Patent Publication Number: US-2021188599-A1

Title: Lifting crane with a system for automated determination of the reeving

Description:
FIELD 
     The invention relates to a lifting crane comprising a jib and a double reeving lifting device designed to distribute and lift a load along the jib. 
     It relates more particularly to a lifting crane wherein the lifting device is reversibly configurable between two reeving configurations including a single reeving configuration with two lifting strands and a double reeving configuration with four lifting strands, and wherein the lifting device comprising a reeving change system allowing a reeving change between the single reeving configuration and the double reeving configuration. 
     The invention finds a preferred, and non-limiting, application in the field of the tower cranes. 
     BACKGROUND 
     In a known manner, a lifting crane includes a monitoring/control unit monitoring all crane movements in order to guarantee a correct use within the authorized limits of the crane, and in particular to guarantee the stability of the crane by permanently monitoring that the load suspended on the lifting device at the reach measured on the jib is less than a maximum load authorized by a predefined load curve. 
     In a known manner with electromechanical monitoring/control units, this function of monitoring the suspended load is carried out by a moment bar calculation which allows directly measuring an elastic deformation of the jib under the suspended load moment, with numerous drawbacks including the cost of such monitoring/control units and the complexity of implementation. 
     It is also known to calculate the suspended load from an actual lifting tension measured on at least one lifting strand (strand of the lifting cable partially supporting the load), then this lifting tension is multiplied by the number of lifting strands in action, which is two in single reeving configuration and four in double reeving configuration. 
     Also, it is necessary for the monitoring/control unit to be aware of the number of lifting strands, in other words of the reeving configuration between the single reeving configuration and the double reeving configuration. 
     Currently, the reeving configuration is known from a declarative mode, that is to say that it is the crane pilot who declares, on an interface, the current reeving configuration. Consequently, the stability of the crane, and therefore compliance with safety conditions, will depend on the correct statement of the reeving configuration by the pilot; it being noted that a poor consideration of the number of involved strands can lead to accepting an overload of a factor of 2 compared to the maximum authorized load, with serious consequences such as for example a tilting of the crane. 
     SUMMARY 
     Thus, the invention proposes removing this declarative mode of the reeving configuration, and at the same time removing the aforementioned drawbacks associated to its implementation, mainly including the risks of false statements, erroneous statements or late statements. 
     To this end, the invention relates to a lifting crane comprising a jib and a lifting device with double reeving designed to distribute and lift a load along the jib, said lifting device being reversibly configurable between two reeving configurations including a single reeving configuration with two lifting strands and a double reeving configuration with four lifting strands, and the lifting device comprising a reeving change system allowing performing a reeving change between the single reeving configuration and the double reeving configuration, and vice versa, said lifting crane being remarkable in that it comprises a system for automated determination of the reeving designed to automatically determine the reeving configuration between the single reeving configuration and the double reeving configuration. 
     Thus, the invention is based on an automated mode of determining the reeving configuration, rather than on a declarative mode, which allows making the recognition of the reeving configuration more reliable and thus allows automatically changing the load curve (adaptation of the load curve depending on the number of lifting strands) without a decision by the crane operator, and by making sure to always have the correct load curve, in particular during the transition phases, throughout the reeving change. 
     The invention also allows making the recognition of the reeving configuration more reliable without using a moment bar calculation which, in addition to being expensive, is complicated to implement. 
     According to one feature, the lifting device comprises a distributing trolley comprising a structure suspended on the jib and connected to a distribution system capable of displacing the distributing trolley along the jib in a forward direction and a rearward direction which are opposite to each other, and a main block suspended from said suspended structure by a lifting cable; 
     the reeving change system comprises a secondary block and a locking/unlocking mechanism cooperating with the main block and the secondary block to pass from the single reeving configuration to the double reeving configuration or vice versa; and 
     the system for automated determination of the reeving comprises at least:
         a system for detecting the presence of the secondary block capable of detecting a presence/absence of the secondary block at a predetermined reference location occupied by said secondary block in either of the reeving configurations, and   a monitoring/control unit connected to the system for detecting the presence of the secondary block and designed to automatically determine the reeving configuration depending on the detection of the absence/presence of the secondary block at the reference location.       

     Thus, the automated determination of the reeving configuration is based on the detection of the absence/presence of the secondary block at a reference location, which has the advantage of having a reliable detection and thus an equally reliable reeving configuration determination. 
     According to one possibility, the system for automated determination of the reeving comprises a storage module connected to the monitoring/control unit for storing at least one last reeving configuration determined by the monitoring/control unit,
         and the monitoring/control unit is designed to automatically determine the reeving configuration also depending on said last reeving configuration stored in the storage module.       

     Thus, during a reeving change, the monitoring/control unit can determine the new reeving configuration and check whether this determination is consistent with the last reeving configuration stored in the memory. Also, the monitoring/control unit can check whether or not a reeving change has been successfully carried out, so as to be able to safely deduce the new reeving configuration and, once the new reeving configuration has been determined, the latter is stored in the storage module until the next reeving change. 
     According to another possibility:
         in the single reeving configuration, the locking/unlocking mechanism unlocks the secondary block which remains positioned inside a block housing provided on the main block such that the lifting cable cooperates with the main block for a two-strand lifting, and   in the double reeving configuration, the locking/unlocking mechanism locks the secondary block on the distributing trolley at a location above the main block such that the lifting cable cooperates with both the main block and the secondary block for a four-strand lifting.       

     In a first embodiment, the system for detecting the presence of the secondary block is configured to detect the presence/absence of the secondary block inside the block housing occupied by the secondary block in the single reeving configuration and/or at the location above the main block occupied by the secondary block in the double reeving configuration. 
     Thus in this first embodiment, the system for detecting the presence of the secondary block implements a direct detection of the presence/absence of the secondary block at a reference location; this reference location corresponding:
         to the inside of the block housing (if the secondary block is inside the block housing then the lifting device is in single reeving configuration);   to the location above the main block (if the secondary block is suspended from the location above the main block then the lifting device is in double reeving configuration).       

     In a second embodiment, the reeving change system comprises a remaining trolley comprising a frame suspended on the jib and supporting the secondary block, wherein:
         in the double reeving configuration, the locking/unlocking mechanism locks together the distributing trolley and the remaining trolley which are assembled and displaceable in association along the jib, and the secondary block is suspended on the remaining trolley at the location above the main block; and   in the single reeving configuration, the locking/unlocking mechanism unlocks the remaining trolley, such that the distributing trolley and the remaining trolley are disassembled, the secondary block is housed inside the block housing provided on the main block and the distributing trolley is displaceable on its own while the remaining trolley is statically positioned with the secondary block at a storage location   and the system for detecting the presence of the secondary block is configured to detect a presence/absence of the remaining trolley at the storage location.       

     Thus, in this second embodiment, the system for detecting the presence of the secondary block implements an indirect detection of the presence/absence of the secondary block at a reference location. Indeed, it is the remaining trolley which is detected as being present/absent at this storage location, in other words:
         if the remaining trolley is present at the storage location, then necessarily the secondary block is inside the block housing and the lifting device is in the single reeving configuration;   if the remaining trolley is absent from the storage location, then necessarily the secondary block is suspended at the location above the main block and the lifting device is in the double reeving configuration.       

     According to one variant, this storage location is located at the foot of the jib. 
     In a particular embodiment, the reeving change system passes the lifting device from the single reeving configuration to the double reeving configuration, and vice versa, by displacing the distributing trolley with the main block thereof, and the monitoring/control unit is connected to the distribution system to drive the displacement of the distributing trolley according to:
         a first automated sequence passing the lifting device from the single reeving configuration to the double reeving configuration; and vice versa   a second automated sequence passing the lifting device from the double reeving configuration to the single reeving configuration;       

     depending on the reeving configuration which is automatically determined by said monitoring/control unit. 
     Thanks to the automated detection of the reeving configuration, it is therefore now advantageous to drive, in an automated manner, the reeving changes, integrally or not from start to finish; just as it is conceivable that this driving comes under steering assistance, for example by monitoring or limiting the speeds and/or the acceleration and/or the braking and/or the stops 
     Advantageously, the monitoring/control unit is designed to enable:
         the first automated sequence at least on condition that the monitoring/control unit has determined that the lifting device is in single reeving configuration;   the second automated sequence at least on condition that the monitoring/control unit has determined that the lifting device is in double reeving configuration.       

     Thus, the invention allows securing the reeving changes, and therefore avoiding erroneous operations. 
     In a particular embodiment, the lifting crane comprises a lifting winch provided with a lifting drum cooperating with the lifting cable to displace the load upward and downward, said lifting winch being equipped with an unwinding sensor capable of measuring an unwound length of the lifting cable, wherein the monitoring/control unit is designed to compare the unwound lengths of the lifting cable at the beginning of a first automated sequence and at the beginning of a second automated sequence which follows or precedes said first automated sequence. 
     According to one possibility, the monitoring/control unit is designed to automatically determine the reeving configuration also depending on the comparison between the unwound lengths of the lifting cable at the beginning of a first automated sequence and at the beginning of a second automated sequence which follows or precedes said first automated sequence. 
     Thus, this comparison allows making the determination of the reeving configuration even more reliable. 
     In an advantageous embodiment, a load sensor coupled to a lifting strand of the lifting cable for measuring a lifting tension on said lifting strand, wherein the monitoring/control unit is connected to the load sensor and is designed to calculate a value of the load depending on said lifting tension on said lifting strand and on the reeving configuration which is automatically determined by said monitoring/control unit. 
     The invention indeed finds an advantageous application for calculating a value of the load suspended from the lifting strands, reliably and without declarative mode, thus offering a reliable solution allowing overcoming human error and thus improving the safety level. 
     Alternatively, the monitoring/control unit is designed to compare the value of the load with a maximum authorized load. 
     The invention also relates to a driving method for driving a lifting crane according to the invention, as described above, comprising the steps of:
         performing a reeving change between the single reeving configuration and the double reeving configuration, or vice versa;   automatically determining the reeving configuration between the single reeving configuration and the double reeving configuration.       

     According to one feature, the driving method comprises the steps of:
         detecting a presence/absence of the secondary block at a predetermined reference location occupied by said secondary block in either of the reeving configurations;   automatically determining the reeving configuration depending on the detection of the absence/presence of the secondary block at the reference location.       

     Advantageously, the driving method comprises a step of storing at least one last automatically determined reeving configuration, and wherein the configuration of the lifting device is automatically determined also depending on said last stored reeving configuration. 
     According to another feature, the driving method comprises a step of driving the displacement of the distributing trolley according to:
         a first automated sequence passing the lifting device from the single reeving configuration to the double reeving configuration; and vice versa   a second automated sequence passing the lifting device from the double reeving configuration to the single reeving configuration; depending on the automatically determined reeving configuration.       

     Advantageously, the driving method comprises the step of enabling:
         the first automated sequence at least on condition that it is automatically determined that the lifting device is in single reeving configuration;   the second automated sequence at least on condition that it is automatically determined that the lifting device is in double reeving configuration.       

     In a particular embodiment, the driving method comprises the steps of:
         measuring an unwound length of the lifting cable, said lifting cable cooperating with a lifting drum of a lifting winch to displace the load upward and downward,   comparing the unwound lengths of the lifting cable at the beginning of a first automated sequence and at the beginning of a second automated sequence which follows or precedes said first automated sequence.       

     According to one possibility, the configuration of the lifting device is automatically determined also depending on the comparison between the unwound lengths of the lifting cable at the beginning of a first automated sequence and at the beginning of a second automated sequence which follows or precedes said first automated sequence. 
     According to another possibility, the driving method comprises the steps of:
         measuring a lifting tension on a strand of the lifting cable;   calculating a value of the load depending on said lifting tension on said strand of the lifting cable and on the automatically determined reeving configuration.       

     Advantageously, the driving method comprises the step of comparing the value of the load with a maximum authorized load. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other features and advantages of the present invention will appear on reading the detailed description below, of a non-limiting example of implementation, made with reference to the appended figures wherein: 
         FIG. 1  is a perspective view of portion of a lifting crane in accordance with the invention, comprising a lifting device illustrated in the double reeving configuration, this lifting device comprising a distributing trolley and a remaining trolley which are assembled to each other, and a lifting cable cooperating with a main block and with a secondary block suspended above the main block; 
         FIG. 2  is a perspective view of portion of the lifting crane of  FIG. 1 , with the lifting device in the double reeving configuration and at the foot of the jib; 
         FIG. 3  is a zoomed view of zone III of  FIG. 2  which is positioned on a system for detecting the presence of the secondary block; 
         FIG. 4  is a view of portion of the lifting crane of  FIG. 1 , with the lifting device in the single reeving configuration, where the distributing trolley and the remaining trolley are disassembled, the secondary block is housed in a block housing of the main block, and the remaining trolley being parked at the foot of the jib; 
         FIG. 5  is a schematic view of a lifting crane according to the invention in the single reeving configuration; and 
         FIG. 6  is a schematic view of a lifting crane similar to that of  FIG. 5  but in the double reeving configuration. 
     
    
    
     DESCRIPTION 
     With reference to the Figures, a lifting crane  1  according to the invention, of the tower crane type, comprises a distributing jib  2  mounted on a tower  3  (also called a mast) at the foot  20  of the jib  2 . Conventionally, the foot  20  of the jib  2  is rotatably mounted on the tower  3  along a vertical axis. The jib  2  can be extended to the other side of tower  3  by a counter-jib  30 , generally provided with ballasts. 
     The lifting crane  1  further includes a lifting device  4  with double reeving designed to distribute a load (not illustrated) along the jib  2 , this lifting device  4  circulating on a rolling path formed on the jib  2 , between the foot  20  and the tip  21  of the jib  2 , also called the free end of the jib  2 . 
     This lifting device  4  comprises a distributing trolley  5  which includes a structure  50  suspended on the rolling path by front and rear primary rolling members formed of rollers or wheels rolling on the rolling path. This suspended structure  50  supports pulleys which ensure the guiding of a lifting cable  40 . 
     The suspended structure  50  is connected to a distribution system  55  capable of displacing the distributing trolley  5  along the rolling path in a forward direction (in other words in the direction of the tip  21  of jib  2 , to the right in the Figures) and an opposite rear direction (in other words in the direction of the foot  20  of the jib  2 , to the left in the Figures). 
     As schematized in  FIGS. 4, 5 and 6 , this distribution system  55  comprises a motor  56  driving a distribution winch  57  coupled to a distribution cable  58  having strands fastened to either side of the distributing trolley  5  and which circulates to a tip  21  of jib  2 . 
     The distributing trolley  5  further comprises a main block  51  suspended from the suspended structure  50  by the lifting cable  40 . This main block  51  supports a lifting member  52 , in the lower portion; this lifting member  52  being provided for hooking the load and could be in the form of a hook hinged on the main block  51 . 
     This lifting device  4  is reversibly configurable between two reeving configurations including:
         as illustrated in  FIGS. 4 and 5 , a single reeving configuration with two lifting strands of the lifting cable  40 ; and   as illustrated in  FIGS. 1, 2 and 6 , a double reeving configuration with four lifting strands of the lifting cable  40 .       

     The lifting device  4  comprises a reeving change system allowing reversibly performing a reeving change between the single reeving configuration and the double reeving configuration, and vice versa. 
     This reeving change system comprises a remaining trolley  6  which is movable on the rolling path. The remaining trolley  6  comprises a frame  60  suspended on the rolling path by front and rear secondary rolling members formed of rollers or wheels rolling on the rolling path. The suspended frame  40  is open on the front, enabling an entry/exit of the distributing trolley  3 . 
     This reeving change system also comprises a secondary block  61  supported by the suspended frame  60  of the remaining trolley  6  in the double reeving configuration. 
     This reeving change system also comprises a locking/unlocking mechanism cooperating with the main block  51  and the secondary block  61  to pass from the single reeving configuration to the double reeving configuration or vice versa, so that:
         in the double reeving configuration which is illustrated in  FIGS. 1, 2 and 6 , the locking/unlocking mechanism locks together the distributing trolley  5  and the remaining trolley  6  which are assembled and displaceable in association along the jib  2 , and thus the locking/unlocking mechanism locks the secondary block  51  on the distributing trolley  5  which is then displaceable with the main block  51  and with the secondary block  61  which is suspended above the main block  51 , such that the lifting cable  40  cooperates both with the main block  51  and the secondary block  61  for a four-strand lifting; and   in the single reeving configuration which is illustrated in  FIGS. 4 and 5 , the locking/unlocking mechanism unlocks the remaining trolley  6  vis-a-vis the distributing trolley  5 , such that the distributing trolley  5  and the remaining trolley  6  are disassembled and the distributing trolley  5  is displaceable on its own while the remaining trolley  5  is statically positioned at a stationary storage location under the jib  2 , and more precisely under the foot  20  of the jib  2 , and thus the locking/unlocking mechanism unlocks the secondary block  51  which remains positioned within a block housing  55  provided on the main block  51 , such that the lifting cable  40  cooperates with the main block  51  for a two-strand lifting.       

     In the embodiment which is illustrated in  FIGS. 1 to 4 , the locking/unlocking mechanism comprises support members secured to the suspended frame  60  of the remaining trolley  6  and on which the secondary block  61  is suspended at a location above of the main block in the double reeving configuration, and the main block  51  comprises the block housing  55  arranged to at least partially house the secondary block  61  in the single reeving configuration. 
     Moreover, the lifting device  4  is arranged to pass from the single reeving configuration to the double reeving configuration, and vice versa, by displacing the distributing trolley  5  with the main block  51  thereof, and to do this the reeving change system and more specifically, the locking/unlocking mechanism thereof are designed to pass from the single reeving configuration to the double reeving configuration, and vice versa, by acting on the distribution system (in order to displace the distributing trolley  5 ) and on the lifting cable  40 . 
     As schematized in  FIGS. 5 and 6 , the lifting crane  1  comprises a lifting system  45  provided with a motor  46  driving a lifting winch  47  provided with a lifting drum coupled to the lifting cable  40  on which the main bock  51  is suspended, and which circulates to the tip  21  of the jib  2 . 
     This type of lifting device  4  is described, in full and detailed manner, in the French patent applications No. FR 3 061 163 and No. FR 3 061 164, and those skilled in the art will usefully refer to these two French patent applications for further structural and functional details, and a summary of the reeving changes is proposed below; it being noted that the invention is not limited to this type of lifting device  4 . 
     The lifting device  4  passes from the double reeving configuration to the single reeving configuration as follows:
         in the double reeving configuration, the suspended structure  50  of the distributing trolley  5  is disposed at least partially inside the suspended frame  60  of the remaining trolley  6 , and the secondary block  61  is carried by the support members of the suspended frame  60  of the remaining trolley  6 , such that the secondary block  61  is locked on the distributing trolley  5  at a location above the main block  51 ;   the main block  51  is raised until the secondary block  61  is unhooked from the support members after being pushed upwards by the main block  51 , and until the secondary block  61  is at least partially housed inside the block housing  55  of the main block  51 ;   the distributing trolley  5  is displaced in translation in the forward direction, the remaining trolley  6  not being displaced in translation and remaining at the predefined storage location under the jib  2 , and this remaining trolley  6  having the suspended frame  60  thereof open on the front to allow a free passage for the lifting cable  40  which follows the distributing trolley  5 ; and   the main block  51  is lowered and the lifting cable  40  cooperates with the main block  51  for a simple reeving work, the secondary block  61  being housed at least partially inside the block housing  55  of the main block  51 .       

     The lifting device  4  passes from the single reeving configuration to the double reeving configuration as follows:
         in the single reeving configuration, the secondary block  61  is housed at least partially inside the block housing  55  of the main block  51 ;   the main block  51  is raised until it makes contact with the suspended frame  60  of the remaining trolley  6 ;   the distributing trolley  5  is displaced in translation in the rearward direction;   the main block  51  is lowered until the secondary block  61  is hooked to the support members, enabling the main block  51  to lower without the secondary block  61  being housed inside the block housing  55  of the main block  51 .       

     With reference to  FIGS. 5 and 6 , and according to the invention, the lifting crane  1  further comprises a system for automated determination of the reeving  7  designed to automatically determine the reeving configuration between the single reeving configuration and the double reeving configuration. 
     This system for automated determination of the reeving  7  comprises at least:
         a presence detection system  8  for detecting the presence of the secondary block  61  capable of detecting a presence/absence of the secondary block  61  at a predetermined reference location occupied by said secondary block  61  in either of the reeving configurations, and   a monitoring/control unit  9  connected to the presence detection system  8  for detecting the presence of the secondary block  61  and designed to automatically determine the reeving configuration depending on the detection of the absence/presence of the secondary block  61  at the reference location.       

     This presence detection system  8  may comprise first means for detecting the presence/absence of the secondary block  61  inside the block housing  55  occupied by the secondary block  61  in the single reeving configuration. Thus, if the secondary block  61  is inside the block housing  55  then the lifting device  4  is in the single reeving configuration, and conversely if the secondary block  61  is absent from the block housing  55  then the lifting device  4  is in the double reeving configuration. This first means may for example comprise a contact sensor, a mechanical sensor, an electrical sensor, an optical sensor, etc., for example disposed in front of or inside the block housing  55 . 
     This presence detection system  8  can comprise second means for detecting the presence/absence of the secondary block  61  at the location above the main block  51  occupied by the secondary block  61  in the double reeving configuration, and in particular the presence/absence of the secondary block  61  in suspension on the support members provided on the remaining trolley  6 . Thus, if the secondary block  61  is present on the support members then the lifting device  4  is in the double reeving configuration, and conversely, if the secondary block  61  is absent from the support members then the lifting device  4  is in the single reeving configuration. This second means can for example comprise a contact sensor, a mechanical sensor, an electrical sensor, an optical sensor, etc. disposed for example in front of or on the support members. 
     This presence detection system  8  can comprise third means for detecting the presence/absence of the remaining trolley  6  at the storage location (under the foot  20  of the jib  2  in the illustrated embodiment), insofar as the presence/absence of the remaining trolley  6  at the storage location is correlated with the localization of the secondary block  61  and with the reeving configuration. Thus, if the remaining trolley  6  is present at the storage location then the lifting device  4  is in the single reeving configuration, and conversely if the remaining trolley  6  is absent from the storage location then the lifting device  4  is in the double reeving configuration. 
     This presence detection system  8  can comprise all or part of the first means, of the second means and of the third means described above. In the illustrated embodiment, the presence detection system  8  comprises the third means, shown in  FIG. 3 , which comprises a proximity sensor  80  associated with a stop  81  mounted to slide in translation on a fixed structural element  22  of the lifting crane  1  placed at the foot  20  of the jib  2 , such that the stop  81  is located in front of the remaining trolley  6  when the latter is at the storage location, under the foot  20  of the jib  2 . 
     This stop  81  comprises a rod  82  extended by an enlarged head  83 . The rod  82  is slidably mounted on the structural element  22  and, as such, the rod  82  passes through this structural element  22  into an orifice or bearing. 
     The rod  82  has a free front end provided with a stop surface  84  provided so that the remaining trolley  6  abuts against said stop surface  84 . As such, the remaining trolley  6  may have, on the rear, a rear stopper  63  capable of bearing on the stop surface  84 . 
     This stop surface  84  is enlarged relative to the rod  82 , and is in particular in the form of a disc of a diameter which is greater than the diameter of the rod  82  if the latter is cylindrical. 
     The rod  82  has a rear end, opposite to the front end and therefore to the stop surface  84 , on which the enlarged head  83  is fastened. Thus, the stop  81  has on either side of the structural element  22 :
         a first end having the stop surface  84  and   a second end having the enlarged head  83 .       

     The enlarged head  83  has a detection surface  85  which is flat and inclined relative to a sliding direction of the stop  81  on the structural element  22 . 
     There is also provided an elastic return member  86  interposed between the structural element  22  and the stop surface  84 , wherein this return member  86  is in the form of a helical compression spring mounted around the rod  82 . 
     The proximity sensor  80  is in turn fixedly mounted on the jib  2  and is disposed opposite to the detection surface  85  of the enlarged head  83  of the stop  81 , wherein the proximity sensor  80  is configured to detect and measure the distance between said proximity sensor  80  and said detection surface  85 . This proximity sensor  80  can for example be an inductive sensor or a light sensor (infrared sensor, etc.). 
     The stop  81  is selectively displaceable between:
         a rest position in the absence of thrust force exerted by the remaining trolley  6  on the stop  81 , in other words in the absence of a thrust force exerted rearwardly (in other words in the direction of the jib foot) by the rear stopper  63  of the remaining trolley  6  on the stop surface  84  of the stop  81 , it being noted that the return member  86  biases this stop  81  towards its rest position; and   at least one detection position in the presence of a thrust force exerted by the remaining trolley  6  on the stop  81 , in other words in the presence of a thrust force exerted rearwardly by the rear stopper  63  of the remaining trolley  6  on the stop surface  84  of the stop  81 , it being noted that the return member  86  offers a force resistant to this thrust force exerted by the remaining trolley  6  on the stop  81 .   In the detection position, the stop  81  has slid (rearwardly), compared to the rest position, which contributes to a modification of the distance between the proximity sensor  80  and the detection surface  85 , and also to a compression of the return member  86  between the structural element  22  and the stop surface  84 . It should be noted that the detection surface  85  is inclined in the direction of a reduction in the distance between the proximity sensor  80  and the detection surface  85  when the stop  81  has slid (rearwardly) from its rest position to the detection position.       

     As the proximity sensor  80  is configured to detect and measure the distance between the proximity sensor  80  and the detection surface  85 , this proximity sensor  80  is then configured to detect the stop  81  in its rest position and in its detection position, wherein:
         the rest position corresponds to a double reeving configuration, the remaining trolley  6  being in displacement with the distributing trolley  5  and therefore absent from the storage location at the foot  20  of the jib  2 ; and   the detection position corresponds to a single reeving configuration, the remaining trolley  6  being present at the storage location at the foot  20  of the jib  2 .       

     Thus, the monitoring/control unit  9  allows automatically determining the reeving configuration depending on the detection operated by the presence detection system  8 . 
     Advantageously, the system for automated determination of the reeving  7  comprises a storage module  90  (or memory) connected to the monitoring/control unit  9  to store at least one last reeving configuration determined by the monitoring/control unit.  9 . In other words, the last reeving configuration is stored in this storage module  90 , such that when a reeving change is operated, the monitoring/control unit  9  is designed to automatically determine the reeving configuration also depending on this last reeving configuration which is stored in the storage module. 
     Once the new reeving configuration has been determined, based on the at least one detection made by the presence detection system  8  and the last stored reeving configuration, it is this new reeving configuration which is stored in the storage module  90  and which therefore becomes the last reeving configuration. 
     In other words, the reeving configuration is updated in the storage module  90  at each reeving change. 
     As schematized in  FIGS. 5 and 6 , this monitoring/control unit  9  can be connected to the distribution system  55  and also to the lifting system  45  to drive the displacement of the distributing trolley  5  and the displacement of the lifting cable  40  (and therefore of the main block  51 ) according to:
         a first automated sequence passing the lifting device  4  from the single reeving configuration to the double reeving configuration; and vice versa   a second automated sequence passing the lifting device  4  from the double reeving configuration to the single reeving configuration;       

     depending on the reeving configuration which is automatically determined by this monitoring/control unit  9 . 
     Also, the monitoring/control unit  9  can enable:
         the first automated sequence at least on condition that the monitoring/control unit  9  has determined that the lifting device  4  is in single reeving configuration;   the second automated sequence at least on condition that the monitoring/control unit  9  has determined that the lifting device  4  is in double reeving configuration.       

     The monitoring/control unit  9  can also be connected to an unwinding sensor provided on the lifting winch  47  and capable of measuring an unwound length of the lifting cable  40 . Thus, the monitoring/control unit  9  can compare the unwound lengths of the lifting cable  40  at the beginning of a first automated sequence and at the beginning of a second automated sequence which follows or precedes this first automated sequence, and the monitoring/control unit  9  can thus automatically determine the reeving configuration also depending on this comparison between the unwound lengths of the lifting cable  40 . 
     If these unwound lengths of the lifting cable  40  are not equivalent, then the monitoring/control unit  9  establishes the presence of an error and automatically restarts the current sequence and/or emits an alarm. Thus, during a first automated sequence, the monitoring/control unit  9  supervises the proper conduct as follows:
         the monitoring/control unit  9  checks, before launching the first sequence, that the lifting device  4  is in the single reeving configuration (for example by detecting the presence of the remaining trolley  6  at the storage location);   checking that the unwound length of the lifting cable  40  is equivalent to the unwound length of the lifting cable  40  memorized during the preceding reeving change;   the monitoring/control unit  9  launches the first sequence by driving the displacement of the distributing trolley  5  and the displacement of the lifting cable  40 ;   the monitoring/control unit  9  checks that the lifting device  4  has passed to the double reeving configuration (for example by detecting the absence of the remaining trolley  6  at the storage location).       

     At the end of these steps, the monitoring/control unit  9  confirms that the reeving configuration is the double reeving configuration if no error has been detected, and memorizes this double reeving configuration in the storage module  90 . 
     Likewise, during a second automated sequence, the monitoring/control unit  9  supervises the proper conduct as follows:
         the monitoring/control unit  9  checks, before launching the second sequence, that the lifting device  4  is in the double reeving configuration (for example by detecting the absence of the remaining trolley  6  at the storage location);   checking that the unwound length of the lifting cable  40  is equivalent to the unwound length of the lifting cable  40  memorized during the preceding reeving change;   the monitoring/control unit  9  launches the second sequence by driving the displacement of the distributing trolley  5  and the displacement of the lifting cable  40 ;   the monitoring/control unit  9  checks that the lifting device  4  has passed to the single reeving configuration (for example by detecting the presence of the remaining trolley  6  at the storage location).       

     At the end of these steps, the monitoring/control unit  9  confirms that the reeving configuration is the single reeving configuration if no error has been detected, and memorizes this single reeving configuration in the storage module  90 . 
     With reference to  FIGS. 5 and 6 , the lifting crane  1  may also comprise a load sensor  91  coupled to a lifting strand of the lifting cable  90  in order to measure a lifting tension on that lifting strand. 
     In this case, the monitoring/control unit  9  is connected to this load sensor  91  and is designed to calculate a value of the load depending on the lifting tension measured on this lifting strand and on the reeving configuration which is automatically determined by the monitoring/control unit  9 , insofar as a single reeving configuration corresponds to a distribution of the load on two lifting strands, and a double reeving configuration corresponds to a distribution of the load on four lifting strands. 
     Thus, the monitoring/control unit  9  can compare the value of the load with a maximum authorized load, and consequently the monitoring/control unit  9  can act on the displacement of the distributing trolley  5  and the displacement of the lifting cable  40  if the maximum authorized load is exceeded, and can in particular stop any displacement of the load if the maximum authorized load is exceeded. 
     The system for automated determination of the reeving, and/or components thereof, may be implemented as, or include, one or more computers having a processor and a non-transitory computer-readable storage medium operably connected to the processor. The one or more computers may also include a communication module configured to facilitate communication (i.e., to transmit and/or receive information) with other components of the system for automated determination of the reeving and/or of the lifting crane. The processor may be a microprocessor. The processor is configured to execute program instructions stored in the computer-readable storage medium to control operations of the lifting crane, or components of the lifting crane, according to the program instructions. In this manner, the methods, steps, operations, processes and the like of the system for automated determination of the reeving, or components thereof, such as the monitoring/control unit and/or the system for detecting the presence of the secondary block, as described above, may be performed by way of the one or more computers.