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EP1528263A1 - Kran - Google Patents

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Publication number
EP1528263A1
EP1528263A1 EP03024718A EP03024718A EP1528263A1 EP 1528263 A1 EP1528263 A1 EP 1528263A1 EP 03024718 A EP03024718 A EP 03024718A EP 03024718 A EP03024718 A EP 03024718A EP 1528263 A1 EP1528263 A1 EP 1528263A1
Authority
EP
European Patent Office
Prior art keywords
conduit
piston rod
cylinder
pressure
side chamber
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.)
Withdrawn
Application number
EP03024718A
Other languages
English (en)
French (fr)
Inventor
Peter ASTRÖM
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.)
Hiab AB
Original Assignee
Hiab AB
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 Hiab AB filed Critical Hiab AB
Priority to EP03024718A priority Critical patent/EP1528263A1/de
Publication of EP1528263A1 publication Critical patent/EP1528263A1/de
Withdrawn legal-status Critical Current

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Classifications

    • 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
    • F15B11/024—Systems essentially incorporating special features for controlling the speed or actuating force of an output member by means of differential connection of the servomotor lines, e.g. regenerative circuits
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B66—HOISTING; LIFTING; HAULING
    • B66C—CRANES; LOAD-ENGAGING ELEMENTS OR DEVICES FOR CRANES, CAPSTANS, WINCHES, OR TACKLES
    • B66C13/00—Other constructional features or details
    • B66C13/18—Control systems or devices
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B66—HOISTING; LIFTING; HAULING
    • B66C—CRANES; LOAD-ENGAGING ELEMENTS OR DEVICES FOR CRANES, CAPSTANS, WINCHES, OR TACKLES
    • B66C23/00—Cranes comprising essentially a beam, boom, or triangular structure acting as a cantilever and mounted for translatory of swinging movements in vertical or horizontal planes or a combination of such movements, e.g. jib-cranes, derricks, tower cranes
    • B66C23/54—Cranes comprising essentially a beam, boom, or triangular structure acting as a cantilever and mounted for translatory of swinging movements in vertical or horizontal planes or a combination of such movements, e.g. jib-cranes, derricks, tower cranes with pneumatic or hydraulic motors, e.g. for actuating jib-cranes on tractors
    • 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
    • F15B11/024—Systems essentially incorporating special features for controlling the speed or actuating force of an output member by means of differential connection of the servomotor lines, e.g. regenerative circuits
    • F15B2011/0243—Systems essentially incorporating special features for controlling the speed or actuating force of an output member by means of differential connection of the servomotor lines, e.g. regenerative circuits the regenerative circuit being activated or deactivated automatically
    • 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
    • F15B2211/30565—Assemblies of multiple valves having multiple valves for a single output member, e.g. for creating higher valve function by use of multiple valves like two 2/2-valves replacing a 5/3-valve
    • F15B2211/3058—Assemblies of multiple valves having multiple valves for a single output member, e.g. for creating higher valve function by use of multiple valves like two 2/2-valves replacing a 5/3-valve having additional valves for interconnecting the fluid chambers of a double-acting actuator, e.g. for regeneration mode or for floating mode
    • 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
    • F15B2211/505—Pressure control characterised by the type of pressure control means
    • F15B2211/50563—Pressure control characterised by the type of pressure control means the pressure control means controlling a differential pressure
    • F15B2211/50581—Pressure control characterised by the type of pressure control means the pressure control means controlling a differential pressure using counterbalance 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
    • F15B2211/5153—Pressure control characterised by the connections of the pressure control means in the circuit being connected to an output member 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
    • F15B2211/70—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
    • F15B2211/7051—Linear output members
    • F15B2211/7057—Linear output members being of the telescopic type
    • 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
    • F15B2211/7114—Multiple output members, e.g. multiple hydraulic motors or cylinders with direct connection between the chambers of different actuators
    • F15B2211/7128—Multiple output members, e.g. multiple hydraulic motors or cylinders with direct connection between the chambers of different actuators the chambers being connected in parallel
    • 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
    • F15B2211/75—Control of speed of the output member

Definitions

  • the present invention relates to a crane, comprising two interconnected beams and, for the displacement of each beam respectively, at least two cylinder/piston units each of which comprises a piston rod that is displaceable in a cylinder and a piston that is connected to the piston rod and separates the cylinder chamber in a cylinder side chamber and a piston rod side chamber, said cylinder being provided with an opening in the cylinder gable in order to permit a displacement of the piston rod out of and into the cylinder, a first conduit for conducting a pressure fluid from a pressure fluid source to the cylinder side chambers, and a second conduit for conducting pressure fluid from the piston rod side chambers to a pressure fluid reservoir that has a lower pressure than the pressure fluid source, and a third conduit for regenerative conduction of pressure fluid from the piston rod side chamber of the first hydraulic unit to the cylinder side chamber thereof,
  • the invention is applicable to all types of cranes, but is particularly applicable to cranes for lifting piece goods, presenting a considerable overhang when in an extended position.
  • the invention will therefore be described by way of example with reference to such an application.
  • hydraulic units according to the invention can be utilized for the purpose of imparting swinging movements as well as longitudinal movements of any beam that forms a part of the crane.
  • the invention is particularly suitable for cranes that comprise a plurality of beams that are arranged in a telescopic way.
  • the beams are displaced in relation to each other by means of a plurality of hydraulic cylinder/piston units, one for each arm.
  • the invention is particularly related to cranes by which said units are successively arranged, or bus-type connected, in the meaning that a first one thereof is more adjacent the pressure source and the reservoir in terms of fluid flow distance than the second one, and that there is a conduit between each pair of units for the purpose of conducting pressure fluid from the piston rod side chamber of one of the units to the piston rod side chamber of the other unit.
  • a common conduit for the regeneration flow of oil is used for all units.
  • This regeneration conduit may be arranged as a single conduit connected, in one end, to a conduit leading from a pressure fluid source to the cylinder side chambers of the cylinder-piston units, and, in the other end, to a conduit leading from the piston rod side chambers of said units to a reservoir of lower pressure than the pressure source.
  • the regeneration conduit is arranged downstream a first cylinder-piston unit, downstream being referred to as between said unit and the pressure source and reservoir respectively.
  • the object of the present invention is achieved by means of a crane as initially defined, characterised in that it comprises a fourth conduit for regenerative conduction of pressure fluid from the piston rod side chamber of the second hydraulic unit to the cylinder side chamber thereof.
  • a crane as initially defined, characterised in that it comprises a fourth conduit for regenerative conduction of pressure fluid from the piston rod side chamber of the second hydraulic unit to the cylinder side chamber thereof.
  • the regenerative flow does not need to go via all the (downstream) piston rod side chambers that are arranged in series before being regenerated via the third conduit and first conduit to the cylinder side chambers.
  • the invention includes such an embodiment.
  • the crane is further characterised in that it comprises at least one valve member arranged for permitting a regenerative flow through the fourth conduit under condition that the pressure in the first conduit is above a pre-determined absolute pressure level and that there is a flow of pressure fluid in the second conduit in a direction from the piston rod side chamber of the second hydraulic unit towards the reservoir.
  • the crane according to the invention comprises a means for detecting whether the pressure in the first conduit is above said pre-determined level, and a means for detecting the fluid flow direction in the second conduit, these means being connected to the at least one valve member for the purpose of controlling the operation thereof.
  • Fig. 1 shows a crane according to the invention.
  • the crane comprises a plurality of beams 1 that are telescopically arranged in relation to each other in order to permit adjustment of its length from a shortest length, in which the beams are inserted into each other, to a maximum length when they are fully extended.
  • the crane comprises a plurality of hydraulic units 2 for driving the beams 1 in way known per se.
  • each hydraulic unit 2 comprises a cylinder 3 and a piston 4 with a piston rod 5.
  • the piston divides the cylinder chamber into a cylinder side chamber 6 and a piston rod side chamber 7.
  • the piston area is larger on the cylinder side than on the piston rod side.
  • the piston rod 5 is arranged to perform a reciprocating movement through an opening 8 in a gable 9 of the cylinder 3 for its operation.
  • the crane For the actuation of the hydraulic unit the crane comprises a first conduit 10 that connects the cylinder side chambers 6 of the hydraulic units 2 with a pressure fluid source 11 via a direction valve 12 in a way known per se.
  • the cylinder side chambers 6 may be regarded as connected in parallel with each other in relation to the source 11.
  • the fluid pressure in the pressure fluid source may, for example, be 28 MPa.
  • the crane also comprises a second conduit 13 that connects the piston rod side chamber 7 of a first one of the hydraulic units 2 with a low pressure reservoir 14 for drainage of pressure fluid from the chamber 7 to the reservoir 14.
  • the fluid pressure in the reservoir 14 may, as here, be equal to atmospheric pressure.
  • the third conduit 15 is arranged for controlled regenerative pressure fluid flow from the piston rod side chambers 7 to the cylinder side chambers 6 during extension of the crane.
  • the crane according to the invention comprises a pressure delimiting member 16 in the second conduit 13.
  • a pilot-controlled valve 17 in the second conduit 13.
  • valve 17 Upon activation of valve 17, it will permit a flow throughthe second conduit 13 towards the reservoir.
  • the regenerative flow through the third conduit 15 is stopped, or at least substantially reduced, as valve 17 is actuated in order to permit a flow of fluid from the piston rod side chamber 7 to the reservoir 14.
  • full extension of the hydraulic unit 2 in question can be attained with a remaining high or even further increased pressure on the cylinder side and a reduced, but still substantial, pressure on the piston rod side thanks to the pressure delimiting member 16.
  • the pressure delimiting member 16 should comprise a counter pressure valve and may comprise any kind of throttle or constriction. It only opens for passage when the pressure in the piston rod side chamber exceeds a given value, in this example 24 MPa.
  • the pressure delimiting member 16 is arranged so as to delimit the pressure in the piston rod side chamber 7 to approximately 24 MPa while the pressure in the cylinder side chamber reaches approximately 28 MPa during the continued piston rod displacement without aid of regenerative flow.
  • Pilot-controlled valve 17 in the second conduit 13 is controlled based on the pressure value measured or detected by the measuring means 18, 19, by means pressure fluid connection from the measuring means 18, 19 to the valve 17 upon the presence of a given pressure in the first conduit 10. It should be emphasized that the term measurement as used in this context also may comprise simple indication of one specific pressure level, and not necessarily a literal measurement. Once a specific pressure acts on the measuring means 18,19, an hydraulic pressure may be applied to the pilot-controlled valve, for example via a leak conduit from the measuring means 18,19.
  • Said measuring means 18,19 comprises a conduit 18 connected to the first conduit 10 and the reservoir 14, via the second conduit, and a (spring-loaded non-return) valve 19.
  • a piloting impulse of pressure fluid is conducted via a further conduit, here indicated with a broken line 21 from the piloting valve 19 to the pilot-controlled valve 17 for the actuation thereof.
  • a constriction 31 is arranged downstream valve 19 in said conduit 18 in order to, together with valve 19, determine the pressure at which the pilot-controlled valve 17 is to open.
  • valve 23 in the third conduit 15 for regenerative flow.
  • the regeneration valve 23 is actuated by the pressure of the first conduit 10, with which it is connected via a pilot flow conduit 20.
  • Said pilot controlled valve 23 upon actuation thereof, opens for regenerative flow of pressure fluid from piston rod side chamber 7 to cylinder side chamber 6.
  • a non-return valve that prevents flow in the opposite direction, that is from cylinder side chamber 6 to piston rod side chamber 7.
  • Valve 23 defines a means for breakingor interrupting the regenerative operation.
  • the third conduit 15 could be directly connected with, for example, the direction valve 12, and that the latter could then be equipped with a slide valve that would take the place and function of the regeneration valve 23 and the non-return valve in series therewith.
  • the individual piston rod side chambers 7 are connected in bus-type in a series via a plurality of conduits 13" each of which is provided between two consecutive piston rod side chambers in the row of hydraulic units 2. However, they could also be connected in a connection of a star-type. Said intermediate conduits 13" can be regarded as parts of the second conduit 13 or as sub-conduits of the second conduit 13.
  • a piston rod side chamber 7 of a first hydraulic unit is connected via the second conduit 13 to the low pressure reservoir 14.
  • Each cylinder-piston unit is arranged for the purpose of displacing or swinging a respective beam of the crane. Except the first unit in such a series of units, which is connected to a crane base in one end and a first beam in the other end, each unit is connected to two adjacent beams for interrelated movement thereof.
  • a fourth conduit 24 for regenerative conduction of pressure fluid from the piston rod side chamber 7 of one of the hydraulic units 2 to the cylinder side chamber 6 thereof.
  • a first end of the fourth conduit 24 is connected to the first conduit 10 and a second end thereof is connected to the intermediate conduit 13" that leads form the piston rod side chamber 7 of one of the units 2 to the piston rod side chamber 7 of the other one of said units 2.
  • the crane comprises a first valve member 25 arranged for permitting a regenerative flow through the fourth conduit under condition that the pressure in the first conduit is above a pre-determined absolute pressure level.
  • a second valve member 26 arranged for permitting a regenerative flow through the fourth conduit under condition that there is a flow of pressure fluid in the second conduit 13 in a direction from the cylinder side chamber 6 of the second hydraulic unit 2 towards the reservoir 14.
  • This pressure sensing means is incorporated in the first valve member 25 since the latter is designed as a spring loaded valve, the spring of which is under action of the pressure in the first conduit 10, the valve 25 being arranged for opening when the force generated by the pressure fluid in the first conduit 10 and acting on the spring exceeds the spring force.
  • the second valve member 26 is a pilot-controlled valve member controlled by the means 27 for detecting the flow direction in the intermediate second conduit 13".
  • the hydraulic connection 28 defines a means for sensing the pressure fall over the means 27 for detecting the flow direction.
  • the means 27 for detecting the flow direction in the intermediate second conduit 13" comprises a spring loaded valve, the spring of which is under action of the pressure in the intermediate second conduit upstream said one way valve 27 as seen in flow direction from the second unit 2 towards the reservoir 14.
  • the valve 27 is opened when the force generated by the pressure fluid in the second conduit and acting on the spring of the valve 27 exceeds the spring force. A fluid pressure pulse from valve 27 will then flow via connection 28 and affect the opening of second valve member 26.
  • the crane comprises a number of elements the function of which are important for a reliable and effective operation of the crane. Accordingly there is a non-return valve 29 provided in parallel with the pressure delimiting member 16 in the second conduit, for allowing a flow of pressure fluid from the reservoir 14 towards the piston rod chambers 7 without throttling caused by the pressure delimiting member 16.
  • a non-return valve 30 is arranged in a corresponding way and for a corresponding purpose, in parallel with the flow direction detecting means 27.
  • non-return valves that normally permit the regenerative flow towards the cylinder side chamber 6 but prevent a flow in the opposite direction, are a natural part of any embodiment of the invention, in order to further improve the operation of the crane.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Automation & Control Theory (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • General Engineering & Computer Science (AREA)
  • Fluid-Pressure Circuits (AREA)
  • Jib Cranes (AREA)
  • Control And Safety Of Cranes (AREA)
EP03024718A 2003-10-29 2003-10-29 Kran Withdrawn EP1528263A1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP03024718A EP1528263A1 (de) 2003-10-29 2003-10-29 Kran

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP03024718A EP1528263A1 (de) 2003-10-29 2003-10-29 Kran

Publications (1)

Publication Number Publication Date
EP1528263A1 true EP1528263A1 (de) 2005-05-04

Family

ID=34400478

Family Applications (1)

Application Number Title Priority Date Filing Date
EP03024718A Withdrawn EP1528263A1 (de) 2003-10-29 2003-10-29 Kran

Country Status (1)

Country Link
EP (1) EP1528263A1 (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2011156829A1 (de) * 2010-06-17 2011-12-22 Palfinger Ag Fahrzeugkran

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4125974A (en) * 1977-07-08 1978-11-21 Harnischfeger Corporation Control system for telescopic boom
GB2159605A (en) * 1984-06-01 1985-12-04 Ming Chuan Shieh Regenerating reflux valve
DE3801007A1 (de) * 1988-01-15 1989-07-27 Joh Tirre Ohg Maschf Eilgangschaltung fuer einen schubzylinder, insbesondere fuer einen schubzylinder eines ladekranes

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4125974A (en) * 1977-07-08 1978-11-21 Harnischfeger Corporation Control system for telescopic boom
GB2159605A (en) * 1984-06-01 1985-12-04 Ming Chuan Shieh Regenerating reflux valve
DE3801007A1 (de) * 1988-01-15 1989-07-27 Joh Tirre Ohg Maschf Eilgangschaltung fuer einen schubzylinder, insbesondere fuer einen schubzylinder eines ladekranes

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2011156829A1 (de) * 2010-06-17 2011-12-22 Palfinger Ag Fahrzeugkran
US8875912B2 (en) 2010-06-17 2014-11-04 Palfinger Ag Vehicle crane

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