EP0279362B1 - Hydraulisches System - Google Patents

Hydraulisches System Download PDF

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Publication number
EP0279362B1
EP0279362B1 EP19880102046 EP88102046A EP0279362B1 EP 0279362 B1 EP0279362 B1 EP 0279362B1 EP 19880102046 EP19880102046 EP 19880102046 EP 88102046 A EP88102046 A EP 88102046A EP 0279362 B1 EP0279362 B1 EP 0279362B1
Authority
EP
European Patent Office
Prior art keywords
hydraulic
motors
line
pump
valve assembly
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
EP19880102046
Other languages
English (en)
French (fr)
Other versions
EP0279362A1 (de
Inventor
Steven Harold Johnson
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.)
Deere and Co
Original Assignee
Deere and Co
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 Deere and Co filed Critical Deere and Co
Publication of EP0279362A1 publication Critical patent/EP0279362A1/de
Application granted granted Critical
Publication of EP0279362B1 publication Critical patent/EP0279362B1/de
Expired 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
    • E02F9/20—Drives; Control devices
    • E02F9/22—Hydraulic or pneumatic drives
    • E02F9/2253—Controlling the travelling speed of vehicles, e.g. adjusting travelling speed according to implement loads, control of hydrostatic transmission
    • 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
    • F15B11/044—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed by means in the return line, i.e. "meter out"
    • F15B11/0445—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed by means in the return line, i.e. "meter out" with counterbalance valves, e.g. to prevent overrunning or for braking
    • 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
    • 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
    • F15B11/22—Synchronisation of the movement of two or more servomotors
    • 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
    • F15B13/022—Flow-dividers; Priority 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
    • F15B2211/305—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
    • F15B2211/305—Directional control characterised by the type of valves
    • F15B2211/3056—Assemblies of multiple 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
    • F15B2211/50545—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
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/605—Load sensing circuits
    • F15B2211/6051—Load sensing circuits having valve means between output member and the load sensing circuit
    • 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
    • F15B2211/705—Output members, e.g. hydraulic motors or cylinders or control therefor characterised by the type of output members or actuators
    • F15B2211/7058—Rotary output members
    • 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
    • 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
    • F15B2211/78—Control of multiple output members
    • F15B2211/782—Concurrent control, e.g. synchronisation of two or more actuators

Definitions

  • the invention is directed to a hydraulic propulsion system comprising first and second hydraulic motors, a pump supplying pressurised hydraulic fluid to the motors, a first compensating valve assembly between one side of the first motor and the pump, and a second compensating valve assembly between the corresponding one side of the second motor and the pump.
  • hydraulic fluid takes the path of least resistance and flows to the area requiring the lowest pressure. This is especially troublesome wherein two hydraulic motors are being used to move a common load, for example two crawler tracks of a crawler excavator, because the low pressure motor will command more hydraulic fluid resulting in an uneven operation of the two motors.
  • compensator valve assemblies are provided to better balance the flow between the two motors by having the high pressure compensator valve assembly meter the low pressure side to even the pressure between the two assemblies.
  • the compensator valve assembly associated with the later opening directional control valve becomes dominated by the earlier opening and now high pressure compensator valve assembly, and tends to reduce flow to the hydraulic motor with which it is associated. Therefore, the hydraulic motor associated with the first opening directional control valve moves faster than the motor associated with the later opening directional control valve resulting in a turning movement by the crawler.
  • the present invention overcomes or reduces this problem.
  • connections between the first and second assemblies and motors are coupled by a first communication hydraulic line.
  • a source of hydraulic fluid supplies hydraulic fluid to two directional control valves each of which direct pressurized hydraulic fluid to a pair of downstream compensator valve assemblies.
  • Each pair of compensator valve assemblies is provided with a forward compenstor valve assembly for controlling forward movement of the crawler and a backward compensator valve assembly for controlling the backward movement of the crawler.
  • the position of the directional control valve determines which one of the compensator valve assemblies in each pair of compensator valves the hyraulic fluid is directed to, thereby controlling the movement of the crawler.
  • Two small communication hydraulic lines are provided for transmitting hydraulic fluid between the two forward compensator valve assemblies and between the two backward compensator valve assemblies.
  • Fig. 1 illustrates an excavator crawler to which the present hydraulic propulsion is particularly well suited.
  • Excavator 10 is provided with a movable boom 12, dipper 14 and bucket 16. The boom, dipper and bucket are controlled by linear hydraulic motors 18, 20 and 22, respectively.
  • Excavator crawler 10 is a self-propelled excavator being supported on two ground engaging tracks 24 (only one shown) which are used to drive and position the excavator at a work site.
  • the tracks are independently driven by rotary hydraulic motors 26 and 28 which are coupled through compensator valve assemblies 30, 32, 34 and 36 to directional control valves 38 and 40.
  • Hydraulic fluid is pumped to the directional control valves 38 and 40 from sump 42 by hydraulic pump 44.
  • the hydraulic pump is driven by an internal combustion engine mounted in the excavator.
  • the operator in cab 46 can move or position the excavator by manipulating the directional control valves to propel the excavator forward or backward, or turning the excavator by operating hydraulic motors 26 and 28 in different directions and at different speeds.
  • Fig. 2 is the hydraulic schematic of the hydraulic propulsion system without the small balancing communication line between the downstream output of the compensator valve assemblies.
  • Each compensator valve assembly is provided with a metering compensator spool 48, 50, 52 and 54, a shuttle spool 56, 58, 60 and 62, and a return flow check valve 64, 66, 68 and 70.
  • hydraulic pump 44 pumps hydraulic fluid into hydraulic pumping line 72 to directional control valve 38.
  • the directional control valve 38 directs the fluid to forward compensator valve assembly 30 and specifically to metering two-position compensator spool 48 having a restricted orifice position and a checked position.
  • Spool 48 is spring biased into a closed position by spring 74 which is overcome by hydraulic pressure in sensing line 76 which pushes the valve into the open position. Hydraulic pressure from line 72 is also directed through hydraulic line 77 to shuttle spool 56 and into compensation communication line 78. Shuttle spool 56 is hydraulically balanced by the hydraulic pressure in line 78 and the pressure downstream of compensator spool 48 as transmitted through line 80. The hydraulic fluid in line 80 is used both for balancing spool 56 and for flowing through spool 56 to line 82 to balance spool 48 by adding to the biasing force of spring 74.
  • Hydraulic fluid passing through valve 48 into line 84 is directed to motor 26 driving one of the crawler tracks of the excavator.
  • the exhausted hydraulic fluid then passes into line 86 where it is directed to backward compensator valve assembly 32.
  • shuttle spool 58 is shifted into the closed position by the hydraulic pressure in compensator communication line 78, and spool 50 is closed by the biasing force of spring 88 and the hydraulic pressure in line 90 which is fluidically coupled to compensator communication line 78 by the closed position of spool 58, the exhausted fluid passes through check valve 66 and into exhaust hydraulic line 92 wherein it is directed into sump 42.
  • Hydaulic fluid does not pass through check valve 64 of compensator valve assembly 30 because of the pressure drop across the restricted orifice of spool 48.
  • both motors are being driven in the same forward direction as determined by directional control valves 38 and 40.
  • compensator valve assembly 30 has become dominant, either because it was triggered first by the operator or because of shorter hydraulic line connections when compared with compensator valve assembly 34.
  • Compensator valve assembly 34 works in an identical manner to that of compensator valve assembly 30 except that because of the hydraulic pressure in compensation communication line 78 shuttle spool 60 tends to be biased into a closed position which in turn directs hydraulic pressure from line 78 through shuttle spool 60 and hydraulic line 94 to aid spring 96 in biasing compensator spool 52 closed.
  • the shuttle and compensating spools are two-position metering spools which are hydraulically balanced. As such, the spools are reciprocated between each of the two positions during operation and they do not normally maintain a fixed position. Therefore, in viewing Fig. 2, it should be noted that dominating compensating spool 48 in compensating valve assembly 30 is opened and transmits more hydraulic fluid because of its higher pressure, if it is the dominating valve assembly, and compensating spool 52, of compensating valve assembly 34 transmits less hydraulic fluid because of its lower hydraulic pressure when compared to dominating compensating valve assembly 30.
  • compensating valve assemblies 30 and 32 hydraulic fluid from pump 44 flows through pumping line 72 to directional control valve 40 where it is transmitted to compensating spool 52. Hydraulic fluid passes through the restricted orifice in compensating spool 52 and is directed to motor 28 from which it is exhausted to compensating valve assembly 36. As with compensating valve assembly 32, hydraulic fluid is prevented from passing through compensating spool 54 and instead passes through check valve 70 and back to sump 42.
  • the balancing hydraulic lines for all of the compensating spools and shuttle spools of compensating valve assemblies 32, 34 and 36 are identical to those explained with regards to compensating valve assembly 30 and function in the same manner.
  • Fig. 3 illustrates the small communication hydraulic lines used for overcoming the problem arising in Fig. 2.
  • Hydraulic lines 98 and 100 fluidically couple hydraulic line 84 to line 102, and line 86 to line 104, respectively.
  • line 98 tends to equalize the hydraulic pressure between compensating valve assembly 30 and compensating valve assembly 34.
  • compensating valve assembly 30 tries to dominate valve assembly 34, hydraulic fluid pressure increases in line 84 increasing the pressure in line 98 and line 102 which in turn increases pressure in line 106 causing metering shuttle spool 60 to remain open for transmitting pressure through line 108 to help bias compensating spool 52 open, and better equalizing the hydraulic flow to both motors.
  • communication line 100 would prevent either compensating valve assembly 32 or 36 from dominating one another.
  • exhaust lines 84 and 102 even though coupled through line 98, would not affect operation of the compensating valve assemblies.
  • lines 98 and 100 must be quite small when compared to hydraulic lines 84, 86, 102 and 104 which are used to transfer hydraulic fluid to the motors.
  • lines 84, 86,102 and 104 can be 0.75 inches in diameter and in accordance therewith communication lines 98 and 100 should be 0.25 inches in diameter.
  • lines 98 and 100 should be provided with an orifice further restricting flow. This orifice should be 0.004 inches in diameter to reduce further the cross flow between the pumping lines.
  • Compensating communication line 78 serves an additional function as indicated by arrow 110 and that is to provide a pressure sensing circuit with a hydraulic feedback to better control the operation of the hydraulic pump.

Landscapes

  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • Mining & Mineral Resources (AREA)
  • Civil Engineering (AREA)
  • Structural Engineering (AREA)
  • Fluid-Pressure Circuits (AREA)
  • Operation Control Of Excavators (AREA)
  • Non-Deflectable Wheels, Steering Of Trailers, Or Other Steering (AREA)

Claims (12)

1. Hydraulisches System mit ersten und zweiten hydraulischen Motoren (26, 28); einer Pumpe (44) zum liefern eines unter Druck stehenden hydraulischen Fluids zu den Motoren (26, 28), einer ersten, zur Kompensation dienenden Ventilanordnung (30) zwischen der einen Seite des ersten Motors (26) und der Pumpe (44) und einer zweiten, zur Kompensation dienenden Ventilanordnung (34) zwischen der korrespondierenden einen Seite des zweiten Motors (28) und der Pumpe (44), dadurch gekennzeichnet, daß die Verbindungen (84, 86) zwischen den ersten und zweiten Anordnungen (30, 34) und den Motoren (26, 28) durch eine erste hydraulische Verbindungsleitung (98) miteinander gekuppelt sind.
2. System nach Anspruch 1, bei dem dieses System eine dritte, zur Kompensation dienende Ventilanordnung (32) zwischen der anderen Seite des ersten Motors (26) und der Pumpe (44) und eine vierte, zur Kompensation dienende Ventilanordnung (36) zwischen der korrespondierenden anderen Seite des zweiten Motors (28) und der Pumpe (44) aufweist, dadurch gekennzeichnet, daß die Verbindungen zwischen der dritten und der vierten Anordnung (32, 36) und den Motoren (26, 28) durch eine zweite hydraulische Verbindungsleitung (100) miteinander gekuppelt sind.
3. System nach Anspruch 1 oder 2, bei dem die ersten, zweiten, dritten und vierten, zur Kompensation dienenden Ventilanordnungen (30, 34, 32, 36) jeweils mit ersten, zweiten, dritten und vierten hydraulischen BypassLeitungen von den zugehörigen Motoren (26, 28) zur Pumpe (44) versehen sind, wobei jede Leitung ein Rückschlagventil (64, 68, 66, 70) aufweist, das eine Strömung nur in der Richtung der Pumpe (44) gestattet.
4. System nach irgendeinem der voranstehenden Ansprüche mit ersten und zweiten Dreistellungs-Steuerventilen (38, 40) zwischen der Pumpe (44) und der ersten und dritten (30, 32) und der zweiten und vierten, zur Kompensation dienenden Ventilanordnungen (34, 36).
5. System nach irgendeinem der voranstehenden Ansprüche, bei dem die zur Kompensation dienenden Ventilanordnungen (30, 32, 34, 36) bezüglich des Fluids miteinander durch eine zur Kompensation dienende Hydraulikleitung (78) gekuppelt sind.
6. System nach Anspruch 5, bei dem jede zur Kompensation dienende Ventilanordnung (30, 32, 34, 36) einen zur Zumessung dienenden Zweistellungs-Kompensatorschieber (48, 50, 52, 54) und einen zum Zumessen dienenden Zweistellungs-Wechselschieber (56, 58, 60, 62) aufweist.
7. System nach irgendeinem der voranstehenden Ansprüche, dadurch gekennzeichnet, daß der Durchmesser der ersten, oder der ersten und der zweiten, zur Kommunikation dienenden Hydraulikleitung bzw.Leitungen (98, 100) kleiner ist als der Durchmesser der Verbindungen (84, 102) zwischen der ersten und der zweiten Anordnung (30, 34) und den Motoren (26, 28).
8. System nach Anspruch 7, dadurch gekennzeichnet, daß der Durchmesser der genannten Leitung oder Leitungen (98, 100) im wesentlichen ein Drittel des Durchmessers der genannten Verbindungen (84, 102) beträgt.
9. Vortriebseinheit für eine industrielle Maschine, dadurch gekennzeichnet, daß die Einheit ein System nach einem der voranstehenden Ansprüche umfaßt, während die Hydraulikmotoren (26, 28) antriebsmäßig mit den am Boden angreifenden Mitteln zum Bewegen der Maschine verbunden sind.
10. Vortriebseinheit nach Anspruch 9, bei der die Mittel zum Bewegen der Maschine Gleisketten (24) sind.
11. Industrielle Maschine, dadurch gekennzeichnet, daß sie eine Vertriebseinheit nach Anspruch 9 oder 10 aufweist.
12. Industrielle Maschine nach Anspruch 11 in welcher die Maschine ein Bagger (10) ist.
EP19880102046 1987-02-19 1988-02-12 Hydraulisches System Expired EP0279362B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US1631887A 1987-02-19 1987-02-19
US16318 1987-02-19

Publications (2)

Publication Number Publication Date
EP0279362A1 EP0279362A1 (de) 1988-08-24
EP0279362B1 true EP0279362B1 (de) 1990-12-05

Family

ID=21776536

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19880102046 Expired EP0279362B1 (de) 1987-02-19 1988-02-12 Hydraulisches System

Country Status (4)

Country Link
EP (1) EP0279362B1 (de)
JP (1) JP2604399B2 (de)
CA (1) CA1274748A (de)
DE (1) DE3861194D1 (de)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5209063A (en) * 1989-05-24 1993-05-11 Kabushiki Kaisha Komatsu Seisakusho Hydraulic circuit utilizing a compensator pressure selecting value
KR920701695A (ko) * 1989-05-24 1992-08-12 가타다 데츄야 유압 회로장치
US6715402B2 (en) * 2002-02-26 2004-04-06 Husco International, Inc. Hydraulic control circuit for operating a split actuator mechanical mechanism

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2912131A (en) * 1957-10-01 1959-11-10 Demag Baggerfabrik Gmbh Hydraulically operated machines
FR1400491A (fr) * 1964-04-14 1965-05-28 Auxitra Système de distribution hydraulique pour excavatrice
GB1035141A (en) * 1964-05-07 1966-07-06 Priestman Brothers Improvements relating to civil engineering machines
LU52175A1 (de) * 1965-10-21 1966-12-19
US3960284A (en) * 1972-10-02 1976-06-01 American Hoist & Derrick Company Hydraulic backhoe circuitry
JPS6244849Y2 (de) * 1981-02-02 1987-11-28
JPS5897030U (ja) * 1981-12-24 1983-07-01 株式会社小松製作所 油圧駆動車の走行用油圧回路
DE3525823A1 (de) * 1985-07-19 1987-01-29 Schmitz Soehne Gmbh Maschf Wegeabhaengige gleichlauf-drucksteuerung fuer zweiseitig arbeitende pressen, insbes. bundpressen

Also Published As

Publication number Publication date
JP2604399B2 (ja) 1997-04-30
JPS63215467A (ja) 1988-09-07
CA1274748A (en) 1990-10-02
DE3861194D1 (de) 1991-01-17
EP0279362A1 (de) 1988-08-24

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