US3550505A - Hydraulic system including two work circuits - Google Patents
Hydraulic system including two work circuits Download PDFInfo
- Publication number
- US3550505A US3550505A US822568A US3550505DA US3550505A US 3550505 A US3550505 A US 3550505A US 822568 A US822568 A US 822568A US 3550505D A US3550505D A US 3550505DA US 3550505 A US3550505 A US 3550505A
- Authority
- US
- United States
- Prior art keywords
- orifice
- valve
- pressure
- flow
- circuit
- 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
Links
Images
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
- F15B11/16—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- 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
- F15B2211/40—Flow control
- F15B2211/405—Flow control characterised by the type of flow control means or valve
- F15B2211/40507—Flow control characterised by the type of flow control means or valve with constant throttles or orifices
-
- 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
- F15B2211/40—Flow control
- F15B2211/405—Flow control characterised by the type of flow control means or valve
- F15B2211/40515—Flow control characterised by the type of flow control means or valve with variable throttles or orifices
-
- 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
- F15B2211/40—Flow control
- F15B2211/405—Flow control characterised by the type of flow control means or valve
- F15B2211/40523—Flow control characterised by the type of flow control means or valve with flow dividers
- F15B2211/4053—Flow control characterised by the type of flow control means or valve with flow dividers using 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
- F15B2211/40—Flow control
- F15B2211/42—Flow control characterised by the type of actuation
- F15B2211/428—Flow control characterised by the type of actuation actuated by fluid 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
- F15B2211/40—Flow control
- F15B2211/45—Control of bleed-off flow, e.g. control of bypass flow to the return line
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/60—Circuit components or control therefor
- F15B2211/605—Load sensing circuits
- F15B2211/6051—Load sensing circuits having valve means between output member and the load sensing circuit
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
- F15B2211/71—Multiple output members, e.g. multiple hydraulic motors or cylinders
- F15B2211/7142—Multiple output members, e.g. multiple hydraulic motors or cylinders the output members being arranged in multiple groups
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
- F15B2211/78—Control of multiple output members
- F15B2211/781—Control of multiple output members one or more output members having priority
Definitions
- both circuits cannot be operated simultaneously when the second is subjected to the higher load pressure.
- the maximum supply rates to the two circuits necessarily are equal. These characteristics limit the utility of this duplex system. For example, it cannot be used on certain backhoes whose swing and steering cylinders require a lower maximum flow rate than the lift, crowd and tilt cylinders and must be actuated simultaneously with one of the other cylinders at times when the second cylinder requires a superior pressure.
- the problem of providing different maximum supply rates can be solved by incorporating in the primary circuit a flow control mechanism of the type disclosed in application Ser. No. 769,858, filed Oct. 23, 1968, but this modification still leaves unanswered the problem of insuring simultaneous operation of the two circuits at times when the second circuit is more heavily loaded than the first.
- the object of this invention is to provide a hydraulic system which affords all of the advantages of the duplex system of U.S. Pat. No. 3,41 1,295, as well as the flow control action of the improvement disclosed in application Ser. No. 769,858, and in addition provides for simultaneous operation of both work circuits regardless of which requires the higher load pressure.
- the improved system proceeds from the prior proposals mentioned above and is characterized in that it:
- a. employs a bypass valve which, in addition to its normal function of diverting fluid to the secondary circuit, also meters flow into the primary circuit;
- FIG. is a schematic diagram of the new hydraulic system.
- the improved system includes a fixed delivery supply pump 1 which is arranged to draw oil from a tank 2 and deliver it under pressure to a pair of work circuits 3 and 4, hereafter referred to as the primary and secondary circuits, respectively.
- Primary circuit 3 comprises two double-acting cylinders 5 and 6 which are under the control of a pair of three-position, manually operated, closed center distributing valves 7 and 8, respectively. These valves are connected in a parallel circuit by the branches 9a and 9b of a supply line 9, and by the branches 11a and 11b of a common exhaust line 11.
- Each distributing valve has a neutral position in which it hydraulically locks the associated cylinder 5 or 6 and isolates its supply and exhaust branches from each other, and is shiftable in opposite directions from this position to progressively open a supply path from branch 9a or 9b to one or the other end of the cylinder and an exhaust path from the remaining end of the cylinder to branch Ila or llb.
- Oil is supplied to the circuits 3 and 4 through a bypass valve 12 which is adapted to meter in reverse senses the flows into the circuits.
- Valve 12 is biased toward the illustrated limiting position by a spring 13, and in this position it interrupts flow to circuit 4 and permits free flow to circuit 3.
- valve 12 moves to the left, it progressively opens a flow path from pump 1 to the line 14 leading to secondary circuit 4 and then, after this path becomes essentially unrestricted, it commences to throttle flow into the supply line 9 of primary circuit 3.
- valve I2 moves to the right from its leftmost limiting position, it first decreases to a minimum the restriction to flow through the path leading to line 9 and then begins to throttle the flow from pump I to line 14.
- Bypass valve 12 is positioned by a servocontrol that responds both to actuation of distributing valves 7 and 8 and to the presence of an excessive flow rate through supply line 9.
- This control consists of a hydraulic Wheatstone bridge including a pair of output junctions l5 and 16 which are connected. respectively, with a pair of opposed hydraulic motors I7 and 18 which shift bypass valve 12, and four conduit legs 19, 21, 22 and 23; the legs 19 and 21 leading from supply line 9 to each of the junctions, and the legs 22 and 23 leading from the junctions to tank 2.
- Leg 19, which is the command leg of the bridge consists of two parallel branches, each comprising one of the supply branches 9a and 9b and one of the conduits 19a and 19b, and a common portion 19c.
- the command branches contain variable command orifices 24 and 25 whose flow areas vary with movement of the distributing valves 7 and 8. These orifices are closed when the distributing valves are in neutral position, and each is opened progressively a the associated valve is shifted away from that position in either direction.
- Bridge leg 23 is the feedback leg of the bridge and contains a variable orifice 26 whose flow area varies in response to movement of bypass valve 12. The flow area of this orifice is a minimum when valve 12 is in the illustrated position and increases progressively as the valve moves to the left.
- the remaining legs of the bridge contain fixed reference orifices 27 and 28, respectively.
- the servocontrol also includes a device for limiting the rate at which oil can be delivered to the cylinders 5 and 6 of the primary circuit.
- This device comprises a reference orifice 29 interposed in supply line 9, and a variable auxiliary orifice 31 which is located in the feedback leg 23 of the Wheatstone bridge and which is controlled in accordance with the pressure differential across the reference orifice.
- the auxiliary orifice 3I is intended to unbalance the bridge in the sense that effects leftward movement of bypass valve 12 (i.e., that causes valve 12 to increase the amount of oil diverted to secondary circuit 4) as the flow rate to valves 7 and 8 exceeds the selected maximum; therefore, the orifice 31 is biased open by a spring 32 and is connected in series with the feedback orifice 26.
- a pair of opposed motors 33 and 34 which respond, respectively, to the pressures upstream and downstream of reference orifice 29, shift auxiliary orifice 31 in the closing direction as the supply rate to the distributing valves tends to exceed the set limit. This limit, of course, can be changed by altering the size of orifice 29.
- the invention may utilize any one of the twelve forms of the Wheatstone bridge circuit disclosed in U.S. Pat. No. 3,41 1,295.
- the auxiliary orifice is in series with the feedback orifice and is biased open.
- the auxiliary orifice is located in a parallel branch of the feedback leg 23 and is biased closed.
- the secondary circuit 4 may employ either conventional open center distributing valves or, as in the illustrated embodiment, closed center distributing valves 35 and 36 and a separate pilot operated bypass valve 37.
- the exact design of this circuit forms no part of the present invention and therefore, since the one chosen for illustration is fully described in US. Pat. No. 3,41 1,295, further description of it would serve no useful purpose.
- command orifices 24 and 25 When the system is in service and distributing valves 7 and 8 are in their illustrated neutral .positions, command orifices 24 and 25 will be closed and auxiliary orifice 31' will be open.
- the oil delivered to supply line 9 through bypass valve 12 escapes to tank 2 through bridge legs 21 and 23, and thereby develops at output junction 16 a pressure higher than the tank pressure prevailing at junction 15.
- motor 18 will shift bypass valve 12 to the left to open the flow path from pump 1 to line 14 and secondary circuit 4.
- feedback orifice 26 opens to thereby reduce the pressure at junction 16; consequently, valve 12 will come to rest in a position in which it permits substantially free flow. to the secondary circuit.
- biasing spring 13 causes valve 12 to impose some restriction to this flow, so the pressure in supply line 9 will be slightly higher, for example 40 p.s.i. higher, than tank pressure. This is necessary in order to insure development of a pressure at junction 15 sufficient to enable motor 17 to shift valve 12 to the right in those cases where one of the command orifices 24 and 25 is opened at a time when secondary circuit 4 is idle and pump 1 is being unloaded to tank 2 through bypass valve 37.
- spring 13 need not be employed for this purpose.
- valve 12 When one of the distributing valves 7 and 8 is shifted away from neutral position to actuate cylinder or 6, the associated command orifice 24 or 25 commences to open, and the pressure at junction 15 rises relatively to the pressure at junction 16. As a result, motor 17 and spring 13 move bypass valve 12 to the right to thereby gradually close the flow path to line 14. This movement of valve 12 is accompanied by a reduction in the flow area of feedback orifice 26 and an increase in the pressure at output junction 16. When the pressure at this junction reaches the level at which motor 18 balances the forces exerted by motor 17 and spring 13, the Wheatstone bridge will again be in balance, and valve 12 will come to rest.
- the new position of this valve will correspond to the present position of the actuated distributing valve 7 or 8 (assuming that the flow control device has not been activated).
- auxiliary orifice 31 increases the pressure at outputjunction l6 relatively to the pressure atjunction 15 and thereby enables motor 18 to prevent further rightward movement of bypass valve 12.
- the flow area of orifice 31 will continue to decrease as long as the flow area of the opened command orifice 24 or 25 continues to increase, so thesupply rate to the cylinder will be held substantially constant at the desired limiting value even through the distributing valve 7 or 8 is shifted all the way to one or the other of its limiting positions.
- bypass valve 12 will have been returned to the initial operating position in which it permits substantially free flow to secondary circuit 4.
- bypass valve 12 will come to rest in a position in which it is throttling the flow into line 9 to the rate corresponding to the setting of orifice 29.
- circuit 3 will supply oil to its loads at the controlled flow rate and the low pressure they require,
- a hydraulic system of the type including: a. a pump 1; b. a pair of work circuits 3, 4, at least the first 3 of which contains a closed center distributing valve 7 or 8 having a control member movable from a neutral position to 'effect progressive opening of a flow path from a supply line-9'to a hydraulic motor Set 6;
- a bypass valve 12 for opening and closing a flowpath leading from the pump to the second work circuit 4;
- a hydraulic .Wheatstone bridge type of control for positioning the bypass valve including a conduit leg 19 containing a command orifice 24 or 25 whose flow area changes in response to movement of said control member. and another conduit leg 23 containing a feedback orifice 26 whose flow area changes in response to movement of the bypass valve 12; and
- auxiliary orifice 31 in the bridge whose flow area is controlled by the pressure differential across a reference orifice 29 in the supply line 9 and which unbalances the bridge to effect opening of the bypass valve as said pressure differential rises above a predetermined value;
- bypass valve 12 closes and opens a flow path from the pump 1 to said supply line 9 as it moves to open and close, respectively, said flow path leading to the second work circuit 4; 2. fluid is supplied to the Wheatstone bridge from the supply 5 line 9; and
- auxiliary orifice 31 is located in the same conduit leg 23 of the bridge as the feedback orifice 26.
- bypass valve 12 commences to restrict to a significant extent flow through the path leading to the supply line 9 only after it has established essentially free flow through the path leading to the second work circuit 4.
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Fluid-Pressure Circuits (AREA)
Description
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US82256869A | 1969-05-07 | 1969-05-07 |
Publications (1)
Publication Number | Publication Date |
---|---|
US3550505A true US3550505A (en) | 1970-12-29 |
Family
ID=25236389
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US822568A Expired - Lifetime US3550505A (en) | 1969-05-07 | 1969-05-07 | Hydraulic system including two work circuits |
Country Status (4)
Country | Link |
---|---|
US (1) | US3550505A (en) |
FR (1) | FR2046209A5 (en) |
GB (1) | GB1242505A (en) |
SE (1) | SE346833B (en) |
Cited By (15)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3768372A (en) * | 1972-07-13 | 1973-10-30 | Borg Warner | Control arrangement for hydraulic systems |
US3851566A (en) * | 1973-01-13 | 1974-12-03 | Bosch Gmbh Robert | Apparatus for controlling a hydraulic-lift tail gate arrangement of a cargo-carrying vehicle |
US3864913A (en) * | 1972-12-04 | 1975-02-11 | Bosch Gmbh Robert | Control apparatus for hydraulic-lift tail gates of vans, and the like |
US3883023A (en) * | 1972-06-12 | 1975-05-13 | Koehring Co | Control means for a pair of fluid motors |
US3927603A (en) * | 1972-06-12 | 1975-12-23 | Koehring Co | Control means for a pair of fluid motors |
US3934416A (en) * | 1974-02-25 | 1976-01-27 | Lebus International, Inc. | Central hydraulic system for marine deck equipment |
US3987623A (en) * | 1976-01-23 | 1976-10-26 | Caterpillar Tractor Co. | Controlled priority fluid system of a crawler type vehicle |
WO1980000821A1 (en) * | 1978-10-12 | 1980-05-01 | Caterpillar Tractor Co | Controlled demand priority hydraulic circuit |
DE2919206A1 (en) * | 1979-05-12 | 1980-11-20 | Bosch Gmbh Robert | DEVICE FOR CONTROLLING A HYDRAULIC CONSUMER |
US6018895A (en) * | 1996-03-28 | 2000-02-01 | Clark Equipment Company | Valve stack in a mini-excavator directing fluid under pressure from multiple pumps to actuable elements |
US6029446A (en) * | 1996-03-28 | 2000-02-29 | Melroe Company | Multifunction valve stack |
FR2903741A1 (en) * | 2006-07-11 | 2008-01-18 | Jtekt Hpi Soc Par Actions Simp | Mechanism`s e.g. retractable roof, control assisting device for motor vehicle, has distribution channels attributed and connected to power steering mechanism or retractable roof to be controlled, and valve placed between pump and channels |
CN105041748A (en) * | 2014-04-29 | 2015-11-11 | 罗伯特·博世有限公司 | Hydraulic control arrangement for a plurality of actuators |
CN113233263A (en) * | 2021-04-20 | 2021-08-10 | 深圳景嘉机电科技有限公司 | Lower cable delivery device in oil well oil pipe |
CN114017402A (en) * | 2021-10-28 | 2022-02-08 | 北京三兴汽车有限公司 | Movable hydraulic control system |
-
1969
- 1969-05-07 US US822568A patent/US3550505A/en not_active Expired - Lifetime
-
1970
- 1970-02-24 GB GB8869/70A patent/GB1242505A/en not_active Expired
- 1970-03-10 SE SE03162/70A patent/SE346833B/xx unknown
- 1970-04-16 FR FR7013737A patent/FR2046209A5/fr not_active Expired
Cited By (17)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3883023A (en) * | 1972-06-12 | 1975-05-13 | Koehring Co | Control means for a pair of fluid motors |
US3927603A (en) * | 1972-06-12 | 1975-12-23 | Koehring Co | Control means for a pair of fluid motors |
US3768372A (en) * | 1972-07-13 | 1973-10-30 | Borg Warner | Control arrangement for hydraulic systems |
DE2335704A1 (en) * | 1972-07-13 | 1974-01-24 | Borg Warner | HYDRAULIC SYSTEM |
US3864913A (en) * | 1972-12-04 | 1975-02-11 | Bosch Gmbh Robert | Control apparatus for hydraulic-lift tail gates of vans, and the like |
US3851566A (en) * | 1973-01-13 | 1974-12-03 | Bosch Gmbh Robert | Apparatus for controlling a hydraulic-lift tail gate arrangement of a cargo-carrying vehicle |
US3934416A (en) * | 1974-02-25 | 1976-01-27 | Lebus International, Inc. | Central hydraulic system for marine deck equipment |
US3987623A (en) * | 1976-01-23 | 1976-10-26 | Caterpillar Tractor Co. | Controlled priority fluid system of a crawler type vehicle |
WO1980000821A1 (en) * | 1978-10-12 | 1980-05-01 | Caterpillar Tractor Co | Controlled demand priority hydraulic circuit |
US4205864A (en) * | 1978-10-12 | 1980-06-03 | Caterpillar Tractor Co. | Controlled demand priority hydraulic circuit |
DE2919206A1 (en) * | 1979-05-12 | 1980-11-20 | Bosch Gmbh Robert | DEVICE FOR CONTROLLING A HYDRAULIC CONSUMER |
US6018895A (en) * | 1996-03-28 | 2000-02-01 | Clark Equipment Company | Valve stack in a mini-excavator directing fluid under pressure from multiple pumps to actuable elements |
US6029446A (en) * | 1996-03-28 | 2000-02-29 | Melroe Company | Multifunction valve stack |
FR2903741A1 (en) * | 2006-07-11 | 2008-01-18 | Jtekt Hpi Soc Par Actions Simp | Mechanism`s e.g. retractable roof, control assisting device for motor vehicle, has distribution channels attributed and connected to power steering mechanism or retractable roof to be controlled, and valve placed between pump and channels |
CN105041748A (en) * | 2014-04-29 | 2015-11-11 | 罗伯特·博世有限公司 | Hydraulic control arrangement for a plurality of actuators |
CN113233263A (en) * | 2021-04-20 | 2021-08-10 | 深圳景嘉机电科技有限公司 | Lower cable delivery device in oil well oil pipe |
CN114017402A (en) * | 2021-10-28 | 2022-02-08 | 北京三兴汽车有限公司 | Movable hydraulic control system |
Also Published As
Publication number | Publication date |
---|---|
FR2046209A5 (en) | 1971-03-05 |
DE2011386A1 (en) | 1970-11-12 |
GB1242505A (en) | 1971-08-11 |
SE346833B (en) | 1972-07-17 |
DE2011386B2 (en) | 1972-10-05 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US3550505A (en) | Hydraulic system including two work circuits | |
US4020867A (en) | Multiple pressure compensated flow control valve device of parallel connection used with fixed displacement pump | |
CA1184830A (en) | Fluid system with flow compensated torque control | |
US4250794A (en) | High pressure hydraulic system | |
US3455210A (en) | Adjustable,metered,directional flow control arrangement | |
US3976097A (en) | Hydraulic control arrangement | |
US3979908A (en) | Priority flow valve | |
US3465519A (en) | Hydraulic flow controlling apparatus | |
US5447093A (en) | Flow force compensation | |
US3179120A (en) | Proportional flow divider | |
US4732076A (en) | Apparatus for the control of a hydromotor | |
US2643516A (en) | Fluid pressure system | |
JPS6011706A (en) | Liquid pressure type apparatus having at least two working apparatuses loaded by one pump | |
US5077972A (en) | Load pressure duplicating circuit | |
US4518322A (en) | Arrangement for regulating a supply flow and for limiting a supply pressure of an adjustable pump | |
US5237908A (en) | Control system for the load-independent distribution of a pressure medium | |
US4065922A (en) | Load lifting and lowering control system | |
US3366064A (en) | Control for hydraulic apparatus | |
US3520231A (en) | Hydraulic supply systems with flow rate-limiting control | |
EP0008523B1 (en) | Improvements relating to hydraulic control systems | |
US3191382A (en) | Hydraulic system | |
US4080994A (en) | Control arrangement for supplying pressure fluid to at least two hydraulically operated consumer devices | |
US2503870A (en) | Flow regulating device | |
US4967554A (en) | Commonly-piloted directional control valve and load pressure signal line relieving switching valve | |
JPS60263705A (en) | Pressure feeder for hydraulic apparatus |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: CONTINENTAL ILLINOIS NATIONAL BANK AND TRUST COMPA Free format text: SECURITY INTEREST;ASSIGNOR:ICM ACQUISITIONS, INC., A CORP. OF DE;REEL/FRAME:005156/0501 Effective date: 19870911 |
|
AS | Assignment |
Owner name: ICM ACQUISITIONS, INC., A DE. CORP. Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:GENERAL SIGNAL CORPORATION, A NY CORP.;REEL/FRAME:004855/0124 Effective date: 19870911 Owner name: HYDRECO, INC. Free format text: CHANGE OF NAME;ASSIGNOR:ICM ACQUISTIONS INC.;REEL/FRAME:004854/0821 Effective date: 19870910 |