US3841795A - Combined engine speed and pressure responsive control for variable displacement pumps - Google Patents

Combined engine speed and pressure responsive control for variable displacement pumps Download PDF

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Publication number
US3841795A
US3841795A US00272408A US27240872A US3841795A US 3841795 A US3841795 A US 3841795A US 00272408 A US00272408 A US 00272408A US 27240872 A US27240872 A US 27240872A US 3841795 A US3841795 A US 3841795A
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United States
Prior art keywords
pressure
responsive
pumps
control
prime mover
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 - Lifetime
Application number
US00272408A
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English (en)
Inventor
G Ferre
M Franz
K Lohbauer
W Mcmillan
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.)
Caterpillar Inc
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Caterpillar Tractor 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 Caterpillar Tractor Co filed Critical Caterpillar Tractor Co
Priority to US00272408A priority Critical patent/US3841795A/en
Priority to BR5193/73A priority patent/BR7305193D0/pt
Priority to GB3357773A priority patent/GB1436613A/en
Priority to DE2336430A priority patent/DE2336430C2/de
Priority to BE133523A priority patent/BE802395A/xx
Priority to JP48080226A priority patent/JPS5918558B2/ja
Priority to FR7326144A priority patent/FR2193424A5/fr
Application granted granted Critical
Publication of US3841795A publication Critical patent/US3841795A/en
Assigned to CATERPILLAR INC., A CORP. OF DE. reassignment CATERPILLAR INC., A CORP. OF DE. ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: CATERPILLAR TRACTOR CO., A CORP. OF CALIF.
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • 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
    • F04B49/002—Hydraulic systems to change the pump delivery
    • 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
    • F04B49/007—Installations or systems with two or more pumps or pump cylinders, wherein the flow-path through the stages can be changed, e.g. from series to parallel

Definitions

  • a hydraulic power system having a plurality of variable displacement pumps for supplying pressurized fluid for manipulation of an implement, and control means operative to automatically adjust pump displacement to the output horsepower of a prime mover driving the pumps of the system.
  • the control system includes a first valve means responsive to the speed of the prime mover to transmit a fluid pressure signal to servo-control means for adjusting the displacement of the pumps.
  • Second valve means is responsive to the output pressure of the variable displacement pumps for overriding the speed responsive means during transient overload conditions.
  • the present invention is directed to hydraulic control systems, and pertains more particularly to a hydraulic control system having a plurality of variable displacement pumps and means for automatically adjusting the displacement of the pumps.
  • circuits are employed for such systems, and may employ a totally different circuit, or separate circuit for each motor or may employ various means for combining the flow from a plurality of pumps to a single one or more of the hydraulic motors.
  • the hydraulic pump is all of these systems is normally driven by a single prime mover such as an internal combustion engine.
  • a single prime mover such as an internal combustion engine.
  • each separate motor and each separate pump may be capable of handling the entire horsepower output of the engine. Thus, if two or more of the motors or pumps are loaded, the engine may stall.
  • the summing valve arrangement provides means which is responsive to the sum of the pressures imposed by the load on the variable displacement pumps for adjusting a control valve which controls the displacement of the various pumps.
  • This type of arrangement has a disadvantage in that it is responsive mainly to the load pressure of the pumps, and not to the load on the engine. Such a system becomes more sensitive to load on the pump, and Iess'sen sitive to the actual load on the engine.
  • variable displacement pumps having a plurality of variable displacement pumps that is operative to vary the pump displacement in accordance with load imposed-on the engine and load imposed on the pumps.
  • a horsepower limiting pump displacement control system embodying the principles of the present invention is schematically illustrated in operative combination with a multiple pump implement control circuit, only a portion of which is illustrated.
  • the implement control circuit is of the type that would be utilized in an implement such as a hydraulic excavator wherein a plurality of hydraulic motors are used in combination, individually, and/or simultaneously, for the manipulation of an implement.
  • the implement control system comprises a plurality 1 of variable displacement pumps and 11, and a fixed displacement pump 12, all driven by suitable prime mover means such as an internal combustion engine 13.
  • Each pump draws fluid from a suitable reservoir or sump 14 and supplies it under pressure by way of respective supply conduits 15, 16 and 17.
  • variable displacement pumps 10 and 11 are provided with suitable servo-control means of conventional design 18 and 19, which is responsive to a pressure signal to vary the displacement of the pumps 10 and 11. g
  • the control system for supplying pressurized control fluid for actuating the servo-control means 18 and 19 comprises a fixed displacement pump 20, directly driven by the'prime mover means 13 drawing fluid from the reservoir 14, and supplying it to the underspeed pump displacement control, generally indicated at 21.
  • the underspeed control means 21 is of the type disclosed in Application Ser. No. 68,317 referred to above.
  • the operation of the underspeed valve 21 is such that it responds to a reduction in the speed of pump 20, as a result of a speed reduction in the engine due to overload or for any other reason.
  • the output fluid flow from the pump flows through an orifice 22 which creates a pressure differential acting on opposite ends of a valve 23, which differential pressure is communicated by way of lines 24 and 25.
  • the pressure differential is a function of the fluid flow, which is a function of engine speed.
  • a predetermined change in a pressure differential across orifice 22 allows valve 21 to be shifted to an open position to communicate pressure from a control pump 20 by way of a line 26 across valve 23 where it is communicated by way ofa line 27 past a shuttle valve 28 where it communicates by way of branch lines 29 and 30 with the servo-control means 18 and 19 of the respective pumps 10 and 11.
  • increased flow through orifice 22 restores the pressure differential across the valve 23 so that it returns to the closed position as shown and thus permits the pumps 10 and 11 to return to a full displacement condition.
  • control pressure from or fluid from pump 20 continues through the underspeed valve 21 and flows along a supply line 31 to a summing valve indicated generally by the reference numeral 32.
  • the summingvalve is of the type illustrated and disclosed in Application Ser. No. 127,738 mentioned above.
  • the pressure summing control means 32 comprises a valve member or spool 33, which is normally biased to the cut-off position but is responsive to force developed by pressure from each of th lines 15, 16 and 17 by way of lines 34, 35 and 36 to pistons 37, 38 and 39 acting on the spool 33.
  • a relief valve 40 in line 31 functions to protect the line from overpressurization, and maintains a nearly constant pressure level downstream of orifice22.
  • the pressure of pump 12 can be ignored where it is not a significant portion of the total load, or where timing is such that the load thereof will not affect the overall load.
  • the entire system is adjusted so that the pump displacements are' primarily under the control of the un derspeed control means 21 until such time as sudden peak pressure conditions occur in the system, at which time the pressure responsive or pressure summing control means 32 takes over, communicating a signal to the pump displacement control means 18 and 19, and reduces the displacement thereof to accommodate the load conditions.
  • the summing valve will immediately sense the pressure and respond quickly to reduce the displacement of the pumps 10 and 11 to control or prevent too much horsepower drain on the engine.
  • the summing valve is set to respond at a higher pressure and therefore a greater horsepower than does the underspeed control 21.
  • a hydraulic power system for an excavator or the like comprising:
  • variable displacement hydraulic pumps for supplying power fluid for said system
  • prime mover means operatively connected to drive said pumps
  • means including a fixed displacement pump for providing a source of pilot control fluid and underspeed valve means responsive to the output of said fixed displacement pump to generate a control signal that is a function of the speed of said prime mover;
  • pressure responsive summing valve means responsive to the sum of the pressure of said power fluid from said plurality of pumps to override said pilot control signal under overload conditions, said underspeed valve means and said summing means being communicated by fluid communication means with said servo-control means.
  • a control system in combination with a prime mover and a plurality of variable displacement pumps operatively driven by said prime mover and operative to supply pressurized fluid for operation of a plurality of hydraulic motors for powering an implement, said control system comprising:
  • pressure responsive servo-control means in selective communication with said source and operative to adjust the displacement of said pumps to correspond to the power output of said prime mover;
  • pressure responsive shuttle valve means disposed between said paths and said servocontrol means and selectively responsive to the higher of the pressures in said paths to direct fluid therefrom to said servocontrol means.
  • a source of pilot pressure including a fixed displacement pump driven by said prime mover for controlling placement of said pumps in relation to the speed output of said prime mover;
  • underspeed control valve means responsive to the speed of said prime mover for normally controlling the communication of said pilot control pressure with said pump displacement means
  • summing valve means comprising a valve having a predetermined bias in the direction to cut off said communication and,
  • a plurality of pressure responsive means responsive to the sum of the pressure output of said variable displacement pumps to bias said valve in a direction to provide open communication between said source of control pressure and said pump displacement controlling means.
  • said pressure responsive means comprises a plurality of pistons disposed in cylinders
  • said cylinders being in communication with the output of said pump at one end of said piston; and, the other end of said piston is in operative engagement with said valve means.
  • a horsepower controlling system said system I comprising in combination:
  • variable displacement pump driven by said prime mover and including pressure responsive means for varying the displacement of said pump
  • first and second valves each having a bore in communication with said common source of actuating pressure and with said pressure responsive means;
  • a spool disposed in each of said bores and operative to control said communication

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Control Of Positive-Displacement Pumps (AREA)
  • Fluid-Pressure Circuits (AREA)
  • Control Of Vehicle Engines Or Engines For Specific Uses (AREA)
  • Control Of Fluid Gearings (AREA)
  • Operation Control Of Excavators (AREA)
US00272408A 1972-07-17 1972-07-17 Combined engine speed and pressure responsive control for variable displacement pumps Expired - Lifetime US3841795A (en)

Priority Applications (7)

Application Number Priority Date Filing Date Title
US00272408A US3841795A (en) 1972-07-17 1972-07-17 Combined engine speed and pressure responsive control for variable displacement pumps
BR5193/73A BR7305193D0 (pt) 1972-07-17 1973-07-12 Sistemas para controle da potencia e de acionamento hidraulico
DE2336430A DE2336430C2 (de) 1972-07-17 1973-07-13 Vorrichtung zur Grenzlaststeuerung von Hydropumpen
GB3357773A GB1436613A (en) 1972-07-17 1973-07-13 Fluid pressure control system for variable displacement pumps
BE133523A BE802395A (fr) 1972-07-17 1973-07-16 Systeme a commande repondant a la vitesse d'un moteur et une pression
JP48080226A JPS5918558B2 (ja) 1972-07-17 1973-07-16 原動機によって駆動される複数の可変容量ポンプと組み合わされた制御装置
FR7326144A FR2193424A5 (enrdf_load_stackoverflow) 1972-07-17 1973-07-17

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US00272408A US3841795A (en) 1972-07-17 1972-07-17 Combined engine speed and pressure responsive control for variable displacement pumps

Publications (1)

Publication Number Publication Date
US3841795A true US3841795A (en) 1974-10-15

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Family Applications (1)

Application Number Title Priority Date Filing Date
US00272408A Expired - Lifetime US3841795A (en) 1972-07-17 1972-07-17 Combined engine speed and pressure responsive control for variable displacement pumps

Country Status (7)

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US (1) US3841795A (enrdf_load_stackoverflow)
JP (1) JPS5918558B2 (enrdf_load_stackoverflow)
BE (1) BE802395A (enrdf_load_stackoverflow)
BR (1) BR7305193D0 (enrdf_load_stackoverflow)
DE (1) DE2336430C2 (enrdf_load_stackoverflow)
FR (1) FR2193424A5 (enrdf_load_stackoverflow)
GB (1) GB1436613A (enrdf_load_stackoverflow)

Cited By (28)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3937597A (en) * 1973-10-03 1976-02-10 Poclain Pressurized fluid feed apparatus
US3963378A (en) * 1975-06-04 1976-06-15 Caterpillar Tractor Co. Part throttle control -- pump override
US3985472A (en) * 1975-04-23 1976-10-12 International Harvester Company Combined fixed and variable displacement pump system
US4008004A (en) * 1975-12-22 1977-02-15 Abex Corporation Control system for variable displacement pumps
US4017218A (en) * 1976-03-15 1977-04-12 Caterpillar Tractor Co. Dual-speed setting underspeed system
US4029439A (en) * 1975-12-22 1977-06-14 Abex Corporation Control system for variable displacement pumps
FR2339759A1 (fr) * 1976-01-30 1977-08-26 Linde Ag Dispositif de commande pour un ensemble de pompes
US4055046A (en) * 1976-12-22 1977-10-25 Caterpillar Tractor Co. Control system having override for fluid operated work elements
US4065228A (en) * 1977-02-24 1977-12-27 Caterpillar Tractor Co. Hydraulic control for variable displacement pumps
US4080979A (en) * 1977-03-22 1978-03-28 Caterpillar Tractor Co. Combined summing and underspeed valve
US4089166A (en) * 1974-03-20 1978-05-16 Tyrone Hydraulics, Inc. Automatic pump control system
FR2385916A1 (fr) * 1977-03-31 1978-10-27 Komatsu Mfg Co Ltd Commande de pompe, simple ou multiple, a deplacement variable a l'aide d'une soupape de mesure d'ecoulement
US4123907A (en) * 1977-04-19 1978-11-07 Caterpillar Tractor Co. Hydraulic system having selective simultaneous pressure and flow control
WO1979000762A1 (en) * 1978-03-15 1979-10-04 Caterpillar Tractor Co Variable flow control valve for steering systems of articulated vehicles
US4248573A (en) * 1978-09-22 1981-02-03 Kabushiki Kaisha Komatsu Seisakusho Hydraulic control system for variable displacement pump
US4248574A (en) * 1978-09-22 1981-02-03 Kabushiki Kaisha Komatsu Seisakusho Hydraulic control system for variable displacement pumps
US4256439A (en) * 1978-11-20 1981-03-17 The Japan Steel Works Ltd. Power control system for multiple pumps
WO1981001031A1 (en) * 1979-10-15 1981-04-16 Hitachi Construction Machinery Method of controlling internal combustion engine and hydraulic pump system
EP0037738A1 (en) * 1980-04-08 1981-10-14 Minnesota Mining And Manufacturing Company Automatic track following feature for helical video recorder
EP0043459B1 (de) * 1980-06-28 1984-09-12 Linde Aktiengesellschaft Regeleinrichtung für ein Aggregat aus mehreren, von einer gemeinsamen Primärenergiequelle angetriebenen Pumpen
US4498847A (en) * 1982-06-29 1985-02-12 Kabushiki Kaisha Komatsu Seisakusho Control system for variable displacement hydraulic pumps
US4531366A (en) * 1981-05-29 1985-07-30 Kabushiki Kaisha Komatsu Seisakusho Hydraulic circuit system for use in swivel type excavators
US4613286A (en) * 1984-12-31 1986-09-23 Kabushiki Kaisha Komatsu Seisakusho Constant torque control system for a variable displacement pump or pumps
US5468126A (en) * 1993-12-23 1995-11-21 Caterpillar Inc. Hydraulic power control system
US5525043A (en) * 1993-12-23 1996-06-11 Caterpillar Inc. Hydraulic power control system
US20090000291A1 (en) * 2006-03-13 2009-01-01 Palo Markku Arrangement and Method for Delivering Hydraulic Fluid in a Work Vehicle
US7549287B2 (en) 2007-09-14 2009-06-23 Cnh America Llc Hydrostatic auto/manual speed control
US20100137102A1 (en) * 2008-12-02 2010-06-03 Caterpillar Inc. Retarding control for a machine

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS57227Y2 (enrdf_load_stackoverflow) * 1973-11-19 1982-01-05
JPS59713B2 (ja) * 1974-04-08 1984-01-07 三菱重工業株式会社 ユアツポンプノ リユウリヨウセイギヨソウチ
JPS5888480A (ja) * 1981-11-21 1983-05-26 Hitachi Constr Mach Co Ltd 原動機で駆動される油圧ポンプの入力制御装置
JP2699491B2 (ja) * 1988-11-30 1998-01-19 石川島播磨重工業株式会社 石油掘削などのライザパイプの格納装置
JPH07111176B2 (ja) * 1988-12-16 1995-11-29 ダイキン工業株式会社 可変容量形液圧装置

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3543508A (en) * 1968-10-16 1970-12-01 Hyster Co Hydrostatic transmission with pressure control
US3609964A (en) * 1969-04-24 1971-10-05 Bosch Gmbh Robert Regulated hydraulic drive
US3633359A (en) * 1969-02-18 1972-01-11 Dowty Hydraulic Units Ltd Hydraulic apparatus
US3672161A (en) * 1970-01-15 1972-06-27 Linde Ag Control system for a stepless hydrostatic drive
US3678684A (en) * 1969-10-06 1972-07-25 Anstailt Fur Elektrohydraulisc Hydraulic systems
US3723026A (en) * 1970-04-22 1973-03-27 I Soyland Effect regulator for constant and variable volume-flow pumps

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1910914A1 (de) * 1969-03-04 1971-04-22 Brueninghaus Hydraulik Gmbh Leistungsregeleinrichtung fuer Axialkolbenpumpen
DE1933951C3 (de) * 1969-07-04 1974-08-29 Hydromatik Gmbh, 7900 Ulm Regelvorrichtung für die Begrenzung der Summe der abgenommenen Leistung zweier oder mehrerer verstellbarer Hydropumpen
DE2100112A1 (de) * 1970-02-23 1971-09-09 VEB Kombinat Orsta-Hydraulik Betrieb Industriewerke Karl-Marx-Stadt, χ 9030 Karl-Marx-Stadt Druckregeleinrichtung

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3543508A (en) * 1968-10-16 1970-12-01 Hyster Co Hydrostatic transmission with pressure control
US3633359A (en) * 1969-02-18 1972-01-11 Dowty Hydraulic Units Ltd Hydraulic apparatus
US3609964A (en) * 1969-04-24 1971-10-05 Bosch Gmbh Robert Regulated hydraulic drive
US3678684A (en) * 1969-10-06 1972-07-25 Anstailt Fur Elektrohydraulisc Hydraulic systems
US3672161A (en) * 1970-01-15 1972-06-27 Linde Ag Control system for a stepless hydrostatic drive
US3723026A (en) * 1970-04-22 1973-03-27 I Soyland Effect regulator for constant and variable volume-flow pumps

Cited By (36)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3937597A (en) * 1973-10-03 1976-02-10 Poclain Pressurized fluid feed apparatus
US4089166A (en) * 1974-03-20 1978-05-16 Tyrone Hydraulics, Inc. Automatic pump control system
US3985472A (en) * 1975-04-23 1976-10-12 International Harvester Company Combined fixed and variable displacement pump system
US3963378A (en) * 1975-06-04 1976-06-15 Caterpillar Tractor Co. Part throttle control -- pump override
FR2336572A1 (fr) * 1975-12-22 1977-07-22 Abex Corp Dispositif de commande d'un systeme hydraulique
US4029439A (en) * 1975-12-22 1977-06-14 Abex Corporation Control system for variable displacement pumps
FR2336573A1 (fr) * 1975-12-22 1977-07-22 Abex Corp Dispositif de commande hydraulique pour un ensemble de pompes a cylindree variable entrainees par un moteur primaire
US4008004A (en) * 1975-12-22 1977-02-15 Abex Corporation Control system for variable displacement pumps
FR2339759A1 (fr) * 1976-01-30 1977-08-26 Linde Ag Dispositif de commande pour un ensemble de pompes
US4115033A (en) * 1976-01-30 1978-09-19 Linde Aktiengesellschaft Control device for a hydraulic system having at least two pumps
US4017218A (en) * 1976-03-15 1977-04-12 Caterpillar Tractor Co. Dual-speed setting underspeed system
US4055046A (en) * 1976-12-22 1977-10-25 Caterpillar Tractor Co. Control system having override for fluid operated work elements
US4065228A (en) * 1977-02-24 1977-12-27 Caterpillar Tractor Co. Hydraulic control for variable displacement pumps
US4080979A (en) * 1977-03-22 1978-03-28 Caterpillar Tractor Co. Combined summing and underspeed valve
US4203712A (en) * 1977-03-31 1980-05-20 Kabushiki Kaisha Komatsu Seisakusho Single or plural variable displacement pump control with an improved flow metering valve
FR2385916A1 (fr) * 1977-03-31 1978-10-27 Komatsu Mfg Co Ltd Commande de pompe, simple ou multiple, a deplacement variable a l'aide d'une soupape de mesure d'ecoulement
US4123907A (en) * 1977-04-19 1978-11-07 Caterpillar Tractor Co. Hydraulic system having selective simultaneous pressure and flow control
FR2388149A1 (fr) * 1977-04-19 1978-11-17 Caterpillar Tractor Co Installation hydraulique comportant une commande simultanee selective de pression et de debit
WO1979000762A1 (en) * 1978-03-15 1979-10-04 Caterpillar Tractor Co Variable flow control valve for steering systems of articulated vehicles
US4248573A (en) * 1978-09-22 1981-02-03 Kabushiki Kaisha Komatsu Seisakusho Hydraulic control system for variable displacement pump
US4248574A (en) * 1978-09-22 1981-02-03 Kabushiki Kaisha Komatsu Seisakusho Hydraulic control system for variable displacement pumps
US4256439A (en) * 1978-11-20 1981-03-17 The Japan Steel Works Ltd. Power control system for multiple pumps
WO1981001031A1 (en) * 1979-10-15 1981-04-16 Hitachi Construction Machinery Method of controlling internal combustion engine and hydraulic pump system
US4395199A (en) * 1979-10-15 1983-07-26 Hitachi Construction Machinery Co., Ltd. Control method of a system of internal combustion engine and hydraulic pump
EP0037738A1 (en) * 1980-04-08 1981-10-14 Minnesota Mining And Manufacturing Company Automatic track following feature for helical video recorder
EP0043459B1 (de) * 1980-06-28 1984-09-12 Linde Aktiengesellschaft Regeleinrichtung für ein Aggregat aus mehreren, von einer gemeinsamen Primärenergiequelle angetriebenen Pumpen
US4531366A (en) * 1981-05-29 1985-07-30 Kabushiki Kaisha Komatsu Seisakusho Hydraulic circuit system for use in swivel type excavators
US4498847A (en) * 1982-06-29 1985-02-12 Kabushiki Kaisha Komatsu Seisakusho Control system for variable displacement hydraulic pumps
US4613286A (en) * 1984-12-31 1986-09-23 Kabushiki Kaisha Komatsu Seisakusho Constant torque control system for a variable displacement pump or pumps
US5468126A (en) * 1993-12-23 1995-11-21 Caterpillar Inc. Hydraulic power control system
US5525043A (en) * 1993-12-23 1996-06-11 Caterpillar Inc. Hydraulic power control system
US20090000291A1 (en) * 2006-03-13 2009-01-01 Palo Markku Arrangement and Method for Delivering Hydraulic Fluid in a Work Vehicle
US7921641B2 (en) * 2006-03-13 2011-04-12 Volvo Construction Equipment Ab Arrangement and method for delivering hydraulic fluid in a work vehicle
US7549287B2 (en) 2007-09-14 2009-06-23 Cnh America Llc Hydrostatic auto/manual speed control
US20100137102A1 (en) * 2008-12-02 2010-06-03 Caterpillar Inc. Retarding control for a machine
US8326499B2 (en) * 2008-12-02 2012-12-04 Caterpillar Inc. Retarding control of a machine through power dissipation through power source and parasitic loads

Also Published As

Publication number Publication date
JPS504601A (enrdf_load_stackoverflow) 1975-01-18
DE2336430C2 (de) 1986-05-22
FR2193424A5 (enrdf_load_stackoverflow) 1974-02-15
JPS5918558B2 (ja) 1984-04-27
BR7305193D0 (pt) 1974-08-15
GB1436613A (en) 1976-05-19
DE2336430A1 (de) 1974-01-31
BE802395A (fr) 1974-01-16

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Legal Events

Date Code Title Description
AS Assignment

Owner name: CATERPILLAR INC., 100 N.E. ADAMS STREET, PEORIA, I

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:CATERPILLAR TRACTOR CO., A CORP. OF CALIF.;REEL/FRAME:004669/0905

Effective date: 19860515

Owner name: CATERPILLAR INC., A CORP. OF DE.,ILLINOIS

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:CATERPILLAR TRACTOR CO., A CORP. OF CALIF.;REEL/FRAME:004669/0905

Effective date: 19860515