Crane with lifting boom configurable in three reeving configurations, one, two or three wire

Abstract

Luffing jib crane (1) comprising: - a lifting winch (2) coupled to a lifting cable (20); - a luffing jib (10) equipped with a jib tip (11) on which are mounted at least two pulleys (32, 35); - a block (4) held by the lifting cable and comprising a block and tackle pulley (41); and - a set of means for operating block and tackle changes between a single-strand, two-strand and three-strand configuration, including a support for holding the block in a fixed position so as to be able to operate the lifting winch downwards to slacken the lifting cable, and an auxiliary traction system (6) mounted on the luffing jib and allowing to pull on the free end (21) of the lifting cable.

Description

[Technical field]

[0001] The invention relates to a luffing jib crane equipped with means for operating changes in the pulley system of its lifting cable between three pulley system configurations, which are a single-strand configuration, a two-strand configuration and a three-strand configuration.

[0002] It also relates to a pulley system allowing changes in the pulley system of the lifting cable of such a luffing jib crane. [State of the art]

[0003] Typically, a luffing jib crane consists of a luffing jib with a jib tip and a boom foot that rotates around a horizontal axis at the top of a mast, allowing the jib to be raised and lowered. This crane also includes a hoisting winch, usually mounted on a counterweight jib, coupled to a hoisting cable that passes over at least one jib pulley located at the jib tip. This cable supports a block and tackle equipped with a hook for attaching a load; the block and tackle includes a pulley block beneath which the hoisting cable can pass.

[0004] It is also known, for example from document EP2411317B1, to have two pulley configurations which are: a single-strand configuration in which, at the exit of the boom pulley, the free end of the lifting cable is fixed to the block so that the block is suspended by a single strand of the lifting cable; a two-strand configuration in which, at the exit of the boom pulley, the lifting cable passes under the block and its free end is fixed to an anchor point provided on the boom tip.

[0005] Increasing the number of strands allows for lifting heavier loads, therefore there is a need for a three-strand configuration, as for example known from US document 1436 608.

[0006] However, a problem arises in moving the lifting cable (and in particular its free end) to position it in one of the different pulley configurations. Indeed, the lifting cable is heavy, rigid, and therefore difficult to handle, especially on high-powered cranes designed for lifting heavy loads, which thus require particularly thick, heavy, and rigid lifting cables. [Summary of the invention]

[0007] One of the aims of the invention is to facilitate the operations of changing pulley systems, in particular between three pulley configurations which are a one-strand configuration, a two-strand configuration and a three-strand configuration.

[0008] To this end, the invention proposes a luffing jib crane comprising a lifting winch coupled to a lifting cable which has a free end, this lifting winch being actuated upwards to raise the free end of the lifting cable and actuated downwards to lower the free end of the lifting cable; and a luffing jib equipped with a jib tip on which are mounted a main pulley over which the lifting cable passes and a secondary pulley.

[0009] This luffing jib crane also includes a pulley block equipped with a lifting device for attaching a load (i.e., a load suspended below the pulley block that needs to be transported, lifted, or moved). The pulley block is held by the lifting cable and has a block and tackle pulley under which the lifting cable can pass. Thus, by operating the lifting winch, the pulley block raises or lowers, either alone or with its suspended load.

[0010] The luffing jib crane includes a set of means enabling changes in the lifting cable's pulley system between three pulley configurations, which are: a single-strand configuration in which, at the exit of the main pulley, the free end of the lifting cable is fixed to the block so that the block is suspended by a single strand of the lifting cable; a two-strand configuration in which, at the exit of the main pulley, the lifting cable passes under the block and its free end is fixed to an anchor point provided on the arrowhead, so that the block is suspended by two strands of the lifting cable; a three-strand configuration in which, at the exit of the main pulley, the lifting cable passes under the block, then goes up to pass over the secondary pulley and finally its free end is fixed to the block, so that the block is suspended by three strands of the lifting cable.

[0011] Thus, this luffing jib crane allows for three pulley configurations, which the crane operator can choose according to the load weight. It should be noted that the lifting cable passes over the main pulley regardless of the pulley configuration (in other words, in all three configurations), while the lifting cable passes over the secondary pulley only in the three-part configuration.

[0012] This set of resources includes at least: a support to hold the pulley in a fixed position so that the lifting winch can be operated downwards to release the lifting cable while leaving the pulley in its fixed position; an auxiliary traction system mounted at least in part on the luffing boom and allowing the free end of the lifting cable to be pulled.

[0013] Thus, the invention proposes a way to support the pulley block in a fixed position, so that its weight is borne or supported by the support. This allows for changes in the pulley system to be carried out without being hindered or constrained by the weight of the block when handling and moving the lifting cable between two pulley configurations. Once the block is supported by the support, it is then possible to slacken the lifting cable (by lowering the lifting winch) and therefore more easily detach, pull, handle, and attach it.

[0014] Furthermore, an auxiliary traction system is proposed that allows the free end of the lifting cable to be pulled, so that at least part of the weight of the lifting cable is supported and handled by this auxiliary traction system, thus facilitating its handling by an operator. It should be noted that when the free end of the lifting cable is pulled using the auxiliary traction system, the lifting winch must be simultaneously operated in a downward direction to extend the lifting cable and thus assist the movement.

[0015] Depending on a characteristic, the support is chosen from: a ground support on which the block can rest; and at least one sling of a given length which can be attached to the arrowhead and to the block in order to suspend the block below the arrowhead.

[0016] Thus, the pulley block can be lowered to rest on the ground support, allowing the previously slack lifting cable to be handled on the ground. Alternatively, the pulley block can be suspended below the boom tip using at least one sling, allowing the previously slack lifting cable to be handled at height.

[0017] According to one possibility, at least one sling comprises a single sling.

[0018] According to another possibility, at least one sling comprises two slings intended to be fixed on each side of the pulley block.

[0019] Also, instead of a single sling, it is possible to use two slings and attach one to each side of the pulley block, in order to promote the balancing of the pulley block thus suspended by the two slings during operations.

[0020] According to one possibility, the auxiliary traction system includes an auxiliary cable of a given length which can be attached to the free end of the lifting cable so as to be able to pull on the free end of the lifting cable via the auxiliary cable.

[0021] Such an auxiliary cable will make it easy to reach the free end of the lifting cable so that it can be pulled and its handling facilitated.

[0022] According to another possibility, the auxiliary traction system includes at least one auxiliary pulley mounted on the arrowhead and over which the auxiliary cable passes.

[0023] Such an auxiliary pulley allows the auxiliary cable to be guided or oriented to avoid obstacles inherent in the crane structure and thus prevent it from rubbing against metal. It also facilitates the distribution of the weight of the auxiliary cable and the lifting cable, making it easier to pull on the free end of the lifting cable.

[0024] In a particular embodiment, the auxiliary traction system includes a traction actuator coupled to the auxiliary cable, such as a winch.

[0025] In this design, the auxiliary traction system is either assisted or motorized, enabling it to pull on the auxiliary cable and thus on the lifting cable via the traction actuator. This auxiliary traction system can, for example, incorporate a winch, a hoist, a capstan, or a jib crane.

[0026] Alternatively, the auxiliary traction system is a manual system that allows the auxiliary cable, and therefore the lifting cable, to be pulled by hand. Such a manual solution would be suitable for a small crane with a small-section lifting cable that can be handled manually, so that the traction would be carried out manually by the operator, preferably with one or more pulleys to redirect the traction cable and facilitate manual pulling.

[0027] It is of course also possible to provide one or more return pulleys for the traction cable in an assisted or motorized system.

[0028] Alternatively, the crane may include at least one auxiliary pulley mounted on the jib tip and positioned below and behind the main pulley. If applicable, this auxiliary pulley is positioned below the auxiliary pulley.

[0029] This accessory pulley will allow the traction cable to follow an auxiliary path which passes under this accessory pulley, then over the secondary pulley to finally be hooked onto the free end of the lifting cable, in order to be able to go towards the three-strand configuration by then pulling on the free end of the lifting cable.

[0030] In a particular embodiment, the set of means includes an anchoring device adapted to be fixed on the lifting cable, and at least one flexible link enabling the anchoring device to be connected to the pulley block or the free end of the lifting cable to be connected to the pulley block or to the anchoring device.

[0031] This type of anchoring device creates a fixed point on the lifting cable, allowing the pulley block to be moved more easily during configuration changes, particularly when the block has been previously rested on the ground support and the free end of the lifting cable has been manipulated / unhooked. The flexible link, meanwhile, supports the block block or the free end of the lifting cable.

[0032] It is also possible to have a flexible link that connects the anchoring device to the pulley block to take over the weight of the pulley block and / or to have a flexible link (if necessary another flexible link) that connects the free end of the lifting cable to the pulley block or to the anchoring device, to facilitate the handling of this free end by an operator.

[0033] The invention also relates to a pulley system for changing the pulley system of the lifting cable of a luffing jib crane as described above, wherein the pulley system comprises at least: support the pulley block by the support in a fixed position so that the lifting winch can be operated downwards to slacken the lifting cable while leaving the pulley block in its fixed position; pull the free end of the lifting cable by means of the auxiliary traction system or operate the lifting winch upwards in order to change the configuration of the lifting cable.

[0034] When switching from a single-strand configuration to a two-strand or three-strand configuration, the auxiliary traction system is used to pull on the free end of the lifting cable to pass under the pulley block and attach to the anchor point provided on the arrowhead (for the two-strand configuration) or on the pulley block after passing over the secondary pulley (for the three-strand configuration).

[0035] When switching from a two-strand or three-strand configuration to a single-strand configuration, the lifting winch is operated upwards to bring the lifting cable back so that it no longer passes under the pulley block, and then to fix it on the pulley block (for the single-strand configuration).

[0036] In a particular embodiment, the pulley system process includes at least the following steps, for a pulley system change from a single-strand configuration to a final configuration, which is either a two-strand or three-strand configuration: With the pulley block supported by the support, operate the lifting winch downwards to slacken the lifting cable while leaving the pulley block in its fixed position; detach the free end of the lifting cable from the pulley block, then pass the lifting cable under the pulley block; attach an auxiliary cable of a given length to the free end of the lifting cable, said auxiliary cable being integrated into the auxiliary traction system; and pull the free end of the lifting cable by means of the auxiliary traction system, via the auxiliary cable, and then fix this free end of the lifting cable in accordance with the final configuration; detach the auxiliary cable from the free end of the lifting cable.

[0037] After supporting the pulley block with the support and before detaching the free end of the lifting cable from the pulley block, it may be necessary to pull on the lifting cable in order to detach its free end from the pulley block.

[0038] Indeed, in some cases, the weight of the upstream lifting cable is such that it leaves the free end of the lifting cable under tension on the pulley block, even if the pulley block is supported and even if the lifting cable has been slackened by operating the lifting winch downwards.

[0039] Depending on one possibility, the lifting cable is pulled using the following steps, known as relief steps: a temporary fixed point of the lifting cable is connected to a temporary fixed point of the crane via a chain hoist type mechanism; the chain hoist is operated in order to pull on the temporary fixed point of the lifting cable, so as to relieve the lifting cable and to be able to detach its free end from the pulley block.

[0040] In the first implementation, the pulley block is supported by a ground support, after the pulley block has been lowered to this ground support, and the pulley block process includes: after passing the lifting cable under the pulley block and before securing the auxiliary cable, attach an anchoring device to the lifting cable and put in place at least one flexible link which connects the anchoring device to the pulley block or which connects the free end of the lifting cable to the pulley block or to the anchoring device, then operate the lifting winch upwards to raise the pulley block, said anchoring device being arranged to hold the pulley block held by the lifting cable; once in the final configuration, detach and remove the anchoring device from the lifting cable (and remove the flexible link).

[0041] It is therefore conceivable to have a flexible link which connects the anchoring device to the pulley for taking up the weight of the pulley and / or to have a flexible link (where appropriate another flexible link) which connects the free end of the lifting cable to the pulley or to the anchoring device, to facilitate the handling of this free end by an operator.

[0042] Depending on one possibility, when attaching the anchoring device to the lifting cable: either the anchoring device is fixed on a descending section of the lifting cable located between the main pulley and the block and tackle pulley, the flexible link is put in place to connect the anchoring device to the block and tackle, and the free end of the lifting cable is fixed on this descending section of the lifting cable or on the anchoring device (either directly or via another flexible link), the block and tackle then being suspended on the anchoring device via the flexible link during the raising of the block and tackle; or the anchoring device is fixed on an end section of the lifting cable located between the block and tackle pulley and its free end, the anchoring device coming to a stop against the block and tackle during the raising of the block and tackle, and the flexible link is put in place to connect the free end of the lifting cable to the block and tackle or to the anchoring device.

[0043] In a second embodiment, the block is supported by the support which includes at least one sling fixed to the arrowhead and to the block (possibly two slings fixed to the arrowhead and to the block), so that the block is suspended below the arrowhead.

[0044] In this second embodiment, the block and tackle is supported by at least one sling (possibly by two slings to balance the block and tackle) by operating as follows, starting from the single-strand configuration: operate the lifting winch upwards to a given high position; fix at least one sling (possibly both slings) between the block and the jib tip, the high position being such that at least one sling is slack (possibly both slings are slack) in this high position; operate the lifting winch downwards at least until at least one sling is taut and supports the block (possibly until both slings are taut and support the block).

[0045] According to a first variant, the final configuration is the two-strand configuration and in this case the auxiliary cable is fixed directly onto the free end of the lifting cable, so that the free end of the lifting cable is pulled directly by the auxiliary cable towards the anchor point to be fixed there in order to be in the two-strand configuration.

[0046] According to a second variant, the final configuration is the three-strand configuration, and in this case the auxiliary cable follows an auxiliary path that passes under an accessory pulley mounted on the boom tip, then over the secondary pulley to finally be hooked onto the free end of the lifting cable; and the free end of the lifting cable is pulled by the auxiliary cable and thus passes over the secondary pulley to finally be fixed to the block and tackle to be in the three-strand configuration.

[0047] In this second version, the anchoring device is not necessary.

[0048] According to another possibility, the pulley system process includes at least the following steps, for a pulley system change from an initial configuration which is the two-strand or three-strand configuration, to the one-strand configuration: With the pulley block supported by the support, operate the lifting winch downwards to slacken the lifting cable while leaving the pulley block in its fixed position; unhook the free end of the lifting cable according to the initial configuration; operate the lifting winch upwards to bring the lifting cable back so that it no longer passes under the pulley block; fix the free end of the lifting cable on the pulley block according to the single-strand configuration.

[0049] Regarding the step of detaching the free end of the lifting cable according to the initial configuration: It either involves unhooking the free end of the lifting cable from the anchor point provided on the arrowhead if the initial configuration is the two-strand configuration; or it involves unhooking the free end of the lifting cable from the pulley block if the initial configuration is the three-strand configuration.

[0050] As previously described, after securing the pulley block to the support and before detaching the free end of the lifting cable from the anchor point or the pulley block, it may be necessary to pull on the lifting cable to detach its free end from the pulley block. In this case, the stress relief steps described above can be implemented.

[0051] In a particular embodiment, the block is supported by the support which includes at least one sling fixed to the arrowhead and to the block, so that the block is suspended below the arrowhead.

[0052] This support by means of at least one sling (and possibly by means of two slings) is particularly suitable for changing the pulley system from the two-strand or three-strand configuration to the one-strand configuration, insofar as the lifting cable is either fixed to the anchor point provided on the end of the boom (if two-strand configuration), or passes over the secondary pulley provided on the end of the boom (if three-strand configuration).

[0053] It is still possible to use an anchoring device associated with a ground support for changing the pulley system from a two-strand or three-strand configuration to a one-strand configuration.

[0054] Advantageously, for a change of pulley system from the initial configuration, which is the two-strand or three-strand configuration, to the one-strand configuration: Before detaching the free end of the lifting cable in accordance with the initial configuration, the free end of the lifting cable is attached to an auxiliary cable, said auxiliary cable being integrated into the auxiliary traction system; when the lifting winch is operated upwards to bring the lifting cable back, the auxiliary traction system allows the auxiliary cable to run out to follow the lifting cable; once in the single-strand configuration, the auxiliary cable is detached from the free end of the lifting cable.

[0055] Thus, the auxiliary cable can accompany the lifting cable and partially support its weight, thereby securing the operation.

[0056] In another particular embodiment, the pulley system process includes at least the following steps for a pulley system change from a two-strand configuration to a three-strand configuration: The block is supported by the support which includes at least one sling fixed to the jib tip and to the block, so that the block is suspended below the jib tip; the lifting winch is operated downwards to slacken the lifting cable while leaving the block in its fixed position; the free end of the lifting cable is unhooked from the anchor point; attach an auxiliary cable of a given length to the free end of the lifting cable, said auxiliary cable being integrated into the auxiliary traction system and following an auxiliary path which passes under an accessory pulley mounted on the jib tip, then over the secondary pulley to finally be hooked onto the free end of the lifting cable;and pull on the free end of the lifting cable by means of the auxiliary traction system, via the auxiliary cable, to pass over the secondary pulley and finally be fixed to the block to be in the three-strand configuration; detach the auxiliary cable from the free end of the lifting cable.

[0057] As previously described, after securing the pulley block to the support and before detaching the free end of the lifting cable from the anchor point, it may be necessary to pull on the lifting cable to detach its free end from the pulley block. In this case, the stress relief steps described above can be implemented.

[0058] In another embodiment, the pulley system process includes at least the following steps for a pulley system change from a three-strand configuration to a two-strand configuration: The block is supported by the support which includes at least one sling fixed to the jib tip and to the block, so that the block is suspended below the jib tip; the lifting winch is operated downwards to slacken the lifting cable while leaving the block in its fixed position; the free end of the lifting cable is unhooked from the block; attach an auxiliary cable of a given length to the free end of the lifting cable, said auxiliary cable being integrated into the auxiliary traction system and passing under an accessory pulley mounted on the jib tip; operate the lifting winch upwards to bring the lifting cable back so that it no longer passes over the secondary pulley and so that the auxiliary cable passes over the secondary pulley to retain the free end of the lifting cable;Secure the free end of the lifting cable to the designated anchor point on the boom tip to create a two-strand configuration; detach the auxiliary cable from the free end of the lifting cable.

[0059] As previously described, after securing the pulley block to the support and before detaching the free end of the lifting cable from the anchor point or the pulley block, it may be necessary to pull on the lifting cable to detach its free end from the pulley block. In this case, the stress relief steps described above can be implemented. [Brief description of the figures]

[0060] 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: There Figure 1is a schematic and partial view of a luffing jib crane, with a zoom on the jib tip (top right) and a zoom on the main pulley and secondary pulley (bottom right); The Figure 2 is a schematic view illustrating three steps (a1) to (a3) ​​for a reeving change from a single-strand to a two-strand configuration; The Figure 3 is a schematic view illustrating three steps (a4) to (a6), following the three steps (a1) to (a3) ​​of the Figure 2 , for a change of pulley system from a single-strand configuration to a two-strand configuration; The Figure 4 is a schematic view illustrating three steps (a7) to (a9), following the three steps (a4) to (a6) of the Figure 3 , for a change of pulley system from a single-strand configuration to a two-strand configuration; The Figure 5is a schematic view illustrating three steps (b1) to (b3) for a change of pulley system from the single-strand configuration to the double-strand configuration, according to an alternative embodiment compared to the embodiment of Figures 2 to 4 ; There Figure 6 is a schematic view illustrating three steps (b4) to (b6), following the three steps (b1) to (b3) of the Figure 5 , for a change of pulley system from a single-strand configuration to a two-strand configuration; The Figure 7 is a schematic view illustrating three steps (b7) to (b9), following the three steps (b4) to (b6) of the Figure 6 , for a change of pulley system from a single-strand configuration to a two-strand configuration; The Figure 8 is a schematic view illustrating a final step (b10), following the three steps (b7) to (b9) of the Figure 7, for a change of pulley system from a single-strand configuration to a two-strand configuration; The Figure 9 is a schematic view illustrating two steps (c1) and (c2) for a change of pulley system from the single-strand configuration to the double-strand configuration, according to another embodiment compared to the embodiment of Figures 2 to 4 and to the realization of Figures 5 to 8 ; There Figure 10 is a schematic view illustrating three steps (c3) to (c5), following the two steps (c1) and (c2) of the Figure 9 , for a change of pulley system from a single-strand configuration to a two-strand configuration; The Figure 11 is a schematic view illustrating three steps (c6) to (c8), following the three steps (c3) to (c5) of the Figure 10 , for a change of pulley system from a single-strand configuration to a two-strand configuration; The Figure 12is a schematic view illustrating three steps (d1) to (d3) for a reeving change from a one-strand to a three-strand configuration; The Figure 13 is a schematic view illustrating three steps (d4) to (d6), following the three steps (d1) to (d3) of the Figure 12 , for a change of pulley system from a single-strand configuration to a three-strand configuration; The Figure 14 is a schematic view illustrating three steps (d7) to (d9), following the three steps (d4) to (d6) of the Figure 13 , for a change of pulley system from a single-strand configuration to a three-strand configuration; The Figure 15 is a schematic view illustrating three steps (e1) to (e3) for a reeving change from a two-strand to a three-strand configuration; The Figure 16is a schematic view illustrating three steps (e4) to (e6), following the three steps (e1) to (e3) of the Figure 15 , for a change of pulley system from a two-strand configuration to a three-strand configuration; and The Figure 17 is a schematic view illustrating three steps (e7) to (e9), following the three steps (e4) to (e6) of the Figure 16 , for a change of pulley system from a two-strand configuration to a three-strand configuration. [Detailed description of several embodiments of the invention]

[0061] With reference to the Figure 1 , a luffing jib crane 1 includes a luffing jib 10 equipped with a jib tip 11 and a jib foot 12 articulated in rotation about a horizontal axis at the top of a mast 13. This luffing jib crane 1 includes a counter jib 14 which is mounted at the top of the mast 13, diametrically opposite to the luffing jib 10.

[0062] The luffing jib crane 1 includes a lifting winch 2 coupled to a lifting cable 20 which has a free end 21, this lifting winch 2 being able to be mounted on the counter jib 14.

[0063] The jib tip 11 is equipped successively with an upper pulley 31 and a main pulley 32, over which the lifting cable 20 passes, regardless of the pulley configuration. The upper pulley 31 is located above and behind the main pulley 32, so the lifting cable 20 passes first over the upper pulley 31 and then over the main pulley 32. It is possible to provide at least one other pulley 33, positioned on the luffing jib 10, between the jib tip 11 and the jib foot 12, over which the lifting cable 20 passes, depending on the length of the luffing jib 10.

[0064] The arrowhead 11 is also equipped with a secondary pulley 35 (clearly illustrated only in Figure 1) over which the lifting cable 20 passes only in the three-strand configuration. In the illustrated example, this secondary pulley 35 is mounted coaxially with the main pulley 32; this is why it is not visible in the Figures 2 to 17 . This secondary pulley 35 is located below and in front of the upper pulley 31.

[0065] The arrowhead 11 has an anchor point 15 located at the rear of the main pulley 32 and below the upper pulley 31.

[0066] The lifting winch 2 can be operated upwards to raise the free end 21 of the lifting cable 20 and can be operated downwards to lower the free end 21 of the lifting cable 20.

[0067] The luffing jib crane 1 includes a block 4 equipped with a lifting device 40 (typically a hook) for attaching a load. The block 4 is held by the lifting cable 20 and has a pulley block 41 under which the lifting cable 20 can pass. The block 4 includes a frame 42 inside which the pulley block 41 is housed, and on which an upper attachment point 43 is provided. In a variant adapted for a four-part configuration, not described hereafter, the block 4 would include another pulley block.

[0068] Three pulley configurations are possible with this luffing jib crane 1, namely: a single-strand configuration (visible on the Figure 1 , there Figure 2 step (a1), the Figure 5 step (b1) and the Figure 9step (c1)) wherein, at the exit of the main pulley 32, the free end 21 of the lifting cable 20 is fixed to the block 4 (and more precisely fixed to the upper attachment point 43) so that the block 4 is suspended by a single strand of the lifting cable 20; a two-strand configuration (visible on the Figure 4 step (a9), the Figure 8 step (b10), the Figure 11 step (c8) and the Figure 15 step (e1)) in which, exiting the main pulley 32, the lifting cable 20 passes under the block and tackle pulley 41 and its free end 21 is fixed to the anchor point 15 provided on the spreader bar 11, so that the block and tackle 4 is suspended by two strands of the lifting cable 20; a three-strand configuration (visible on the Figure 14 step (d9) and the Figure 17step (e9)) in which, at the exit of the main pulley 32, the lifting cable 20 passes under the pulley block 41, then goes up to pass over the secondary pulley 35 and finally its free end is fixed on the pulley block 4 (and more precisely fixed on the upper attachment point 43) so that the pulley block 4 is suspended by three strands of the lifting cable 20.

[0069] The luffing jib crane 1 includes a set of means for operating changes in the lifting cable 20 pulley system between the three pulley system configurations.

[0070] This assembly includes a support 50, 51 that holds the pulley 4 in a fixed position, allowing the lifting winch 2 to be lowered to slacken the lifting cable 20 while leaving the pulley 4 in its fixed position. Thus, with the pulley 4 supported by the bracket to remain fixed, it is possible to lower the lifting winch 2 without moving the pulley 4 (which remains fixed). Consequently, the lifting cable 20 slackens, providing slack that allows it to be manipulated to change its configuration.

[0071] In the projects illustrated on the Figure 2 steps (a2) and (a3) ​​and on the Figure 5In steps (b2) and (b3), the support is a ground support 50, such as a trestle, on which the pulley 4 can rest after being lowered to this ground support 50. Once the pulley 4 rests on this ground support 50, it is possible to operate the lifting winch 2 downward without moving the pulley 4 (which remains on the ground support 50), and therefore the lifting cable 20 relaxes and has slack.

[0072] In the projects illustrated on the Figure 10 steps (c3) to (c5), on the Figure 12 step (d3), on the Figure 13 steps (d4) to (d6), on the Figure 15 step (e3) and on the Figure 16 steps (e4) to (e6), the support includes at least one sling 51 having a given length and which can be fixed on the arrowhead 11 and on the block 4 (advantageously on an attachment point other than the upper attachment point 43) in order to suspend the block 4 below the arrowhead 11.

[0073] Advantageously, the at least one sling 51 comprises two slings 51 of the same length which can be fixed to the arrowhead 11 and to the block 4; with a sling 51 on the right fixed to the right side of the block 4 and to the right side of the arrowhead 11, and a sling 51 on the left fixed to the left side of the block 4 and to the left side of the arrowhead 11, so as to balance the suspension of the block 4 to remain straight during operations.

[0074] Once the pulley block 4 is suspended by the sling(s) 51, it is possible to lower the lifting winch 2 without moving the pulley block 4 (which remains suspended), and therefore the lifting cable 20 slackens. In some situations, it may be advantageous and necessary to assist the lifting cable 20 by relieving it of some of its weight upstream, for example by connecting a temporary fixed point on the lifting cable 20 to a temporary fixed point on the crane via a chain hoist mechanism.

[0075] The sling(s) 51 can be fixed on the arrowhead below the main pulley 32. In the case where two slings 51 are used, these two slings 51 can be fixed on either side of the main pulley 32 and the secondary pulley 35.

[0076] This assembly includes an auxiliary traction system 6 mounted on the luffing boom 10, which allows the free end 21 of the lifting cable 20 to be pulled. In the illustrated versions, the auxiliary traction system 6 includes an auxiliary cable 60 coupled to a traction actuator 61, such as a winch. In a manual variant, a traction actuator 61 may not be provided, allowing the traction cable 60 to be pulled manually. The auxiliary cable 60 has a free end 62 that can be attached to the free end 21 of the lifting cable 20, so that the lifting cable 20 can be pulled by pulling on the traction cable 60, and the lifting cable 20 can be held by holding the traction cable 60.

[0077] The auxiliary traction system 6 includes at least one auxiliary pulley 63 mounted on the arrowhead 11 and over which the auxiliary cable 60 passes. This auxiliary pulley 63 is located behind the main pulley 32 and above the anchor point 15.

[0078] The auxiliary traction system 6 includes at least one accessory pulley 64 mounted on the arrowhead 11 and positioned below and behind the main pulley 32, and also below the auxiliary pulley 63. Its purpose will be described later.

[0079] As described later in certain steps implementing the ground support 50, this set of means may also include an anchoring member 52 adapted to be fixed to the lifting cable 20 and which is provided with at least one flexible link 53 for connecting the anchoring member 52 to the pulley block 4. This anchoring member 52 may be in the form of a stirrup or a clevis which can be tightened securely around the lifting cable 20. The flexible link 53 may be in the form of a cable, a chain or a rope.

[0080] The remainder of the description concerns the pulley system used to change the pulley system of the lifting cable 20 of the luffing jib crane 1 described above, with several illustrated implementation examples on the Figures 2 to 17 .

[0081] THE Figures 2 to 4illustrate a first method for a change of pulley system from the single-strand configuration to the two-strand configuration, and which implements the following steps (a1) to (a9).

[0082] In a first step (a1) illustrated in Figure 2 , the lifting cable 20 is in its single-strand configuration with the pulley block 4 suspended by a single strand of the lifting cable 20.

[0083] In a second step (a2) illustrated in Figure 2 The lifting winch is operated downwards to lower the pulley block 4 until it is supported by the ground support 50 in a fixed position. Once the pulley block 4 is supported by the ground support 50, the lifting winch is again operated downwards to slacken the lifting cable 20 while leaving the pulley block 4 in its fixed position on the ground support 50.

[0084] In a third step (a3) ​​illustrated in Figure 2, the free end 21 of the lifting cable 20 is detached from the pulley 4, then the lifting cable 20 is passed under the pulley 41 and then comes out of the pulley 4. The lifting cable 20 thus has a terminal section 22 which protrudes from the pulley 4 and which is disposed between the pulley 41 and its free end 21.

[0085] In a fourth step (a4) illustrated in Figure 3 , the anchoring device 52 is fixed on the lifting cable 20, and more specifically the anchoring device 52 is fixed on the terminal section 22 of the lifting cable 20 and the flexible link 53 is put in place to connect the free end 21 of the lifting cable 20 to the pulley 4 (or alternatively to the anchoring device 52).

[0086] In a fifth step (a5) illustrated in Figure 3The lifting winch is operated upwards to raise the pulley block 4. During this ascent of the pulley block 4, the anchoring device 52 holds the pulley block 4 held by the lifting cable 20. Indeed, the anchoring device 52 is against the frame 42 of the pulley block 4 while the lifting winch pulls on the lifting cable 20 to raise the pulley block 4.

[0087] In a sixth step (a6) illustrated in Figure 3 , the free end 62 of the traction cable 60 is attached to the flexible link 53; the traction cable 60 passing for reference over the auxiliary pulley 63.

[0088] In a seventh step (a7) illustrated in Figure 4The flexible link 53 is detached from the pulley block 4 (or alternatively from the anchoring device 52), while remaining attached to the free end 21 of the lifting cable 20. Next, the traction cable 60 is pulled, which in turn pulls the flexible link 53 and thus also the free end 21 of the lifting cable 20. In other words, the free end 21 of the lifting cable 20 is pulled by means of the auxiliary traction system 6, via the auxiliary cable 60 and also the flexible link 53, and then this free end 21 of the lifting cable 20 is secured to the anchor point 15 in accordance with the two-strand configuration. While the traction cable 60 pulls on the free end 21 of the lifting cable 20, the lifting winch is simultaneously driven downwards to unwind the lifting cable 20 and thus accompany the movement.

[0089] In an eighth step (a8) illustrated in Figure 4, the flexible link 53 detached from the free end 21 of the lifting cable 20 and is removed (so that the auxiliary cable 60 is also detached from the lifting cable 20), and the lifting winch is operated downwards to lower the pulley 4 and tension the terminal section 22 of the lifting cable 20.

[0090] In a ninth step (a9) illustrated in Figure 4 , the anchoring device 52 is detached from the lifting cable 20 and is removed, and thus the lifting cable 20 is in its two-strand configuration with the pulley block 4 suspended by two strands of the lifting cable 20.

[0091] THE Figures 5 to 7 illustrate a second method for a change of pulley system from the single-strand configuration to the two-strand configuration, and which implements the following steps (b1) to (b10).

[0092] In a first step (b1) illustrated in Figure 5, the lifting cable 20 is in its single-strand configuration with the pulley block 4 suspended by a single strand of the lifting cable 20.

[0093] In a second step (b2) illustrated in Figure 5 The lifting winch is operated downwards to lower the pulley block 4 until it is supported by the ground support 50 in a fixed position. Once the pulley block 4 is supported by the ground support 50, the lifting winch is again operated downwards to slacken the lifting cable 20 while leaving the pulley block 4 in its fixed position on the ground support 50.

[0094] In a third step (b3) illustrated in Figure 5, the free end 21 of the lifting cable 20 is unhooked from the block 4, then the lifting cable 20 is passed under the block 41 and then out of the block 4. The lifting cable 20 thus has a terminal section 22 which protrudes from the block 4 and is located between the block 41 and its free end 21. The lifting cable 20 also has a descending section 23 located between the main pulley 32 and the block 41. Next, the anchoring member 52 is fixed to the lifting cable 20, and more precisely the anchoring member 52 is fixed to the descending section 23, just above the block 4, and the flexible link 53 which connects the anchoring member 52 to the block 4 is put in place; this flexible link 53 being in a relaxed state because it is longer than the distance between the pulley 4 and the anchoring device 52.The terminal section 22 is raised and fixed to the descending section 23 of the lifting cable 20 above the anchoring member 52 or is fixed to the anchoring member 52. Thus, the free end 21 of the lifting cable 20 is fixed to this descending section 23 of the lifting cable 20 above the anchoring member 52 or is fixed to the anchoring member 52. Alternatively, the free end 21 of the lifting cable 20 is fixed to the descending section 23 of the lifting cable 20 or to the anchoring member 52 via another flexible link.

[0095] In a fourth step (b4) illustrated in Figure 6 The lifting winch is operated upwards to raise the pulley 4. During this ascent of the pulley 4, the anchoring device 52 holds the pulley 4 held by the lifting cable 20. Indeed, the pulley 4 is suspended from the anchoring device 52 by the flexible link 53.

[0096] In a fifth step (b5) illustrated in Figure 6, the free end 62 of the traction cable 60 is attached to the free end 21 of the lifting cable 20; the traction cable 60 passing for reference over the auxiliary pulley 63.

[0097] In a sixth step (b6) illustrated in Figure 6 , the terminal section 22 of the lifting cable 20 is detached from the descending section 23 of the lifting cable 20 or is detached from the anchoring element 52; the terminal section 22 of the lifting cable 20 then passes into a slack state, while being held by the traction cable 60.

[0098] In a seventh step (b7) illustrated in Figure 7The traction cable 60 is pulled, which in turn pulls the free end 21 of the lifting cable 20. In other words, the free end 21 of the lifting cable 20 is pulled by means of the auxiliary traction system 6, via the auxiliary cable 60, and then this free end 21 of the lifting cable 20 is secured to the anchor point 15 according to the two-strand configuration. While the traction cable 60 pulls on the free end 21 of the lifting cable 20, the lifting winch is simultaneously driven downwards to unwind the lifting cable 20 and thus assist the movement.

[0099] In an eighth step (b8) illustrated in Figure 7 , the auxiliary cable 60 is detached from the lifting cable 20.

[0100] In a ninth step (b9) illustrated in Figure 7, the lifting winch is operated downwards to lower the pulley 4 and tension the terminal section 22 of the lifting cable 20, which also leads to slackening the flexible link 53.

[0101] In a tenth step (b10) illustrated in Figure 8 , the flexible link 53 is detached from the pulley 4, and then the anchoring member 52 is detached from the lifting cable 20 and removed, and thus the lifting cable 20 is in its two-strand configuration with the pulley 4 suspended by two strands of the lifting cable 20.

[0102] THE Figures 9 to 11 illustrate a third method for a change of pulley system from the single-strand configuration to the two-strand configuration, and which implements the following steps (c1) to (c8).

[0103] In a first step (c1) illustrated in Figure 9, the lifting cable 20 is in its single-strand configuration with the pulley 4 suspended by a single strand of the lifting cable 20; the pulley 4 being positioned high and close to the arrowhead 11, in a given high position.

[0104] In a second step (c2) illustrated in Figure 9 , at least one sling 51 is fixed between the block 4 and the arrowhead 11, the high position of the block 4 being such that at least one sling 51 is slack in this high position.

[0105] In a third step (c3) illustrated in Figure 10 , the lifting winch is operated downwards at least until at least one sling 51 is taut and supports the pulley block 4 in a fixed position.

[0106] In a fourth step (c4) illustrated in Figure 10Once the block 4 is supported by at least one sling 51, the lifting winch is again operated downwards to slacken the lifting cable 20 while leaving the block 4 in its fixed position. The free end 21 of the lifting cable 20 is then unhooked from the block 4, and the lifting cable 20 is passed under the block and tackle pulley 41 and then out of the block 4. Next, the free end 62 of the traction cable 60 is attached to the free end 21 of the lifting cable 20; the traction cable 60 then passes over the auxiliary pulley 63.

[0107] In a fifth step (c5) illustrated in Figure 10The traction cable 60 is pulled, which in turn pulls the free end 21 of the lifting cable 20. In other words, the free end 21 of the lifting cable 20 is pulled by means of the auxiliary traction system 6, via the auxiliary cable 60, and then this free end 21 of the lifting cable 20 is secured to the anchor point 15 according to the two-strand configuration. While the traction cable 60 pulls on the free end 21 of the lifting cable 20, the lifting winch is simultaneously driven downwards to unwind the lifting cable 20 and thus assist the movement.

[0108] Of course, it is possible to use other methods to go from step (c3) to step (c5), for example during step (c1) or (c2) the free end 21 of the lifting cable 20 is connected to an intermediate cable which passes under the pulley block 41, then during step (c4) the free end 62 of the traction cable 60 is attached to this intermediate cable, which will make it easier to connect to the lifting cable 20.

[0109] In a sixth step (c6) illustrated in Figure 11 , the auxiliary cable 60 is detached from the lifting cable 20.

[0110] In a seventh step (c7) illustrated in Figure 11 , the lifting winch is operated upwards to raise the pulley block 4 to the high position, which leads to the relaxation of at least one sling 51.

[0111] In an eighth step (c8) illustrated in Figure 11, at least one sling 51 is detached from the pulley 4 and is removed, and thus the lifting cable 20 is in its two-strand configuration with the pulley 4 suspended by two strands of the lifting cable 20.

[0112] THE Figures 12 to 14 illustrate a method for a reeving change from a one-strand configuration to a three-strand configuration, and which implements the following steps (d1) to (d9).

[0113] In a first step (d1) illustrated in Figure 12 , the lifting cable 20 is in its single-strand configuration with the pulley 4 suspended by a single strand of the lifting cable 20; the pulley 4 being positioned high and close to the arrowhead 11, in a given high position.

[0114] In a second step (d2) illustrated in Figure 12, at least one sling 51 is fixed between the block 4 and the arrowhead 11, the high position of the block 4 being such that at least one sling 51 is slack in this high position.

[0115] In a third step (d3) illustrated in Figure 12 , the lifting winch is operated downwards at least until at least one sling 51 is taut and supports the pulley block 4 in a fixed position.

[0116] In a fourth step (d4) illustrated in Figure 13 , the traction cable 60 is put in place to follow an auxiliary path which passes first over the auxiliary pulley 63, then passes under the accessory pulley 64, then passes over the secondary pulley 35.

[0117] In a fifth step (d5) illustrated in Figure 13The lifting winch is then operated downwards to slacken the lifting cable 20 while leaving the block 4 in its fixed position. The free end 21 of the lifting cable 20 is then unhooked from the block 4, and the lifting cable 20 is passed under the block and tackle pulley 41 and then out of the block 4. Finally, the free end 62 of the traction cable 60 is attached to the free end 21 of the lifting cable 20.

[0118] In a sixth step (d6) illustrated in Figure 13The traction cable 60 is pulled, which pulls the free end 21 of the lifting cable 20. Thus, the lifting cable 20 follows the reverse path of the auxiliary path, so that the lifting cable 20 passes over the secondary pulley 35 with its free end 21 which is positioned before the accessory pulley 64. While the traction cable 60 pulls on the free end 21 of the lifting cable 20, the lifting winch is simultaneously operated downwards to unwind the lifting cable 20 and thus accompany the movement.

[0119] In a seventh step (d7) illustrated in Figure 14 , the auxiliary cable 60 is detached from the lifting cable 20 and the free end 21 of the lifting cable 20 is then hooked onto the pulley 4, to be in the three-strand configuration.

[0120] In an eighth step (d8) illustrated in Figure 14, the lifting winch is operated upwards to raise the pulley block 4 to the high position, which leads to the relaxation of at least one sling 51.

[0121] In a ninth step (d9) illustrated in Figure 14 , at least one sling 51 is detached from the pulley 4 and is removed, and thus the lifting cable 20 is in its three-strand configuration with the pulley 4 suspended by three strands of the lifting cable 20.

[0122] THE Figures 15 à 17 illustrate a method for a reeving change from the two-strand configuration to the three-strand configuration, and which implements the following steps (e1) to (e9).

[0123] In a first step (e1) illustrated in Figure 15 , the lifting cable 20 is in its two-strand configuration with the pulley 4 suspended by two strands of the lifting cable 20; the free end 21 of the lifting cable 20 being fixed on the anchor point 15 and the pulley 4 being positioned high and close to the arrowhead 11, in a given high position.

[0124] In a second step (e2) illustrated in Figure 15 , at least one sling 51 is fixed between the block 4 and the arrowhead 11, the high position of the block 4 being such that at least one sling 51 is slack in this high position.

[0125] In a third step (e3) illustrated in Figure 15 , the lifting winch is operated downwards at least until at least one sling 51 is taut and supports the pulley block 4 in a fixed position.

[0126] In a fourth step (e4) illustrated in Figure 16 , the traction cable 60 is put in place to follow an auxiliary path which passes first over the auxiliary pulley 63, then passes under the accessory pulley 64, then passes over the secondary pulley 35.

[0127] In a fifth step (e5) illustrated in Figure 16 , the free end 21 of the lifting cable 20 is unhooked from the anchor point 15, and then the free end 62 of the traction cable 60 is attached to the free end 21 of the lifting cable 20.

[0128] In a sixth step (e6) illustrated in Figure 16 The traction cable 60 is pulled, which pulls the free end 21 of the lifting cable 20. Thus, the lifting cable 20 follows the reverse path of the auxiliary path, so that the lifting cable 20 passes over the secondary pulley 35 with its free end 21 which is positioned before the accessory pulley 64. While the traction cable 60 pulls on the free end 21 of the lifting cable 20, the lifting winch is simultaneously operated downwards to unwind the lifting cable 20 and thus accompany the movement.

[0129] In a seventh step (e7) illustrated in Figure 17 , the auxiliary cable 60 is detached from the lifting cable 20 and the free end 21 of the lifting cable 20 is then hooked onto the pulley 4, to be in the three-strand configuration.

[0130] In an eighth step (e8) illustrated in Figure 17 , the lifting winch is operated upwards to raise the pulley block 4 to the high position, which leads to the relaxation of at least one sling 51.

[0131] In a ninth step (e9) illustrated in Figure 17 , at least one sling 51 is detached from the pulley 4 and is removed, and thus the lifting cable 20 is in its three-strand configuration with the pulley 4 suspended by three strands of the lifting cable 20.

[0132] In general, to reverse the configuration changes, simply perform the steps in reverse order.

[0133] A method for changing a pulley system from a two-strand to a one-strand configuration can be described by referring to the Figures 9 à 11 , but this time read backwards (for this reading, you must not take into account the arrows indicating cable movements).

[0134] In a first step (c8) illustrated in Figure 11 , the lifting cable 20 is in its two-strand configuration with the pulley 4 suspended by two strands of the lifting cable 20; the free end 21 of the lifting cable 20 being fixed on the anchor point 15 and the pulley 4 being positioned high and close to the arrowhead 11, in a given high position.

[0135] In a second step (c7) illustrated in Figure 11 , at least one sling 51 is fixed between the block 4 and the arrowhead 11, the high position of the block 4 being such that at least one sling 51 is slack in this high position.

[0136] In a third step (c6) illustrated in Figure 11 , the lifting winch is operated downwards at least until at least one sling 51 is taut and supports the pulley block 4 in a fixed position.

[0137] In a fourth step (c5) illustrated in Figure 10 , the free end 62 of the traction cable 60 is attached to the free end 21 of the lifting cable 20; the traction cable 60 passing for reference over the auxiliary pulley 63.

[0138] In a fifth step (c4) illustrated in Figure 10 , the free end 21 of the lifting cable 20 is unhooked from the anchor point 15, and then the free end 62 of the traction cable 60 is attached to the free end 21 of the lifting cable 20; the traction cable 60 thus retaining the lifting cable 20.

[0139] In a sixth step (c3) illustrated in Figure 10 , the lifting winch is operated upwards to pull the lifting cable 20 (with the traction cable 60), so as to bring the lifting cable 20 back so that it no longer passes under the pulley block 41, and then the free end 21 of the lifting cable 20 is fixed on the pulley block 4 in accordance with the single-strand configuration, and the free end 62 of the traction cable 60 is unhooked from the lifting cable 20.

[0140] In a seventh step (c2) illustrated in Figure 9 , the lifting winch is operated upwards to raise the pulley block 4 to the high position, which leads to the relaxation of at least one sling 51.

[0141] In an eighth step (c1) illustrated in Figure 9 , at least one sling 51 is detached from the pulley 4 and removed, and thus the lifting cable 20 is in its single-strand configuration with the pulley 4 suspended by a single strand of the lifting cable 20.

[0142] A method for changing a pulley system from a three-strand to a one-strand configuration can be described by referring to the Figures 12 à 14 , but this time read backwards (for this reading, you must not take into account the arrows indicating cable movements).

[0143] In a first step (d9) illustrated in Figure 14 , the lifting cable 20 is in its three-strand configuration with the pulley 4 suspended by three strands of the lifting cable 20; the free end 21 of the lifting cable 20 being fixed on the pulley 4 which is positioned high and close to the arrowhead 11, in a given high position.

[0144] In a second step (d8) illustrated in Figure 14 , at least one sling 51 is fixed between the block 4 and the arrowhead 11, the high position of the block 4 being such that at least one sling 51 is slack in this high position.

[0145] In a third step (d7) illustrated in Figure 14 The lifting winch is operated downwards at least until at least one sling 51 is taut and supports the pulley block 4 in a fixed position. The traction cable 60 is then laid along an auxiliary path that passes first over the auxiliary pulley 63, and then over the rear of the accessory pulley 64.

[0146] In a fourth step (d6) illustrated in Figure 13 , the free end 62 of the traction cable 60 is attached to the free end 21 of the lifting cable 20, and the free end 21 of the lifting cable 20 is unhooked from the pulley block 4.

[0147] In a fifth step (d5) illustrated in Figure 13 , the lifting winch is operated upwards to pull the lifting cable 20 (with the traction cable 60), so as to bring the lifting cable 20 back so that it no longer passes over the secondary pulley 35; the traction cable 60 guiding and holding the lifting cable 20.

[0148] In a sixth step (d4) illustrated in Figure 13 , we continue to operate the lifting winch upwards to pull the lifting cable 20 (with the traction cable 60) further, so as to bring the lifting cable 20 back so that it no longer passes under the pulley block 41, and then we fix the free end 21 of the lifting cable 20 on the pulley block 4 in accordance with the single-strand configuration, and we unhook the free end 62 of the traction cable 60 from the lifting cable 20.

[0149] In a seventh step (d3) illustrated in Figure 12 , the 60 traction cable can be removed (but it can also remain in place, waiting).

[0150] In an eighth step (d2) illustrated in Figure 12 , the lifting winch is operated upwards to raise the pulley block 4 to the high position, which leads to the relaxation of at least one sling 51.

[0151] In a ninth step (d1) illustrated in Figure 12 , at least one sling 51 is detached from the pulley 4 and removed, and thus the lifting cable 20 is in its single-strand configuration with the pulley 4 suspended by a single strand of the lifting cable 20.

[0152] A method for changing a pulley system from a three-strand to a two-strand configuration can be described by referring to the Figures 15 à 17 , but this time read backwards (for this reading, you must not take into account the arrows indicating cable movements).

[0153] In a first step (e9) illustrated in Figure 17 , the lifting cable 20 is in its three-strand configuration with the pulley 4 suspended by three strands of the lifting cable 20; the free end 21 of the lifting cable 20 being fixed on the pulley 4 which is positioned high and close to the arrowhead 11, in a given high position.

[0154] In a second step (e8) illustrated in Figure 17 , at least one sling 51 is fixed between the block 4 and the arrowhead 11, the high position of the block 4 being such that at least one sling 51 is slack in this high position.

[0155] In a third step (e7) illustrated in Figure 17 The lifting winch is operated downwards at least until at least one sling 51 is taut and supports the pulley block 4 in a fixed position. The traction cable 60 is put in place to follow an auxiliary path which passes first over the auxiliary pulley 63, then under and over the rear of the accessory pulley 64.

[0156] In a fourth step (e6) illustrated in Figure 16 , the free end 62 of the traction cable 60 is attached to the free end 21 of the lifting cable 20, and the free end 21 of the lifting cable 20 is unhooked from the pulley block 4.

[0157] In a fifth step (e5) illustrated in Figure 16 , the lifting winch is operated upwards to pull the lifting cable 20 (with the traction cable 60), so as to bring the lifting cable 20 back so that it no longer passes over the secondary pulley 35; the traction cable 60 guiding and holding the lifting cable 20.

[0158] In a sixth step (e4) illustrated in Figure 16 , the lifting winch is operated downwards to give slack, and then the free end 21 of the lifting cable 20 is fixed on the anchor point 15 in accordance with the two-strand configuration, and the free end 62 of the traction cable 60 is unhooked from the lifting cable 20.

[0159] In a seventh step (e3) illustrated in Figure 15 , the 60 traction cable can be removed (but it can also remain in place, waiting).

[0160] In an eighth step (e2) illustrated in Figure 15 , the lifting winch is operated upwards to raise the pulley block 4 to the high position, which leads to the relaxation of at least one sling 51.

[0161] In a ninth step (e1) illustrated in Figure 15, at least one sling 51 is detached from the pulley 4 and removed, and thus the lifting cable 20 is in its single-strand configuration with the pulley 4 suspended by a single strand of the lifting cable 20.

Claims

1. Luffing jib crane (1) comprising: - a lifting winch (2) coupled to a lifting cable (20) which has a free end (21), said lifting winch (2) being actuated upwards to raise the free end (21) of the lifting cable (20) and actuated downwards to lower the free end (21) of the lifting cable (20); - a luffing jib (10) equipped with a jib tip (11) on which are mounted a main pulley (32) over which the lifting cable (20) passes and a secondary pulley (35); - a block (4) equipped with a hooking device (40) for hooking a load, in which said block (4) is held by the lifting cable (20) and includes a block and tackle pulley (41) under which said lifting cable (20) can pass;in which the luffing jib crane (1) includes a set of means for operating changes in the lifting cable (20) between three reeving configurations which are: - a single-strand configuration in which, at the exit of the main pulley (32), the free end (21) of the lifting cable (20) is fixed on the pulley (4) so ​​that the pulley (4) is suspended by a single strand of the lifting cable (20); - a two-strand configuration in which, at the exit of the main pulley (32), the lifting cable (20) passes under the reeving pulley (41) and its free end is fixed on an anchor point (15) provided on the jib tip (11), so that the pulley (4) is suspended by two strands of the lifting cable (20);- a three-strand configuration in which, exiting the main pulley (32), the lifting cable (20) passes under the block and tackle pulley (41), then rises to pass over the secondary pulley (35) and finally its free end (21) is fixed on the block (4), so that the block (4) is suspended by three strands of the lifting cable (20); in which the set of means comprises at least: - a support (50; 51) enabling the block (4) to be supported in a fixed position in order to be able to operate the lifting winch (2) downwards to slacken the lifting cable (20) while leaving the block (4) in its fixed position; - an auxiliary traction system (6) mounted at least in part on the luffing boom (10) and enabling the free end (21) of the lifting cable (20) to be pulled.

2. Luffing jib crane (1) according to claim 1, wherein the support (50; 51) is selected from: - a ground support (50) on which the block (4) can rest; and - at least one sling (51) having a given length and which can be fixed on the jib tip (11) and on the block (4) in order to suspend the block (4) below the jib tip (11).

3. Luffing jib crane (1) according to claim 1 or 2, wherein the auxiliary traction system (6) comprises an auxiliary cable (60) having a given length and which can be fixed on the free end (21) of the lifting cable (20) so as to be able to pull on the free end (21) of the lifting cable (20) by means of the auxiliary cable (60).

4. Luffing jib crane (1) according to claim 3, the auxiliary traction system (6) includes at least one auxiliary pulley (63) mounted on the jib tip (11) and over which the auxiliary cable (60) passes.

5. Luffing jib crane (1) according to claim 3 or 4, wherein the auxiliary traction system (6) comprises a traction actuator (61) coupled to the auxiliary cable (60), such as for example a winch.

6. Luffing jib crane (1) according to any one of claims 3 to 5, comprising at least one accessory pulley (64) mounted on the jib tip (11) and positioned below and behind the main pulley (32).

7. Luffing jib crane (1) according to any one of the preceding claims, wherein the means assembly includes an anchoring member (52) adapted to be fixed on the lifting cable (20), and at least one flexible link (53) for connecting the anchoring member (52) to the pulley block (4) or for connecting the free end (21) of the lifting cable (20) to the pulley block (4) or to the anchoring member (52).

8. A pulley system for making pulley changes of the lifting cable (20) of a luffing jib crane (1) according to any one of the preceding claims, wherein the pulley system comprises at least: - supporting the pulley (4) by the support (50; 51) in a fixed position so as to be able to operate the lifting winch (2) downwards to slacken the lifting cable (20) while leaving the pulley (4) in its fixed position; - pulling the free end (21) of the lifting cable (20) by means of the auxiliary traction system (6) or operating the lifting winch (2) upwards in order to change the configuration of the lifting cable (20).

9. A pulley system according to claim 8, comprising at least the following steps, for a pulley system change from a single-strand configuration to a final configuration, which is a two-strand or three-strand configuration: - with the pulley (4) supported by the support (50; 51), operate the lifting winch (2) downwards to slacken the lifting cable (20) while leaving the pulley (4) in its fixed position; - detach the free end (21) of the lifting cable (20) from the pulley (4), then pass the lifting cable (20) under the pulley (41); - attach an auxiliary cable (60) of a given length to the free end (21) of the lifting cable (20), said auxiliary cable (60) being integrated into the auxiliary traction system (6);and - pull the free end (21) of the lifting cable (20) by means of the auxiliary traction system (6), via the auxiliary cable (60), and then fix this free end (21) of the lifting cable (20) in accordance with the final configuration; - detach the auxiliary cable (60) from the free end (21) of the lifting cable (20).

10. A pulley system according to claim 9, wherein the pulley (4) is supported by the support which is a ground support (50), after lowering the pulley (4) to this ground support (50), and the pulley system comprises: - after passing the lifting cable (20) under the pulley (41) and before attaching the auxiliary cable (60), attaching an anchoring member (52) to the lifting cable (20) and putting in place at least one flexible link (53) which connects the anchoring member (52) to the pulley (4) or which connects the free end (21) of the lifting cable (20) to the pulley (4) or to the anchoring member (52), then operating the lifting winch (2) upwards to raise the pulley (4), said anchoring member (52) being arranged to keep the pulley (4) held by the lifting cable (20); - once in the final configuration, detach and remove the anchoring device (52) from the lifting cable (20).

11. A pulley system according to claim 9 or 10, wherein the final configuration is the two-strand configuration and in this case the auxiliary cable (60) is fixed directly to the free end (21) of the lifting cable (20), so that the free end (21) of the lifting cable (20) is pulled directly by the auxiliary cable (60) towards the anchor point (15) to be fixed therein in order to be in the two-strand configuration.

12. A pulley system according to claim 9 or 10, wherein the final configuration is the three-strand configuration and in this case the auxiliary cable (60) follows an auxiliary path which passes under an accessory pulley (64) mounted on the arrowhead (11), then passes over the secondary pulley (35) to finally be hooked onto the free end (21) of the lifting cable (20); and the free end (21) of the lifting cable (20) is pulled by the auxiliary cable (60) and thus passes over the secondary pulley (35) to finally be fixed onto the pulley block (4) to be in the three-strand configuration.

13. A pulley system according to any one of claims 8 to 12, comprising at least the following steps, for a pulley system change from an initial configuration, which is the two-strand or three-strand configuration, to the single-strand configuration: - with the pulley block (4) supported by the support (50; 51), operate the lifting winch (2) downwards to slacken the lifting cable (20) while leaving the pulley block (4) in its fixed position; - unhook the free end (21) of the lifting cable (20) in accordance with the initial configuration; - operate the lifting winch (2) upwards to bring the lifting cable (20) back so that it no longer passes under the pulley block (41); - fix the free end (21) of the lifting cable (20) on the pulley block (4) in accordance with the single-strand configuration.

14. A pulley system according to any one of claims 8 to 13, comprising at least the following steps for a pulley system change from a two-leg configuration to a three-leg configuration: - the pulley (4) is supported by the support which includes at least one sling (51) fixed to the boom tip (11) and to the pulley (4), so that the pulley (4) is suspended below the boom tip (11); - the lifting winch (2) is operated downwards to slacken the lifting cable (20) while leaving the pulley (4) in its fixed position; - the free end (21) of the lifting cable (20) is unhooked from the anchor point (15);- attach an auxiliary cable (60) of a given length to the free end (21) of the lifting cable (20), said auxiliary cable (60) being integrated into the auxiliary traction system (6) and following an auxiliary path which passes under an accessory pulley (64) mounted on the boom tip (11), then passes over the secondary pulley (35) to finally be hooked onto the free end (21) of the lifting cable (20); and - pull on the free end (21) of the lifting cable (20) by means of the auxiliary traction system (6), via the auxiliary cable (60), to pass over the secondary pulley (35) and finally be fixed onto the block (4) to be in the three-strand configuration; - detach the auxiliary cable (60) from the free end (21) of the lifting cable (20).

15. A pulley system according to any one of claims 8 to 14, comprising at least the following steps for a pulley system change from a three-leg configuration to a two-leg configuration: - the pulley (4) is supported by the support which includes at least one sling (51) fixed to the boom tip (11) and to the pulley (4), so that the pulley (4) is suspended below the boom tip (11); - the lifting winch (2) is operated downwards to slacken the lifting cable (20) while leaving the pulley (4) in its fixed position; - the free end (21) of the lifting cable (20) is unhooked from the pulley (4); - fix an auxiliary cable (60) having a given length on the free end (21) of the lifting cable (20), said auxiliary cable (60) being integrated into the auxiliary traction system (6) and passing under an accessory pulley (64) mounted on the end of the boom (11);- operate the lifting winch (2) upwards to bring the lifting cable (20) back so that it no longer passes over the secondary pulley (35) and so that the auxiliary cable (60) passes over the main pulley (32) to hold the free end (21) of the lifting cable (20); - fix the free end (21) of the lifting cable (20) on the anchor point (15) provided on the arrow tip (11) to be in the two-strand configuration; - detach the auxiliary cable (60) from the free end (21) of the lifting cable (20).

Images