EP0667421A1 - Dispositif de commande hydraulique pour engins de travaux publics - Google Patents

Dispositif de commande hydraulique pour engins de travaux publics Download PDF

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Publication number
EP0667421A1
EP0667421A1 EP94926381A EP94926381A EP0667421A1 EP 0667421 A1 EP0667421 A1 EP 0667421A1 EP 94926381 A EP94926381 A EP 94926381A EP 94926381 A EP94926381 A EP 94926381A EP 0667421 A1 EP0667421 A1 EP 0667421A1
Authority
EP
European Patent Office
Prior art keywords
hydraulic
directional control
control valve
blade
lowering
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.)
Ceased
Application number
EP94926381A
Other languages
German (de)
English (en)
Other versions
EP0667421A4 (fr
Inventor
Shinichi Chiyoda-House 7-401 Sato
Seiji 6227-26 Ohaza-Koibuchi Tamura
Fumimasa Saeki
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.)
Hitachi Construction Machinery Co Ltd
Original Assignee
Hitachi Construction Machinery Co Ltd
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 Hitachi Construction Machinery Co Ltd filed Critical Hitachi Construction Machinery Co Ltd
Publication of EP0667421A1 publication Critical patent/EP0667421A1/fr
Publication of EP0667421A4 publication Critical patent/EP0667421A4/fr
Ceased 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
    • E02F9/2221—Control of flow rate; Load sensing arrangements
    • E02F9/2239—Control of flow rate; Load sensing arrangements using two or more pumps with cross-assistance
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02F—DREDGING; SOIL-SHIFTING
    • E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
    • E02F9/20—Drives; Control devices
    • E02F9/22—Hydraulic or pneumatic drives
    • E02F9/2278—Hydraulic circuits
    • E02F9/2292—Systems with two or more pumps

Definitions

  • the present invention relates to a hydraulic drive system which is equipped on construction machines such as small-sized hydraulic excavators and is able to perform the combined operation of up-and-down movement of a blade and travel of the machine.
  • Fig. 3 is a circuit diagram showing one example of prior art hydraulic drive systems of the above-mentioned type.
  • the illustrated prior art system includes three primary hydraulic pumps, i.e., a first hydraulic pump 1, a second hydraulic pump 2, and a third hydraulic pump 26.
  • the system also includes a left-hand track motor 4 for driving a left-hand crawler belt which constitutes an undercarriage (not shown), a boom cylinder 5 for driving a boom which constitutes a front attachment (not shown), and a bucket cylinder 6 for driving a bucket which constitutes the front attachment (not shown), as actuators driven by a hydraulic fluid delivered from the first hydraulic pump 1; a right-hand track motor 7 for driving a right-hand crawler belt which constitutes the undercarriage (not shown) and an arm cylinder 8 for driving an arm which constitutes the front attachment (not shown), as actuators driven by a hydraulic fluid delivered from the second hydraulic pump 2; and a blade lifting/lowering cylinder 9 for driving a blade (not shown) and a swing motor 10 for driving an upper structure (not shown) which constitutes a machine body with a cab installed thereon, as actuators driven by a hydraulic fluid delivered from the third hydraulic pump 3.
  • a left-hand track motor 4 for driving a left-hand crawler belt which constitutes an underc
  • the system includes a left-hand track directional control valve 34, a boom directional control valve 35 and a bucket directional control valve 36 for controlling respective flows of the hydraulic fluid supplied from the first hydraulic pump 1 to the left-hand track motor 4, the boom cylinder 5 and the bucket cylinder 6; a right-hand track directional control valve 37 and an arm directional control valve 38 for controlling respective flows of the hydraulic fluid supplied from the second hydraulic pump 2 to the right-hand track motor 7 and the arm cylinder 8; and a blade lifting/lowering directional control valve 39 and a swing directional control valve 40 for controlling respective flows of the hydraulic fluid supplied from the third hydraulic pump 26 to the blade lifting/lowering cylinder 9 and the swing motor 10.
  • a left-hand track directional control valve 34 for controlling respective flows of the hydraulic fluid supplied from the first hydraulic pump 1 to the left-hand track motor 4, the boom cylinder 5 and the bucket cylinder 6
  • a right-hand track directional control valve 37 and an arm directional control valve 38 for controlling respective flows of the hydraulic fluid supplied from the second hydraulic pump 2 to the right-hand
  • the combined operation of up-and-down movement of the blade and travel of the machine is carried out by shifting the left-hand track directional control valve 34, the right-hand track directional control valve 37 and the blade lifting/lowering directional control valve 39. More specifically, the left-hand track directional control valve 34 is shifted to supply the hydraulic fluid from the first hydraulic pump 1 to the left-hand track motor 4, the right-hand track directional control valve 37 is shifted to supply the hydraulic fluid from the second hydraulic pump 2 to the right-hand track motor 7, and the blade lifting/lowering directional control valve 39 is shifted to supply the hydraulic fluid from the third hydraulic pump 26 to the blade lifting/lowering cylinder 9. As a result, the left-hand crawler belt, the right-hand crawler belt and the blade which constitute the undercarriage (not shown) are driven to carry out the combined operation of up-and-down movement of the blade and travel of the machine.
  • Fig. 4 is a circuit diagram showing another example of prior art hydraulic drive systems of the above-mentioned type.
  • the illustrated other prior art system includes only two primary hydraulic pumps, i.e., a first hydraulic pump 1 and a second hydraulic pump 2.
  • a left-hand track directional control valve 34 for controlling the driving of a left-hand track motor 4 is connected to the first hydraulic pump 1, and a boom directional control valve 35 for controlling the driving of a boom cylinder 5 and a bucket directional control valve 36 for controlling the driving of a bucket cylinder 6 are connected in parallel downstream of the left-hand track directional control valve 34.
  • a blade lifting/lowering directional control valve 39 for controlling the driving of a blade lifting/lowering cylinder 9 a swing directional control valve 40 for controlling the driving of a swing motor 10, and an arm directional control valve 38 for controlling the driving of an arm cylinder 8 are connected to the second hydraulic pump 2 in parallel.
  • a right-hand track directional control valve 37 for controlling the driving of a right-hand track motor 7 is connected downstream of those directional control valves 39, 40 and 38.
  • the system also includes a communication line 12 for communicating an inlet port 11 of the left-hand track directional control valve 34 and an inlet port 11 of the right-hand track directional control valve 37 with each other, a switching valve 13 connected in the communication line 12, a hydraulic source 11, a line 11 a for communicating the hydraulic source 11 with a drive sector of the switching valve 13, a throttle 11 provided in the line 11 a, and a line 11 c having one end connected to a portion of the line 11 a between the throttle 11 b and the drive sector of the switching valve 13 and the other end communicated with a reservoir through the directional control valves 39, 40, 38, 37, 36, 35 and 34.
  • the left-hand track directional control valve 34 and the right-hand track directional control valve 37 are connected to the first hydraulic pump 1 in parallel, and the hydraulic fluid from the first hydraulic pump 1 is supplied to both the left-hand track motor 4 and the right-hand track motor 7 for driving the left-hand crawler belt and the right-hand crawler belt which constitute the undercarriage (not shown), to thereby travel the machine.
  • the hydraulic fluid from the second hydraulic pump 2 fails to be supplied to the right-hand track motor 7 because the load of the blade lifting/lowering cylinder 9 is lighter than that of the right-hand track motor 7.
  • the present invention has been made in view of the state of art described above, and its object is to provide a hydraulic drive system for a construction machine which can suppress an abrupt reduction in the traveling speed when a blade is operated with a load lighter than the travel load while the machine is traveling.
  • a hydraulic drive system for a construction machine comprising a first hydraulic pump, a second hydraulic pump, a plurality of actuators including at least two track motors and a blade lifting/lowering cylinder which are driven by hydraulic fluids delivered from the first and second hydraulic pumps, and a plurality of directional control valves including at least two track directional control valves and a blade lifting/lowering directional control valve for controlling respective flows of the hydraulic fluids supplied from the first and second hydraulic pumps to the plurality of actuators, the blade lifting/-lowering directional control valve including a load check valve disposed in its feeder line, the system being capable of performing the combined operation of up-and-down movement of a blade and travel of the machine, one of the two track directional control valves and the blade lifting/lowering directional control valve are connected to one of the first hydraulic pump and the second hydraulic pump in parallel, and a throttle valve is disposed upstream of the load check valve in the feeder line of the blade
  • additional supply means capable of replenishing a hydraulic fluid is connected downstream of the load check valve in the feeder line of the blade lifting/lowering directional control valve.
  • the additional supply means includes a pilot pump as a hydraulic source.
  • at least some of the plurality of directional control valves are of the hydraulic pilot operated type, and the hydraulic drive system further comprises a pilot operating system including a pilot pump and control lever means which are associated with those hydraulic pilot operated directional control valves and produce signal pressures depending on input amounts of the control lever means based on a hydraulic fluid from the pilot pump for shifting the corresponding directional control valves, the hydraulic pump in the pilot operating system doubling as the pilot pump of the additional supply means.
  • an opening of the throttle valve is set such that the hydraulic fluid delivered from the one second hydraulic pump is supplied to the one track directional control valve and the blade lifting/lowering directional control valve in a distributed manner during work of moving the blade down.
  • the blade lifting/lowering cylinder when the hydraulic fluid is supplied to the bottom side of the blade lifting/lowering cylinder and the hydraulic fluid in the rod side thereof is drained to a return line, the blade lifting/lowering cylinder is extended to carry out work of moving the blade down.
  • the blade lifting/lowering cylinder is contracted to carry out work of moving the blade up.
  • the hydraulic fluid delivered from the one hydraulic pump is distributed by the throttle valve disposed upstream of the load check valve in the feeder line of the blade lifting/lowering directional control valve, and is then supplied to both the one track directional control valve and the blade lifting/lowering directional control valve. Therefore, the hydraulic fluid delivered from the second hydraulic pump can be supplied to the track motor as well through that track directional control valve. It is thus possible to suppress an abrupt reduction in the traveling speed during the combined operation of travel and blade movement.
  • a pilot hydraulic fluid can be replenished by the additional supply means including the pilot pump, for example.
  • the pilot hydraulic fluid is replenished by the additional supply means so that an abrupt reduction in the traveling speed during the combined operation of travel and blade movement can be suppressed as with the above case and an reduction in the lifting/lowering speed of the blade can also be suppressed.
  • the illustrated small-sized hydraulic excavator comprises a left-hand crawler belt 20 constituting an undercarriage, a right-hand crawler belt (not shown), an upper structure 21 constituting a machine body with a cab installed thereon, a boom 22 rotatably mounted in front of the upper structure 21 and driven by a boom cylinder 5, an arm 23 rotatably mounted to the boom 22 and driven by an arm cylinder 8, a bucket 24 rotatably mounted to the arm 23 and driven by a bucket cylinder 6, and a blade 25 rotatably mounted to the undercarriage and driven by a blade lifting/lowering cylinder 9.
  • the hydraulic drive system of this embodiment includes two primary hydraulic pumps, i.e., a first hydraulic pump 1 and a second hydraulic pump 2, and one auxiliary hydraulic pump, i.e., a pilot pump 3.
  • a left-hand track directional control valve 34 for controlling the driving of a left-hand track motor 4 for operating the left-hand crawler belt, a boom directional control valve 35 for controlling the driving of the boom cylinder 5 for turning the boom 22, and a bucket directional control valve 36 for controlling the driving of the bucket cylinder 6 for turning the bucket 24 are connected to the first hydraulic pump 1.
  • the boom directional control valve 35 and the bucket directional control valve 36 are connected downstream of the left-hand track directional control valve 34 in tandem relation to the left-hand track directional control valve 34 so that a hydraulic fluid delivered from the first hydraulic pump 1 is supplied to the left-hand track directional control valve 34 with priority, and both the valves are connected in parallel to the first hydraulic pump 1 through a parallel line 15.
  • a right-hand track directional control valve 37 for controlling the driving of a right-hand track motor 7 for operating the right-hand crawler belt are connected to the second hydraulic pump 2 in parallel through a parallel line 16.
  • the system of this embodiment also includes a communication line 12 for communicating an inlet port 11 d of the left-hand track directional control valve 34 and an inlet port 11 of the right-hand track directional control valve 37 with each other, a switching valve 13 connected in the communication line 12, a line 11 a for communicating the pilot pump 3 with a drive sector of the switching valve 13, a throttle 11 provided in the line 11 a, and a line 11 having one end connected to a portion of the line 11 a between the throttle 11 b and the drive sector of the switching valve 13 and the other end communicated with a reservoir through the directional control valves 39, 40, 38, 37, 36, 35 and 34.
  • the directional control valves 34, 37 are each of the internal structure formed to hold the communication with the line 11 c and hence the reservoir when it is in any of a neutral position as shown and upper and lower shift positions
  • the directional control valves 39, 40, 38, 36 and 35 are each of the internal structure formed to hold the communication with the line 11 c and hence the reservoir when it is in a neutral position as shown, but to cut off the communication with the line 11 c and hence the reservoir when it is shifted from the neutral position to an upper or lower shift position.
  • the communication line 12, the switching valve 13, the pilot pump 3, the line 11 a, the throttle 11 b, the line 11 c, and the internal structures of the directional control valves 39, 40, 38, 36 and 35 jointly constitute communication means for selectively communicating the inlet port 11 of the left-hand track directional control valve 34 and the inlet port 11 e of the right-hand track directional control valve 37 with each other.
  • the directional control valves 34 to 40 are of the hydraulic pilot operated type.
  • a pilot operating system including a pair of control lever units 60, 61 is associated with those hydraulic pilot operated directional control valves 35, 36, 38 and 40.
  • the control lever unit 60 produces signal pressures e, e'; f, f' depending on the input amount of its control lever based on a hydraulic fluid from the pilot pump 3, thereby shifting the directional control valves 40, 38, and the control lever unit 61 produces signal pressures g, g'; h, h' depending on the input amount of its control lever by utilizing the hydraulic fluid from the pilot pump 3, thereby shifting the directional control valves 36, 35.
  • a throttle valve 50 is disposed upstream of a load check valve 53 in a feeder line 49 of the blade lifting/lowering directional control valve 39.
  • the throttle valve 50 has its opening set such that the hydraulic fluid delivered from the second hydraulic pump 2 is supplied to the right-hand track directional control valve 37 (the right-hand track motor 7) and the blade lifting/lowering directional control valve 39 (the blade lifting/lowering cylinder 9) in a distributed manner during the combined operation of travel and movement of the blade 25 in which the blade 25 undergoes a lighter load, e.g., during the combined operation of travel and work of moving the blade 25 down.
  • the system of this embodiment further includes a line 52 having one end connected downstream of the load check valve 53 in the feeder line 49 of the blade lifting/lowering directional control valve 39 for filling up a lack of the hydraulic fluid caused by the above-described distributing function of the throttle valve 50, a check valve 51 connected to the other end of the line 52 for preventing the hydraulic fluid delivered from the second hydraulic pump 2 from being supplied toward the pilot pump 3, and a line 54 having one end connected to the check valve 51 and the other end connected to the line 11 a which is communicated with the pilot pump 3.
  • the pilot pump 3, the line 54, the check valve 51 and the line 52 are connected downstream of the load check valve 53 in the feeder line 49 of the blade lifting/lowering directional control valve 39, and jointly constitute additional supply means capable of replenishing the hydraulic fluid.
  • the pilot pump 3 doubles as a hydraulic source for the pilot operating system including the control lever units 60, 61 and a hydraulic source for the additional supply means.
  • Denoted by reference numeral 56 is a main relief valve for specifying a pressure of the hydraulic fluid delivered from the first hydraulic pump 1
  • 55 is a main relief valve for specifying a pressure of the hydraulic fluid delivered from the second hydraulic pump 2
  • 57 is a pilot relief valve for specifying a pressure of the hydraulic fluid delivered from the pilot pump 3.
  • the left-hand track directional control valve 34 and the right-hand track directional control valve 37 are shifted, whereupon the hydraulic fluid from the first hydraulic pump 1 is supplied to the left-hand tack motor 4 through the left-hand track directional control valve 34 for driving the left-hand track motor 4 to thereby operate the left-hand crawler belt 20 constituting the undercarriage and, simultaneously, the hydraulic fluid from the second hydraulic pump 2 is supplied to the right-hand tack motor 7 through the right-hand track directional control valve 37 for driving the right-hand track motor 7 to thereby operate the right-hand crawler belt (not shown) constituting the undercarriage.
  • the sole operation of travel is carried out.
  • the blade lifting/lowering directional control valve 39 When the blade lifting/lowering directional control valve 39 is additionally shifted for transition from the above sole operation of travel to the combined operation of travel and blade movement in which the blade undergoes a lighter load, e.g., the combined operation of travel and work of moving the blade down, the communication between the line 11 C and the reservoir is cut off in response to the shifting of the blade lifting/lowering directional control valve 39. Therefore, the pressure downstream of the throttle 11 b is raised, causing the switching valve 13 to be shifted against the resilient force of a spring into an open position, i.e., a lower shift position in Fig. 2.
  • the inlet port 11 d of the left-hand track directional control valve 34 and the inlet port 11 e of the right-hand track directional control valve 37 are communicated with each other through the communication line 12.
  • the hydraulic fluid from the first hydraulic pump 1 is supplied to the left-hand track motor 4 through the left-hand track directional control valve 34 for driving the left-hand track motor 4 to thereby operate the left-hand crawler belt 20 constituting the undercarriage, and a part of the hydraulic fluid from the first hydraulic pump 1 is also supplied to the right-hand track directional control valve 37 through the communication line 12.
  • the hydraulic fluid from the second hydraulic pump 2 is distributed and supplied through the throttle valve 50 to the right-hand track directional control valve 37 and the blade lifting/lowering directional control valve 39.
  • the right-hand track directional control valve 37 is supplied with a part of the hydraulic fluid from the first hydraulic pump 1 introduced through the communication line 12 and a part of the hydraulic fluid from the second hydraulic pump 2 distributed through the throttle valve 50 in a joined manner.
  • the joined hydraulic fluid is then supplied to the right-hand track motor 7, whereupon the right-hand track motor 7 is driven to operate the right-hand crawler belt (not shown) which constitute the undercarriage.
  • the remainder of the hydraulic fluid from the second hydraulic pump 2 distributed through the throttle valve 50 is supplied to the bottom side 9a of the blade lifting/lowering cylinder 9, whereupon the blade lifting/-lowering cylinder 9 is extended to carry out the work of moving the blade 25 down.
  • the hydraulic fluids supplied to the left-hand track motor 4 and the right-hand track motor 7 can be prevented from abruptly reducing in their flow rate, and hence an abrupt reduction in the traveling speed can be suppressed.
  • the pilot hydraulic fluid from the pilot pump 3 can be replenished through the line 11 a, the line 54, the check valve 51 and the line 52.
  • the pilot hydraulic fluid is additionally supplied to the blade lifting/lowering directional control valve 39 to suppress a reduction in the lifting/lowering speed of the blade while suppressing an abrupt reduction in the traveling speed during the combined operation of travel and blade movement.
  • the combined operation of travel and blade movement is carried out in such a manner as moving the blade 25 up and down to perform light-load operation, e.g., leveling of the ground, while the machine is traveling straightly, the satisfactory lifting/lowering speed of the blade can be ensured with additional supply of the pilot hydraulic fluid delivered from the pilot pump 3 under a relatively low pressure.
  • the hydraulic fluid from the second hydraulic pump 2 having a pressure specified by the main relief valve 55 is supplied to the blade lifting/lowering cylinder 9 through the throttle valve 50 and the blade lifting/lowering directional control valve 39 and, therefore, the satisfactory lifting/lowering speed of the blade can be ensured.
  • the pilot hydraulic fluid from the pilot pump 3 can be additionally supplied to the blade lifting/lowering directional control valve 39 during the combined operation of travel and blade movement, a reduction in the lifting/lowering speed of the blade 25 can also be suppressed. By so suppressing a reduction in the lifting/lowering speed of the blade 25, the higher operability of the combined operation of travel and blade movement can be achieved and the working efficiency can be further improved correspondingly.
  • a reduction in the lifting/lowering speed of the blade can also be suppressed with the provision of the additional supply means.
  • a reduction in the lifting/lowering speed of the blade there can be obtained an advantage of ensuring the higher operability of the combined operation of travel and blade movement and hence further improving the working efficiency.

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  • Engineering & Computer Science (AREA)
  • Mining & Mineral Resources (AREA)
  • Civil Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Structural Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Operation Control Of Excavators (AREA)
  • Fluid-Pressure Circuits (AREA)
EP94926381A 1993-09-09 1994-09-09 Dispositif de commande hydraulique pour engins de travaux publics. Ceased EP0667421A4 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
JP224595/93 1993-09-09
JP5224595A JPH0776859A (ja) 1993-09-09 1993-09-09 建設機械の油圧駆動装置
PCT/JP1994/001497 WO1995007390A1 (fr) 1993-09-09 1994-09-09 Dispositif de commande hydraulique pour engins de travaux publics

Publications (2)

Publication Number Publication Date
EP0667421A1 true EP0667421A1 (fr) 1995-08-16
EP0667421A4 EP0667421A4 (fr) 1997-12-17

Family

ID=16816194

Family Applications (1)

Application Number Title Priority Date Filing Date
EP94926381A Ceased EP0667421A4 (fr) 1993-09-09 1994-09-09 Dispositif de commande hydraulique pour engins de travaux publics.

Country Status (3)

Country Link
EP (1) EP0667421A4 (fr)
JP (1) JPH0776859A (fr)
WO (1) WO1995007390A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0913586A1 (fr) * 1996-07-26 1999-05-06 Komatsu Ltd. Appareil d'alimentation en huile hydraulique

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP6575916B2 (ja) 2016-08-17 2019-09-18 日立建機株式会社 作業車両

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4024710A (en) * 1976-03-25 1977-05-24 Koehring Company Load sensing hydraulic circuit having power matching means
US4112821A (en) * 1976-12-03 1978-09-12 Caterpillar Tractor Co. Fluid control system for multiple circuited work elements
EP0059471A2 (fr) * 1981-03-03 1982-09-08 Hitachi Construction Machinery Co., Ltd. Système d'entraînement hydrostatique pour machines de travaux publics
EP0108347A1 (fr) * 1982-11-01 1984-05-16 Valmet Oy Système hydraulique pour tracteur ou équivalent
JPS6131535A (ja) * 1984-07-20 1986-02-14 Kayaba Ind Co Ltd 建設車両等の油圧制御回路
US4850191A (en) * 1986-12-30 1989-07-25 Mannesmann Rexroth Gmbh Control arrangement for at least two hydraulic consumers fed by at least one pump
EP0404946A1 (fr) * 1988-05-16 1991-01-02 Kabushiki Kaisha Komatsu Seisakusho Dispositif de circuit hydraulique de vehicule de construction

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS60144432A (ja) * 1983-12-30 1985-07-30 Handoothe- Kogyo Kk ド−ザ−付き掘削機における油圧回路
JPH0745744B2 (ja) * 1987-09-29 1995-05-17 日立建機株式会社 油圧駆動装置
JPH0649634Y2 (ja) * 1988-02-01 1994-12-14 油谷重工株式会社 ドーザ切換装置
JPH0791849B2 (ja) * 1990-06-26 1995-10-09 日立建機株式会社 作業機械の油圧回路

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4024710A (en) * 1976-03-25 1977-05-24 Koehring Company Load sensing hydraulic circuit having power matching means
US4112821A (en) * 1976-12-03 1978-09-12 Caterpillar Tractor Co. Fluid control system for multiple circuited work elements
EP0059471A2 (fr) * 1981-03-03 1982-09-08 Hitachi Construction Machinery Co., Ltd. Système d'entraînement hydrostatique pour machines de travaux publics
EP0108347A1 (fr) * 1982-11-01 1984-05-16 Valmet Oy Système hydraulique pour tracteur ou équivalent
JPS6131535A (ja) * 1984-07-20 1986-02-14 Kayaba Ind Co Ltd 建設車両等の油圧制御回路
US4850191A (en) * 1986-12-30 1989-07-25 Mannesmann Rexroth Gmbh Control arrangement for at least two hydraulic consumers fed by at least one pump
EP0404946A1 (fr) * 1988-05-16 1991-01-02 Kabushiki Kaisha Komatsu Seisakusho Dispositif de circuit hydraulique de vehicule de construction

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 010, no. 187 (M-493), 2 July 1986 & JP 61 031535 A (KAYABA IND CO LTD), 14 February 1986, *
See also references of WO9507390A1 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0913586A1 (fr) * 1996-07-26 1999-05-06 Komatsu Ltd. Appareil d'alimentation en huile hydraulique
EP0913586A4 (fr) * 1996-07-26 2000-09-20 Komatsu Mfg Co Ltd Appareil d'alimentation en huile hydraulique

Also Published As

Publication number Publication date
EP0667421A4 (fr) 1997-12-17
JPH0776859A (ja) 1995-03-20
WO1995007390A1 (fr) 1995-03-16

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