CA980658A - Load control and holding valve - Google Patents

Load control and holding valve

Info

Publication number
CA980658A
CA980658A CA160,862A CA160862A CA980658A CA 980658 A CA980658 A CA 980658A CA 160862 A CA160862 A CA 160862A CA 980658 A CA980658 A CA 980658A
Authority
CA
Canada
Prior art keywords
load control
holding valve
holding
valve
load
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
CA160,862A
Other languages
English (en)
Other versions
CA160862S (en
Inventor
Hugh J. Stacey
Thomas J. Malott
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
Individual
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 Individual filed Critical Individual
Application granted granted Critical
Publication of CA980658A publication Critical patent/CA980658A/en
Expired legal-status Critical Current

Links

Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B11/00Servomotor systems without provision for follow-up action; Circuits therefor
    • F15B11/02Systems essentially incorporating special features for controlling the speed or actuating force of an output member
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B13/00Details of servomotor systems ; Valves for servomotor systems
    • F15B13/01Locking-valves or other detent i.e. load-holding devices
    • F15B13/015Locking-valves or other detent i.e. load-holding devices using an enclosed pilot flow valve
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/20Fluid pressure source, e.g. accumulator or variable axial piston pump
    • F15B2211/205Systems with pumps
    • F15B2211/2053Type of pump
    • F15B2211/20538Type of pump constant capacity
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/30Directional control
    • F15B2211/305Directional control characterised by the type of valves
    • F15B2211/30505Non-return valves, i.e. check valves
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/30Directional control
    • F15B2211/305Directional control characterised by the type of valves
    • F15B2211/30525Directional control valves, e.g. 4/3-directional control valve
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/30Directional control
    • F15B2211/31Directional control characterised by the positions of the valve element
    • F15B2211/3105Neutral or centre positions
    • F15B2211/3116Neutral or centre positions the pump port being open in the centre position, e.g. so-called open centre
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/30Directional control
    • F15B2211/31Directional control characterised by the positions of the valve element
    • F15B2211/3122Special positions other than the pump port being connected to working ports or the working ports being connected to the return line
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/30Directional control
    • F15B2211/31Directional control characterised by the positions of the valve element
    • F15B2211/3122Special positions other than the pump port being connected to working ports or the working ports being connected to the return line
    • F15B2211/3127Floating position connecting the working ports and the return line
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/30Directional control
    • F15B2211/315Directional control characterised by the connections of the valve or valves in the circuit
    • F15B2211/3157Directional 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
    • F15B2211/31576Directional 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 a single pressure source and a single output member
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/40Flow control
    • F15B2211/405Flow control characterised by the type of flow control means or valve
    • F15B2211/40507Flow control characterised by the type of flow control means or valve with constant throttles or orifices
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/50Pressure control
    • F15B2211/505Pressure control characterised by the type of pressure control means
    • F15B2211/50509Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means
    • F15B2211/50545Pressure 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
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/50Pressure control
    • F15B2211/505Pressure control characterised by the type of pressure control means
    • F15B2211/50563Pressure control characterised by the type of pressure control means the pressure control means controlling a differential pressure
    • F15B2211/50581Pressure control characterised by the type of pressure control means the pressure control means controlling a differential pressure using counterbalance valves
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/50Pressure control
    • F15B2211/505Pressure control characterised by the type of pressure control means
    • F15B2211/50563Pressure control characterised by the type of pressure control means the pressure control means controlling a differential pressure
    • F15B2211/50581Pressure control characterised by the type of pressure control means the pressure control means controlling a differential pressure using counterbalance valves
    • F15B2211/5059Pressure control characterised by the type of pressure control means the pressure control means controlling a differential pressure using counterbalance valves using double counterbalance valves
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/50Pressure control
    • F15B2211/515Pressure control characterised by the connections of the pressure control means in the circuit
    • F15B2211/5153Pressure control characterised by the connections of the pressure control means in the circuit being connected to an output member and a directional control valve
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/50Pressure control
    • F15B2211/52Pressure control characterised by the type of actuation
    • F15B2211/528Pressure control characterised by the type of actuation actuated by fluid pressure
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/50Pressure control
    • F15B2211/555Pressure control for assuring a minimum pressure, e.g. by using a back pressure valve
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/50Pressure control
    • F15B2211/56Control of an upstream pressure
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/50Pressure control
    • F15B2211/57Control of a differential pressure
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/70Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/705Output members, e.g. hydraulic motors or cylinders or control therefor characterised by the type of output members or actuators
    • F15B2211/7051Linear output members
    • F15B2211/7053Double-acting output members
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15BSYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00Circuits for servomotor systems
    • F15B2211/70Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/76Control of force or torque of the output member
    • YGENERAL 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
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T137/00Fluid handling
    • Y10T137/2496Self-proportioning or correlating systems
    • Y10T137/2544Supply and exhaust type
    • YGENERAL 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
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10TTECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T137/00Fluid handling
    • Y10T137/8593Systems
    • Y10T137/87169Supply and exhaust
    • Y10T137/87233Biased exhaust valve
    • Y10T137/87241Biased closed

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Safety Valves (AREA)
  • Fluid-Pressure Circuits (AREA)
  • Details Of Valves (AREA)
  • Fluid-Driven Valves (AREA)
CA160,862A 1972-01-10 1973-01-09 Load control and holding valve Expired CA980658A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US21656972A 1972-01-10 1972-01-10

Publications (1)

Publication Number Publication Date
CA980658A true CA980658A (en) 1975-12-30

Family

ID=22807580

Family Applications (1)

Application Number Title Priority Date Filing Date
CA160,862A Expired CA980658A (en) 1972-01-10 1973-01-09 Load control and holding valve

Country Status (5)

Country Link
US (1) US3795255A (enExample)
JP (1) JPS4881124A (enExample)
CA (1) CA980658A (enExample)
FR (1) FR2167907A1 (enExample)
GB (1) GB1387773A (enExample)

Families Citing this family (28)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5237225A (en) * 1975-09-19 1977-03-23 Toho Gasu Kougiyou Kk Valve
US4165675A (en) * 1977-04-07 1979-08-28 Caterpillar Tractor Co. Load check valve cylinder mounted
US4167892A (en) * 1977-04-07 1979-09-18 Caterpillar Tractor Co. Load check with mechanical venting means
US4130049A (en) * 1977-04-07 1978-12-19 Caterpillar Tractor Co. Vent control for cylinder mounted load check valves
US4204459A (en) * 1978-04-19 1980-05-27 Caterpillar Tractor Co. Combination check and flow control valve for hydraulic systems
US4223693A (en) * 1978-07-27 1980-09-23 Modular Controls Corporation Counterbalance valve
US4211254A (en) * 1978-10-30 1980-07-08 Modular Controls Corporation Normally closed pressure compensated flow control valve
US4291718A (en) * 1979-02-26 1981-09-29 Sanin Sergei A Pressure valve
WO1981001034A1 (en) * 1979-10-15 1981-04-16 D Bianchetta Hydraulic load lifting system with automatic blocking valve
US4286502A (en) * 1979-10-15 1981-09-01 Caterpillar Tractor Co. Hydraulic load lifting system with automatic blocking valve
WO1982001042A1 (en) * 1980-09-15 1982-04-01 D Bianchetta Vent valve for cylinder mounted check valve
SE8404666L (sv) * 1984-09-17 1986-01-13 Spiromec Ab Fyllningsventil for fyllning av gasflaskor
DE4207803A1 (de) * 1991-05-14 1992-11-19 Bosch Gmbh Robert Druckhalteventil
US5188015A (en) * 1991-12-26 1993-02-23 Kelley Company, Inc. Automatically sequenced hydraulic cylinder mechanism
JP3397454B2 (ja) * 1994-08-05 2003-04-14 株式会社小松製作所 落下防止弁装置
DE29813971U1 (de) * 1998-08-04 1999-12-16 Beringer-Hydraulik AG, Neuheim, Zug Druckbegrenzungsventil
DE102005025917A1 (de) * 2005-06-06 2006-12-07 Marco Systemanalyse Und Entwicklung Gmbh Ventilpatrone und Ventilanordnung
CN103352887B (zh) * 2013-07-18 2015-08-19 武汉科技大学 一种单叶片水压自伺服转阀
CN103557202B (zh) * 2013-11-04 2015-07-29 中石化胜利油建工程有限公司 大流量电液换向阀的中位卸荷减震回路
CH708875A1 (de) * 2013-11-19 2015-05-29 Liebherr Machines Bulle Sa Hydraulikventilanordnung mit Steuerungs-/Regelungsfunktion.
CH708877B9 (de) * 2013-11-19 2017-02-15 Liebherr Machines Bulle Sa Hydraulikventilanordnung mit Steuerungs-/Regelungsfunktion und zugehöriges Rücklaufventil.
CH708876B1 (de) * 2013-11-19 2016-03-31 Liebherr Machines Bulle Sa Hydraulikventilanordnung mit Steuerungs-/Regelungsfunktion und zugehöriges Rücklaufventil.
CN103939649B (zh) * 2014-04-03 2016-06-22 浙江方众阀门有限公司 自力式截止阀
JP6417281B2 (ja) * 2015-06-10 2018-11-07 Kyb株式会社 緩衝器
JP6673547B2 (ja) * 2016-04-27 2020-03-25 Smc株式会社 流体制御弁
EP3252360B1 (en) * 2016-06-03 2018-12-12 Alfa Laval Corporate AB Control of supply of air to a pneumatic valve actuator
US11085585B2 (en) * 2018-10-30 2021-08-10 Pressure Specialist, Inc. Fill station
CN113124012B (zh) * 2021-04-06 2022-05-27 中联重科股份有限公司 负载保持阀和工程机械

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2653626A (en) * 1946-09-14 1953-09-29 Vickers Inc Power transmission
US2756724A (en) * 1955-06-23 1956-07-31 Henderson Y Stewart Safety valve lock arrangement
US3145734A (en) * 1961-10-06 1964-08-25 Borg Warner Pressure compensated flow control valve
US3362430A (en) * 1966-07-20 1968-01-09 Parker Hannifin Corp Relief-check assembly for directional control valve
US3595264A (en) * 1970-01-09 1971-07-27 Parker Hannifin Corp Load control and holding valve

Also Published As

Publication number Publication date
US3795255A (en) 1974-03-05
GB1387773A (en) 1975-03-19
FR2167907A1 (enExample) 1973-08-24
JPS4881124A (enExample) 1973-10-30

Similar Documents

Publication Publication Date Title
CA980658A (en) Load control and holding valve
CA970653A (en) Control valve
CA968252A (en) Control valve and system
CA985124A (en) Control valve
CA970651A (en) Control valve and system
CA984263A (en) Control valve
CA985127A (en) Control valve
CA937485A (en) Control valve and system
CA978049A (en) Control valve
CA985126A (en) Control valve
CA998912A (en) Control valve and system
CA994835A (en) Control valve and system
CA937484A (en) Control valve and system
CA990263A (en) Control valve and method
CA984262A (en) Control valve
CA986972A (en) Control valve and system
AU2958571A (en) Control valve
CA992675A (en) Isolation valve and control system employing the same
CA969060A (en) Control valve and system
CA953608A (en) Control valve
CA954008A (en) Control valve
CA900823A (en) Combined stop and control valve
CA999213A (en) Three-way valve
CA908540A (en) Valve structure and controller operated thereby
CA839131A (en) Control valve and system