Punching structure for a crane including a rocker leg at the foot of the punching arm

Abstract

Punch structure (3) for a crane (1), comprising: - a punch arm (4) extending longitudinally along a punch axis (40) and having a foot (41) and a top (42) on which a sling attachment is provided; and - at least one tie rod (5) having an upper tie rod end fixed to the top of the punch arm; - at least one rocker leg (8) mounted on the foot of the punch arm opposite the tie rod and having a lower end intended to form a rocker support for the punch structure in a rocker position of at least one rocker leg. Abstract figure: Figure 1

Description

Title of the invention: Punch structure for a crane comprising a tilting leg at the foot of the punch arm. Technical field

[0001] The invention relates to a punch structure for a crane.

[0002] It relates more particularly to a punch structure comprising a punch arm, and at least one tie rod fixed on one side to the punch arm and intended to be fixed on the other side to a counter-jib of the crane.

[0003] The invention finds application in the field of cranes, and in particular modular cranes. Previous technique

[0004] In a known manner, a modular crane is composed of independent structural elements, also called frame elements, which are assembled to form a structure or framework, and in particular to form a mast also called a pylon (made up of several mast elements), a base on which the mast is mounted, as well as a rotating part which includes a jib at the top of the mast, a jib (made up of several jib elements) mounted hinged on the front of the jib, a counter-jib mounted on the rear of the jib, and a punch structure mounted on the counter-jib.

[0005] The handling and carrying of the punch structure is generally done by slinging, whether during the assembly and disassembly of the crane, i.e. by positioning slings on the punch structure, and by attaching these same slings to a hook of a lifting device, such as a mobile crane.

[0006] However, during this operation, there is a risk of the punch arm, and therefore the punch structure, tipping over, which can damage the punch structure and / or destabilize the lifting device. Indeed, during the operation, the punch arm (which is a long piece extending along a punch axis) moves from a horizontal position to a vertical position, or vice versa, with its base resting on the ground. This causes the center of gravity of the punch structure to shift from one side of the punch arm to the other, thus creating a risk of tipping and therefore overturning. Summary of the invention

[0007] The invention proposes a punch structure designed to minimize, or even avoid, the risk of tipping of the punch structure during its handling by slinging, in the assembly phase as well as in the disassembly phase.

[0008] To this end, the invention proposes a punch structure for a crane, comprising a punch arm extending longitudinally along a punch axis and having a foot and a top on which is provided a sling attachment device; and at least one tie rod having an upper tie rod end fixed on the top of the punch arm.

[0009] This punch structure is remarkable in that it includes at least one rocker leg mounted on the foot of the punch arm opposite the tie rod and having a lower end intended to form a rocker support for the punch structure in a rocker position of at least one rocker leg.

[0010] Thus, at least one rocker leg allows the point of contact with the ground to be shifted when the punch arm moves from a horizontal position to a vertical position; that is, the point of contact is initially located on the foot of the punch arm, then this point of contact changes to be located on the lower end of at least one rocker leg. This change in the point of contact prevents a change in equilibrium when the punch arm is raised, and thus the rocker leg prevents the punch structure from falling.

[0011] It should be noted that at least one rocker leg is mounted opposite the tie rod, which means that it is on the rear (counter-arrow side), opposite the front (arrow side).

[0012] Advantageously, in the tilting position, the lower end of at least one tilting leg is positioned below the foot of the punch arm when a theoretical equilibrium axis is arranged vertically, this theoretical equilibrium axis being an axis passing through the hooking member and through the center of gravity of the punch structure.

[0013] In this tilting position, the lower end of at least one tilting leg is below the foot when the theoretical equilibrium axis is vertical, so that, when the punch structure is raised, the foot is initially in contact with the ground, and then the lower end of at least one tilting leg comes to rest on the ground, instead of the foot, to prevent tipping or falling.

[0014] Advantageously, in the rocking position, the theoretical balance axis is positioned between the lower end of at least one rocker leg and the punch axis when said theoretical balance axis is arranged vertically.

[0015] To prevent the punch structure from tipping and falling, it is indeed advantageous for the lower end of at least one rocker leg to be behind (on the counter-cam side) the theoretical equilibrium axis passing through the center of gravity of the punch structure. In this way, the rocker leg bears weight behind this theoretical equilibrium axis, improving balance during the lifting of the punch structure and preventing it from tipping over.

[0016] According to one feature, at least one rocker leg is selectively movable between the rocker position and a rest position in which at least one rocker leg is retracted (or withdrawn) compared to the rocker position.

[0017] In an advantageous embodiment, in the rest position, the lower end of at least one rocker leg is positioned above the foot of the punch arm when the theoretical balance axis is arranged vertically.

[0018] Thus, at least one rocker leg is movable between the rocker position (used during handling operations by slinging, whether in assembly and disassembly) and the rest position (used during and after assembly on the counter-jib, so that at least one rocker leg is not a hindrance).

[0019] According to one possibility, at least one rocker leg is movable (or mobile) in pivoting or translation between the rocker position and the rest position.

[0020] According to another possibility, at least one rocker leg is mounted on a support which is assembled on the foot of the punch arm by a mechanical linkage.

[0021] According to another possibility, the punch structure includes a locking mechanism mounted on the support to lock at least one rocker leg in the rocker position and in the rest position.

[0022] Advantageously, the mechanical link between the support and the foot of the punch arm is a removable mechanical link.

[0023] Thus, it is possible to dismantle the support, with at least one rocker leg, which is advantageous when the punch structure is assembled with the other elements of the crane to form transportable packages.

[0024] In a particular embodiment, the removable mechanical link is a pin link which includes at least one connecting pin ensuring a junction between the support and the foot of the punch arm.

[0025] It should be noted that the pin connection consists of a detachable assembly comprising a connecting pin (also called a spindle or axle) passing through two elements, such as a clevis and a tenon in order to have a clevis / tenon connection.

[0026] In a particular embodiment, the punch structure includes at least one reinforcing bar having an upper bar end fixed on the punch arm, between the foot and the top.

[0027] This embodiment of the punch structure is adapted for high-rise cranes, with the use of at least one reinforcing bar (also called a counter-buckling bar) whose function is to prevent buckling of the punch arm, in particular under heavy load at the end of the boom.

[0028] In a particular embodiment, the punch arm comprises two punch arm sections, which are a right-hand punch arm section and a left-hand punch arm section, and at least one rocker leg comprises two rocker legs, which are a right-hand rocker leg attached to the right-hand punch arm section and a left-hand rocker leg attached to the left-hand punch arm section.

[0029] The invention also relates to a crane comprising a rotating part at the top of a mast, said rotating part comprising a jib holder, a jib articulated on the jib holder, a counter jib mounted on the jib holder and a punch structure as described above, in which the foot of the punch arm is assembled on the counter jib by a first removable mechanical linkage, and at least one tie rod is assembled on the counter jib by a second removable mechanical linkage.

[0030] The invention also relates to a method of handling by slinging a punch structure as described above, during which at least one rocker leg is in its rocking position so that its lower end forms a rocker support for the punch structure on a floor when the punch arm moves from a horizontal lying position to a vertically raised position, or vice versa. Brief description of the drawings

[0031] Other features and advantages of the present invention will become apparent from the following detailed description of a non-limiting example of implementation, made with reference to the accompanying figures in which:

[0032] [Fig-1] is a schematic side and partial view of a rotating part of a crane, in which the jib carrier, the jib, the counter jib and the punch structure are visible;

[0033] [Fig.2] is a schematic side view of the punch structure of [Fig.1] during handling by slinging, with a zoom on a rocker leg in rocker position;

[0034] [Fig.3] is a schematic side view of the punch structure of [Fig.1] in situ on the counter-jib, where at least one rocker leg is in rest position, and with a first zoom on a connecting element between a tie rod, a reinforcing bar and the counter-jib, and a second zoom on a removable intermediate connection between an upper half-puncher and a lower half-puncher;

[0035] [Fig.4] is a schematic perspective and partial view of the punch structure of [Fig.2] in position on the counter-arrow;

[0036] [Fig. 5] is a schematic view of the punch structure of Figures 1 to 3 once disassembled into two sub-assemblies;

[0037] [Fig.6] is a schematic perspective view zoomed in on the connecting element between the tie rod, the reinforcement bar and the counter-camber, and on the length adjustment arrangement of the reinforcement bar;

[0038] [Fig.7] is a schematic side and partial view of the punch structure of the Figures 1 to 3, with a zoom on the connecting element between the tie rod, the reinforcement bar and the counter-curve, and on the length adjustment arrangement of the reinforcement bar.

[0039] [Detailed description of an embodiment of the invention]

[0040] With reference to [Fig. 1], a crane 1, here a luffing jib crane with modular assembly, comprises a base chassis (not shown), fixed or mobile on the ground, above which rises a mast (not shown) which extends along a vertical axis Z and which has a top on which is mounted, by means of a slewing device (not shown), a rotating part 2 orientable around the vertical axis Z.

[0041] This rotating part 2 includes a boom carrier 20 at the top of the mast, a boom 21 (made up of several boom elements) mounted hinged on the front of the boom carrier 20, a counter boom 22 mounted on the rear of the boom carrier 20, and a punch structure 3 mounted on the counter boom 22.

[0042] The boom 21 is mounted movable in rotation around a horizontal axis on the boom holder 20 so that the boom 21 can be raised and lowered.

[0043] The counter-jib 22 is fixedly mounted on the boom support 20 so as to be rotationally fixed to the latter. The counter-jib 22 includes a platform for carrying equipment which includes, in particular, a lifting winch 10 connected to the boom 21 for raising / lowering the boom 21 and a lifting winch 11 connected to a lifting hook (not shown) for lifting loads. The counter-jib 22 also carries counterweights 12.

[0044] More specifically, the lifting winch 10 has a drum, around which is wound a lifting cable which passes over a pulley 13 disposed at the top of the punch structure 3, and which also passes over the pulleys of a lifting block 14 (illustrated in [Fig.1]), located at the top 42 of the punch structure 3. The lifting block 14 is connected, by a line of tie rods (not illustrated), to the boom 21.

[0045] The lifting winch 11 has a drum on which is wound a lifting cable, which passes through the punch structure 3, passes over at least one pulley (not shown) arranged on the boom 21, then is directed towards the tip of the boom 21 and extends to the lifting hook, with or without a pulley block; the loads to be lifted being suspended from the lifting hook when using the crane 1.

[0046] The counter-jib 22 can be mechanically coupled to the jib carrier 20 by means of a reinforcing beam 23 (visible on [Fig.4]) extending between the underside of the counter-jib 22 and the jib carrier 20.

[0047] The punch structure 3 comprises a punch arm 4 extending longitudinally along a punch axis 40 and having a foot 41 and a tip 42 (this tip 42 forming the tip of the punch structure 3). In operation, this punch arm 4 extends obliquely upwards and backwards. The punch axis 40 is thus inclined backwards relative to the vertical axis Z at a punch angle of between 10 and 50 degrees.

[0048] The foot 41 of the punch arm 4 is assembled on the counter-arrow 22 by a first removable mechanical link 43 which may be a pin link; a pin link consisting of a removable assembly comprising a connecting pin (also called a pin or axis) passing through two elements, such as for example a clevis and a tenon in order to have a clevis / tenon link.

[0049] The top 42 of the punch arm 4 is equipped with a hooking member 420 for hooking a sling, such as for example a hooking ring or slinging ring.

[0050] The punch structure 3 also includes at least one tie rod 5 having an upper tie rod end 51 fixed to the top 42 of the punch arm 4 and a lower tie rod end 52 assembled to the counter-jib 22 by a second removable mechanical linkage 60, which may be a pin linkage. Thus, in operation, the punch arm 4 is held by the counter-jib 22 by means of the tie rod(s) 5.

[0051] The punch structure 3 includes at least one reinforcing bar 7 having an upper bar end 71 fixed on the punch arm 4, between the foot 41 and the top 42, and a lower bar end 72 assembled on the counter-jib 22.

[0052] The punch structure 3 includes at least one connecting element 6 for a mechanical connection between at least one reinforcing bar 7 and at least one tie rod 5. This at least one connecting element 6 is intended to be assembled on the counter-jib 22 by the second removable mechanical connection 60 which, as a reminder, can be a pin connection.

[0053] The lower tie end 52 of at least one tie 5 is assembled on the connecting element 6 by at least one lower removable mechanical link 53 which may be a pin link comprising a lower connecting pin 530.

[0054] The lower bar end 72 of at least one reinforcing bar 7 is fixed to the connecting element 6. The lower bar end 72 of at least one reinforcing bar 7 can be fixed securely to the connecting element, for example by welding.

[0055] Thus, at least one tie rod 5 and at least one reinforcing bar 7 are assembled on the counter-arrow 22 by the second removable mechanical link 60 of at least one connecting element 6.

[0056] According to one possibility, the at least one reinforcing bar 7 has a length adjustment arrangement 73 for adjusting the length of the at least one reinforcing bar 7, as seen in [Fig.4] and [Fig.5], which is for example positioned at the lower bar end 72.

[0057] In the illustrated example visible in Figures 6 and 7, this length adjustment arrangement 73 includes a screw tensioner equipped with a reverse threaded nut 74, such as for example a lantern nut.

[0058] Such a length adjustment arrangement 73 is advantageous because it avoids hyperstaticity in the assembly of the punch structure 3; the adjustment of the length of the reinforcing bar(s) 7 provides an advantageous degree of freedom to facilitate assembly operations.

[0059] As seen in [Fig.4]: - the punch arm 4 comprises two punch arm sections 45, 46, which are a right-hand punch arm section 45 and a left-hand punch arm section 46 which extend parallel along the punch axis 40 and which are joined by means of the foot 41, the top 42 and intermediate spacers 430; - at least one tie rod 5 comprises two tie rods 5, which are a right tie rod and a left tie rod extending parallel, where the right tie rod is fixed to the top 42 of the punch arm 4 on the right side of the punch arm section 45, and the left tie rod is fixed to the top 42 of the punch arm 4 on the left side of the punch arm section 46; - at least one reinforcing bar 7 comprises two reinforcing bars 7, which are a reinforcing bar 7 on the right and a reinforcing bar 7 on the left extending parallel to each other, where the reinforcing bar 7 on the right is fixed to the right-hand punch arm section 45 and the reinforcing bar 7 on the left is fixed to the left-hand punch arm section 46; and - at least one connecting element 6 comprises two connecting elements 6 which are a connecting element 6 on the right and a connecting element 6 on the left arranged side by side on two separate beams 220 of the counter-camber 22, where the connecting element 6 on the right is assembled with the tie 5 on the right and the reinforcing bar 7 on the right and the connecting element 6 on the left is assembled with the tie 5 on the left and the reinforcing bar 5 on the left.

[0060] Thus, the lower tie rod end 52 of the tie rod 5 on the right is assembled onto the connecting element 6 on the right by a removable lower mechanical link 53 on the right, and the lower tie rod end 52 of the tie rod 5 on the left is assembled onto the connecting element 6 on the left by a lower removable mechanical link 53 on the left. In other words, the at least one lower removable mechanical link 53 comprises a lower removable mechanical link 53 on the right and a lower removable mechanical link 53 on the left which respectively connect the tie rod 5 on the right to the connecting element 6 on the right and the tie rod 5 on the left to the connecting element 6 on the left.

[0061] Furthermore, the lower bar end 72 of the reinforcing bar 7 on the right is fixed on the connecting element 6 on the right, and the lower bar end 72 of the reinforcing bar 7 on the left is fixed on the connecting element 6 on the left.

[0062] In the illustrated example, the reinforcement bar 7 on the right and the reinforcement bar 7 on the left each have the length adjustment arrangement 73.

[0063] According to one feature and as seen in Figures 3 and 5, the punch arm 4 is decomposed into an upper punch arm 47 and a lower punch arm 48 assembled end to end by a removable intermediate mechanical link 49, the foot 41 being part of the lower punch arm 48 and the top 42 being part of the upper punch arm 47.

[0064] This removable intermediate mechanical link 49 can be a pin link which includes at least one intermediate connecting pin 490 ensuring a junction between the upper punch half-arm 47 and the lower punch half-arm 48. In the illustrated example, the removable intermediate mechanical link 49 includes two intermediate connecting pins 490.

[0065] The upper punch half-arm 47 includes a lower end 470 opposite the top 42, the lower punch half-arm 48 includes an upper end 480 opposite the foot 41 and at least one intermediate connecting pin 490 provides a junction between this lower end 470 and this upper end 480.

[0066] Furthermore, the upper bar end 71 of at least one reinforcing bar 7 is fixed to the lower punch arm 48. According to one possibility, the upper bar end 71 of at least one reinforcing bar 7 is fixed to the upper end 480 of the lower punch arm 48, as seen in [Fig.3].

[0067] As a reminder, in the illustrated example, the punch arm 4 comprises two punch arm sections 45, 46, which are a right-hand punch arm section 45 and a left-hand punch arm section 46, such that: - the right-hand punch arm section 46 is divided into an upper half-section of the right-hand punch arm and a lower half-section of the right-hand punch arm assembled end to end by the removable intermediate mechanical link 49; - the left-hand punch arm section 46 is divided into an upper half of the left-hand punch arm section and a lower half of the arm section punch on the left assembled end to end by the removable intermediate mechanical link 49; - the upper punch arm half 47 comprises the upper punch arm half section on the right and the upper punch arm half section on the left joined together; - the lower punch arm half 48 comprises the lower punch arm half section on the right and the lower punch arm half section on the left joined together.

[0068] Thus, the tie rod 5 on the right and the tie rod 5 on the left are fixed respectively on the upper half-section of the punch arm on the right and the upper half-section of the punch arm on the left, and the reinforcing bar 7 on the right and the reinforcing bar 7 on the left are fixed respectively on the lower half-section of the punch arm on the right and the lower half-section of the punch arm on the left.

[0069] Thus, and as can be seen in [Fig. 5], the punch structure 3 can be disassembled into two sub-assemblies, after disassembly of the intermediate removable mechanical link 49 and at least one lower removable mechanical link 53, which are: - an upper subassembly 31 comprising the upper punch half-arm 47 and at least one tie rod 5 (or both tie rods 7 in the illustrated example); and - a lower subassembly 32 comprising the lower punch half-arm 48 and at least one reinforcing bar 7 (or both reinforcing bars 7 in the illustrated example) and at least one connecting element 6 (or both connecting elements 6 in the illustrated example) which remains attached to at least one reinforcing bar 7.

[0070] Thus, the design of the punch structure 3 is based on a decomposition into two sub-assemblies 31, 32 of general triangular shape, such that the upper sub-assembly 31 can be disassembled from the lower sub-assembly 32 and the counter-hook 22 in order to be carried separately, then the lower sub-assembly 32 can be disassembled from the counter-hook 22 in order to be carried separately in turn, before disassembly of the counter-hook 22 which constitutes another element.

[0071] According to one possibility, the upper sub-assembly 31 has a first mass which is less than 10 Tonnes, the lower sub-assembly 32 has a second mass which is less than 10 Tonnes and the punch structure 3 has a total mass which corresponds to the sum of the first mass and the second mass and which is greater than 10 Tonnes.

[0072] The punch structure 3 comprises at least one rocker leg 8 mounted on the foot 41 of the punch arm 4 opposite the tie rod 5 (i.e., on the rear side or the side of the counter-jib 22) and having a lower end 80 intended to form a rocker support for the punch structure 3 because, in a rocker position (illustrated in the [Fig.2]), this at least one rocker leg 8 is deployed to have its lower end 80 below the foot 41 of the punch arm 4 when a theoretical equilibrium axis W is disposed vertically (i.e. the theoretical equilibrium axis W extends parallel to the vertical axis Z); this theoretical equilibrium axis W being an axis passing through the hooking member 420 and through the center of gravity G of the punch structure 3.

[0073] As seen in [Fig.2], in the rocking position of the rocker leg 8, the theoretical equilibrium axis W is positioned between the lower end 80 of at least one rocker leg 8 and the punch axis 40 when this theoretical equilibrium axis W is arranged vertically; in other words, the lower end 80 of at least one rocker leg 8 is behind (counter-swing side) the theoretical equilibrium axis W, thus promoting the balancing of the punch structure 3 to prevent it from falling.

[0074] This at least one rocker leg 8 is movable or retractable in a rest position (illustrated in Figures 1, 3, 4 and 5), in which the at least one rocker leg 8 is retracted to have its lower end 80 above the foot 41 of the punch arm 4 when the theoretical equilibrium axis W is arranged vertically.

[0075] Thus, this at least one rocker leg 8 is mounted movably on a support 81 between its rocker position and its rest position; this support 81 being assembled on the foot 41 of the punch arm 4 by a mechanical linkage 82, and for example by a removable mechanical linkage such as a pin linkage which includes at least one connecting pin 83 ensuring a junction between the support 81 and the foot 41 of the punch arm 4.

[0076] A locking mechanism mounted on the support 81 is also provided for locking at least one rocker leg 8 in the rocker position and in the rest position. This locking mechanism may include a locking pin that passes through the support 81 to lock the rocker leg 8 in the rocker position and in the rest position.

[0077] As seen in [Fig.4], the at least one rocker leg 8 comprises two rocker legs 8, which are a rocker leg 8 on the right attached to the right punch arm section 45 and a rocker leg 8 on the left attached to the left punch arm section 46.

[0078] In position on the crane 1, that is, once the punch structure 3 is mounted and assembled on the counter-jib 22, at least one rocker leg 8 is in its rest position. At least one rocker leg 8 is even placed in its rest position during assembly on the counter-jib 22, so as not to come interfere with or bump against the counter-arrow 22, in particular when assembling the foot 41 of the punch arm 4 onto the counter-arrow 22.

[0079] On the other hand, and as can be seen in [Fig.2], during the handling operations by slinging of the punch structure 3, in particular on the ground when the punch structure 3 is lifted to straighten it or conversely when the punch structure 3 is lowered to lie down, at least one rocker leg 8 is in its rocker position, so that its lower end 80 forms a rocker support for the punch structure 3 on the ground (see the zoom of [Fig.2]) when the punch arm 4 passes from a horizontal lying position to a vertical raised position, or vice versa.

Claims

Demands

1. Punch structure (3) for a crane (1), comprising: - a punch arm (4) extending longitudinally along a punch axis (40) and having a foot (41) and a top (42) on which is provided a sling attachment device (420); and - at least one tie rod (5) having an upper tie rod end (51) fixed on the top (42) of the punch arm (4); said punch structure (3) being characterized in that it comprises at least one rocker leg (8) mounted on the foot (41) of the punch arm (4) opposite the tie rod (5) and having a lower end (80) intended to form a rocker support for the punch structure (3) in a rocker position of at least one rocker leg (8).

2. Punch structure (3) according to claim 1, wherein, in the tilting position, the lower end (80) of at least one tilting leg (8) is positioned below the foot (41) of the punch arm (4) when a theoretical balance axis (W) is arranged vertically, said theoretical balance axis (W) being an axis passing through the hooking member (420) and through the center of gravity (G) of the punch structure (3).

3. Punch structure (3) according to claim 2, wherein, in the rocking position, the theoretical balance axis (W) is positioned between the lower end (80) of at least one rocker leg (8) and the punch axis (40) when said theoretical balance axis (W) is arranged vertically.

4. Punch structure (3) according to any one of the preceding claims, wherein at least one rocker leg (8) is selectively movable between the rocker position and a rest position in which at least one rocker leg (8) is retracted relative to the rocker position.

5. Punch structure (3) according to claims 2 and 4, wherein, in the rest position, the lower end (80) of at least one rocker leg (8) is positioned above the foot (41) of the punch arm (4) when the theoretical balance axis (W) is arranged vertically.

6. Punch structure (3) according to claim 4 or 5, wherein at least one rocker leg (8) is movable by pivoting or translation between the rocker position and the rest position.

7. Punch structure (3) according to any one of the preceding claims, wherein at least one rocker leg (8) is mounted on a support (41) which is assembled on the foot (41) of the punch arm (4) by a mechanical linkage (82).

8. Punch structure (3) according to claims 6 and 7, comprising a locking mechanism mounted on the support (81) for locking at least one rocker leg (8) in the rocker position and in the rest position.

9. Punch structure (3) according to claim 7 or 8, wherein the mechanical linkage (82) between the support (81) and the foot (41) of the punch arm (4) is a removable mechanical linkage (82).

10. Punch structure (3) according to claim 9, wherein the removable mechanical linkage (82) is a pin linkage which includes at least one connecting pin (83) ensuring a junction between the support (81) and the foot (41) of the punch arm (4).

11. Punch structure (3) according to any one of the preceding claims, comprising at least one reinforcing bar (7) having an upper bar end (71) fixed on the punch arm (4), between the foot (41) and the top (42).

12. Punch structure (3) according to any one of the preceding claims, wherein the punch arm (4) comprises two punch arm sections (45, 46), which are a right-hand punch arm section (45) and a left-hand punch arm section (46), and at least one rocker leg (8) comprises two rocker legs (8), which are a right-hand rocker leg (8) attached to the right-hand punch arm section (45) and a left-hand rocker leg (8) attached to the left-hand punch arm section (46).

13. A crane (1) comprising a rotating part (2) at the top of a mast, said rotating part (2) comprising a jib holder (20), a jib (21) hinged on the jib holder (20), a counter-jib (22) mounted on the jib holder (20), and a punch structure (3) according to any one of the preceding claims, wherein the foot (41) of the punch arm (4) is assembled to the counter-jib (22) by a first detachable mechanical connection (43), and at least one tie rod (5) is assembled on the counter-arrow (22) by a second removable mechanical link (60).

14. Method of handling by slinging a punch structure (3) according to any one of claims 1 to 12, wherein at least one rocker leg (8) is in its rocker position such that its lower end (80) forms a rocker support for the punch structure (3) on a floor when the punch arm (4) moves from a horizontally lying position to a vertically raised position, or vice versa.

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