EP3368462B1 - Method for operating at least two lifting devices as a group, and assembly comprising a least two lifting devices - Google Patents

Description

The invention relates to a method for operating at least two hoists in a group operation, wherein each hoist comprises a hoist, can be raised by a lifting operation or lowered by a lowering operation in each case a load receiving means in the group mode in a synchronous mode First, a common lifting operation by the at least two hoists is carried out to move a load attached to the load receiving means, after the common lifting operation for a change from the synchronous operation to a single operation or a multi-operation at least one of the common Hoist participating lifting is disabled and at least one of the hoists involved remains activated, so that only each activated hoist relative to each deactivated hoist can perform a lifting or lowering.

The invention also relates to an arrangement with at least two hoists.

In the German Offenlegungsschrift DE 10 2011 053 014 A1 A method for operating at least two hoists in a normal mode and in a group mode is described. Within the group operation, a tandem operation is possible, in which the hoists of both cranes are operated synchronously via a single control switch and can also be moved horizontally. Also, a single operation is possible within the group operation, in which the cranes and in particular their hoists and load-receiving means can be moved individually relative to each other.

As a result of the tandem operation, it may come to critical operating conditions such as an inclination of the load, the elimination of which a single operation is required. In this case, since the distribution of the load on the load-bearing hoists and load-carrying means is changed, this can lead to an overload of the disabled for the individual operation hoist and subsequently to a load crash.

Although it is known that hoists overload protection with a load sensor and a load value corresponding thereto is determined, which corresponds to a load acting on the hoist during a lifting operation, the determined load value is compared with a permissible limit value and the lifting operation is prevented when the determined load value exceeds the limit value. By such overload protection, which detects and monitors active hoists only during a lifting operation, however, the overload of a deactivated hoist can not be detected and a threat of load crash can not be prevented.

From the German patent application DE 31 47 158 A1 It is known to prevent an inclined position of the load in two operated in a tandem cranes. For this purpose, a sensor is arranged on a load traverse, which is suspended on lifting devices of the two Kranhubwerke, via which the position of the load cross member is determined and evaluated. Since a deactivated after tandem operation hoist can be overloaded without discernible inclination of the load, a threat of load crash can not be reliably prevented by such a sensor.

From the German patent application DE 10 2006 040 782 A1 It is known to operate two luffing cranes each in a normal operation and to coordinate their independent movements in order to move a common load with both cranes. This is referred to in the cited document as tandem operation. A successful over a single control switch synchronous operation of the two cranes is not done here. Instead, in normal operation, the controls of the two cranes are active so that the crane operator of each crane can initiate movements of his crane. In this case, the overload safety devices of both cranes are integrated in order not to cause any overload conditions on the other crane due to movements of one crane. The movements of the slewing gear and the luffing gear caused by the respective crane operators in this coordinated normal operation are not carried out if one of the overload safety devices detects an overload. It is also described that the control of a crane can be deactivated and the slewing gear and the luffing mechanism of this crane can be controlled from another crane.

The invention is based on the object, a method for operating at least two hoists in a group operation and a corresponding be provided operable arrangement with at least two hoists, which are particularly safe.

This object is achieved by a method having the features of claim 1 and an arrangement having the features of claim 9. In claims 2 to 8 advantageous embodiments of the invention are given. Further details of the invention will become apparent from the following description.

To a method for operating at least two hoists in a group operation, each hoist comprises a hoist, via each of which a lifting device can be raised by a lifting operation or lowered by a lowering operation, in the group mode in a mode synchronous operation First, a common lifting operation is performed by the at least two hoists to move a load attached to the load receiving means, after the common lifting operation for a change from the synchronous operation in a single operation or a multiple operation at least one of the common lifting process involved Hoists is disabled and at least one of the hoists involved remains activated, so that only each activated hoist can perform relative to each deactivated hoist lifting or lowering process to provide, which is particularly safe, it is provided that even after the change of the Synchronous operation in the single loading drove or multiple operation for each previously involved in the common lifting synchronous operation hoist, in particular each deactivated hoist, a load value corresponding to a load acting on the hoist part load, determined and compared with a respective allowable limit. In this way, it can be recognized whether in the planned after synchronous operation single operation or multiple operation overloading of at least one deactivated hoist and thus a load crash threatens. If an overload is detected, it is possible to react accordingly and, for example, to return to synchronous operation and to lower the load in synchronous operation of the at least two hoists. The method is also particularly practical and easily applicable by implementing appropriate software routines without additional hardware overhead. This makes it possible to adapt the method flexibly to changes in the permissible loading conditions occurring during the course of the operation. In particular, no additional, complex and complex programmable Control in the sense of a safety PLC required.

The hoists are operated together in synchronous operation via a single control switch, in particular synchronously and thus in parallel and in the same direction in the sense of rectified and gleichschnschn movements. Opposing or rectified movements at different speeds are not provided in synchronous operation. The synchronous operation therefore differs from a coordinated normal operation of two hoists, in which the hoists are also operated simultaneously, but the control of each other independently via two control switches and not in the sense of synchronous operation via a single control switch. In a coordinated normal operation of two hoists and opposite movements and different speeds of the two hoists are possible. Further explanations of the synchronous operation and other mentioned modes can be found in the following description.

Advantageously, it is also provided that the lifting operation or the lowering process of each activated hoist is prevented when in the at least one deactivated hoist a load value is determined which exceeds a permissible limit. As a result, the safety is further increased because a lifting or lowering operation is not possible in case of overload of the at least one deactivated hoist.

A further increase in safety can be achieved by continuously determining load values for each hoist and comparing them with a respective permissible limit value. In this way, a continuous overload protection can be achieved.

Advantageously, it is provided that for each hoist participation in synchronous operation, in particular the common lifting process is stored and based on this information after switching to single or multiple operation of a control of at least one activated hoist the respectively determined Load values and limit values of all hoists originally involved in synchronous operation are compared.

In a structurally simple manner, it is provided that each hoist is independent of the lifting or lowering by a driving operation in at least one horizontal direction movable and the driving of each active hoist is prevented when in the at least one deactivated hoist a load value is determined, the one exceeds the permitted limit. As a result, the above benefits also affect more complex load handling.

It is advantageously provided that the limit value can vary depending on different operating situations and in particular can be set in a control of the respective hoisting gear. This makes a particularly flexible embodiment of the method for a variety of loads handling possible.

In a structurally simple manner, it is provided that each hoist is designed as a crane with a crane girder, in particular as a bridge crane.

The safety of an arrangement with at least two hoists, in particular two cranes, can be increased by the fact that the hoists and in particular their controls are designed to operate according to one of the methods described above can.

Hereinafter, the present invention is explained in more detail with reference to an embodiment shown in a drawing. It shows:
FIG. 1 a schematic representation of two interconnected for a group operation overhead cranes.

In the FIG. 1 is shown schematically an arrangement with two hoists. The hoists are formed by a first crane 1a and a second crane 1b or are part of the respective crane 1a, 1b. Each crane 1a, 1b has a horizontal crane girder in the usual way. At each crane girder a crane rake is arranged, which carries a hoist and with this together in the direction of the longitudinal extent of the crane girder is movable (not shown). The first and the second crane 1a, 1b are each designed as a bridge crane. Accordingly, each crane girder is along with the trolley carrying trolley along Can be moved by crane rails not shown in the direction transverse to its longitudinal extent. The first crane 1a has a first controller S1 comprising a first crane controller 2a and a first cat controller 3a. The second crane 1b likewise has a second control S2, which comprises a second crane control 2b and a second cat control 3b. The first and second crane controls 2a, 2b each have the task of controlling the first and second crane traction motors 4a, 4b in order to move the respective crane carrier along the crane rails. By means of the first and second cat control 3a, 3b are first and second Katzfahrmotoren 5a, 5b driven to move the respective trolley along the crane girder. In addition, via the first and second Katzsteuerung 3a, 3b first and second Hubwerksmotoren 6a, 6b driven to each control the associated arranged on the appropriate crane hoist and raise or lower a lifting device over this. The hoist motors 6a, 6b assigned and not shown hoists are designed as cables. In principle, it is also possible to design the hoists as chain hoists. A mixed operation of chain and cable trains are conceivable. The aforementioned motors 4a, 4b, 5a, 5b, 6a and 6b are designed as electric motors.

In order to be able to transmit and receive operating signals and safety signals, the crane controls 2a, 2b and the cat controllers 3a, 3b are each connected to a bus 7 via bus coupling modules (not shown). This bus 7 preferably works with the CAN protocol. In addition, the bus 7 is constructed locally from a first wired bus portion 7a in the area of the first crane 1a, from a second wired bus portion 7b in the area of the second crane 1b and a wireless bus 7c connecting the first bus portion 7a and the second bus portion 7b , For this purpose, a first coupling module 8a is connected to the first bus section 7a and a second coupling module 8b is connected to the second bus section 7b. By means of the coupling modules 8a, 8b, the signals on the first bus section 7a and the second bus section 7b are converted into wireless signals and transmitted via transmitter and receiver modules between the coupling modules 8a, 8b. By means of the coupling modules 8a, 8b, all bus subscribers such as the crane controls 2a, 2b, the cat controllers 3a, 3b and also directly or indirectly the first and the second control switches 9a, 9b are connected to a common bus 7. Preferably, the wireless bus 7c is as

Radio bus trained. It is also possible to provide an infrared bus.

The crane controls 2a, 2b and the cat controls 3a, 3b are provided with circuit breakers, safety switches, sensors, a switching logic and bus coupling modules, not shown and generally known. The bus coupling modules can be part of the switching logic.

Furthermore, a first wireless control switch 9a associated with the first crane 1a and a second wireless control switch 9b associated with the second crane 1b are provided. The control switch 9a is connected via a first wireless connection 10a to a first switch coupling module 11a. The wireless connection 10a is bidirectional. The same applies to the second control switch 9b, to which a second wireless connection 10b and a second switch-coupling module 11b are assigned. The first switch coupling module 11a and the second switch coupling module 11b are connected to the bus 7 as further bus subscribers. The control switches 9a, 9b are equipped in the usual way with a plurality of push-button elements to control the individual directions of movement and possibly existing speed levels of the crane drive motors 4a, 4b, the Katzfahrmotoren 5a, 5b and the Hubwerksmotoren 6a, 6b. In this way, each hoist in the context of a driving operation on the crane traction motors 4a, 4b and / or the Katzfahrmotoren 5a, 5b in the horizontal direction, that is in Kran- and / or this perpendicular Katzfahrrichtung, and thus in particular in a horizontal plane are moved and independently of this, each load-carrying means can be raised via the hoist motors 6a, 6b as part of a lifting operation or lowered in the course of a reverse lowering operation.

Alternatively, instead of the two wireless control switches 9a, 9b and the two switch coupling modules 11a, 11b as shown in FIG FIG. 1 dashed lines cable control switch 9c are provided. The cable control switch 9c are designed as a hanging switch and connected directly via the supply line to the bus 7 as a bus subscriber to take over the functions of the control switches 9a, 9b.

The cranes 1a and 1b described above can via the associated

Control switches 9a and 9b are operated individually and independently of each other to move the respective load-receiving means and optionally a load attached thereto. This operating mode is referred to below as normal operation. Within normal operation, the first control switch 9a is then assigned to the first crane 1a and the second control switch 9b is assigned to the second crane 1b and activated. Both control switches 9a, 9b are therefore in an active state during normal operation.

It is also possible to register the two cranes 1 a, 1 b to a so-called group operation, in which the cranes 1 a, 1 b are interconnected in such a way that they coordinate via a single control switch 9 a or 9 b and in this case in particular synchronously together and thus in parallel and can be operated in the same manner in a synchronous operation defined below in more detail or individually and independently of each other and relative to each other in a single operation defined in more detail below. In group mode, a load to be moved is taken up by load handling devices of all hoists of the cranes 1a, 1b that are involved in group operation. In this case, more than one load-receiving means may be provided per hoist. As a result, the group operation is particularly suitable when a long and / or heavy load moves and in this case not only lifted or lowered and translationally moved in the horizontal direction, but also to be rotated and this in a normal operation with a single crane 1a or 1b is no longer possible.

In order to be able to switch between the normal mode and the group mode, a pushbutton switching element as a registration key 12a and a pushbutton switching element as a logout key 12b are respectively formed on both control switches 9a, 9b. Instead of certain registration and Abmeldetasten 12a, 12b, a predetermined operating sequence of Tastschaltelementen trigger the change between normal and group operation.

By pressing the logout key 12b of one of the two control switches 9a or 9b, this is deactivated in a first step and triggered by the change in the passive state, a termination of the normal operation. At the same time, the bus 7 and in the direction of the first controller S1 and the second controller S2 or the crane controls 2a, 2b and the cat controllers 3a, 3b included in the direction of a release signal that the Deactivated control switch 9a or 9b associated crane 1a or 1b for group operation is available and can be included in this.

In addition, it is also preferable to press the emergency / stop button to actuate the logout button 12b or to log out at the end of an operating sequence. Thus, it can also be visually recognized on the control switch 9a, 9b by the pressed emergency stop that this control switch 9a, 9b is in the passive state and is available for group operation.

In order to register and finally set up the group operation, the registration key 12a of the control switch 9a or 9b, which is still in the active state, must be actuated in a second step. This signals and sets via the bus 7 in the direction of the first controller S1 and the second controller S2 that the still activated control switch 9a or 9b now from both the first controller S1 and the second controller S2 or all thereof included crane controls 2a, 2b and Katzsteuerungen 3a, 3b is accepted as a source of control and safety signals.

In this way, the crane 1a or 1b released for group operation in the above first step is registered for group operation or included in the group operation. The establishment of the group operation thus requires both previously described steps in the sense of an acknowledgment process. Alternatively, a reverse order of the two steps is possible. Accordingly, first of all, the actuation of the registration key 12a can take place as a request for participation in group operation, which must be confirmed by actuating the logout key 12b.

To end the group operation, the logout key 12b is operated on the single activated control switch 9a or 9b. A corresponding deregistration signal is sent via the bus 7 to the crane controls 2a, 2b and the cat controls 3a, 3b. Optionally, the emergency / stop button is deactivated in the previously in passive state control switch 9a or 9b and the registration button 12a is pressed. It can also be provided that the deactivated control switch 9a or 9b can only be activated and thus a change to the normal mode can be effected if none of the touch-sensitive switching elements of this Control switch 9a or 9b is actuated. A corresponding registration signal of the previously deactivated control switch 9a or 9b is sent automatically or by actuation of a corresponding push-button element via the bus 7 to the crane controls 2a, 2b and the cat controls 3a, 3b. Both control switches 9a, 9b and the associated cranes 1a and 1b are then again in the normal operation state. The termination of the group operation also requires the two steps described above in reverse order in the sense of an acknowledgment. Thus, the two cranes 1a, 1b are operatively separated from one another, but still connected to each other via the bus 7, in order to be able to respond to a future request of a re-group operation.

In connection with the logon and logoff sequences for switching between normal and group operation and vice versa, the steps of deselecting one of the two control switches 9a, 9b, which is followed by logging on by the other of the two control switches 9a, 9b, of the Crane controls 2a, 2b and the cat controls 3a, 3b monitored, detected, checked and checked for admissibility. For this purpose, the crane controls 2a, 2b and the Katzsteuerungen 3a, 3b exchange with each other. Only log off and logon sequences in a predetermined manner, such as the above two steps, are taken into account, and also the sequence of skipping and logging steps are checked to ensure a safe switch between normal and group operation. This achieves a high degree of security. In the crane controls 2a, 2b and the Katzsteuerungen 3a, 3b the Ab- and registration sequences are preset so that a corresponding detection, testing and at the end of the actual change between normal and group operation in the crane controls 2a, 2b and the Katzsteuerungen 3a 3b can be made as soon as the correct sequence and type of logout and logon sequences has been recognized.

In the group mode, only the first control switch 9a or only the second control switch 9b is in an active state and the remaining control switch 9a or 9b is in a passive state. In the passive state, the corresponding control switch 9a or 9b is deactivated and thus locked against an operator. Accordingly, all actuations of key switch elements that are made on the deactivated control switch 9a or 9b are ignored, which are directed to the triggering of a driving, lifting or lowering operation. It is thus prevented that the Bus 7 is applied with related control commands in the form of corresponding control signals or these are executed by the controllers S1 and S2. In other words, no driving, lifting or lowering operation can be triggered by the deactivated and passive state control switch 9a or 9b. This and also beyond going coordination of participating in group operation cranes 1a, 1b is possible only on the only in the active state activated control switch 9a or 9b. The first controller S1 and the second controller S2 are set in group mode accordingly.

Within the group operation comprising two cranes 1a and 1b, two modes are possible, one synchronous mode and one single mode. The selection of the operating mode is carried out by actuation of one of the Tastschaltelemente the activated control switch 9a or 9b, which serves as a selection key 12c corresponding manner. Depending on the selected operating mode, the cranes 1a and 1b respond differently to the control signals sent by the activated control switch 9a or 9b to the bus 7.

A synchronous operation, which takes place in the present embodiment with two cranes 1a, 1b, is also referred to as tandem operation. In the synchronous mode, the only activated control switch 9a or 9b is simultaneously assigned to all cranes registered for group operation, in the present case both cranes 1a, 1b, in such a way that the motors 4a, 4b, 5a, 5b, 6a and 6b run parallel to the cranes respond from the activated control switch 9a or 9b sent control signals and execute the corresponding control commands. By the parallel control of the crane traction motors 4a, 4b, Katzfahrmotoren 5a, 5b and hoist motors 6a, 6b, the motors 4a, 4b, 5a, 5b, 6a and 6b of the first crane 1a and the second crane 1b move together and synchronously, creating a gleichläufiger Driving and / or lifting or lowering process takes place.

Within group operation, and in particular within synchronous operation, critical operating conditions may occur in which the synchronous and parallel operation of the motors 4a, 4b, 5a, 5b, 6a and 6b must be interrupted to resume shortly thereafter or later become. This may be the case if, by the method of the two cranes 1a, 1b in synchronous operation, the load gets into an undesired and unstable inclination, in the example Slings having load-carrying means slipping out and crash of the load threatens. Also, in a load in the form of a bulk container containing in synchronous operation slipping of the bulk material can occur to an unstable inclination of the container. This necessitates, in each case, a rotational change or correction of the position of the load in order to correct the inclination and to restore a stable horizontal alignment of the load. A correction of the relative position of the cranes 1 a, 1 b to one another, in particular the crane carrier and / or the crane trolleys carrying the respective hoist, is conceivable in this context. This may also be required without skewing the load.

For such corrections, the operation of the selection key 12c switches from the synchronous or tandem operation to a single operation. The group operation is not left here. Accordingly, in the single mode, only one of the control switches 9a or 9b continues to be in the active state and the other control switch 9a or 9b remains deactivated in the passive state. In addition, for the single operation one of the two cranes 1a, 1b is deactivated and thus put into a passive state, so that only one of the two cranes 1a, 1b remains activated. The coordination, that is, the selection and deactivation of the respective crane 1a or 1b, via the activated control switch 9a, 9b by the operation of a corresponding Tastschaltelements. In this case, the selection of the respectively activated or deactivated crane 1a or 1b can be changed via the activated control switch 9a, 9b.

The respective disabled crane 1a or 1b then ignored at least such control signals or does not execute the corresponding control commands, which are directed to the triggering of a driving, lifting or lowering operation. On the other hand, control signals aimed at reactivating the deactivated crane 1a or 1b to switch to synchronous operation are not ignored. The deactivation of one of the two cranes 1a or 1b thus results in only the other of the two cranes 1a, 1b being activated as the only crane 1a or 1b in an active state in the sense that it responds to control signals that are triggered a driving, lifting or lowering are directed, and executes them. The first controller S1 and the second controller S2 are in single operation according to the selection, which crane 1a, 1b in the active state and which in Passive state should be, set.

This can be moved independently of and relative to the second crane 1 b and in particular the hoist and load-carrying means in the individual operation of the first crane 1 a and in particular its hoist and load-receiving means. It is not necessary to switch to normal operation, in which each crane 1a, 1b is operated via its associated control switch 9a, 9b. As a result, the operator does not have to switch between the control switches 9a, 9b, but can perform the operation continuously through one and the same control switch 9a or 9b.

The controls S1 and S2 of the cranes 1a, 1b are decentralized and divided into the modules crane control 2a, 2b and Katzsteuerung 3a, 3b, each for themselves to the respective control signals of the control switches 9a, 9b for switching between normal and group operation or synchronous and single operation respond. For switching between normal and group operation and within the group operation between synchronous operation and single operation thus the existing crane control 2a, 2b and the existing Katzsteuerung 3a, 3b used.

As previously mentioned, within group operation, it may be necessary to switch from synchronous operation to single operation to correct a critical operating condition achieved by synchronous operation. For this purpose, at least one driving, lowering and / or lifting operation is then carried out as a correction movement in single operation. During the correction movement, the distribution of the load changes to the hoists and load-carrying devices that are involved in the group operation and involved in the load. As a result, there is a risk that the deactivated crane 1 a or 1 b or its hoisting gear which is not involved in the correction movement will be overloaded by the correction movement, without this necessarily having to be accompanied by an optically perceivable inclination of the load. It is also conceivable that an overloading of the deactivated crane 1a or 1b or its hoist is present even before the planned start of the correction movement in single operation. An overload can damage the load handler, hoist and / or fall of the load and should therefore be prevented.

For this purpose, the present method provides for the following measures. Each hoist is provided in a known manner with a load sensor having overload protection (not shown) to determine continuously at the respective hoist load values corresponding to an attacking on the hoist part load, and to compare continuously with a respective permissible and parameterizable limit. The execution of a driving, lifting and / or lowering operation is prevented by the controller S1 or S2 in case of overload, that is, when a load value is determined in the corresponding hoist, which exceeds an allowable limit. This applies to both normal operation and group operation.

In single operation, however, unlike in the prior art described above, not only the activated crane 1a or 1b or its hoist is monitored with regard to a possible overload, but also the deactivated crane 1a or 1b or its hoist. For this purpose, the associated controller S1 or S2 stores the previous involvement of each crane 1a, 1b or hoist on the common lifting operation in synchronous operation. Furthermore, the respective load values and limit values are available to both controls S1 and S2 via the bus 7. The limit values can vary depending on different operating situations and can be set in each case in the two controllers S1 and S2. As such operating situations can be considered, for example, load-dependent to be maintained crane relationship hoist distances, required static load reductions or load limits or different experience profiles of operators. The determined load values and limit values are compared. If an overload is applied to the deactivated hoist, it is prevented by the corresponding control S1 or S2 that the activated hoist can perform a driving, lifting and / or lowering operation. The driving, lifting and / or lowering operation in single operation is accordingly stopped or can not even be started until an overload of the deactivated crane 1a or 1b or its hoist is present even before the planned start of the correction movement in single operation.

In the aforementioned cases, the load can always be replaced by a change back to Synchronous operation can be lowered with all hoists previously involved in the common lifting process.

Although in the present embodiment the invention is described with reference to a group operation with two cranes 1a, 1b, the above-described principle of the invention is also applicable to a group operation with more than two cranes 1a, 1b. Here, the synchronous operation is then analogous to tandem operation with all of the at least three cranes, which are logged as described above for group operation and interconnected accordingly in terms of control. In this case, as described above, a single operation is available as the second operating mode, in which case only a single crane remains activated. In addition, as a third operating mode, there is also a multiple operation. The selection of synchronous, multiple or single operation also takes place by a corresponding operation of the selection key 12c. The multiple operation represents a kind of "small" synchronous operation in the sense of a less-synchronous operation. In multiple operation, accordingly, at least two cranes are activated and at least one of the cranes is deactivated. All activated cranes can be operated parallel and synchronously, as well as relative to the deactivated cranes, in the same way as regular synchronous operation, in which all cranes involved in group operation are activated. The activation of the cranes participating in the multiple operation takes place by actuation of one of the key-switching elements of the activated control switch 9a or 9b, which serves as activation key 12d in a corresponding manner. The activation key 12d also deactivates the cranes which, starting from the synchronous or multiple operation, are not or no longer intended to participate in the multiple operation. However, a single operation or multiple operation following a synchronous operation is only possible if, as described above, no overload is detected on any deactivated crane or its hoist. For this purpose, the participation in synchronous operation in the associated control is also stored for each crane or hoist. On the basis of this information, the respectively determined load values and limit values of all hoists originally involved in synchronous operation are compared by the control of the at least one activated hoist after switching to single or multiple operation in order to control a driving, lifting and / or overrunning in the event of an overload. or to prevent lowering of the at least one activated hoist. The stored information about the common lifting operation in synchronous operation or the hoists involved in this synchronous operation are deleted as soon as load values are determined for all of these hoists, which exclude the overload of that hoist with the lowest limit.

The method described above is not limited to the operation of cranes whose hoists are moved horizontally, but in principle also applicable to the operation of hoists or their respective stationary hoist, in their operation accordingly only lifting operations and lowering operations and no driving done.

LIST OF REFERENCE NUMBERS

1a

first crane

1b

second crane

2a

first crane control

2 B

second crane control

3a

first cat control

3b

second cat control

4a

first crane drive motor

4b

second crane drive motor

5a

first trolley motor

5b

second trolley motor

6a

first hoist motor

6b

second hoist motor

7

bus

7a

first bus section

7b

second bus section

7c

Drahtlosbus

8a

first coupling module

8b

second coupling module

9a

first control switch

9b

second control switch

9c

Cable control switch

10a

first wireless connection

10b

second wireless connection

11a

first switch coupling module

11b

second switch coupling module

12a

registration key

12b

Out button

12c

selection key

12d

activation button

S1

first control

S2

second control

Claims (9)

1. Method for operating at least two lifting gears in a group operation, wherein each lifting gear has a hoist, via which a respective load picking-up means can be raised by a lifting procedure or can be lowered by a lowering procedure, in which group operation, in a synchronous operating mode, firstly a common lifting procedure is carried out by means of the at least two hoists in order to move a load fastened to the load picking-up means, after the common lifting procedure, for changing from the synchronous operation to an individual operation or a multi-operation, at least one of the hoists involved in the common lifting procedure is deactivated, and at least one of the involved hoists remains activated such that only each activated hoist can carry out a lifting procedure or lowering procedure relative to each deactivated hoist, characterised in that even after changing from the synchronous operation to the individual operation or the multi-operation for each hoist previously involved in the common lifting procedure of the synchronous operation, in particular each deactivated hoist, a load value corresponding to a partial load acting upon the hoist is determined and compared to a respectively permissible threshold value.
2. Method as claimed in claim 1, characterised in that the lifting procedure or the lowering procedure of each activated hoist is prevented if, in the case of the at least one deactivated hoist, a load value is determined which exceeds a permissible threshold value.
3. Method as claimed in claim 1 or 2, characterised in that for each hoist load values are continuously determined and compared to a respectively permissible threshold value.
4. Method as claimed in any one of claims 1 to 3, characterised in that for each hoist, the involvement in the synchronous operation, in particular in the common lifting procedure, is stored and, after the change to the individual operation or multi-operation by a controller (S1, S2) of the at least one activated hoist, the respectively determined load values and threshold values of all of the hoists originally involved in the synchronous operation are compared using this information.
5. Method as claimed in any one of claims 1 to 4, characterised in that each hoist can be moved in at least one horizontal direction by a travel procedure independently of the lifting or lowering procedure and the travel procedure of each activated hoist is prevented if, in the case of the at least one deactivated hoist, a load value is determined which exceeds a permissible threshold value.
6. Method as claimed in any one of claims 1 to 5, characterised in that the threshold value can vary in dependence upon different operating situations and can be set in particular in a controller (S1, S2) of the respective hoist.
7. Method as claimed in any one of claims 1 to 6, characterised in that each lifting gear is designed as a crane (1a, 1b) comprising a crane girder, in particular as a bridge crane.
8. Method as claimed in any one of claims 1 to 7, characterised in that the lifting gears are operated together, in particular synchronously, in the synchronous operation via a single control switch (9a, 9b).
9. Assembly comprising at least two lifting gears, in particular two cranes (1a, 1b), characterised in that the lifting gears and in particular the controllers (S1, S2) thereof are designed in order to be able to be operated according to one of the methods as claimed in any one of claims 1 to 8.

Images