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GB2171152A - Hydraulically powered system - Google Patents

Hydraulically powered system Download PDF

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Publication number
GB2171152A
GB2171152A GB08604228A GB8604228A GB2171152A GB 2171152 A GB2171152 A GB 2171152A GB 08604228 A GB08604228 A GB 08604228A GB 8604228 A GB8604228 A GB 8604228A GB 2171152 A GB2171152 A GB 2171152A
Authority
GB
United Kingdom
Prior art keywords
pressure
engine
speed
hydraulic
sensor
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.)
Granted
Application number
GB08604228A
Other versions
GB8604228D0 (en
GB2171152B (en
Inventor
Douglas Walter Crampton
Nigel Bacon
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.)
Perkins Engines Group Ltd
Original Assignee
Perkins Engines Group 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 Perkins Engines Group Ltd filed Critical Perkins Engines Group Ltd
Publication of GB8604228D0 publication Critical patent/GB8604228D0/en
Publication of GB2171152A publication Critical patent/GB2171152A/en
Application granted granted Critical
Publication of GB2171152B publication Critical patent/GB2171152B/en
Expired legal-status Critical Current

Links

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
    • E02F9/2246—Control of prime movers, e.g. depending on the hydraulic load of work tools
    • 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
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B1/00—Engines characterised by fuel-air mixture compression
    • F02B1/02—Engines characterised by fuel-air mixture compression with positive ignition
    • F02B1/04—Engines characterised by fuel-air mixture compression with positive ignition with fuel-air mixture admission into cylinder
    • 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
    • F15B2211/20507—Type of prime mover
    • F15B2211/20523—Internal combustion engine
    • 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
    • F15B2211/20538—Type of pump constant capacity
    • 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
    • F15B2211/315—Directional control characterised by the connections of the valve or valves in the circuit
    • F15B2211/3157—Directional control characterised by the connections of the valve or valves in the circuit being connected to a pressure source, an output member and a return line
    • F15B2211/31576—Directional control characterised by the connections of the valve or valves in the circuit being connected to a pressure source, an output member and a return line having a single pressure source and a single output member
    • 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
    • F15B2211/32—Directional control characterised by the type of actuation
    • F15B2211/321—Directional control characterised by the type of actuation mechanically
    • F15B2211/324—Directional control characterised by the type of actuation mechanically manually, e.g. by using a lever or pedal
    • 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
    • F15B2211/50518—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means using pressure relief 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
    • F15B2211/515—Pressure control characterised by the connections of the pressure control means in the circuit
    • F15B2211/5151—Pressure control characterised by the connections of the pressure control means in the circuit being connected to a pressure source and a 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
    • F15B2211/50—Pressure control
    • F15B2211/55—Pressure control for limiting a pressure up to a maximum pressure, e.g. by using a pressure relief 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
    • F15B2211/60—Circuit components or control therefor
    • F15B2211/63—Electronic controllers
    • F15B2211/6303—Electronic controllers using input signals
    • F15B2211/6306—Electronic controllers using input signals representing a pressure
    • F15B2211/6309—Electronic controllers using input signals representing a pressure the pressure being a pressure source supply 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
    • F15B2211/63—Electronic controllers
    • F15B2211/6303—Electronic controllers using input signals
    • F15B2211/633—Electronic controllers using input signals representing a state of the prime mover, e.g. torque or rotational speed
    • 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
    • F15B2211/63—Electronic controllers
    • F15B2211/6303—Electronic controllers using input signals
    • F15B2211/6346—Electronic controllers using input signals representing a state of input means, e.g. joystick position
    • 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
    • F15B2211/665—Methods of control using electronic components
    • F15B2211/6651—Control of the prime mover, e.g. control of the output torque or rotational speed
    • 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
    • F15B2211/80—Other types of control related to particular problems or conditions
    • F15B2211/875—Control measures for coping with failures
    • F15B2211/8752—Emergency operation mode, e.g. fail-safe operation mode

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)
  • Operation Control Of Excavators (AREA)

Abstract

A hydraulically powered system includes a pump (10) driven by an engine (13) and a sensor (24) that senses the pressure in the system and serves to trigger a reduction in the speed of the engine (13) once a predetermined hydraulic pressure is exceeded corresponding to a pressure just below that at which a hydraulic relief valve (11) is set to open. By this means, operation of the relief valve (11) and consequent venting of pressurised hydraulic fluid is reduced or avoided, thereby reducing or avoiding energy losses. Thus the system hydraulic pressure is limited through control of engine speed rather than operation of a relief valve. A controller (20) receives signals from the sensor (24) and a manual control (21, 22, 23) and provides an output signal to a further controller (18), the latter receiving a speed dependent signal from a sensor (17) and providing an engine speed control signal to an actuator (19). <IMAGE>

Description

SPECIFICATION Hydraulically powered system Technical field This invention relates to a hydraulically powered system in which an engine drives a hydraulic pump to pressurise the working hydraulic fluid.
In known hydraulic powered systems, for example, the hydraulic system of a tractor digger loader, the transmitted power is varied by varying the speed of the engine through control of the fuel supply. The fuel pump of the engine incorporates an all speed mechanical governor with a throttle lever that is controlled by the operator. A pressure relief valve is incorporated in the system and determines the maximum level of hydraulic pressure that can exist in the system. If this pressure is exceeded, the relief valve opens to vent hydraulic fluid back to the low pressure reservoir. However, when this happens, there is a loss of useful energy. An object of the present invention is to reduce or overcome this problem.
Disclosure of the invention Accordingly, the present invention consists in providing a hydraulically powered system with an engine speed control system including a sensor that senses the pressure in the system and serves to trigger a reduction in the speed of the engine once a predetermined hydraulic pressure is exceeded corresponding to a pressure just below that at which a hydraulic relief valve is set to open. By this means, operation of the relief valve and consequent venting of pressurised hydraulic fluid is reduced or avoided, thereby reducing or avoiding energy losses. Thus the system hydraulic pressure is limited through control of engine speed ratherthan operation of a relief valve.
Description ofthe drawing The drawing shows a schematic illustration of a tractor digger loader with an engine speed control system according to the invention.
Best mode of carrying out the invention The illustrated tractor digger loader has a back hoe 1 with a hydraulically powered control system including a boom cylinder 2 to raise and lowerthe boom 3 of the back hoe, a dipper cylinder 4 to swing the dipper arm 5 on the end of the boom, and a bucket cylinder 6 to operate the bucket 7 at the end of the dipper arm 5. An additional actuator (not shown) serves to control swivelling of the whole back hoe about the vertical axis 8. Each of the cylinders 2, 4, 6 is connected into a hydraulic circuit of the control system so as to be controlled by an associated spool valve. However, for simplicity of illustration, just one spool valve 9 is shown in the drawing controlling dipper cylinder 4, and this is supplied with working hydraulic fluid by a fixed displacement hydraulic pump 10.It will be appreciated that similar spool valves are provided for the boom cylinder 2, the bucket cylinder 6 and the boom swivel actuator, and in all cases working hydraulic fluid is supplied by the pump 10. A pressure relief valve 11 is connected into the hydraulic circuit between the pump 10 and the spool valve 9 so as to vent excess pressure back to the reservoir 12 if the system pressure exceeds a predetermined maximum level.
The pump 10 is driven by a diesel engine 13 supplied with fuel by a conventional fuel pump 14 having a throttle lever 15 that is controlled to vary the fuel supply and thereby the engine speed. An electronic governor 16 controls the setting of the throttle lever 15 and comprises an engine speed sensor 17, a controller 18 that has an input from the sensor 17 and compares the engine speed with a selected engine speed and produces a corresponding output signal, and an actuator 19 connected to the throttle lever 15 and supplied with the output signal from the controller so that the engine speed is adjusted to match the selected engine speed. A load control unit 20 determines the selected engine speed, dependent upon operator demand and subjectto certain limits and conditions, as explained hereafter.
Operator demand is determined by a hand and/or foot throttle control 21/22 linked to a position sensor 23 that produces an output dependent on the throttle setting. Two or more similar position sensors 23 may be provided and the load control unit 20 is then set to select between them according to predetermined rules, for example, the throttle output signal corresponding to the highest speed is selected. The selected throttle output signal is then passed to the controller 18 as the selected engine speed provided it lies within a predetermined speed range and provided certain over-ride conditions do not exist.
A pressure sensor 24 is provided in the hydraulic circuit of the digger loader between the pump 10 and the spool valve 9 and transmits a signal to the load control unit 20 corresponding to the sensed hydraulic pressure. The load control unit 20 is set to be triggered when this pressure signal rises above a preset level which lies just below said predetermined maximum level corresponding to the setting of the pressure valve 11. The load control unit 20 then responds by over-riding the speed signal derived from the throttle setting, and instead passes a signal to reduce the engine speed. The reduced engine speed reduces the speed of the pump 10 and thus the flow in the hydraulic circuit. Engine deceleration and minimum engine speed are pre-setwithin the load control unit 20.Once the hydraulic pressure falls below said preset level, the load control unit 20 produces a signal to increase engine speed at predetermined acceleration until the speed determined by the signal from the throttle setting is re-established. Thus the pressure sensor 24 and load control unit 20 together serve to control the maximum pressure through control of engine speed, and thereby avoid wasteful operation of the pressure relief valve 11. The pressure relief valve 11 merely acts as a safety back up and is set at a higher pressure setting than it would be in the known system. However, an electrical switch 25 may be provided in association with the pressure sensor 24 to allow the latter to be disabled, thereby setting the system in a condition in which it is dependent upon operation of the pressure relief valve for pressure control at the higher pressure setting. The switch 25 can therefore be operated to boost the maximum pressure, maybe for emergency operating conditions.
Although the invention has been described by way of example with reference to a diesel engine above, it will be appreciated that the invention is equally applicable to any internal combustion engine, whether a petrol engine or gas engine, which incorporates an engine speed control system.

Claims (5)

1 A hydraulically powered system comprising an engine, a hydraulic pump that is driven by the engine to pressurise a working hydraulic fluid in the hydraulic system, a relief valve that is set to vent said fluid from the hydraulic system at a predetermined vent pressure, and a control system that controls the speed of the engine including a sensor that senses the pressure of said fluid in the hydraulic system and serves to trigger a reduction in the speed of the engine once a predetermined pressure is exceeded corresponding to a pressure just below said predetermined vent pressure.
2. A system as claimed in claim 1 in which the control system comprises a governor that regulates the speed of the engine at a selected engine speed, and a load controller that determines said selected engine speed dependent upon an input from a power demand control operable by an operator of the hydraulically powered system to register power demand.
3. A system as claimed in claim 2 in which said sensor applies a pressure signal to the load controller, and the load controller compares said pressure signal with said predetermined pressure and reduces said selected engine speed when said pressure in the hydraulic system exceeds said predetermined pressure.
4. A system as claimed in any one of the preceding claims which includes means that is selectively operable to disable the sensor so that pressure is not regulated at said predetermined pressure but can rise to said predetermined vent pressure.
5. A hydraulically powered system substantially as herein described with reference to the accompanying drawing.
GB08604228A 1985-02-20 1986-02-20 Hydraulically powered system Expired GB2171152B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB858504343A GB8504343D0 (en) 1985-02-20 1985-02-20 Hydraulically powered system

Publications (3)

Publication Number Publication Date
GB8604228D0 GB8604228D0 (en) 1986-03-26
GB2171152A true GB2171152A (en) 1986-08-20
GB2171152B GB2171152B (en) 1988-06-29

Family

ID=10574787

Family Applications (2)

Application Number Title Priority Date Filing Date
GB858504343A Pending GB8504343D0 (en) 1985-02-20 1985-02-20 Hydraulically powered system
GB08604228A Expired GB2171152B (en) 1985-02-20 1986-02-20 Hydraulically powered system

Family Applications Before (1)

Application Number Title Priority Date Filing Date
GB858504343A Pending GB8504343D0 (en) 1985-02-20 1985-02-20 Hydraulically powered system

Country Status (1)

Country Link
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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0532756A4 (en) * 1990-06-06 1994-06-01 Komatsu Mfg Co Ltd Device for and method of controlling vehicle for loading work
FR2946401A1 (en) * 2009-06-03 2010-12-10 Airbus France ACTUATOR WITH ELECTRIC POWER AND METHOD OF CONTROLLING SUCH ACTUATOR.
EP1837509A4 (en) * 2004-11-22 2011-05-11 Hitachi Construction Machinery Controller for hydraulic construction machine

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB782381A (en) * 1955-02-09 1957-09-04 Ace Machinery Ltd Improvements in or relating to hoisting apparatus
GB1334769A (en) * 1970-10-26 1973-10-24 Leistikow J Device for the control of a high pressure pump
US3997282A (en) * 1973-03-15 1976-12-14 Waterous Company Pump pressure control device
GB2046833A (en) * 1979-04-03 1980-11-19 Woma Maasberg Co Gmbh W Control means for a diesel motor pump drive
US4330238A (en) * 1980-03-04 1982-05-18 The United States Of America As Represented By The Secretary Of The Navy Automatic actuator for variable speed pump

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB782381A (en) * 1955-02-09 1957-09-04 Ace Machinery Ltd Improvements in or relating to hoisting apparatus
GB1334769A (en) * 1970-10-26 1973-10-24 Leistikow J Device for the control of a high pressure pump
US3997282A (en) * 1973-03-15 1976-12-14 Waterous Company Pump pressure control device
GB2046833A (en) * 1979-04-03 1980-11-19 Woma Maasberg Co Gmbh W Control means for a diesel motor pump drive
US4330238A (en) * 1980-03-04 1982-05-18 The United States Of America As Represented By The Secretary Of The Navy Automatic actuator for variable speed pump

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0532756A4 (en) * 1990-06-06 1994-06-01 Komatsu Mfg Co Ltd Device for and method of controlling vehicle for loading work
EP1837509A4 (en) * 2004-11-22 2011-05-11 Hitachi Construction Machinery Controller for hydraulic construction machine
FR2946401A1 (en) * 2009-06-03 2010-12-10 Airbus France ACTUATOR WITH ELECTRIC POWER AND METHOD OF CONTROLLING SUCH ACTUATOR.
US8261545B2 (en) 2009-06-03 2012-09-11 Airbus Operations (Sas) Electric power actuator and control method for such an actuator

Also Published As

Publication number Publication date
GB8604228D0 (en) 1986-03-26
GB2171152B (en) 1988-06-29
GB8504343D0 (en) 1985-03-20

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PCNP Patent ceased through non-payment of renewal fee

Effective date: 20010220