WO1997029038A1 - A load control system preferably for hydraulic cranes - Google Patents
A load control system preferably for hydraulic cranes Download PDFInfo
- Publication number
- WO1997029038A1 WO1997029038A1 PCT/DK1997/000054 DK9700054W WO9729038A1 WO 1997029038 A1 WO1997029038 A1 WO 1997029038A1 DK 9700054 W DK9700054 W DK 9700054W WO 9729038 A1 WO9729038 A1 WO 9729038A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- load
- crane
- control system
- control unit
- penalty
- Prior art date
Links
Classifications
-
- 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
- B66C23/88—Safety gear
- B66C23/90—Devices for indicating or limiting lifting moment
Definitions
- a load control system preferably for hydraulic cranes.
- the present invention concerns a load control sys- tem, preferably for hydraulic boom cranes of the kind com ⁇ prising a boom pivotable relative to a base about one end in a vertical plane by a hydraulic cylinder and comprising at least one relevant signal emitter connected to a surveillance unit which in the case of loading the crane in excess of its no imal load deactivates the functions in the control valve block that may cause an increase of the load of the crane.
- the nominal load of cranes is determined with a certain safety margin depending on how great a moment may be absorbed by the turning point of the crane, i.e. the bearing supporting the crane, and which then is transmitted to the support of the bearing, e.g. the chassis of a lorry, and in that connection to possibly extended supporting legs without the crane tipping over.
- the known load control systems for use in hydrauli- cally driven cranes are of the kind mounted as accesories on e.g. a lorry or definite mobile cranes.
- the known load con ⁇ trol systems may comprise at least one or more pressure transducers provided on the hydraulic cylinders of the crane.
- the pressure transducers are connected to a control unit connected with controlable valves in connection with the con ⁇ trol valve block of the crane.
- a such load control system is known from EP 0 708 053 Al, where the control unit is ar ⁇ ranged in such a way that it by a registrated maximum allow ⁇ able pressure registered by a sensor placed on the main cyl- inder of the crane blocks for all further maneuvering of the crane by its control valve block.
- the blocking may subsequently be deactivated in a short period (3-5 sec.) by a manually controlled liberating element, so that it is possi ⁇ ble to get out of an otherwise "impossible lifting situa- tion".
- An "impossible lifting situation” may be defined in that any movement of the crane boom allowed by the control system with the intention of reducing the load will be impos ⁇ sible in practice because of the physical circumstances in the ongoing lift so that the only possibility of getting out of this lifting situation is a deactivation of the load con ⁇ trol system in a short pre-determined period, wherein a forced increase of the load is possible.
- the said load con- trol system also comprise acoustic and visual signal emitters coming into action at different load levels about the maximum allowable load level for the crane.
- Other load control systems may furthermore comprise position indicators on the boom sections to be pivoted in a vertical plane, besides the pressure transducers on the hy ⁇ draulic cylinders, and which are also connected to the con ⁇ trol unit.
- the signals from the position indicators are used in the control unit for indicating whether a movement of the pivotable parts of the boom in a desired direction will cause an increased load on the crane.
- the control of the load with position indicators works in the way that the control unit at a registered maximum allowable load of the crane (the nominal load) ensures that the operator of the crane cannot perform load increasing operations as the control unit at the activa- tion of the previously mentioned controlable valves is hin ⁇ dering such movements of the boom.
- control unit allows all movements of the boom that by experience cause an immediate reduction of the moment load in proportion to the maximum allowable moment load of the crane, e.ge. a reduction of the distance between the load and the turning point of the crane in an operation wherein the length of the boom is re ⁇ cuted.
- the load control systems described above are rela ⁇ tively costly since they often comprise up to several pres ⁇ sure transducers and one or more position indicators that by wired connections are connected to the control unit, which again are connected to the control valves in the control valve block. Looking at service procedures the large number of components and wire connections become expensive.
- the known load control systems easily permit the op- erator to exceed/override the deactivation of the maneuver ⁇ ability of the crane in connection with overload situations which inevitably leads to some indifference towards the load control system, since exceeding the the maximum allowable load of the crane do not have any consequence as long as op- erations take place with more or less virtuosity in the alarm range and with an intrepid use of the said deactivation pe ⁇ riod preceeding a total blocking of the control system.
- the deeper meaning with the alarm is to call the operatoris at ⁇ tention to the fact that operation takes place in a poten- tially dangerous area and that measures for a return to harm ⁇ less conditions immediately has to be taken, e.g.
- the lorry is driven to a position closer to the burden to be lifted.
- the operator may then decide to try anyway from the consideration that in the said deactivating period he may come in time to discontinue the alarm creating act if the transgression is so great that it downright may give rise to an educative blocking signal.
- a new load control system comprising a pressure transducer situated on the main lifting cylinder of the crane and connected to a control unit with the output connected to a by-pass valve, also called “dump valve”, controlling the oil supply to the maneuvering valve block of the crane, which control unit is arranged in such a way that the transgression of the nominal load capability of the crane in question will result in acti ⁇ vation of the said "dump valve", so that all the functions of the crane are made inactive in a period of time calculated by the control unit, a so-called penalty period, whereafter the dump valve is deactivated.
- the load control system according to the invention does not give any immediate possibility for the crane operator to rectify a transgression of the nominal load of the crane since it is not possible to relieve the load as long as the functions of the control valve block of the crane are deactivated during the penalty period.
- control unit deactivates the dump valve and the crane becomes aneuverable again. If the load on the crane is reduced to a level below the nominal load nothing further will happen, i.e. the work may continue freely.
- control unit With the purpose of giving the operator a possibil ⁇ ity of remedying any arised impossible load situations the control unit is arranged in such a way that it allow a fur- ther load on the crane to a calculated level (within the safety margin) in excess of the nominal load after the expi ⁇ ration of the penalty period. If this calculated level for the load is exceeded the dump valve is activated again by the control unit, this time in an perceptibly longer period of time than the first activation. After the expiration of this so-called penalty period the dump valve is deactivated again.
- control unit will continuously calculate a new, lower value for the maximum allowable load and penalty period in case of a trans ⁇ gression concurrently with the relieving of load until the nominal load is reached. However, if the operator of the crane tries to increase the load during the relieving the control unit will immediately release a new penalty period.
- the load control according to the invention may be programmed with several limits of load levels between the nominal load for the crane and an absolute acceptable maximum within the safety margin. Transgression of the individual load levels/limits will release an increasing penalty period concurrently with the magnitude and number of transgressions.
- the cabinet of the control unit may be provided with a percent graduated scale with light diodes that are switched on and off concurrently with a load increase and de ⁇ crease, respectively.
- the control unit may also be provided with an acoustic alarm emitting a periodic alarm signal at an existing load between 95% and 100%. During an imposed penalty period at the trans ⁇ gression of the nominal load (100%) a continuous signal is given. Therefore, the operator has to accept that his over ⁇ loading of the crane is made widely known.
- control unit may be provided with a logging unit that is registering data in a ring buffer mem ⁇ ory for all load transgressing actions with the crane, so that data concerning the latest load transgressing events af ⁇ terwards may be read from the ring buffer memory on e.g. a hand terminal, and that is registering data concerning the largest registered overloads in another data memory, the lat ⁇ ter also being readable on a hand terminal.
- a logging unit that is registering data in a ring buffer mem ⁇ ory for all load transgressing actions with the crane, so that data concerning the latest load transgressing events af ⁇ terwards may be read from the ring buffer memory on e.g. a hand terminal, and that is registering data concerning the largest registered overloads in another data memory, the lat ⁇ ter also being readable on a hand terminal.
- the load control system described in the above be- ing more simple in arrangement as compared to the known load control systems contains thus some increased degrees of free ⁇ dom and important educational principles.
- the increased degrees of freedom consist in that the operator at the transgression of the nominal load up to an absolute allowable maximum limit within the safety margin and after the expiration of penalty period has the possibil ⁇ ity of getting out of an "impossible" lifting situation by utilizing all of the maneuvering functions of the crane, even with a short-term, smaller load increase allowed after the expiration of a penalty period.
- the educational element consist in that the opera ⁇ tor of the crane will be inclined to learn a better percep ⁇ tion of the load situations implying transgression of the nominal load of the crane, because the penalty period con- nected with a transgression of the nominal load will slow down the work procedures in connection with the use of the crane and thereby for the operator as well as for the person or persons cooperating in the work within the hazard area of the crane.
- the invention is explained in more detail in the following with reference to the drawing, where:
- Fig. 1 is a perspective view of a hydraulic crane provided with a load control system according to the inven ⁇ tion
- Fig. 2 is a functional example of the load control system.
- a hydraulic crane 2 in ⁇ tended for mounting on a vehicle, for example a lorry.
- the crane comprise a basic frame 4 for mounting on the chassis of the lorry.
- the basic frame has also laterally extendable girders 5 at the ends of which vertically extendable legs 6 are provided.
- the column 10 of the crane is supported by the bearing 8.
- the bearing car- ries the support for the main cylinder 12 of the crane that is connected to the main arm 14 of the crane.
- the bending arm 16 of the crane is pro ⁇ vided and in this a number of telescopic arms 18.
- a pressure transducer 20 which by a wire connection 21 transmits an oil pressure signal to a control unit 22.
- the control unit 22 is provided with a not shown sig ⁇ nal receiving block performing filtering, stabilization and compensation of the received oil pressure signal from the pressure transducer 20 before the signal is transmitted to the control unit for further processing.
- the control unit is connected to a by-pass valve 24, in the following called dump valve that is placed on the oil supply pipe for the maneuvering valve block 25 of the crane, through a wire connection 23, so that the dump valve in its active position will cause that the oil in the supply pipe is returned directly to the hydraulic oil tank through a not shown by-pass pipe and around the maneuvering valve block 25 whereby maneuvering of the crane is not possible.
- a by-pass valve 24 in the following called dump valve that is placed on the oil supply pipe for the maneuvering valve block 25 of the crane, through a wire connection 23, so that the dump valve in its active position will cause that the oil in the supply pipe is returned directly to the hydraulic oil tank through a not shown by-pass pipe and around the maneuvering valve block 25 whereby maneuvering of the crane is not possible.
- the inactive position of the dump valve the hydraulic oil is sup- plied to the valve of the maneuvering valve block whereby it is possible to maneuver the crane.
- the control unit 22 comprise a cabinet the front of which is furnished with a number of bulbs 28 placed in con ⁇ junction with a percentage scale, one bulb 30 placed by the word "run”, an acoustic signal emitter 32, and a stop switch 34.
- the shown scaling indicate the existing load on the crane proportional to the nominal load of the crane in the range between 80 and 100%. At a load below 80% of the nominal load only one bulb 30 opposite the word "run" is lit. At a load on the crane within the range 80-100% the bulbs are lit concurrently with the increased load so that the operator has a possiblility of following the development of the existing load of the crane. At a load over 95% of the nominal load the control unit activates the acoustic signal emitter 32, which emits a periodic signal. At a load on the crane corresponding to 100% or more the control unit cause a continuous signal to be sounded from the emitter 32 during the said penalty pe ⁇ riod.
- Fig. 2 shows a coordinate system with abscissa indicating time and ordi- nate indicating the load of the crane proportional to the nominal load of the crane.
- the load control system do not react.
- the control unit per ⁇ form a gradual activation of the bulbs 28 opposite the per ⁇ centage indications on the cabinet of the control unit.
- control unit activate the acoustic signal emitter 32 so that it gives a periodic signal which at 100% nominal load changes to a continuous signal in connection with the running of a penalty period.
- signal emitter changes to the periodic signal indicating that the crane functions are active again, but the existing load of the crane is more than 95% of the nominal load.
- the control unit 22 activates the dump valve 24 in the short period of time calculated by the control unit, a so-called penalty period A, cf Fig. 2, wherein the functions of the crane are paralyzed. After that the load on the crane should be reduced below nominal load capability. The load on the crane may be increased at the expiration of the penalty period A in order to give the operator of the crane the pos ⁇ sibility to get out of an adverse lifting situation which is possible up to 102% of nominal load in the given example. If the load is increased in excess of the level determined by the control unit, the control unit activates the dump valve in at penalty period B that is longer than the first period. During this penalty period the control unit calculates a new stop level, e.g.
- the control unit 22 calculates the development in the length of the penalty period in relation to the current load of the crane and the current number of attempts of additional overloading.
- the control unit 22 further comprises an "override" button 36 which by the operator may be activated in case of an "impossible" lifting situation that has to be rectified immediately.
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Jib Cranes (AREA)
- Control And Safety Of Cranes (AREA)
Abstract
Description
Claims
Priority Applications (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AT97901526T ATE263731T1 (en) | 1996-02-07 | 1997-02-07 | HYDRAULIC Jib CRANE WITH LOAD CONTROL SYSTEM |
DK97901526T DK0879208T3 (en) | 1996-02-07 | 1997-02-07 | A hydraulic boom crane with load control system |
AU15408/97A AU1540897A (en) | 1996-02-07 | 1997-02-07 | A load control system preferably for hydraulic cranes |
DE69728522T DE69728522T2 (en) | 1996-02-07 | 1997-02-07 | HYDRAULIC EXTRACTION CRANE WITH LOAD CONTROL SYSTEM |
EP97901526A EP0879208B1 (en) | 1996-02-07 | 1997-02-07 | A hydraulic boom crane with load control system |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DK0123/96 | 1996-02-07 | ||
DK12396 | 1996-02-07 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1997029038A1 true WO1997029038A1 (en) | 1997-08-14 |
Family
ID=8090009
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/DK1997/000054 WO1997029038A1 (en) | 1996-02-07 | 1997-02-07 | A load control system preferably for hydraulic cranes |
Country Status (6)
Country | Link |
---|---|
EP (1) | EP0879208B1 (en) |
AT (1) | ATE263731T1 (en) |
AU (1) | AU1540897A (en) |
DE (1) | DE69728522T2 (en) |
ES (1) | ES2221949T3 (en) |
WO (1) | WO1997029038A1 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP2145852A1 (en) | 2008-07-16 | 2010-01-20 | Manitowoc Crane Companies, Inc. | Load monitoring and control system with selective boom-up lockout |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4516116A (en) * | 1981-12-16 | 1985-05-07 | Safety Devices (Engineering) Limited | Apparatus for visually displaying the load-moment, axle-load, or payload of a vehicle |
DE4219369A1 (en) * | 1991-06-17 | 1993-01-14 | Senergy | Monitoring load lifting unit with hydraulically controlled lift part - having two different preset alarm thresholds so that above one threshold further work can only be done by intended handling, and over second general alarm is raised and hydraulic power shut=off |
EP0708053A1 (en) * | 1994-08-26 | 1996-04-24 | Hiab Export A/S | Overload protection system for hydraulic boom cranes, especially of the type used on motor vehicles |
-
1997
- 1997-02-07 AT AT97901526T patent/ATE263731T1/en active
- 1997-02-07 WO PCT/DK1997/000054 patent/WO1997029038A1/en active IP Right Grant
- 1997-02-07 AU AU15408/97A patent/AU1540897A/en not_active Abandoned
- 1997-02-07 DE DE69728522T patent/DE69728522T2/en not_active Expired - Lifetime
- 1997-02-07 ES ES97901526T patent/ES2221949T3/en not_active Expired - Lifetime
- 1997-02-07 EP EP97901526A patent/EP0879208B1/en not_active Expired - Lifetime
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4516116A (en) * | 1981-12-16 | 1985-05-07 | Safety Devices (Engineering) Limited | Apparatus for visually displaying the load-moment, axle-load, or payload of a vehicle |
DE4219369A1 (en) * | 1991-06-17 | 1993-01-14 | Senergy | Monitoring load lifting unit with hydraulically controlled lift part - having two different preset alarm thresholds so that above one threshold further work can only be done by intended handling, and over second general alarm is raised and hydraulic power shut=off |
EP0708053A1 (en) * | 1994-08-26 | 1996-04-24 | Hiab Export A/S | Overload protection system for hydraulic boom cranes, especially of the type used on motor vehicles |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP2145852A1 (en) | 2008-07-16 | 2010-01-20 | Manitowoc Crane Companies, Inc. | Load monitoring and control system with selective boom-up lockout |
US7677401B2 (en) | 2008-07-16 | 2010-03-16 | Manitowoc Crane Companies, Inc. | Load monitoring and control system with selective boom-up lockout |
AU2009202448B2 (en) * | 2008-07-16 | 2010-09-30 | Manitowoc Crane Companies, Inc. | Load monitoring and control system with selective boom-up lockout |
Also Published As
Publication number | Publication date |
---|---|
ES2221949T3 (en) | 2005-01-16 |
DE69728522D1 (en) | 2004-05-13 |
DE69728522T2 (en) | 2005-04-07 |
EP0879208A1 (en) | 1998-11-25 |
ATE263731T1 (en) | 2004-04-15 |
AU1540897A (en) | 1997-08-28 |
EP0879208B1 (en) | 2004-04-07 |
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