GB1313876A - Pressure controlled directional systems for fluid motors - Google Patents

Pressure controlled directional systems for fluid motors

Info

Publication number
GB1313876A
GB1313876A GB3047670A GB3047670A GB1313876A GB 1313876 A GB1313876 A GB 1313876A GB 3047670 A GB3047670 A GB 3047670A GB 3047670 A GB3047670 A GB 3047670A GB 1313876 A GB1313876 A GB 1313876A
Authority
GB
United Kingdom
Prior art keywords
valve
pump
valves
pilot
motor
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
Application number
GB3047670A
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.)
Parker Hannifin Corp
Original Assignee
Parker Hannifin Corp
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Parker Hannifin Corp filed Critical Parker Hannifin Corp
Publication of GB1313876A publication Critical patent/GB1313876A/en
Expired legal-status Critical Current

Links

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
    • F15B11/08—Servomotor systems without provision for follow-up action; Circuits therefor with only one servomotor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B30—PRESSES
    • B30B—PRESSES IN GENERAL
    • B30B15/00—Details of, or accessories for, presses; Auxiliary measures in connection with pressing
    • B30B15/16—Control arrangements for fluid-driven presses
    • 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
    • F15B11/006—Hydraulic "Wheatstone bridge" circuits, i.e. with four nodes, P-A-T-B, and on-off or proportional valves in each link
    • 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
    • F15B13/00—Details of servomotor systems ; Valves for servomotor systems
    • F15B13/02—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors
    • F15B13/04—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors for use with a single servomotor
    • F15B13/0401—Valve members; Fluid interconnections therefor
    • F15B13/0405—Valve members; Fluid interconnections therefor for seat valves, i.e. poppet 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
    • F15B2211/20—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
    • F15B2211/3056—Assemblies of multiple valves
    • F15B2211/30565—Assemblies of multiple valves having multiple valves for a single output member, e.g. for creating higher valve function by use of multiple valves like two 2/2-valves replacing a 5/3-valve
    • F15B2211/30575—Assemblies of multiple valves having multiple valves for a single output member, e.g. for creating higher valve function by use of multiple valves like two 2/2-valves replacing a 5/3-valve in a Wheatstone Bridge arrangement (also half bridges)
    • 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
    • F15B2211/315—Directional control characterised by the connections of the valve or valves in the circuit
    • F15B2211/3157—Directional control characterised by the connections of the valve or valves in the circuit being connected to a pressure source, an output member and a return line
    • F15B2211/31582—Directional control characterised by the connections of the valve or valves in the circuit being connected to a pressure source, an output member and a return line having multiple pressure sources and a single output member
    • 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
    • F15B2211/30—Directional control
    • F15B2211/35—Directional control combined with flow control
    • F15B2211/353—Flow control by regulating means in return line, i.e. meter-out control
    • 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
    • F15B2211/50518—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means using pressure relief 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
    • F15B2211/50—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
    • F15B2211/505—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
    • F15B2211/50545—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means using braking valves to maintain a back 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
    • F15B2211/50—Pressure control
    • F15B2211/505—Pressure control characterised by the type of pressure control means
    • F15B2211/50563—Pressure control characterised by the type of pressure control means the pressure control means controlling a differential pressure
    • F15B2211/50581—Pressure control characterised by the type of pressure control means the pressure control means controlling a differential pressure using counterbalance 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
    • F15B2211/50—Pressure control
    • F15B2211/505—Pressure control characterised by the type of pressure control means
    • F15B2211/50563—Pressure control characterised by the type of pressure control means the pressure control means controlling a differential pressure
    • F15B2211/50581—Pressure control characterised by the type of pressure control means the pressure control means controlling a differential pressure using counterbalance valves
    • F15B2211/5059—Pressure control characterised by the type of pressure control means the pressure control means controlling a differential pressure using counterbalance valves using double counterbalance 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
    • F15B2211/50—Pressure control
    • F15B2211/515—Pressure control characterised by the connections of the pressure control means in the circuit
    • F15B2211/5151—Pressure control characterised by the connections of the pressure control means in the circuit being connected to a pressure source and a directional control 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
    • F15B2211/50—Pressure control
    • F15B2211/515—Pressure control characterised by the connections of the pressure control means in the circuit
    • F15B2211/5153—Pressure control characterised by the connections of the pressure control means in the circuit being connected to an output member and a directional control 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
    • F15B2211/50—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
    • F15B2211/50—Pressure control
    • F15B2211/55—Pressure control for limiting a pressure up to a maximum pressure, e.g. by using a pressure relief 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
    • F15B2211/50—Pressure control
    • F15B2211/57—Control of a differential 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
    • F15B2211/80—Other types of control related to particular problems or conditions
    • F15B2211/86—Control during or prevention of abnormal conditions
    • F15B2211/8606—Control during or prevention of abnormal conditions the abnormal condition being a shock
    • 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
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T137/00—Fluid handling
    • Y10T137/8593—Systems
    • Y10T137/87169—Supply and exhaust
    • Y10T137/87193—Pilot-actuated
    • Y10T137/87201—Common to plural valve motor chambers

Abstract

1313876 Hydraulic motor control circuits PARKER-HANNIFIN CORP 23 June 1970 [30 June 1969] 30476/70 Heading F1P The control circuit of a double acting hydraulic motor 5 Fig. 1 comprises (1) supply valves 3A, 3B having their inlets connected in parallel to a pump 1 and their outlets connected to opposite ends A, B of the motor, (2) return valves 6A, 6B having their inlets and outlets respectively connected to the motor ends A, B and to a return reservoir, (3) a four way closed centre solenoid valve 4 having an inlet port P connected to a pilot pressure pump 2, a tank port T and outlets A', B<1> respectively in conduit connection with pilot passages 11, 19 of supply valve 3B and return valve 6A and with similar pilot passages of valves 3A, 6B; valve 4 when in the neutral position shown serves to connect to tank the upper large area face of the movable valve elements 7, 15 of the supply and return valves thereby closing the latter, and valve 4 when in one or other end position e. g. when moved to the right serves to close valves 3B, 6A and vent the upper large area faces of elements 7, 15 of valves 3A, 6B thus allowing the latter to open and connect the delivery of pump 1 to motor port A and connect motor port B to tank. Pilot pump 2 normally delivers at a pressure above that of pump 1 but in the event of a sudden pressure rise upstream of valves 3A, 3B a portion is passed through a check valve 29 to the pilot circuit and pump 2 delivers through a valve 28 to drain. In a modification wherein the motor is of the differential piston type and wherein the pilot, supply and return valves are housed at 31 Fig. 4 a solenoid valve 47 when moved to the left at the start of the downward stroke of piston 48 connects the return fluid line to the delivery of the main pump 46 and thus augments the supply to motor port A. Also during the downward stroke, at least a part of the pilot pump delivery passes a valve 51 to augment the main pump delivery and thus increases the speed of stroke.
GB3047670A 1969-06-30 1970-06-23 Pressure controlled directional systems for fluid motors Expired GB1313876A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US83785469A 1969-06-30 1969-06-30

Publications (1)

Publication Number Publication Date
GB1313876A true GB1313876A (en) 1973-04-18

Family

ID=25275626

Family Applications (1)

Application Number Title Priority Date Filing Date
GB3047670A Expired GB1313876A (en) 1969-06-30 1970-06-23 Pressure controlled directional systems for fluid motors

Country Status (3)

Country Link
US (1) US3608435A (en)
DE (1) DE2032070A1 (en)
GB (1) GB1313876A (en)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2136055A (en) * 1983-02-25 1984-09-12 Same Spa Hydraulic Feed Circuits for Actuators
US4555220A (en) * 1979-11-07 1985-11-26 Towler Hydraulics, Inc. Regeneration system for a hydraulic intensifier unit
GB2173259A (en) * 1985-02-13 1986-10-08 Hydrolux Sarl Hydraulic control block
GB2194293A (en) * 1986-08-20 1988-03-02 British Nuclear Fuels Plc Improvements in hydraulic lift systems
GB2215700A (en) * 1988-03-16 1989-09-27 Massey Ferguson Mfg Hydraulic circuits
GB2243879A (en) * 1990-03-09 1991-11-13 Kubota Kk Hydraulic circuit for a working vehicle having a plurality of hydraulic actuators
GB2294505A (en) * 1994-10-25 1996-05-01 Nisshin Spinning Hydraulic circuit for driving the ram of a hydraulic press

Families Citing this family (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5032378A (en) * 1973-07-24 1975-03-29
DE2340096B2 (en) * 1973-08-08 1976-03-18 DEVICE FOR CONTROLLING THE PRESSURE AND SPEED OF THE INJECTION PROCESS OF AN INJECTION MOLDING MACHINE FOR THE PROCESSING OF THERMOPLASTIC PLASTICS
US4199293A (en) * 1977-03-07 1980-04-22 Caterpillar Tractor Co. High pressure implement circuit for loader with slow and fast dump position
US4250794A (en) * 1978-03-31 1981-02-17 Caterpillar Tractor Co. High pressure hydraulic system
US4320691A (en) * 1979-11-16 1982-03-23 Caterpillar Tractor Co. Hydraulic load lifting system with hydraulic surcharge to make up valve pilot lines
JPS58501426A (en) * 1981-09-11 1983-08-25 キヤタピラ−　トラツクタ−　カンパニイ Work vehicle hydraulic control circuit with selective pressure stages
EP0312130B1 (en) * 1987-10-05 1993-09-01 Hitachi Construction Machinery Co., Ltd. Hydraulic drive system
DE3804744A1 (en) * 1988-02-16 1989-08-24 Danfoss As CONTROL DEVICE FOR A HYDRAULIC ACTUATOR
DE68917303T2 (en) * 1988-06-10 1995-04-06 Impianti Termoelettrici Ind HYDRAULIC PRESSING DEVICE.
IT1244021B (en) * 1990-11-21 1994-06-28 Siti HYDRAULIC CIRCUIT FOR A PRESSING EQUIPMENT AND PRESSING EQUIPMENT USING THE HYDRAULIC CIRCUIT
US7213502B2 (en) * 2005-09-09 2007-05-08 Caterpillar Inc Robustly stable servo-controlled metering poppet valve
DE112010004009A5 (en) * 2009-10-12 2012-08-23 Ixetic Bad Homburg Gmbh HYDRAULIC PUMP ARRANGEMENT

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4555220A (en) * 1979-11-07 1985-11-26 Towler Hydraulics, Inc. Regeneration system for a hydraulic intensifier unit
GB2136055A (en) * 1983-02-25 1984-09-12 Same Spa Hydraulic Feed Circuits for Actuators
GB2173259A (en) * 1985-02-13 1986-10-08 Hydrolux Sarl Hydraulic control block
GB2194293A (en) * 1986-08-20 1988-03-02 British Nuclear Fuels Plc Improvements in hydraulic lift systems
GB2215700A (en) * 1988-03-16 1989-09-27 Massey Ferguson Mfg Hydraulic circuits
GB2243879A (en) * 1990-03-09 1991-11-13 Kubota Kk Hydraulic circuit for a working vehicle having a plurality of hydraulic actuators
GB2243879B (en) * 1990-03-09 1993-12-08 Kubota Kk Hydraulic circuit for a working vehicle having a plurality of hydraulic actuators
US5289680A (en) * 1990-03-09 1994-03-01 Kubota Corporation Two pump hydraulic system with relief valves having different relief pressures
GB2294505A (en) * 1994-10-25 1996-05-01 Nisshin Spinning Hydraulic circuit for driving the ram of a hydraulic press
GB2294505B (en) * 1994-10-25 1998-04-08 Nisshin Spinning Hydraulic circuit for driving a ram of hydraulic press

Also Published As

Publication number Publication date
DE2032070A1 (en) 1971-01-21
US3608435A (en) 1971-09-28

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Legal Events

Date Code Title Description
PS Patent sealed [section 19, patents act 1949]
PLE Entries relating assignments, transmissions, licences in the register of patents
PCNP Patent ceased through non-payment of renewal fee