EP1352870A1 - Device for erecting and unfolding the mast and for erecting the jib of a crane - Google Patents

Abstract

The device (23) for raising the crane comprising a foldable mast (7) composed of two elements (8,9) and a jib (14) composed of several successive elements (15,16,17) comprises a double acting actuator (24). The actuator connects a lower connecting rod assembly (25) to an upper connecting rod assembly (26). The lower assembly is connected to the lower part of the mast upper element (9) and the upper part of the mast lower element (8). The upper assembly is connected to the upper part of the upper mast element and to the foot of the jib (15).

Description

The present invention relates to lifting or handling, and more particularly the cranes. This invention relates, more specifically, to a motorized device for raising and unfolding the mast and lifting the boom of a crane, and even more particularly of a crane with multi-function arrow as described by the document FR 2792627 A in the name of the Applicant.

This document concerns a crane with an editable configuration, which includes a mast mounted on a chassis, and a compound distributor arrow successive elements articulated together around horizontal axes, the first boom member said boom foot itself being hinged about an axis horizontal at the top of the mast. This first arrow element, and possibly the following element, can be brought to a substantially vertical position, in the alignment of the mast erected, so as to enhance this mast. All boom members include a raceway for the same carriage. So, the crane can be used as a long boom crane or shortened, horizontal or inclined, or as a boom crane swan ", depending on the configuration of the boom elements, the height of the crane being also adjustable according to the number of arrow elements brought into the extension of the mast.

In such a multi-function boom crane, the mast can itself be unfoldable and usable in several positions, the various configurations of the boom elements can thus be combined with the variable configurations of the mast. In particular, the folding mast is composed of two mast elements, namely a lower mast element articulated on the frame of the crane, and an articulated upper mast element at the top of the lower mast element. The lower mast element is articulated in particular on a rotating frame, orientable about a vertical axis on a chassis of base, mounted on wheels, the crane can thus be presented as a machine rolling stock.

For the motorization of the different articulations of such a crane, the aforementioned document provides devices with cylinder, or cylinder and linkage. It results in a multiplicity of cylinders and linkages, given the total number of joints to motorize.

As another known example of motorization of the unfolding of a folding crane, one can also quote the document FR 2682096 A in the name of Applicant. This document concerns a crane that includes a folding mast in two elements and an arrow in two main elements. For such crane structure, the motorized lifting and unfolding device includes a cylinder located between the two elements of the mast, and articulated on the one hand on the lower part of the lower mast element, on the other hand on the part lower part of the upper mast element via a crankshaft. The unfolding of the mast is achieved using this linkage. The lifting of the arrow is made using a tie rod connected on the one hand to a fixed point of the rotating frame of the crane, and on the other hand at a fixed point of the spire.

• Le vérin placé entre les deux éléments de mât possède un encombrement important, qui est gênant notamment dans la position repliée de transport de la grue.
• Les mouvements de relevage-dépliage du mât et de relevage de la flèche sont simultanés, et ne permettent pas de changement de configuration durant le travail de la grue, la configuration de travail étant obligatoirement pré-définie avant relevage et dépliage de la grue.
• De toute façon, partant de cette conception de grue, on doit prévoir deux systèmes de motorisation, à savoir : un système pour le relevage et dépliage du mât et le relevage de la flèche, puisque ces mouvements sont associés, et un système pour le dépliage de la flèche, et le dispositif ici considéré n'est pas directement applicable à une grue avec flèche à fonctions multiples.

Such a technique retains various disadvantages:

• The jack placed between the two mast elements has a large size, which is particularly troublesome in the folded transport position of the crane.
• The movements of lifting-unfolding of the mast and lifting boom are simultaneous, and do not allow configuration change during the work of the crane, the work configuration is necessarily pre-defined before lifting and unfolding the crane.
• Anyway, starting from this design of crane, one must provide two systems of motorization, namely: a system for the raising and unfolding of the mast and the raising of the boom, since these movements are associated, and a system for the unfolding of the boom, and the device here considered is not directly applicable to a crane with multi-function boom.

The present invention aims at avoiding the disadvantages previously exposed, by providing an improved lifting device and unfolding the mast and lifting the boom of a crane, especially adapted to a crane with multi-function boom, this device comprising a minimum number of cylinders that can be used both for lifting and unfolding for the work of the crane, allowing various configurations of this crane, while having a small footprint especially to reduce the height of the crane in the folded transport position.

For this purpose, the subject of the invention is a motorized device for lifting and unfolding the mast and lifting the boom of a crane of the kind concerned, this device essentially comprising a hydraulic cylinder with double effect whose two ends are respectively connected to a lower and upper linkage, the lower linkage intended for to raise and unfold the mast being also connected to the lower part of the element of upper mast and the upper part of the lower mast element, and the upper linkage intended to raise the arrow and to move it in various working positions being also connected to the upper part of the mast element and at the foot of the boom, the device comprising at least one stay connecting the lower part of the upper mast element to a point of the frame of the crane on which is articulated the lower part of the element of lower mast, and locking means of the lower end of the jack mentioned above, in at least two distinct positions, on the lower part of the upper mast element, and finally a stop located in the upper part the upper mast element and intended to cooperate with the crankshaft superior.

Thus, the inventive idea consists in providing a single jack associated with two linkages to perform both the unfolding and folding functions of the mast, raising-lowering the boom, and working in "arrow flight", that is to say with a lifting movement of the arrow. Both positions the actuator interlock, respectively, in the position "mast unfolded "and in the" folded mast "position. simple and safe kinematics: it does not imply a combination of movements, nor manual intervention in its operation. It also provides a total independence of the movements and positions of the mast and the boom, allowing all possible configurations, especially from a position with mast folded substantially horizontally, or a position with substantially unfolded mast vertical.

The need for a single cylinder for various movements or functions also leads to an economic realization. Moreover, the jack is not not positioned between the two mast members when they are folded, but it rests on the upper mast element, which increases the angle of vision of the driver from his cabin.

According to one embodiment of the device which is the subject of the invention, the lower linkage comprises a first connecting rod, preferably a connecting rod double, articulated at one of its ends to the corresponding end of the cylinder, articulated at an intermediate point to the lower part of the upper mast, and hinged at its other end at one end of a year connecting rod, preferably a double rod, itself articulated to its other end to the upper part of the lower mast element.

As for the upper linkage, this includes advantageously an elbow, preferably a double rod, hinged at one of its ends to the upper part of the upper mast element and articulated, at its other end, both at the corresponding end of the cylinder and at one end of another connecting rod, preferably a simple connecting rod, whose other end is articulated to the foot of arrow. The angled connecting rod allows here at the upper linkage to "bypass" the articulation of the arrow foot at top of the mast.

• d'une part, à l'extrémité inférieure du vérin, un verrou transversal constitué d'un vérin auxiliaire à double effet, dont le corps et la tige sont respectivement solidaires de deux axes opposés, montés coulissants dans des parties latérales respectives d'une tête du vérin principal, un ressort de sécurité étant prévu pour le maintien du verrou en position active ;
• d'autre part, sur la partie inférieure de l'élément de mât supérieur, un ensemble de guidage composé de deux glissières parallèles à cet élément de mât, et munies respectivement de trous de brochage inférieurs et supérieurs situées en correspondance, la tête du vérin étant montée déplaçable entre les deux glissières dont les trous de brochage inférieurs sont prévus pour recevoir respectivement les deux axes du verrou dans la position "mât replié", et dont les trous de brochage supérieurs sont prévus pour recevoir respectivement les deux axes du verrou dans la position "mât déplié".

The locking means of 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 lock consisting of a double-acting auxiliary jack, whose body and the rod are respectively integral with two opposite axes, slidably mounted in respective lateral parts of a head of the main cylinder, a safety spring being provided for maintaining the lock in the active position;
• on the other hand, on the lower part of the upper mast element, a guide assembly composed of two rails parallel to this mast element, and respectively provided with corresponding lower and upper pinning holes, the cylinder head being mounted movably between the two slides, the lower pinning holes of which are designed to respectively receive the two pins of the latch in the "folded mast" position, and whose upper pinning holes are provided for respectively receiving the two axes of the latch in the latch. position "unfolded mast".

Lockings have the role of not introducing constraints unnecessary in the lower linkage, notably by preventing the rotation of the first rod (three points) of this linkage in the folded position of transport.

The main cylinder allows not only the lifting of the mast and the foot of the boom when the crane was first put in place, but obtaining all intermediate arrow positions, by ordering the more or less significant output of the rod of this cylinder. Since the arrow itself consists of two or more elements, articulated between them, the unfolding of these arrow elements relative to each other is obtained by an auxiliary motor, in particular by jack and linkage, no directly concerned by the present invention.

Figure 1 est une vue de côté d'une grue équipée du dispositif selon l'invention, en position repliée de transport ;

Figures 2, 3, 4, 5 et 6 sont des vues de côté, similaires à la figure 1, illustrant des phases successives du relevage et dépliage du mât et du relevage de la flèche de cette grue ;

Figures 7, 8 et 9 sont des vues de côté de la même grue, dans diverses positions de travail ;

Figure 10 est une vue de côté du dispositif de relevage et de dépliage selon l'invention, représenté seul et plus en détail, en position repliée ;

Figure 11 est une vue en perspective correspondant à la figure 10 ;

Figure 12 montre, en perspective, le détail A agrandi de la figure 11 concernant les moyens de verrouillage du vérin ;

Figures 13 et 14 sont des vues en coupe de ces moyens de verrouillage, dans deux positions ;

Figure 15 est une vue en perspective du dispositif, en position dépliée.

The invention will be better understood with the aid of the description which follows, with reference to the appended schematic drawing representing, by way of example, an embodiment of this device for raising and unfolding the mast and lifting the boom. of a crane:

Figure 1 is a side view of a crane equipped with the device according to the invention, in the folded transport position;

Figures 2, 3, 4, 5 and 6 are side views, similar to Figure 1, illustrating successive phases of lifting and unfolding of the mast and lifting the boom of the crane;

Figures 7, 8 and 9 are side views of the same crane, in various working positions;

Figure 10 is a side view of the lifting device and unfolding according to the invention, shown alone and in more detail, in the folded position;

Figure 11 is a perspective view corresponding to Figure 10;

Figure 12 shows, in perspective, the enlarged detail A of Figure 11 relating to the locking means of the cylinder;

Figures 13 and 14 are sectional views of these locking means in two positions;

Figure 15 is a perspective view of the device in the unfolded position.

The crane shown in the drawing, in various positions, possesses a base carrier frame 1, mounted on wheels 2 and provided with stabilizers 3. On the base frame 1 is mounted a rotating frame 4, orientable about a vertical axis 5, and provided with a driving cabin 6 on one of its sides.

On the other side of the rotating frame 4 is mounted a folding mast 7, composed of a lower mast element 8 and an upper mast element 9, each of polygonal section and box structure. The mast element 8 is articulated by its base, about a horizontal axis 10, on a part lower part of the rotating chassis 4. The upper mast element 9 is hinged by its base, around a horizontal axis 12, at the top of the mast element lower 8, this intermediate articulation of the mast 7 allowing pivoting relative elements 8 and 9 on an angle of about 180 °.

The folding mast 7 is maintained by a double stay cable 13, which connects the base of the upper mast element 9 at the top of the chassis rotating 4.

At its summit, the folding mast 7 carries a dispensing arrow 14, which is composed of three successive arrow elements 15, 16 and 17, each of box structure, which all three, at their face lower, a raceway 18 for an arrow carriage 19.

The first boom element 15, also called an arrow foot, is articulated at its rear end, about a horizontal axis 20, at the top of the upper mast element 9, this articulation allowing relative pivoting at an angle of about 180 °. The second boom element 16 is articulated by its rear end, around a horizontal axis 21, at the front end of the foot 15. The third boom element 17, also referred to as a point of arrow, is articulated by its rear end, around a horizontal axis 22, to the front end of the second boom member 16.

The crane is equipped with a motorized device, designated overall by 23, for the lifting and unfolding of its mast 7 and the raising of its boom 14. The device 23 comprises a hydraulic cylinder 24, a lower linkage 25 and an upper linkage 26.

The hydraulic cylinder 24, which is a double-acting cylinder, has a body 27 whose end is connected to the lower linkage 25, and a rod 28 whose end is connected to the upper linkage 26.

• à l'une de ses extrémités, autour d'un axe 30, avec l'extrémité du corps 27 du vérin 24 ;
• en un point intermédiaire de sa longueur, autour d'un axe 31, sur la partie inférieure de l'élément de mât supérieur 9 ;
• à son autre extrémité, autour d'un axe 32, avec une extrémité d'une autre bielle double 33.

The lower linkage 25 comprises a double rod 29 three points, which is articulated:

• at one of its ends, around an axis 30, with the end of the body 27 of the jack 24;
• at an intermediate point of its length, about an axis 31, on the lower part of the upper mast element 9;
• at its other end, about an axis 32, with one end of another double rod 33.

At its other end, the double rod 33 is articulated, around a axis 34, on the upper part of the lower mast element 8.

• à l'une de ses extrémités, autour d'un axe 36, sur la partie supérieure de l'élément de mât supérieur 9 ;
• à son autre extrémité, autour d'un axe 37, à la fois avec une extrémité d'une bielle simple 38, et avec l'extrémité de la tige 28 du vérin 24.

The upper linkage 26 comprises a double crank rod 35 which is articulated:

• at one of its ends, around an axis 36, on the upper part of the upper mast element 9;
• at its other end, about an axis 37, both with one end of a simple connecting rod 38, and with the end of the rod 28 of the jack 24.

The simple connecting rod 38 is articulated at its other end, around a axis 39, with the foot of arrow 15.

The double stay 13, mentioned above, also participates in 23 unfolding lifting device, forming a deformable quadrilateral with: the lower part of the upper mast element 9, the whole of the lower mast element 8, and the rotating chassis 4.

The device 23 also comprises a locking system 40 of the lower end of the jack 24, therefore the end of the body 27 of this jack 24, this locking system 40 being located at the base of the mast element upper 9, and being shown more particularly in Figures 12 to 14.

• d'un vérin hydraulique auxiliaire 43 à double effet, disposé transversalement ;
• de deux axes opposés 44 et 45, solidaires respectivement du corps et de la tige du vérin auxiliaire 43, et montés coulissants dans les parties latérales de la tête de vérin 42 ;
• d'un ressort de sécurité 46, intégré au vérin auxiliaire 43, et agissant dans le sens de la sortie de la tige de ce vérin, donc dans le sens de l'écartement des deux axes 44 et 45.

The locking system 40 comprises a latch 41, located at the end of the body 27 of the jack 24, which end forms an enlarged head 42. The latch 41 is composed of:

• an auxiliary hydraulic jack 43 with double effect, arranged transversely;
• two opposite axes 44 and 45, respectively integral with the body and the rod of the auxiliary cylinder 43, and slidably mounted in the side portions of the cylinder head 42;
• a safety spring 46 integrated in the auxiliary cylinder 43, and acting in the direction of the output of the rod of the cylinder, so in the direction of the spacing of the two axes 44 and 45.

The locking system 40 further comprises a set of guide, consisting of two parallel slides 47 and 48, carried by the element upper mast 9 and also extending parallel to this mast element 9. Both slides 47 and 48 are provided with pin holes, located in corresponding, on the one hand, a pair of pinholes 49, and on the other hand a pair of upper broaching holes 50. The two axes 44 and 45 of the latch 41 are provided to be engaged in the holes 49 (in "folded mast" position), or in the holes of upper broaching 50 (in position "unfolded mast"), the cylinder head 42 being movable mounting between the two slides 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 linkage 26, more particularly with the double cranked rod 35, so as to make a stop in rotation of this rod 35 in certain phases of operation.

The operation of the device 23 is as follows, starting the folded crane transport position (Figure 1):

Initially, the crane is folded on the rotating frame 4, and this rotating frame 4 is itself locked in orientation on the base frame 1. The assembly constituted by the mast 7 folded and by the arrow 14 folded takes place on the side of the driver's cab 6. The rod 28 of the cylinder 24 is partially out.

From this position, it is first carried out by lifting and unfolding of the mast 7, as shown in Figures 2 to 4. For this purpose, the cylinder 24 is controlled in the sense of the return of its stem 28, which actuates the lower linkage 25 by rotating its rods 29 and 33, while the upper linkage 26 remains in abutment on the stop 51. This movement causes simultaneous raising and unfolding of the two mast elements 8 and 9, also using the aforesaid deformable quadrilateral of which one of the sides is formed by the double stay 13. Figures 2 and 3 show positions intermediate, being lifted and unfolded, while Figure 4 shows the final position, obtained when the rod 28 of the jack 24 is completely September. The two mast elements 8 and 9 then came to a stop one against the other, by means of support plates located respectively at top of the lower mast element 8 and at the base of the mast element 9. These two mast elements 8 and 9 are thus stopped in position aligned. The arrow 14 remains, until then, folded against the mast 7.

We will now describe the intervention of the locking system 40, during the previously described phase:

Initially (Figures 1, 12 and 13), the mast 7 being folded, the latch 41 is locked by its axes 44 and 45 into the lower pin holes 49 slides 47 and 48, which fixes the relative position of the two elements of mast 8 and 9 through the lower linkage 25. Before unfolding the mast 7, the auxiliary cylinder 43 is actuated, in the direction of retraction of its rod, and its position "retracted stem" is maintained between the two slides 47 and 48 - see figure 14.

When the crane reaches the "unfolded mast" position (Figure 4), the latch 41 is locked by its axes 44 and 45 in the pin holes upper 50 slides 47 and 48, which sets the new relative position the two mast elements 8 and 9, again via the crankshaft lower 25.

From this position, the lifting and unfolding is carried out arrow 14, starting with the lifting of the boom foot 15. At this point, Indeed, the jack 24 is controlled in the direction of the output of its rod 28, which actuates the upper linkage 26 and causes the lifting of the jib foot 15, to a substantially horizontal position, makes it a slightly inclined upwards (eg at an angle of approximately 5 °) - see figure 5. The intermediate element 16 of the arrow 14, and the arrowhead 17, remain then folded on the foot of arrow 15.

Finally, the complete unfolding of the arrow 14, until the alignment of its three elements 15, 16 and 17, is obtained by an auxiliary motorization by cylinder and linkage, not shown. The crane thus arrives in a working configuration, with its arrow 14 substantially horizontal (Figure 6).

• Toutes positions de flèche intermédiaires, telles que celle de la figure 7, la flèche 14 restant alignée, peuvent être obtenues entre la position sensiblement horizontale (figure 6) et une position sensiblement verticale (figure 8).
• La position sensiblement verticale de la flèche 14 (figure 8) est atteinte lors de la butée de la tige 28 du vérin 24 en position de fin de course de sortie.

Other working positions of the crane are obtained by controlling the jack 24, in the output direction of its rod 28:

• Any intermediate arrow positions, such as that of Figure 7, the arrow 14 remaining aligned, can be obtained between the substantially horizontal position (Figure 6) and a substantially vertical position (Figure 8).
• The substantially vertical position of the arrow 14 (Figure 8) is reached during the abutment of the rod 28 of the cylinder 24 in the end of stroke position.

Folding and lowering the boom 14, then the mast 7, until the return to the folded transport position, are obtained by means of reverse maneuvers of those described previously.

The lifting and unfolding operations of the mast 7 and the boom 14, and the reverse folding and lowering operations are performed according to an automatic cycle, controlled by a control-command unit including a calculator. This triggers the succession of orders movements, taking into account the information provided by a group of sensors, for example force, position and speed sensors, for perform a cycle of preprogrammed movements each phase of which is controlled by sensors that allow or not the control of the phase next.

The crane can still be used in another configuration, illustrated in FIG. 9, in which its mast 7 is partially unfolded, and pressed on the rotating chassis via a rear stand 52. This configuration allows a distribution of the loads, associated with a possibility of displacement of the base carrier frame 1, for example for the loading and unloading of trucks.

Finally, with reference to FIG. 15, the longitudinal axis of the arrow 14 is advantageously offset laterally with respect to the longitudinal axis of the mast 7, and also with respect to the device 23, the foot of arrow 15 being thus on the side of the upper linkage 26. The simple connecting rod 38 of the crankshaft upper 26 is articulated about an axis 39 integral with screeds of a cross 53 welded laterally on the boom foot 15. With this offset side, an additional gain in lateral visibility is obtained for the driver posted in the driver's cab 6, when the crane is in position folded transport.

• en modifiant les détails constructifs du dispositif, par exemple de ses embiellages ;
• en réalisant le mât et les éléments de flèche sous la forme de structures de forme et de section quelconques, par exemple avec une structure en treillis et non plus en caisson ;
• en modifiant le nombre des éléments successifs de la flèche ;
• en appliquant le dispositif à une grue montée sur un châssis de base, ou autre élément porteur, de tout type et de toute forme, roulant ou non ;
• en prévoyant, sur la grue, tout agencement de cabine ou de poste de conduite, pouvant différer de l'exemple particulier représenté.

One would not depart from the scope of the invention, as defined in the appended claims:

• modifying the constructive details of the device, for example of its links;
• by making the mast and the boom elements in the form of structures of any shape and section, for example with a lattice structure and no longer in a box;
• by modifying the number of successive elements of the arrow;
• applying the device to a crane mounted on a base frame, or other carrier, of any type and shape, rolling or not;
• by providing, on the crane, any arrangement of cabin or driving position, which may differ from the particular example shown.

Claims (6)

Motorized device for lifting and unfolding the mast and folding the boom of a crane, more particularly a crane with multi-function boom, with an adjustable configuration, which comprises a folding mast (7) consisting of a mast element lower (8) articulated on a frame (4), and an upper mast member (9) hinged to the top of the lower mast member (8), and a distributing boom (14) composed of successive elements (15, 16, 17) hinged together, the first boom element, said boom foot (15) being itself hinged to the top of the mast (7), and this first boom element (15), and possibly the following element ( 16), which can be brought into a substantially vertical position, in alignment with the upright mast (7), so as to raise this mast (7), all the boom elements (15, 16, 17) comprising a raceway ( 18) for the same carriage (19), characterized in that it comprises a hydraulic cylinder double link (24) whose two ends are respectively connected to a lower linkage (25) to an upper linkage (26), the lower linkage (25) for raising and unfolding the mast (7) being also connected to the lower part of the upper mast element (9) and the upper part of the lower mast element (8), and the upper linkage (26) intended to raise the boom (14) and to move it in various working positions are also connected to the upper part of the upper mast element (9) and to the boom foot (15), the device further comprising at least one stay (13) connecting the lower part of the upper mast (9) at a point of the frame (4) of the crane on which is articulated the lower part of the lower mast element (8), and locking means (40) of the lower end of the cylinder ( 24), in at least two distinct positions, on the inf upper member of the upper mast member (9), and finally a stop (51) located in the upper part of the upper mast member (9) and provided to cooperate with the upper linkage (26). Device according to claim 1, characterized in that the lower linkage (25) comprises a first connecting rod (29), preferably a double connecting rod, articulated at one of its ends (30) to the corresponding end of the jack ( 24), articulated at an intermediate point (31) to the lower part of the upper mast element (9), and articulated at its other end (32) at one end of a second connecting rod (33), preferably a double rod, itself hinged at its other end (34) to the upper part of the lower mast member (8). Device according to claim 1 or 2, characterized in that the upper linkage (26) comprises a first bent rod (35), preferably a double rod, articulated at one of its ends (36) to the upper part of the upper mast member (9), and articulated at its other end (37), both at the corresponding end of the jack (24) and at one end of another rod (38), preferably a single rod, the other end (39) is articulated to the foot of arrow (15). Device according to any one of claims 1 to 3, characterized in that the locking means (40) of the lower end of the jack (24) on the lower part of the upper mast element (9) comprise: on the one hand, at the lower end of the jack (24), a transverse lock (41) consisting of an auxiliary jack (43) double acting, whose body and the rod are respectively secured to two opposite axes (44). , 45), slidably mounted in respective side portions of a head (42) of the main cylinder, a safety spring (46) being provided for holding the latch (41) in the active position; on the other hand, on the lower part of the upper mast element (9), a guide assembly composed of two rails (47, 48) parallel to this mast element (9), and provided respectively with pinning holes lower (49) and upper (50) corresponding, the cylinder head (42) being movably mounted between the two slides (47, 48) whose lower pinholes (49) are provided to receive respectively the two axes ( 44, 45) of the latch (41) in the "folded mast" position, and whose upper pinning holes (50) are provided for respectively receiving the two pins (44, 45) of the latch (41) in the "mast" position. unfolded ". Device according to any one of claims 1 to 4, characterized in that the jack (24) is provided not only for the lifting of the mast (7) and the jib foot (15), during the initial installation of the crane, but still to obtain any intermediate boom positions, by controlling the greater or lesser output of the rod (28) of the cylinder (24). Device according to any one of claims 1 to 5, characterized in that the longitudinal axis of the boom (14) is offset laterally with respect to the longitudinal axis of the mast (7), and also relative to the device (23). ), the jib foot (15) thus being on the side of the upper linkage (26).

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