US3726093A - Pump control system - Google Patents

Pump control system Download PDF

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Publication number
US3726093A
US3726093A US00198747A US3726093DA US3726093A US 3726093 A US3726093 A US 3726093A US 00198747 A US00198747 A US 00198747A US 3726093D A US3726093D A US 3726093DA US 3726093 A US3726093 A US 3726093A
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United States
Prior art keywords
pump
orifice
pressure
directional control
fluid
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Expired - Lifetime
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US00198747A
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English (en)
Inventor
T Malott
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Parker Intangibles LLC
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Parker Hannifin Corp
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Assigned to PARKER INTANGIBLES INC., A CORP. OF DE reassignment PARKER INTANGIBLES INC., A CORP. OF DE ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: PARKER-HANNIFIN CORPORATION
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B49/00—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00
    • F04B49/08—Regulating by delivery 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
    • F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
    • F15B11/02—Systems essentially incorporating special features for controlling the speed or actuating force of an output member
    • F15B11/04—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed
    • F15B11/05—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed specially adapted to maintain constant speed, e.g. pressure-compensated, load-responsive
    • 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
    • F15B2211/25—Pressure control functions
    • F15B2211/253—Pressure margin control, e.g. pump pressure in relation to 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
    • F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
    • F15B2211/26—Power 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
    • F15B2211/305—Directional control characterised by the type of valves
    • F15B2211/30525—Directional control valves, e.g. 4/3-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
    • F15B2211/30—Directional control
    • F15B2211/31—Directional control characterised by the positions of the valve element
    • F15B2211/3105—Neutral or centre positions
    • F15B2211/3111—Neutral or centre positions the pump port being closed in the centre position, e.g. so-called closed 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
    • F15B2211/35—Directional control combined with flow control
    • F15B2211/351—Flow control by regulating means in feed line, i.e. meter-in 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
    • F15B2211/40—Flow control
    • F15B2211/405—Flow control characterised by the type of flow control means or 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
    • F15B2211/40—Flow control
    • F15B2211/415—Flow control characterised by the connections of the flow control means in the circuit
    • F15B2211/41563—Flow control characterised by the connections of the flow control means in the circuit being connected to a pressure source and a 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
    • F15B2211/40—Flow control
    • F15B2211/45—Control of bleed-off flow, e.g. control of bypass flow to the return line

Definitions

  • the pump control system herein utilizes the variable area metering orifice of a directional control valve to vary the output flow of the pump, the control piston of the pump sensing the pressure drop across said variable area orifice to enable variation of the speed of actuation of the fluid motor controlled by the directional control valve in accordance with the setting of the variable area orifice.
  • the system herein also embodies motor load pressure limiting means which decreases the pump output flow when the demand set by the variable orifice and the motor load pressure approaches the maximum available horsepower.
  • the system When the directional control valve is of the closed center type the system also embodies a de-stroking valve which automatically bypasses the pump output to minimize standby power drain when the directional control valve is in neutral position closing the pump control variable orifice therein.
  • FIGURE is a cross-section view somewhat diagrammatic in character illustrating a hydraulic system embodying the present invention.
  • the hydraulic system herein comprises a variable volume pump 1 having therein a displacement adjusting mechanism 2 and a power limiting valve 3; a directional control valve 4; a fluid motor 5; a de-stroking valve 6; and an optional de-stroke valve 7 for remote de-stroking of the pump 1.
  • the pump 1 herein is an axial piston pump, the housing 8 of which has an inlet port 9 communicating with a fluid reservoir 10 and anoutlet port 11 communicating by way of conduit 12 with the inlet port 14 of the directional control valve housing 15.
  • the pump drive shaft 16 is journaled in the pump housing 8 and has splined thereto a cylinder block 17, said cylinder block 17 having a circular array of bores in which the pistons 18 reciprocate through strokes determined by the angular position of the cam plate or swash plate 19 which is tiltable about the axis of the support shaft 20 thereof.
  • the cylinder block 17 and housing 8 have mating plane valve surfaces with the housing surface opening in kidney shaped inlet and outlet slots with which the cylinder openings 21 in the cylinder block surface successively register as the pistons 18 move upwardly and downwardly.
  • the pistons 18 are biased by springs 23 in an upward direction and are connected at their upper ends to thrust plates 24 which bear against the inclined bottom face of the swash plate 19.
  • the cylinder block 17 and housing 8 valve surfaces are urged into sealing engagement not only by the piston biasing springs 23, but also by the center springs 25 which urge the retainer plate 26 upwardly against the bottoms of the thrust plates 24.
  • the swash plate 19 has a lever arm 27 which is coupled by means of pin 28 to the control piston 29 of the pump adjusting mechanism 2 and to the control rod 30 of the power limiting valve 3.
  • the directional control valve4 herein shown is of the four-way closed center type for controlling the actuation of the double acting fluid motor 5 and comprises the housing 15 having a bore intersected axially therealong by the inlet port 14, by a pair of motor ports 31 and by a pair of return ports 32.
  • the motor ports 31 are communicated with the ports of the fluid motor 5 by way of check valves 34 one of which opens when the associated motor port 31 is pressurized and the other of which is cam-opened when the associated motor port 31 is communicated with the adjacent return port 32.
  • Reciprocable in the housing 15 is a cam spool 35 which, when in the neutral position asshown, has a land 36 which blocks communication of the inlet port 14 with both motor ports 31, the latter then being open to the respective return ports 32.
  • the spool land 36 has variable area orifices or metering slots 37 therein to meter the flow of fluid under pressure from the inlet port 14 to a selected motor port 31, thus to control the speed of actuation of the fluid motor 5 in either direction.
  • check valves 34 may be of the pilot operated type such as disclosed in the copending U. S. Pat. application of Hugh .1. Stacey, Ser. No. 7,836, filed Feb. 2, 1970 and in the patent to Hugh J. Stacey U.S. Pat. No. 3,216,448 granted Nov. 9, 1965.
  • the adjustment mechanism 2 if the adjustment mechanism 2 is responsive to departure from a constant AP, the flow Q through the orifices 37 is directly related to the area a A thereof i.e. the position of the spool 35 in the directional control valve housing 15.
  • the adjustment mechanism 2 decreases the output flow of the pump 1 when the pressure drop across the orifices 37 exceeds AP (for example 50 p.s.i.) and increases the output flow of the pump 1 when the pressure drop across the orifices 37 is less than AP.
  • control piston 29 has a lost-motion connection with the piston rod 43 of a sensing piston 45, the latter having opposite sides thereof exposed to fluid pressure upstream and downstream of the orifices 37 viz, the pressures in passage 42 and in the feedback conduit 40.
  • the pressure differential AP is 50 p.s.i.
  • the spring 46 acting on the piston rod 43 maintains the latter in a position whereat the chamber 47 is vented to the low pressure inlet chamber 48 within the pump 1 via the passages 49.
  • the housing has two passages leading from the respective motor ports 31 to a feedback conduit 40 via the check valves 41 in the respective passages, said feedback conduit 40 passing through the de-stroke valve 7 which may be provided for remote de-stroking of the pump 1 and through the power limiting valve 3 to the pump displacement adjusting mechanism 2.
  • a passage 42 from the pump outlet 11 whereby said pump adjusting mechanism 2 has conducted thereto fluid pressures of different magnitudes upstream and downstream of the variable area orifices 37 whereby the pressure drop across such orifices 37 is utilized to actuate the pump adjusting mechanism 2 in a manner now to be described in detail.
  • the pressure differential (less than 50 p.s.i.) on opposite sides of the sensing piston 45 will permit the spring 46 to close the passages 49 whereby upstream pressure builds up in the chamber 47 through orifice 50 to urge the control piston 29 upwardly to increase the tilt angle of the swash plate 19 whereby the pump displacement will be increased to desired value to actuate the fluid motor 5 at desired speed.
  • the upstream pressure on the top of the sensing piston 45 moves the same downwardly against the spring 46 to re-open the passages 48 thus to vent the chamber 47 and thereby discontinue the upward movement of the control piston 29.
  • the pump 1 has in the feedback circuit a power limiting valve 3 which vents the feedback downstream thereof and closes the feedback upstream thereof when the load pressure in the feedback conduit 40 and in the pressurized motor port 31 increases to a value in relation to the pump 1 output flow nearing the available horsepower input to the pump 1.
  • the horsepower input to the pump 1 varies as the product of the output flow and the load pressure and hence the power limiting valve 3 herein is designed to limit the load pressure in reverse relation to the output flow to avoid overloading of the pump 1.
  • horsepower varies as the product of the output flow and load pressure and when the swash plate 19 is at a low displacement position, a higher load pressure may be tolerated whereby the limiter spring 56 is compressed to greater degree at such low displacement position than at a higher displacement position of the swash plate 19. Accordingly, the limiter spring 56 force is inversely proportional to the displacement of the pump 1 so that overloading of the pump 1 cannot occur.
  • valve 7 for remote de-stroking of the pump 1.
  • valve member 57 When the valve member 57 is moved downwardly the upstream portion of the feedback conduit 40 is blocked and the downstream portion of the feedback conduit 40 is opened to the reservoir 10, thus to decrease the pressure on the underside of the sensing piston 45 whereby the control piston 29 will be moved downwardly to a minimum displacement position.
  • the de-stroking valve 6 comprises a valve housing 58 having ports 59 and 60 respectively connected to the pump output conduit 12 and to the reservoir 10 and a port 61 connected to the feedback conduit 40 whereby the valve member 62 is exposed to the differential pressures upstream and downstream of the variable orifice 37 when the spool 35 is in operating position.
  • the pressure in the feedback conduit 40 decreases to tank pressure whereupon the inlet pressure in conduit 12 acting on the valve member 62 urges the same toward the left against the bias of spring 63 thus to open communication between the inlet line 12 and the reservoir through the fixed bypass orifice 64 in the valve member 62.
  • the bias spring 63 on the de-stroke valve member 62 is designed to require, for example, a 25 percent increase in pressure above the normal control differential pressure of say, 50 psi. to overcome its load. Once the inlet line 12 pressure meets this pressure requirement, the de-stroke valve member 62 shifts to the left to uncover the fixed bypass orifice 64 to the reservoir 10.
  • the orifice 64 area is selected such that only a small output flow from the pump 1 is needed to maintain enough pressure drop across the de-stroke orifice 64 to keep the de-stroke valve member in shifted position. Because the de-stroke pressure drop is also the pump control differential, the pump 1 is commanded to a minimum stroke at a low working pressure.
  • the present hydraulic system provides a pump 1 output flow which in the case of rectangular metering orifices 37 as shown is linearly related to the spool 35 position. Moreover, the power demands on the system are matched to the load and are limited to the available horsepower whereby if the output flow demand setting is too great in relation to load pressure, the pump 1 is de-stroked to avoid overloading. Moreover, the de-stroking valve provides for a minimum standby power drain.
  • a fluid power system comprising a variable volume pump means, a directional control valve, and a fluid motor operatively interconnected whereby fluid delivered by said pump means is conducted to said fluid motor via said directional control valve; said directional control valve having variable area orifice means to determine the speed of actuation of said fluid motor; and said pump means having output adjustment means responding to the pressure drop between the upstream and downstream sides of said orifice means to adjust the output of said pump means according to the flow demand set by said variable orifice means.
  • said directional control valve comprises a housing, and a valve member movable in said housing to vary the flow area of said orifice means.
  • said directional control valve comprises a housing having a bore intersected axially therealong by an inlet port communicated with the outlet port of said pump means, a motor port communicated with said fluid motor, and a return port adapted for communication with a fluid reservoir; and a valve spool reciprocable in said bore from a neutral position whereat communication between said inlet and motor ports is blocked to operating positions selectively communicating said motor port with said inlet port via said orifice means or with said return port.
  • feedback conduit means intercommunicates said directional control valve with said adjustment means to conduct fluid pressure on the downstream side of said orifice means to said adjustment means; and wherein said pump means has a passage communicating the pump output pressure upstream of said orifice means with said adjustment means whereby said adjustment means is exposed to both pressures for movement by the difference to a position increasing or decreasing the output flow of said pump according to the flow demand set by said orifice means.
  • a power limiting valve isolates excessive load pressure downstream of said orifice means from said adjustment means and vents such downstream pressure from said pump adjustment means whereby the latter by reason of predominance of upstream pressure acting thereon adjusts said pump to a lower output flow to preclude overloading thereof.
  • said directional control valve is of the closed-center type in which a valve member therein has neutral and operating positions which respectively block or permit flow of fluid from said pump means to said fluid motor; and wherein a de-stroke valve is operatively interposed between said pump means and said directional control valve to open restricted communication between the upstream side of said orifice means and a fluid reservoir when said valve member is in neutral position and to close such restricted communication when said valve member is in operating position; said de-stroke valve having a destroke valve member therein exposed to pressure upstream and downstream of said orifice means and movable under predominant fluid pressure on the upstream side of said orifice means to open restricted communication as aforesaid, the predominant upstream pressure being effective to actuate said adjustment means to adjust said pump means to a minimum displacement position when said directional control valve member is in neutral position.
  • a fluid power system comprising a variable volume pump means, a directional control valve, and a fluid motor operatively interconnected whereby fluid delivered by said pump means is conducted to said fluid motor via said directional control valve;
  • said directional control valve comprising a housing, and a valve member movable in said housing and defining therewith a variable area orifice means to determine the speed of actuation of said fluid motor according to the position of said valve member in said housing; and said pump means having output adjustment means responsive to increase or decrease of pressure drop between the upstream and downstream sides of said orifice means above or below a predetermined value to decrease or increase the output of said pump means according to decrease or increase of the area of said orifice means as determined by the position of said valve member in said housing.
  • valve member comprises a valve spool reciprocable in a bore in said housing and wherein said orifice means comprises metering slots in said spool which vary in flow area according to the position of said spool in said housing.
  • a feedback conduit means between said directional control valve and said pump adjustment means conducts fluid pressure downstream of said orifice means to act on one side of a piston in said pump adjustment means and wherein said pump means has a passage communicating with the output port of said pump means upstream of said orifice means to act on the other side of said piston, said pump adjustment means maintaining a constant output of said pump means upon predetermined pressure differential acting on opposite sides of said piston, said piston being interconnected to said pump means to increase or decrease the output of said pump means in response to decrease or increase of the pressure dif-

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Reciprocating Pumps (AREA)
  • Control Of Fluid Gearings (AREA)
  • Fluid-Pressure Circuits (AREA)
  • Control Of Positive-Displacement Pumps (AREA)
US00198747A 1971-11-15 1971-11-15 Pump control system Expired - Lifetime US3726093A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US19874771A 1971-11-15 1971-11-15

Publications (1)

Publication Number Publication Date
US3726093A true US3726093A (en) 1973-04-10

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Application Number Title Priority Date Filing Date
US00198747A Expired - Lifetime US3726093A (en) 1971-11-15 1971-11-15 Pump control system

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US (1) US3726093A (ja)
JP (1) JPS5710301B2 (ja)
AU (1) AU466456B2 (ja)
CA (1) CA956543A (ja)
DE (1) DE2255708A1 (ja)
FR (1) FR2160484B1 (ja)
GB (1) GB1401839A (ja)
SE (1) SE380586B (ja)

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3809501A (en) * 1973-01-08 1974-05-07 Gen Signal Corp Hydraulic load sensitive system
US3902320A (en) * 1974-09-05 1975-09-02 Parker Hannifin Corp Mobile power steering system
US3979907A (en) * 1973-09-10 1976-09-14 Parker-Hannifin Corporation Priority control valve
US4142841A (en) * 1977-08-31 1979-03-06 Parker-Hannifin Corporation Variable displacement pump control
US4162874A (en) * 1977-11-07 1979-07-31 Parker-Hannifin Corporation Horsepower summation control for variable displacement
US5159812A (en) * 1989-12-29 1992-11-03 Mannesmann Rexroth Gmbh Circuitry for controlling control coils of servo devices in a hydraulic system
US6164924A (en) * 1998-09-01 2000-12-26 Oil-Rite Corporation Piston and drive assembly for use in a pump
WO2007090193A2 (en) * 2006-02-01 2007-08-09 Petro Hydraulic Lift System, L.L.C. Hydraulic oil well pumping apparatus
US20090194291A1 (en) * 2008-01-28 2009-08-06 Petro Hydraulic Lift System, L.L.C. Hydraulic oil well pumping apparatus
US20100236399A1 (en) * 2009-03-18 2010-09-23 Navneet Gulati Control Valve for a Variable Displacement Pump
US20110017321A1 (en) * 2009-07-27 2011-01-27 Reiner Kunz Directional control valve arrangement
CN101479481B (zh) * 2006-02-01 2012-10-10 佩特罗水力起重系统有限公司 液压油井抽油装置
US20150192151A1 (en) * 2014-01-03 2015-07-09 Danfoss Power Solutions Aps Hydraulic valve arrangement
US20160377098A1 (en) * 2014-04-11 2016-12-29 Kyb Corporation Valve structure
US9617837B2 (en) 2013-01-14 2017-04-11 Lufkin Industries, Llc Hydraulic oil well pumping apparatus

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US4034564A (en) * 1976-01-23 1977-07-12 Caterpillar Tractor Co. Piston pump assembly having load responsive controls
DE3708492A1 (de) * 1987-03-16 1988-09-29 Rexroth Mannesmann Gmbh Regelvorrichtung fuer eine hydraulische anlage

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US2941365A (en) * 1957-07-23 1960-06-21 Sundstrand Corp Hydraulic transmission
US3429123A (en) * 1967-08-29 1969-02-25 Leblond Mach Tool Co R K Speed control system
US3465519A (en) * 1967-08-18 1969-09-09 Webster Electric Co Inc Hydraulic flow controlling apparatus

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US2579134A (en) * 1948-03-31 1951-12-18 Deere Mfg Co Valve control means for fluid pressure systems
JPS4527170Y1 (ja) * 1965-08-06 1970-10-21
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US3486334A (en) * 1968-05-16 1969-12-30 Cessna Aircraft Co Hydraulic power transmission control
US3592216A (en) * 1968-09-06 1971-07-13 Borg Warner Flow control valve
US3662783A (en) * 1970-02-02 1972-05-16 Parker Hannifin Corp Spool valve assembly

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US25702A (en) * 1859-10-04 Nathan
US2941365A (en) * 1957-07-23 1960-06-21 Sundstrand Corp Hydraulic transmission
US3465519A (en) * 1967-08-18 1969-09-09 Webster Electric Co Inc Hydraulic flow controlling apparatus
US3429123A (en) * 1967-08-29 1969-02-25 Leblond Mach Tool Co R K Speed control system

Cited By (23)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3809501A (en) * 1973-01-08 1974-05-07 Gen Signal Corp Hydraulic load sensitive system
US3979907A (en) * 1973-09-10 1976-09-14 Parker-Hannifin Corporation Priority control valve
US3902320A (en) * 1974-09-05 1975-09-02 Parker Hannifin Corp Mobile power steering system
US4142841A (en) * 1977-08-31 1979-03-06 Parker-Hannifin Corporation Variable displacement pump control
US4162874A (en) * 1977-11-07 1979-07-31 Parker-Hannifin Corporation Horsepower summation control for variable displacement
US5159812A (en) * 1989-12-29 1992-11-03 Mannesmann Rexroth Gmbh Circuitry for controlling control coils of servo devices in a hydraulic system
US6164924A (en) * 1998-09-01 2000-12-26 Oil-Rite Corporation Piston and drive assembly for use in a pump
EA015467B1 (ru) * 2006-02-01 2011-08-30 ПЕТРО ХАЙДРОЛИК ЛИФТ СИСТЕМ, ЭлЭлСи Гидравлическое насосное устройство нефтяной скважины (варианты)
CN101479481B (zh) * 2006-02-01 2012-10-10 佩特罗水力起重系统有限公司 液压油井抽油装置
WO2007090193A3 (en) * 2006-02-01 2008-01-10 Petro Hydraulic Lift System L Hydraulic oil well pumping apparatus
US20070261841A1 (en) * 2006-02-01 2007-11-15 Fesi Michael A Hydraulic oil well pumping apparatus
US7762321B2 (en) 2006-02-01 2010-07-27 Petro Hydraulic Lift System, L.L.C. Hydraulic oil well pumping apparatus
US8235107B2 (en) 2006-02-01 2012-08-07 Lufkin Industries, Inc. Hydraulic oil well pumping apparatus
US20110014064A1 (en) * 2006-02-01 2011-01-20 Petro Hydraulic Lift System, L.L.C. Hydraulic oil well pumping apparatus
WO2007090193A2 (en) * 2006-02-01 2007-08-09 Petro Hydraulic Lift System, L.L.C. Hydraulic oil well pumping apparatus
US20090194291A1 (en) * 2008-01-28 2009-08-06 Petro Hydraulic Lift System, L.L.C. Hydraulic oil well pumping apparatus
US20100236399A1 (en) * 2009-03-18 2010-09-23 Navneet Gulati Control Valve for a Variable Displacement Pump
US8647075B2 (en) 2009-03-18 2014-02-11 Eaton Corporation Control valve for a variable displacement pump
US20110017321A1 (en) * 2009-07-27 2011-01-27 Reiner Kunz Directional control valve arrangement
US8479768B2 (en) * 2009-07-27 2013-07-09 Robert Bosch Gmbh Directional control valve arrangement
US9617837B2 (en) 2013-01-14 2017-04-11 Lufkin Industries, Llc Hydraulic oil well pumping apparatus
US20150192151A1 (en) * 2014-01-03 2015-07-09 Danfoss Power Solutions Aps Hydraulic valve arrangement
US20160377098A1 (en) * 2014-04-11 2016-12-29 Kyb Corporation Valve structure

Also Published As

Publication number Publication date
AU4853972A (en) 1974-05-09
DE2255708A1 (de) 1973-05-24
FR2160484A1 (ja) 1973-06-29
CA956543A (en) 1974-10-22
SE380586B (sv) 1975-11-10
GB1401839A (en) 1975-07-30
FR2160484B1 (ja) 1977-08-26
JPS5710301B2 (ja) 1982-02-25
JPS4861852A (ja) 1973-08-29
AU466456B2 (en) 1975-10-30

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