US3698580A - Control system for material handling equipment - Google Patents
Control system for material handling equipment Download PDFInfo
- Publication number
- US3698580A US3698580A US887013A US3698580DA US3698580A US 3698580 A US3698580 A US 3698580A US 887013 A US887013 A US 887013A US 3698580D A US3698580D A US 3698580DA US 3698580 A US3698580 A US 3698580A
- Authority
- US
- United States
- Prior art keywords
- movement
- hydraulic
- flow control
- valve
- spool
- 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
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Classifications
-
- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
- E02F9/20—Drives; Control devices
- E02F9/22—Hydraulic or pneumatic drives
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T74/00—Machine element or mechanism
- Y10T74/20—Control lever and linkage systems
- Y10T74/20012—Multiple controlled elements
- Y10T74/20201—Control moves in two planes
Definitions
- ABSTRACT A control system for a hydraulic motor actuated material handling mechanism including a source of fluid power, a directional flow control valve interposed between the source of fluid power and the hydraulic motor, a bridge circuit including a source of electrical energy and having a first variable impedance branch varied by a command control lever and a second variable impedance branch associated with the flow control valve, comparator means connected to the output of the bridge circuit for detecting and amplifying an unbalance in the bridge circuit and means interconnected. between the comparator and the directional flow control valve for controlling said valve in a manner corresponding to command movement of the variable impedance branch.
- This invention relates to a unique electro-hydraulic or electrical control system for controlling one or more hydraulic motors. More specifically the invention concerns a control system for a material handling mechanism mounted upon a vehicle in which the several linkages and hydraulic motors of the material handling device may be easily controlled in a manner to improve cycle times with a measurable amount of reduced operator fatigue.
- the instant invention relates to a novel and unique electrical control circuit for controlling actuation of these various linkages of the article-handling equipment.
- Preferred embodiments, hereinafter disclosed incorporate a circuit between a-command lever and the flow control valve in such a manner to easily control actuation of the flow control valve and is of such simple construction as to permit utilization of a single lever to operate several such valves.
- control system it is a general object to provide an economical and easily assembled electrical control circuit for any hydraulic motor which results in unique operating characteristics of precise and accurate control of a linkage or hydraulic motor as well as the ability to accurately meter fluid through a directional flow control valve.
- a control system may be easily adapted in fields unrelated to arti- LII cle handling and would include machine tools and other diverse areas.
- an electrical control system for a hydraulic motor in which either a followup system or a positioncontrol system can be readily realized.
- FIG. 1 is a perspective view of the rear portion of a vehicle having mounted thereon a conventional backhoe;
- FIG. 2 is a rear elevational view of the directional flow control valves which are utilized to direct flow to and from the hydraulic motors actuating the various linkages of the backhoe;
- FIG. 3 is an exploded perspective view of the single handle control utilized to actuate the directional flow control valves which in turn direct fluid to and from the hydraulic motors;
- FIG. 4 is a side elevational view of the rotary actuator of the backhoe having the boom attached thereto with a schematic disclosure of the electro-hydraulic control system utilized in controlling the boom of the backhoe; t
- FIG. 5 is a schematic view of an electro-hydraulic circuit for controlling the hydraulic motor which in turn operates the boom of the backhoe;
- FIG. 6 is a side elevational view of the rotary actuator and the boom of the backhoe attached thereto with a schematic view of an 'electro-hydraulic control system which actuates the rotary actuator in turn controlling rotational movement of the backhoe boom;
- FIG. 7 is a sc hematic'view of the electro-hydraulic control system of FIG. 6;
- FIG. 8 is a top view disclosing rotary actuation of the backhoe unit and its correlated movement of the control handle;
- FIG. 9 is a perspective view of a mounting element for the control lever of FIG. 3.
- FIG. 10 is a schematic view of an additional control circuit.
- this material-handling apparatus comprises a backhoe having a support stand 12 suitably attached to the tractor by conventional means and being further supported upon the ground surface by stabilizer arms 14 (only one of which is here shown), the stabilizer itself being controlled by hydraulic motor 15.
- brackets 16, 16 extending rearwardly from support stand 12 carry a rotary hydraulic motor 30 constrained from rotation by suitable means and having a shaft 31 extending therethrough for rotatably driving the swing mount 17 as fluid energy is directed to the actuator 30.
- the swing mount 17 in turn rotatably mounts a boom 18, dipper stick 19 and bucket 20, these linkages and the bucket being controlled in their movement by hydraulic rams 21, 22, and 23 respectively.
- valve bank 62 Disposed underneath the operators station 13 for conveniently controlling the movement of the rams 15, the rotary actuator 30, and the hydraulic rams 21, 22 and 23, is a valve bank 62 comprising six directional flow control valves 61.
- a conventional end cap 63 Upon one end of this valve bank is mounted a conventional end cap 63 to which is connected an intake conduit 67 for delivering fluid from a pump to thevalves.
- Adjacent the opposite end of the valve bank 62 is another identical end cap 63 to which is connected a conduit 79 for returning hydraulic fluid to the reservoir.
- These valves 61 are substantially similar to that disclosed in US. Pat. No.'2,873,762 issued to F. H. Tennis and dated Feb. 17, l959. Further reference may be had to a cross sectional view of these same valves in FIGS. 4 and 6 for a clearer understand-' ing thereof.
- FIGS. 4 Reference may now be had to FIGS. 4 and in which one of the control valves 61 is integrated into the control circuit of the instant invention for the hydraulic motor 21 which effectuates movement of the boom 18 of the backhoe. (As later explained, such a circuit is associated with each element of the backhoe).
- a pump P delivers fluid from reservoir S to directional control valve 61 through a conduit 67. As disclosed in FIG. 2 such fluid would normally be delivered to an end cap 63 of valve bank 62, such being omitted from FIG. 4 for purposes of simplicity. This fluid is then directed into an open center passage 68 and normally flows directly out of this valve and into the opposite end cap and back to sump. As more fully disclosed in US.
- a spool 70 is reciprocable within the valve 61 whereby the reduced diameters of said spool in conjunction with various lands and porting will control the direction of fluid flow to and from the hydraulic motor 21.
- spool 70 is shifted either to the right or to the left and fluid can no longer flow through the open or low pressure passage 68 since the normal diameter of the spool precludes such, and fluid is then directed into a high pressure passage 69 for delivery to the hydraulic motor 21 via one of the motor ports 72 or 73.
- Movement of the spool 70 of the valve 61 is controlled by expansionable chamber device or servo motor 85 and includes a housing 86 connected to the valve 61 and having a piston element 87 attached to the spool whereby any unbalance of fluid energy delivered through a port 88 or a port 89 is effective to cause reciprocation of the piston 87 and the spool 70 to control the direction of fluid flow to hydraulic motor 21.
- Fluid is supplied to the servo motor from a pump P1 delivering fluid through a conduit 113 to solenoid operated valves and 111.
- solenoid valves may appropriately be a conventional normally open three-way valve in which the fluid is normally directed through the valve to the ports 88 and 89 of servo motor 85 but upon selective actuation they will dump both supply fluid and fluid on the appropriate side of piston 87 to sump S whereby the normal pressure on the opposing side of the piston will cause the spool to reciprocate.
- Another preferable solenoid valve would include the four-way normally open normally open solenoid valve, Type V955 made and sold by Skinner Precision Industries, Inc. of New Jersey, Connecticut. This valve is basically a combination of two three-way valves disclosed above, but incorporated into one housmg.
- a bridge circuit is interposed between a control member or lever 35 and spool 70 of the control valve 61.
- a bridge circuit is established in which two potentiometers 44 and 92 are connected in parallel and a voltage impressed across them.
- the wiper of potentiometer 44 is rotatably attached to the control lever 35 as hereinafter explained, and the wiper of potentiometer 92 is rotatably attached by assembly 91 (see FIG.'2) to the spool 70 of control valve 61.
- the wiper leads are then connected to a null detector means or comparator means 109 which will detect any unbalance or voltage differential in the bridge circuit and amplify a signal created by said unbalance to actuate the appropriate solenoid valve 110 and 111.
- the comparator means 109 will actuate solenoid valve 1 10 or 111 so as to dump fluid from the appropriate chamber on one side of piston 87 and normal pressure on the opposite side will effectuate reciprocation of spool 70, the spool movement rotating the wiper of potentiometer 92 such that the bridge circuit will again be balanced and fluid will continue to be pumped until the potentiometer 44 is returned to neutral.
- null detector or comparator means 109 is a conventional item and readily obtainable in the market in various forms.
- An example of other forms of the electrical circuits which may provide excellent alternatives would include a series connection of two variable resistances in parallel with a series connection of two fixed resistances, the comparator 109 being interconnected between the resistances of each parallel branch.
- the pump delivering fluid to the solenoid valves is preferably a low volume and low pressure pump, but may be the same pump utilized to deliver fluid to the backhoe itself if acceptable flow rates are provided.
- the solenoid valves selected for the system should preferably have a small flow rate for the intended pump and pressure since more accurate movement of the spool 70-may be obtained. It should be appreciated that solenoid members acting directly upon the spool could be utilized as well as other systems including conventional electro-hydraulic servo valves should the potentiometer reading be taken from the valve in such a manner as to be proportional to the flow rate through such valve.
- the potentiometer 92 is attached to the. spool 70 in a simple mechanical manner.
- a bracket 93 is fixedly attached to the console 13 of the backhoe apparatus with the potentiometer secured therein and constrained against rotation.
- a link 94 is then constrained for rotation with the wiper of the potentiometer 92, reciprocation of the spool causing rotation of this link through a pivotal element 95 so as to vary the impedance of this branch of the bridge circuit.
- Each of the directional flow control valves 61 associated with the rotary actuator, and the hydraulic motors 21, 22 and 23 may be conveniently provided with such an electrical control circuit.
- this control means 35 comprises a vertical support 36 which may be appropriately journaled in a housing 57 in a manner permitting rotational movement thereof. Attached to the lower end of this vertical support 36'is a gear 38 which upon rotation will drive a pinion 39 constrained for rotation with the stem of a potentiometer 40, the latter being fixedly supported in housing 57.
- a yoke 37 is provided on the upper end of vertical support 36, and common apertures 45 connect same to another yoke member 41 as well as to an extensible arm 46, the latter connection being made rigid by pin connections extending the adjacent diagonal apertures (unnumbered).
- the yoke 41 then extends downwardly from the pivotal connection 53 with the extending arm carrying the potentiometer 44 constrained for movement therewith.
- the stem of the potentiometer 44 carries a pinion 43 which is driven by a rack 42 mounted on yoke 37, and thus as the extensible arm 46 is rotated about a horizontal axis passing through a pivotal connection 53, the stern of the poten tiometer 44 is rotated so as to obtain a variable impedance or resistance.
- This potentiometer 44 appropriately controls movement of the boom 18 as previously discussed in relation to FIGS. 4 and 5 by connecting same with another bridge circuit element attached to the spool of the directional flow control valve 61 associated with hydraulic motor 21.
- the extensible arm 46 may additionally consist of an outer extensible member 47 and an inner member 48 over which the outer member is telescoped.
- a potentiometer 49 is then fixed by a bracket 50 upon said outer member, and upon extension and retraction of outer member 47, a rack 52 and a gear 51 constrained for rotation with the stern of potentiometer 49 creates a variable impedance in said potentiometer.
- this potentiometer may be integrated in a bridge circuit with a potentiometer associated with the flow control valve 61 which is connected to hydraulic motor 22 effectuating movement of the dipper stick 19.
- a handle 54 is rotatably secured upon the end of extensible member 47, and a bolt member 55 constrained for rotation. by any conventional means with handle 54 extends through the handle and is joined to the stern of potentiometer 56 secured to member 47. Again, rotation of the control handle 54 will vary the impedance of potentiometer 56, and if this potentiometer is integrated into the electro-hydraulic circuit of FIGS. 4 and 5 which is further associated with motor 23, rolling movement of control handle 54 will cause rolling of the bucket 20.
- control means 35 permits motions analogous to that of the backhoe itself.
- the operator desires to rotate the backhoe, he merely rotates control lever 35 about its vertical axis causing an unbalance in the bridge circuit of the associated potentiometers and fluid may be directed to the hydraulic actuator 30 to rotate the backhoe.
- rotational motion of the extensible arm 46 about a horizontal axis passing through the pivotal connection 53 causes actuation of the hydraulic valve controlling the boom and such movement is somewhat analogous to movement of the control means.
- FIGS. 6 and 7 disclose an additional embodiment of the instant invention in which the directional control valve movement not only corresponds to movement of the control means 35, but the hydraulic motor and associated linkage itself will accurately correspond to movement of control means 35 whereby a position conthereon a potentiometer 131 whose stem is constrained for rotation with the shaft 31 of the motor 30.
- this potentiometer 131 is placed in parallel with the potentiometer 40 but stem rotation is such that a positive increasing voltage of potentiometer 40 will result in a decreasing voltage in potentiometer 131 upon rotation of actuator 30.
- the comparator 109 compares the voltage difference between potentiometer 92 and potentiometers 40 and 130.
- a tubular member 57 may be mounted upon the console 13 to rotatably support control lever 35, apertures 58 being provided in the upper end surface of member 57.
- dowel pins 59 may be inserted into these apertures to limit the rotational movement of control means 35 about a vertical axis. Consequently, if the position control system of FIGS. 6 and 7 is utilized to control swing movement of the backhoe, a position controlled system may additionally yield a return to dig system.
- FIG. 10 discloses a circuit for controlling hydraulic motors which position the stabilizer arms 14, and support the boom structure during the digging operation. Since continuous movement is not desired, the two end valves of bank 62 are not provided with potentiometers, and the solenoid valves are operated by on-off switches, 120 and 121. As opposed to the bridge arrangement previously discussed the remainder of the system, e.g., valve 61, solenoids, and chamber device 85 remain the same.
- a single lever capable of several distinct movements may effectively be designed so as to control several directional flow control valves and their associated hydraulic motors. Further, such movements may be correlated with the anticipated movement of the elements to be controlled and a follow-up system is effected in which a command signal is followed by a correlated movement of the associated motor controlled element. In addition to this follow-up system, provision has been made for anaccurate position control.
- a control system for effecting movement of said motor comprising:
- a directional flow control valve including a reciprocating spool and interconnected between said source and the hydraulic motor for controlling flow to and from the hydraulic motor upon displacement of said spool from a normally closed position
- command means on said vehicle capable of a directional movement analogous to a movement of said mechanism
- electric circuit means having two variable impedances, one of said impedances associated with and responsive to actuation of said spool, the other impedance being associated with and responsive to movement of said command means,
- detector means interconnectible across said impedances for detecting a voltage difference in the respective electrical signals developed across said impedances
- electro'hydraulic means interconnected between said detector means and said flow control valve for actuating said flow control means to displacesaid spool in a direction and for a distance corresponding to the direction and distance movement of said command means so as to nullify any voltage difference in said impedances and to effect a corresponding directional movement of said material 2.
- an electrically operated hydraulic means for 10 directing fluid flow to and from said expansible chamber device for actuating said directional flow control valve, said valve means and said expansible chamber device being of such a capacity as to per mit incremental movement of said directional flow control. valve so as to meter hydraulic fluid to and from the hydraulic motor.
- each of said impedances is a potentiometer, one of said potentiometers having its resistance varied by the spool of said valve and said other potentiometer having its resistance controlled by said command means.
- lever means includes means for permitting movement thereof analogous to potential movement of the motor actuated tool.
- a material handling vehicle having an operator control station and having a moveable linkage coupled at one end portion to said vehicle and supporting a work implement at an opposite end portion, and having a source of hydraulic fluid energy and a control system comprising:
- actuating means comprising a manually operable actuating member located at said operator control station and capable of positional movement functionally analogous to that of said linkage;
- an electrically operated hydraulic means for directing fluid flow to andfrom said expansible chamber device for actuating said directional flow control valve, said valve directional flow control and said expansible chamber device being of such a capacity as to permit incremental movement of said directional flow control valve so as to meter hydraulic fluid to and from the hydraulic motor.
- each of said impedances is a potentiometer, the potentiometer associated with the flow control valve having its resistance varied by movement of and hydraulic circuit therefor, acontrol system for con- 2.
- directional flow control valve means including a trolling movement of said motor comprising: valve member moveable in opposite directions 1.
- flow control valve in said hydraulic circuit having from a central closed position which precludes a movable member therein for controlling the flow of hydraulic fluid energyto said motor for direction and flow rate of hydraulic fluid, permitting flow of said hydraulic fluid energy to 2.
- lever means on said vehicle capable of a movesaid motor to move said'linkage in corresponding ment related to a movement of said tool, opposite directions;
- circuit means including an electrical source and 3. first sensing means coupled to said manually having a first variable impedance associated with operable actuating member for developing a first the movable member of the flow control valve, and sensing signal representative of the position of said a second variable impedance associated with said actuating member; lever means, 4. second sensing means coupled to said moveable 4. comparator means interconnected with said cirlinkage for developing a second sensing signal cuit means for detecting and amplifying an unrepresentative of the position of said linkage; balance in the respective electrical signals 5.
- third sensing means coupled to said valve member developed across said variable impedances, for developing a third sensing signal representative 5. electrical means interconnected between said of the position of said valve member;
- control means responsive to a differential in amtrolling said movable member in a manner so as to plitude between said first and third sensing signals eliminate said unbalance in said respective electriattendant movement of said actuating member ca] signals. from a neutral position for displacing said valve 6.
- said flow control valve includes a reciprocating flow of'hydraulic fluid energy to said motor to inspool therein for controlling fluid flow, itiate movement of said linkage in a corresponding direction and responsive to said second sensing signal for gradually restoring said valve member to said closed position as said linkage moves to a position corresponding to that of said actuating member.
- stop means associated with said linkage for establish- 5 ing adjustable limit positions of movement for said linkage and at least one direction of movement thereof.
Abstract
Description
Claims (29)
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US88701369A | 1969-12-22 | 1969-12-22 |
Publications (1)
Publication Number | Publication Date |
---|---|
US3698580A true US3698580A (en) | 1972-10-17 |
Family
ID=25390269
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US887013A Expired - Lifetime US3698580A (en) | 1969-12-22 | 1969-12-22 | Control system for material handling equipment |
Country Status (4)
Country | Link |
---|---|
US (1) | US3698580A (en) |
CA (1) | CA924609A (en) |
DE (1) | DE2061176A1 (en) |
GB (1) | GB1340339A (en) |
Cited By (20)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3800969A (en) * | 1972-01-03 | 1974-04-02 | Hydra Mac Inc | Front end loader vehicle |
US3828950A (en) * | 1972-08-24 | 1974-08-13 | Harnischfeger Corp | Universally movable control lever assembly |
US3880304A (en) * | 1972-02-11 | 1975-04-29 | Jr William A Strickland | Mimic positioning controller for a hydraulically actuated back hoe |
US3929239A (en) * | 1974-04-25 | 1975-12-30 | Case Co J I | Backhoe actuator |
US3963135A (en) * | 1973-11-21 | 1976-06-15 | Societe Anonyme: Poclain | Method of subordinating the orientation of a grab on a public works machine to the rotation of the turrest of this machine and to the machine |
US4304389A (en) * | 1979-07-09 | 1981-12-08 | Union Oil Company Of California | Remote control apparatus for hydraulically actuated devices |
US4410049A (en) * | 1977-06-21 | 1983-10-18 | Atlas Copco Aktiebolag | Directional valve means for positioning machine units |
WO1984004341A1 (en) * | 1983-04-22 | 1984-11-08 | Barry Frank Hughes | Back hoe |
US4516894A (en) * | 1980-06-28 | 1985-05-14 | Alb Klein Gmbh & Co. Kg | Load pressure feedback system having at least one control valve for controlling an apparatus |
US4552503A (en) * | 1982-12-24 | 1985-11-12 | Kubota, Ltd. | Excavating vehicle |
US4943205A (en) * | 1987-11-11 | 1990-07-24 | Schuett Heinz | Earth moving machine |
US4960359A (en) * | 1989-01-23 | 1990-10-02 | Lovitt Jr Estel L | Demountable swing boom hoist for front end loaders |
US5088020A (en) * | 1988-11-18 | 1992-02-11 | Kubota Ltd. | Pivotal movement control device for boom-equipped working machine |
US5112184A (en) * | 1990-06-11 | 1992-05-12 | Reach All | Multi-function hydraulic control handle |
US5440970A (en) * | 1994-09-21 | 1995-08-15 | Caterpillar Inc. | Hydraulic rotary actuator |
US5497568A (en) * | 1991-03-06 | 1996-03-12 | Strickland; William A. | Integrated group of excavator control assemblies |
EA002454B1 (en) * | 2000-02-21 | 2002-04-25 | Общественный Благотворительный Фонд "Монтажстройтехника" | Excavator |
US20030152452A1 (en) * | 2002-02-08 | 2003-08-14 | J.C. Bamford Excavators Limited | Control apparatus |
US20070196200A1 (en) * | 2006-02-17 | 2007-08-23 | Nate Martindale | Remotely positionable control system for a container hoist |
US11298093B2 (en) * | 2004-07-30 | 2022-04-12 | Neurologica Corp. | Anatomical imaging system with centipede belt drive |
-
1969
- 1969-12-22 US US887013A patent/US3698580A/en not_active Expired - Lifetime
-
1970
- 1970-10-19 CA CA095911A patent/CA924609A/en not_active Expired
- 1970-12-11 DE DE19702061176 patent/DE2061176A1/en active Pending
- 1970-12-22 GB GB6085770A patent/GB1340339A/en not_active Expired
Cited By (21)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3800969A (en) * | 1972-01-03 | 1974-04-02 | Hydra Mac Inc | Front end loader vehicle |
US3880304A (en) * | 1972-02-11 | 1975-04-29 | Jr William A Strickland | Mimic positioning controller for a hydraulically actuated back hoe |
US3828950A (en) * | 1972-08-24 | 1974-08-13 | Harnischfeger Corp | Universally movable control lever assembly |
US3963135A (en) * | 1973-11-21 | 1976-06-15 | Societe Anonyme: Poclain | Method of subordinating the orientation of a grab on a public works machine to the rotation of the turrest of this machine and to the machine |
US3929239A (en) * | 1974-04-25 | 1975-12-30 | Case Co J I | Backhoe actuator |
US4410049A (en) * | 1977-06-21 | 1983-10-18 | Atlas Copco Aktiebolag | Directional valve means for positioning machine units |
US4304389A (en) * | 1979-07-09 | 1981-12-08 | Union Oil Company Of California | Remote control apparatus for hydraulically actuated devices |
US4516894A (en) * | 1980-06-28 | 1985-05-14 | Alb Klein Gmbh & Co. Kg | Load pressure feedback system having at least one control valve for controlling an apparatus |
US4552503A (en) * | 1982-12-24 | 1985-11-12 | Kubota, Ltd. | Excavating vehicle |
WO1984004341A1 (en) * | 1983-04-22 | 1984-11-08 | Barry Frank Hughes | Back hoe |
US4943205A (en) * | 1987-11-11 | 1990-07-24 | Schuett Heinz | Earth moving machine |
US5088020A (en) * | 1988-11-18 | 1992-02-11 | Kubota Ltd. | Pivotal movement control device for boom-equipped working machine |
US4960359A (en) * | 1989-01-23 | 1990-10-02 | Lovitt Jr Estel L | Demountable swing boom hoist for front end loaders |
US5112184A (en) * | 1990-06-11 | 1992-05-12 | Reach All | Multi-function hydraulic control handle |
US5497568A (en) * | 1991-03-06 | 1996-03-12 | Strickland; William A. | Integrated group of excavator control assemblies |
US5440970A (en) * | 1994-09-21 | 1995-08-15 | Caterpillar Inc. | Hydraulic rotary actuator |
EA002454B1 (en) * | 2000-02-21 | 2002-04-25 | Общественный Благотворительный Фонд "Монтажстройтехника" | Excavator |
US20030152452A1 (en) * | 2002-02-08 | 2003-08-14 | J.C. Bamford Excavators Limited | Control apparatus |
US11298093B2 (en) * | 2004-07-30 | 2022-04-12 | Neurologica Corp. | Anatomical imaging system with centipede belt drive |
US11883218B2 (en) | 2004-07-30 | 2024-01-30 | Neurologica Corp. | Anatomical imaging system with centipede belt drive |
US20070196200A1 (en) * | 2006-02-17 | 2007-08-23 | Nate Martindale | Remotely positionable control system for a container hoist |
Also Published As
Publication number | Publication date |
---|---|
GB1340339A (en) | 1973-12-12 |
CA924609A (en) | 1973-04-17 |
DE2061176A1 (en) | 1971-07-15 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: DRESSER INDUSTRIES, INC., A CORP. OF DEL., STATELE Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:INTERNATIONAL HARVESTER COMPANY;REEL/FRAME:004130/0646 Effective date: 19821101 Owner name: DRESSER INDUSTRIES, INC., A CORP. OF DEL. Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:INTERNATIONAL HARVESTER COMPANY;REEL/FRAME:004130/0646 Effective date: 19821101 |
|
AS | Assignment |
Owner name: KOMATSU DRESSER COMPANY, E. SUNNYSIDE 7TH ST., LIB Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:DRESSER FINANCE CORPORATION, A CORP. OF DE.;REEL/FRAME:004994/0077 Effective date: 19880901 Owner name: DRESSER FINANCE CORPORATION, DALLAS, TX., A DE COR Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:DRESSER INDUSTRIES, INC.;REEL/FRAME:004994/0061 Effective date: 19880831 |