 passing to the tank and causes the flow to pass into pressure line 3.
  • the delay introduced by the device 13 prevents transient pressure surges from cutting flow from pump P2 out of the implement hydraulic circuit and consequently the occurrence of harmful vibrations.
  • the second electrical circuit 13b which includes solenoid 16a incorporates two further switches and 21.
  • Switchs 20, 21 are operated by spool valves 4a and 41; respectively in either direction away from their mid-positions.
  • the two switches 20 and 21 are in parallel.
  • valve 16 permits valve 14 to remain in its normally open position and solenoid 16a has to be energized to enable pressure from line 3 to close valve 14.
  • the main work pump P1 supplies flow for the implement hydraulic circuit
  • the stand-by pump P2 supplies additional flow thereto
  • a steering pump P3 supplies the steering hydraulic circuit 17b which includes steering cylinders 42.
  • a steering wheel actuated valve 43 controls the flow to cylinder 42.
  • the pumps P2 and P3 draw fluid through line 17a.
  • Pump P3 delivers to circuit 17b which contains a throttle 2212.
  • Pressure sensing lines 220 are applied to valve actuators 22d which operate on a flow divider valve 22a.
  • This flow divider valve 22a receives the flow from standby pump P2 through line 170.
  • valve 22a In the condition where the engine is running at high speed and there is no demand from the steering valve the pressure downstream of throttle 22b will be almost zero and the lower actuator 22d will cause valve 22a to take up the third position where all the flow from P2 is diverted to valve 14 where it may or may not be diverted to assist the flow from P1 depending on the condition of switches 20, 21 and 11 as explained previously with reference to FIG. 4.
  • a hydraulic control system comprising a reservoir for hydraulic fluid, a main pump, a fluid pressure actuator and a control valve for control of pressure fluid therebetween, an auxiliary pump and an auxiliary valve means adapted to channel pressure fluid from said auxiliary pump alternatively into said circuit or to the reservoir, control means for conditioning said auxiliary valve means including a conduit for sensing the pressure of said actuator in response to a pressure level of predetermined value in said actuator wherein said control means incorporates a time delay device which is operative in response to the pressure in said conduit to delay the change in condition of said auxiliary valve means when the pressure level reaches said predetermined value.
  • control means includes i. a first circuit having the time delay device, a pressure sensitive switch responsive to presssure in the fluid pressure actuator and a first electric actuator for a second switch,
  • a second circuit including said second switch and a second electric actuator and iii. a hydraulic valve movable between first and second positions by said second electric actuator so that presence of a pressure in excess of a predetermined pressure in said fluid pressure actuator causes after a delay said hydraulic valve to move from its first position in which it maintains said auxiliary valve means in a position where auxiliary pump flow enters said circuit, to a second position in which auxiliary pump flow is channelled to the reservoir.
  • a hydraulic control system according to claim 1 wherein said time delay device is operative to delay the conditioning of said auxiliary valve means from a condition where it is channelling pressure fluid into said 7.
  • a hydraulic system according to claim 1 in which the pressure sensitive switch is positioned between the control valve and the main pump.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mining & Mineral Resources (AREA)
  • Civil Engineering (AREA)
  • Structural Engineering (AREA)
  • Fluid Mechanics (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Fluid-Pressure Circuits (AREA)
  • Operation Control Of Excavators (AREA)
  • Servomotors (AREA)
US523378A 1973-11-14 1974-11-13 Hydraulic controls Expired - Lifetime US3916624A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19732356809 DE2356809C3 (de) 1973-11-14 Hydraulikanlage für Fahrzeuge, insbesondere Baumaschinen

Publications (1)

Publication Number Publication Date
US3916624A true US3916624A (en) 1975-11-04

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US523378A Expired - Lifetime US3916624A (en) 1973-11-14 1974-11-13 Hydraulic controls

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US (1) US3916624A (pt)
BR (1) BR7409621A (pt)
CA (1) CA1025749A (pt)
ES (1) ES431959A1 (pt)
FR (1) FR2250908B3 (pt)
GB (1) GB1466605A (pt)
IT (1) IT1025707B (pt)

Cited By (29)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4006662A (en) * 1972-11-22 1977-02-08 Danfoss A/S Hydraulic Steering apparatus
US4188772A (en) * 1977-06-06 1980-02-19 Harrington Manufacturing Company Hydraulic speed control system for the pick-up reel of a peanut combine
EP0104613A2 (en) * 1982-09-23 1984-04-04 Vickers Incorporated Power transmission
EP0191275A1 (en) * 1985-02-14 1986-08-20 TRINOVA S.p.A. Anti-saturation system for hydraulic control circuits for working members of earth-moving machines
WO1986006772A1 (en) * 1985-05-08 1986-11-20 Rudolf Hausherr & Söhne Gmbh & Co Kg Switching arrangement for the hydraulic supply of aggregate of a loader
EP0302942A1 (en) * 1987-02-04 1989-02-15 Kabushiki Kaisha Komatsu Seisakusho Front frame of wheeled loader
EP0404946A1 (en) * 1988-05-16 1991-01-02 Kabushiki Kaisha Komatsu Seisakusho Hydraulic circuit device of construction vehicle
US5136846A (en) * 1989-04-18 1992-08-11 Kubota, Ltd. Hydraulic circuit with a switchover valve for switching between a high and a low-pressure relief
WO1993019254A1 (de) * 1992-03-17 1993-09-30 Schneider Hans Sr Verfahren und vorrichtung zum entfernen der kiesschicht auf flachdächern
US5829251A (en) * 1996-07-04 1998-11-03 Fki Fai Komatsu Industries S.P.A. Hydraulic control circuit for working components, in particular in earth-moving machines
US6018895A (en) * 1996-03-28 2000-02-01 Clark Equipment Company Valve stack in a mini-excavator directing fluid under pressure from multiple pumps to actuable elements
US6029446A (en) * 1996-03-28 2000-02-29 Melroe Company Multifunction valve stack
US6241420B1 (en) 1999-08-31 2001-06-05 Caterpillar Paving Products Inc. Control system for a vibratory compactor
US20040079541A1 (en) * 2002-10-23 2004-04-29 Marquardt Lonnie L. Grader attachment for a skid steer
US20050072145A1 (en) * 2003-10-01 2005-04-07 Jervis Mark J. Power conserving hydraulic pump bypass compensator circuit
US20060213715A1 (en) * 2005-03-23 2006-09-28 Clark Equipment Company Self-synchronizing hydraulic system
US20070144819A1 (en) * 2005-03-23 2007-06-28 Clark Equipment Company Passively rephasing piston
US20070163252A1 (en) * 2006-01-13 2007-07-19 Clark Equipment Company Multi-purpose hydraulic system
US20070240413A1 (en) * 2006-04-17 2007-10-18 Clark Equipment Company Fluid circuit with multiple flows from a series valve
EP2065519A1 (en) * 2007-11-29 2009-06-03 Caterpillar Inc. Hydraulic work arm system with boost possibility
US8152407B1 (en) 2010-11-08 2012-04-10 Saudi Arabian Oil Company Auxiliary pressure relief reservoir for crash barrier
US8152406B1 (en) 2010-11-08 2012-04-10 Saudi Arabian Oil Company Crash barrier with over-pressure relief system
US20130074486A1 (en) * 2011-09-22 2013-03-28 Erik W. McWethy Multi-pump system with pump-flow diversion
US20160108937A1 (en) * 2014-10-17 2016-04-21 Mitsubishi Heavy Industries, Ltd. Pressure maintaining apparatus, machine tool, and method of running pressure maintaining apparatus in machine tool
EP3101180A1 (en) * 2015-06-05 2016-12-07 CNH Industrial Italia S.p.A. Hydraulic actuation system for work machine
US20170037602A1 (en) * 2015-08-06 2017-02-09 Caterpillar Inc. Hydraulic System for an Earth Moving Machine
US10352335B2 (en) * 2015-12-22 2019-07-16 Kubota Corporation Hydraulic system of work machine
US10480643B2 (en) * 2016-12-12 2019-11-19 Hyundai Motor Company Hydraulic control system of automatic transmission for vehicle provided with idle stop and go system
US20220364578A1 (en) * 2021-05-12 2022-11-17 HAWE Hydraulik (Wuxi) Co., Ltd. Hydraulic control system

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2535195C2 (de) * 1975-08-07 1985-01-31 Robert Bosch Gmbh, 7000 Stuttgart Hydraulische Steuereinrichtung
GB2215700A (en) * 1988-03-16 1989-09-27 Massey Ferguson Mfg Hydraulic circuits
AT399130B (de) * 1992-03-18 1995-03-27 Hoerbiger Fluidtechnik Gmbh Anordnung zur hydraulischen betätigung eines fahrzeugverdeckes
GB9414694D0 (en) * 1994-07-21 1994-09-07 Thwaites Limited A dumper vehicle

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Publication number Priority date Publication date Assignee Title
US2323519A (en) * 1941-01-24 1943-07-06 Ternstedt Mfg Co Vacuum operated window regulator
US3171247A (en) * 1962-05-24 1965-03-02 Webster Electric Co Inc Motor vehicle and hydraulic system
US3443380A (en) * 1968-01-02 1969-05-13 Allis Chalmers Mfg Co Two-pump system for lift cylinder

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2323519A (en) * 1941-01-24 1943-07-06 Ternstedt Mfg Co Vacuum operated window regulator
US3171247A (en) * 1962-05-24 1965-03-02 Webster Electric Co Inc Motor vehicle and hydraulic system
US3443380A (en) * 1968-01-02 1969-05-13 Allis Chalmers Mfg Co Two-pump system for lift cylinder

Cited By (48)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4006662A (en) * 1972-11-22 1977-02-08 Danfoss A/S Hydraulic Steering apparatus
US4188772A (en) * 1977-06-06 1980-02-19 Harrington Manufacturing Company Hydraulic speed control system for the pick-up reel of a peanut combine
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Also Published As

Publication number Publication date
BR7409621A (pt) 1976-05-25
ES431959A1 (es) 1976-10-16
DE2356809A1 (de) 1975-06-19
GB1466605A (en) 1977-03-09
IT1025707B (it) 1978-08-30
CA1025749A (en) 1978-02-07
FR2250908B3 (pt) 1977-08-12
FR2250908A1 (pt) 1975-06-06
DE2356809B2 (de) 1976-02-19

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