Patent Publication Number: US-6991120-B2

Title: Device for raising and unfolding the mast and for raising the jib of a crane

Description:
BACKGROUND 
   The present invention is concerned with lifting or handling appliances and more particularly with cranes. This invention relates more specifically to a motorized device for raising and unfolding the mast and for raising the jib of a crane and even more particularly of a crane with a jib having multiple functions, such as is described by the document FR 2792627 A in the Applicant&#39;s name. 
   RELATED ART 
   The subject of this document is a crane of modifiable configuration which comprises a mast, mounted on a chassis, and a distributing jib, composed of successive elements articulated on one another about horizontal axes, the first jib element, called a jib foot, itself being articulated about a horizontal axis at the top of the mast. This first jib element and, if appropriate, the following element can be brought into a substantially vertical position, in alignment with the raised mast, so as to increase the height of this mast. All the jib elements comprise a rolling track for the same carriage. Thus, the crane may be used as a crane with a long or shortened, horizontal or inclined distributing jib or else as a crane with a “swan neck” jib, depending on the configuration of the jib elements, the height of the crane also being adjustable according to the number of jib elements brought into the prolongation of the mast. 
   In such a crane with a jib having multiple functions, the mast may itself be capable of being unfolded and being used in a plurality of positions, and the various configurations of the jib elements may thus be combined with the variable configurations of the mast. In particular, the foldable mast is composed of two mast elements, to be precise a lower mast element, articulated on the chassis of the crane, and an upper mast element, articulated on the top of the lower mast element. In particular, the lower mast element is articulated on a revolving chassis orientable about a vertical axis on a basic chassis mounted an wheels, the crane thus being capable of taking the form of an independent rolling appliance. 
   For motorizing the various joints of such a crane, the abovementioned document provides devices with a jack or with a jack and a rod assembly. This results in a multiplicity of jacks and of rod assemblies, bearing in mind the total number of joints to be motorized. 
   As another known example of the motorization of the unfolding of a foldable crane, mention may also be made of the document FR 2682096 A in the Applicant&#39;s name. This document is concerned with a crane which comprises is a foldable mast consisting of two elements and a jib consisting of two main elements. For such a crane structure, the motorized raising and unfolding device comprises a jack located between the two elements of the mast and articulated, on the one hand, on the lower part of the lower mast element and, on the other hand, on the lower part of the upper mast element by means of a rod assembly. The unfolding of the mast is carried out with the aid of this rod assembly. The raising of the jib is carried out with the aid of a tie connected, on the one hand, to a fixed point of the revolving chassis of the crane and, on the other hand, to a fixed point of the jib. 
   Such a technique has various disadvantages:
         The jack placed between the two mast elements possesses considerable bulk which is obstructive particularly in the folded transport position of the crane.   The movements of the raining/unfolding of the mast and of the raising of the jib are simultaneous and do not make it possible to change configuration during the work of the crane, the working configuration being obligatorily predefined before the raising and unfolding of the crane.   At all events, proceeding from this crane design, two motorization systems must be provided, to be precise; a system for raising and unfolding the mast and for raising the jib, since these movements are associated, and a system for unfolding the jib, and the device considered here cannot be applied directly to a crane with a jib having multiple functions.       

   SUMMARY 
   The present invention is aimed at avoiding the disadvantages set out above by providing an improved device for raising and unfolding the mast and for raising the jib of a crane, said device being more particularly suitable for a crane with a jib having multiple functions, this device comprising a minimum number of jacks capable of being used both for raising/unfolding and for the work of the crane, by making it possible to have various configurations of this crane, while at the same time possessing a small bulk, particularly for reducing the height of the crane in the folded transport position. 
   For this purpose, the subject of the invention is a motorized device for raising and unfolding the mast and for raising the jib of a crane of the type in question, this device comprising essentially a double-action hydraulic jack, the two ends of which are connected respectively to a lower rod assembly and to a upper rod assembly, the lower rod assembly intended for raising and unfolding the mast being also connected to the lower part of the upper mast element and to the upper part of the lower mast element, and the upper rod assembly intended for raising the jib and for moving it into various working positions being also connected to the upper part of the upper mast element and to the jib foot, the device also comprising at least one guy connecting the lower part of the upper mast element to a point of the chassis of the crane on which the lower part of the lower mast element is articulated, and means for locking the lower end of the abovementioned jack, in at least two separate positions, on the lower part of the upper mast element, and, finally, a stop located in the upper part of the upper mast element and provided for cooperating with the upper rod assembly. 
   Thus, the inventive idea involves providing a single jack, associated with two rod assemblies, for performing both the functions of unfolding/folding the mast, of raising/lowering the jib and of working with “luffing motion”, that is to say with a jib raising movement. The two locking positions of the jack occur respectively in the “mast unfolded” position and in the “mast folded” position. The proposed system possesses simple and reliable kinematics: it does not entail either a combination of movements or manual action on its functioning. It also affords complete independence of the movements and positions of the mast and of the jib, thus allowing all possible configurations, particularly from a position with the mast folded substantially horizontally or from a position with the mast unfolded substantially vertically. 
   The need for a single jack for various movements or functions also leads to economical implementation. Moreover, the jack is not positioned between the two mast elements when these are folded, but, instead, it rests on the upper mast element, thus making it possible to increase the driver&#39;s angle of sight from his cab. 
   According to one embodiment of the device which is the subject of the invention, the lower rod assembly comprises a first rod, preferably a double rod, articulated at one or its ends on the corresponding end of the jack, articulated at an intermediate point on the lower part of the upper mast element and articulated at its other end on one end of a second rod, preferably a double rod, itself articulated at its other end on the upper part of the lower mast element. 
   As regards the upper rod assembly, the latter advantageously comprises a bent rod, preferably a double rod, articulated at one of its ends on the upper part of the upper mast element and articulated, at its other end, both on the corresponding end of the jack and on one end of another rod, preferably a single rod, the other end of which is articulated on the jib foot. The bent rod here allows the upper rod assembly to “bypass” the articulation of the jib foot on the top of the mast. 
   The means for locking the lower end of the jack on the lower part of the upper mast element comprise in a particular embodiment:
         on the one hand, at the lower end of the jack, a transverse bolt consisting of a double-acting auxiliary jack, the body and stem of which are respectively integral with two opposite axles mounted slideably in the respective lateral parts of a head of the main jack, a safety spring being provided for keeping the bolt in the active position;   on the other hand, on the lower part of the upper mast element, a guide assembly composed of two slideways which are parallel to this mast element and are equipped respectively with lower and upper broaching holes corresponding to one another, the head of the jack being mounted displaceably between the two slideways, the lower broaching holes of which are provided for receiving respectively the two axles of the bolt in the “mast folded” position and the upper broaching holes of which are provided for receiving respectively the two axles of the bolt in the “mast unfolded” position.       

   The locking means have the function of not introducing useless stresses into the lower rod assembly, particularly by preventing the rotation of the first rod (three-point) of this rod assembly in the folded transport position. 
   The main jack makes it possible not only to raise the mast and the jib foot when the crane is initially being put in place, but also to obtain all intermediate jib positions via control of the greater or lesser extension of the stem of this jack. Inasmuch as the jib is itself composed of two or more elements articulated on one another, the unfolding of these jib elements in relation to one another is obtained by means of auxiliary motorization, in particular by jack and rod assembly, with which the present invention is not directly concerned. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be understood more clearly from the following description, with reference to the accompanying diagrammatic drawing illustrating, by way of example, one embodiment of this device for raising and unfolding the mast and for raising the jib of a crane: 
       FIG. 1  is a side view of a crane equipped with the device according to the invention, in folded transport position; 
       FIGS. 2 ,  3 ,  4 ,  5  and  6  are aide views, similar to  FIG. 1 , illustrating successive phases in the raising and unfolding the mast and in the raising of the jib of this crane; 
       FIGS. 7 ,  8  and  9  are side views of the same crane in various working positions; 
       FIG. 10  is a side view of the raising and unfolding device according to the invention, illustrated alone and in more detail, in the folded position; 
       FIG. 11  is a perspective view corresponding to  FIG. 10 ; 
       FIG. 12  shows, in perspective, in large detail A of  FIG. 11 , relating to the locking means of the jack; 
       FIGS. 13 and 14  are sectional views of these locking means in two positions; 
       FIG. 15  is a perspective view of the device, in the unfolded position. 
   

   DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
   The crane illustrated in the drawing in various positions possesses a basic carrying chassis  1  mounted so as to roll on wheels  2  and provided with stabilizers  3 . Mounted on the basic chassis  1  is a revolving chassis  4  orientable about a vertical axis  5  and provided with a driver&#39;s cab  6  on one of its sides. 
   On the other side of the revolving chassis  4  is mounted a foldable mast  7  composed of a lower mast element a and of a upper mast element  9 , each of polygonal cross section and of caisson-type structure The lower mast element  8  is articulated by means of its base, about a horizontal axis  10  on a lower part of the revolving chassis  4 . The upper mast element  9  is articulated by means of its base, about a horizontal axis  12 , on the top of the lower mast element  8 , this intermediate joint of the mast  7  allowing a relative pivoting of the elements  8  and  9  through an angle of approximately 180°. 
   The foldable mast  7  is held by means of a double guy  13  which connects the base of the upper mast element  9  to the upper part of the revolving chassis  4 . 
   At its top, the foldable mast  7  carries a distributing jib  14  which is composed of three successive jib elements  15 ,  16  and  17 , each of caisson-type structure, which all three comprise, level with their lower face, a rolling track  18  for a jib carriage  19 . 
   The first jib element  15 , also called a jib foot, is articulated at its rear end, about a horizontal axis  20 , at the top of the upper mast element  9 , this joint allowing a relative pivoting through an angle of approximately 180°. The second jib element  16  is articulated by means of its rear end, about a horizontal axis  21 , on the front end of the jib foot  15 . The third jib element  17 , also designated as the jib point, is articulated by means of its rear end, about a horizontal axis  22 , on the front end of the second jib element  16 . 
   The crane is provided with a motorized device, designated as a whole by  23 , for raising and unfolding its mast  7  and for raising its jib  14 . The device  23  comprises a hydraulic jack  24 , a lower rod assembly  25  and an upper rod assembly  26 . 
   The hydraulic jack  24 , which is a double-acting jack, possesses a body  27 , the end of which is connected to the lower rod assembly  25 , and a stem  26 , the end of which is connected to-the upper rod assembly  26 . 
   The lower rod assembly  25  comprises a three-point double rod  29  which is articulated:
         at one of its ends, about an axis  30 , on the end of the body  27  of the jack  24 ;   at an intermediate point along its length, about an axis  31 , on the lower part of the upper mast element  9 ;   at its other end, about an axis  32 , on one end of another double rod  33 .       

   At its other end, the double rod  33  is articulated, about an axis  34 , on the upper part of the lower mast element  8 . 
   The upper rod assembly  26  comprises a bent double rod  35  which is articulated:
         at one of its ends, about an axis  36 , on the upper part of the upper mast element  9 ;   at its other end, about an axis  37 , both on one end of a single rod  38  and on the end of the stem  28  of the jack  24 .       

   The single rod  38  is articulated at its other end, about an axis  39 , on the jib foot  15 . 
   The abovementioned double guy  13  also participates in the raising and unfolding device  23  by forming a deformable quadrilateral with: the lower part of the upper mast element  9 , the whole of the lower mast element  8  and the revolving chassis  4 . 
   The device  23  also comprises a system  40  for locking the lower end of the jack  24 , that is to say the end of the body  27  of this jack  24 , this locking system  40   0 being located at the base of the upper mast element  9  and being illustrated more particularly in  FIGS. 12 to 14 . 
   The locking system  40  comprises a bolt  41  located at the end of the body  27  of the jack  24 , said end forming a widened head  42 . The bolt  41  is composed:
         of a double-acting auxiliary hydraulic jack  43  arranged transversely;   of two opposite axles  44  and  45  integral respectively with the body and with the stem of the auxiliary jack  43  and mounted slideably in the lateral parts of the jack head  42 ;   of a safety spring  46  integrated into the auxiliary jack  43  and acting in the direction of extension of the stem of this jack, that is to say in the direction of separation of the two axles  44  and  45 .       

   The locking system  40  also comprises a guide assembly composed of two parallel slideways  47  and  48  carried by the upper mast element  9  and also extending parallel to this mast element  9 . The two slideways  47  and  48  are equipped with broaching holes corresponding to one another, which comprise, on the one hand, a pair of lower broaching holes  49  and, on the other hand, a pair of upper broaching holes  50 . The two axles  44  and  45  of the bolt  41  are intended to be engaged into the lower broaching holes  49  (in the “mast folded” position) or into the upper broaching holes  50  (in the “mast unfolded” position), the jack head  42  being mounted displaceably between the two slideways  47  and  48 . 
   Finally, the device  23  comprises a stop  51  located at the top of the upper mast element  9  (see  FIGS. 2 and 3 ) and cooperating with the upper rod assembly  26 , more particularly with the bent double rod  35 , so as to effect a stopping of rotation of this rod  35  in certain operating phases. 
   The operation of the device  23  is established, as follows, starting from the folded crane transport position ( FIG. 1 ): 
   Initially, the crane is folded on the revolving chassis  4 , and this revolving chassis  4  is itself locked in terms of orientation on the basic chassis  1 . The assembly consisting of the folded mast  7  and of the folded jib  14  takes its place at the side of the driver&#39;s cab  6 . The stem  28  of the jack  24  is partially extended. 
   Starting from this position, the raising and unfolding of the mast  7  are carried out first of all, as shown in  FIGS. 2 to 4 . For this purpose, the jack  24  is controlled in the direction of the retraction of its stem  28 , thus actuating the lower rod assembly  25  by causing the rods  29  and  33  or the latter to pivot, while the upper rod assembly  26  remains in bearing contact on the stop  51 . This movement brings about the simultaneous raising and unfolding of the two mast elements  8  and  9 , likewise with the aid of the above-mentioned deformable quadrilateral, one of the sides of which consists of the double guy  13 .  FIGS. 2 and 3  show intermediate positions during raising and unfolding, while  FIG. 4  shows the final position obtained when the stem  28  of the jack  24  is retracted completely. The two mast elements  8  and  9  have then come into abutment against one another by means of bearing plates located respectively at the top of the lower mast element  8  and at the base of the upper mast element  9 . These two mast elements  8  and  9  are thus detained in the aligned position. The jib  14 , up to then, remains folded against the mast  7 . 
   The action of the locking system  40  during the phase described above will now be described: 
   Initially, ( FIGS. 1 ,  12  and  13 ), with the mast  7  folded, the bolt  41  is locked by means of its axles  44  and  45  in the lower broaching holes  49  of the slideways  47  and  48 , thus fixing the relative position of the two mast elements  8  and  9  by means of the lower rod assembly  25 . Before the mast  7  is unfolded, the auxiliary jack  43  is actuated in the direction of the retraction of its stem, and its “stem retracted” position is maintained between the slideways  47  and  48  —see  FIG. 14 . 
   When the crane reaches the “mast unfolded” position ( FIG. 4 ), the bolt  41  is locked by means of its axles  44  and  45  in the upper broaching holes  50  of the slideways  47  and  48 , thus fixing the new relative position of the two mast elements  8  and  9 , still by means of the lower rod assembly  25 . 
   Starting from this position, the raising and unfolding of the jib  14  are carried out, commencing with the raising of the jib foot  15 . For this purpose, the jack  24  is controlled in the direction of extension of its stem  28 , thus actuating the upper rod assembly  26  and causing the raising of the jib foot  15  into a substantially horizontal position, in fact a position slightly inclined upward (for example, at an angle of approximately 5°)—see  FIG. 5 . The intermediate element  16  of the jib  14  and the jib point  17  then remain folded on the jib foot  15 . 
   Finally, the complete unfolding of the jib  14  up to the alignment of its three elements  15 ,  16  and  17  is obtained by means of auxiliary motorization, not illustrated, by jack and rod assembly. The crane thus assumes a working configuration, with its jib  14  substantially horizontal ( FIG. 6 ). 
   Other working positions of the crane are obtained by means of the control of the jack  24  in the direction of extension of its stem  28 :
         All intermediate jib positions, such as that of  FIG. 7 , the jib  14  remaining aligned, may be obtained between the substantially horizontal position ( FIG. 6 ) and a substantially vertical position ( FIG. 8 ).   The substantially vertical position of the jib  14  ( FIG. 8 ) is reached when the stem  28  of the jack  24  comes into abutment in the extension limit position.       

   The folding and lowering of the jib  14 , and then of the mast  7 , up to the return to the folded transport position are obtained by means of maneuvers opposite to those described above. 
   The operations of raising and unfolding the mast  7  and the jib  14  and the opposite folding and lowering operations are carried out to an automatic cycle governed by a control/command unit comprising a computer. The latter triggers the sequence of movement commands, taking into account information supplied by the set of sensors, for example force, position and speed sensors, in order to execute a cycle of preprogrammed movements, each phase of which is monitored by sensors which permit the command of the following phase or not. 
   The crane may also be used in another configuration, illustrated in  FIG. 9 , in which its mast  7  is partially unfolded and brought to bear on the revolving chassis by means of a rear prop  52 . This configuration allows a distribution of the loads which is associated with a possibility of displacement of the basic carrying chassis  1 , for example for the loading and unloading of trucks. 
   Finally, referring to  FIG. 15 , the longitudinal axis of the jib  14  is advantageously offset laterally with respect to the longitudinal axis of the mast  7  and also with respect to the device  23 , the jib foot  15  thus being located at the side of the upper rod assembly  26 . The single rod  38  of the upper rod assembly  26  is articulated about an axis  39  integral with yokes of a crossmember  53  welded laterally to the jib foot  15 . By virtue of this lateral offset, an additional gain in lateral visibility is obtained for the driver stationed in the driver&#39;s cab  6  when the crane is in the folded transport position. 
   There will be no departure from the scope of the invention, as defined in the accompanying claims:
         by modifying the structural details of the device, for example of its rod assemblies,   by producing the mast and the jib elements in the form of structures of any shape and cross section, for example with a lattice-type structure instead of a caisson-type structure;   by modifying the number of successive elements of the jib;   by applying the device to a crane mounted on a basic chassis or other carrying element of any type and of any form, whether rolling or not;   by providing, on the crane, any arrangement of driver&#39;s cab or station which may differ from the particular example illustrated.