Luffing jib crane configurable in three pulley configurations: one, two, or three strands.

Abstract

A 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 at least two pulleys (32, 35) are mounted; - a block (4) held by the lifting cable and comprising a block and tackle pulley (41); and - a set of means for changing the block and tackle configuration between a single-leg, two-leg, and three-leg configuration, including a support for holding the block and tackle in a fixed position so that the lifting winch can be lowered to slacken the lifting cable, and an auxiliary traction system (6) mounted on the luffing jib for pulling on the free end (21) of the lifting cable. Figure 1

Description

Title of the invention: Luffing jib crane configurable in three pulley configurations, with one, two or three strands. Technical field

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

[0002] It also relates to a pulley system for changing the pulley system of the lifting cable of such a luffing jib crane. Prior art

[0003] Typically, a luffing jib crane comprises a luffing jib equipped with a jib tip and a jib foot articulated for rotation about a horizontal axis at the top of a mast, so that the jib can be raised and lowered. This crane also includes a lifting winch, generally positioned on a counter-jib, coupled to a lifting cable that passes over at least one jib pulley positioned on the jib tip to support a block equipped with a hooking device for attaching a load; this block having a pulley block below which the lifting cable can pass.

[0004] It is further 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 tackle pulley and its free end is fixed on an anchor point provided on the boom tip.

[0005] Increasing the number of strands allows for lifting heavier loads, thus requiring a three-strand configuration. 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-power cranes designed for lifting heavy loads, which thus require particularly thick, heavy, and rigid lifting cables. Summary of the invention

[0006] One of the aims of the invention is to facilitate the operations of changing pulley systems, in particular between three pulley system configurations which are a one-strand configuration, a two-strand configuration and a three-strand configuration.

[0007] 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 in ascending order to raise the free end of the lifting cable and actuated in descending order 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.

[0008] This luffing jib crane also includes a block and tackle equipped with a hooking device for attaching a load (namely, a load suspended below the block and to be transported / lifted / moved). The block and tackle is held by the lifting cable and has a pulley block under which the lifting cable can pass. Thus, by operating the lifting winch, the block and tackle raises or lowers, either alone or with its suspended load.

[0009] The luffing jib crane includes a set of means for operating changes in the lifting cable pulley system between three pulley system 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 pulley block and its free end is fixed on an anchor point provided on the arrow point, so that the pulley 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 and tackle pulley, then goes up to pass over the secondary pulley and finally its free end is fixed on the block and tackle, so that the block and tackle is suspended by three strands of the lifting cable.

[0010] Thus, this luffing jib crane allows for three pulley configurations, which the crane operator can choose according to the weight of the load. It should be noted that the lifting cable passes over the main pulley regardless of the pulley configuration (in other words, in all three pulley configurations), while the lifting cable passes over the secondary pulley only in the three-strand configuration.

[0011] This set of means includes at least: - a support to hold the pulley block in a fixed position so that the lifting winch can be operated downwards to release the lifting cable while leaving the pulley block in its fixed position; - an auxiliary traction system mounted at least in part on the lifting boom and allowing to pull on the free end of the lifting cable.

[0012] 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 the pulley block to be changed without being hindered or constrained by its weight when handling and moving the lifting cable between two pulley block configurations. Once the pulley block is supported by the support, it is then possible to slacken the lifting cable (by lowering the lifting winch) and thus more easily detach, pull, handle, and attach it.

[0013] 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 by means of the auxiliary traction system, the lifting winch must be simultaneously operated in a downward direction to unwind the lifting cable and thus assist the movement.

[0014] According to one feature, the support is chosen from: - a ground support on which the pulley block can rest; and - at least one sling having a given length and which can be fixed on the arrowhead and on the pulley block in order to suspend the pulley block under the arrowhead.

[0015] Thus, the pulley block can be lowered to rest on the support on the ground, thereby allowing the previously slack lifting cable to be handled on the ground. Alternatively, the pulley block can be suspended below the boom tip by means of at least one sling, thus allowing the previously slack lifting cable to be handled at height.

[0016] According to one possibility, the at least one sling comprises a single sling.

[0017] According to another possibility, the at least one sling comprises two slings intended to be fixed on each side of the pulley block.

[0018] Also, instead of a single sling, it is possible to use two slings and to fix one on each side of the pulley block, so as to promote the balancing of the pulley block thus suspended by the two slings during the operations.

[0019] According to one possibility, the auxiliary traction system includes an auxiliary cable having a given length and which can be fixed on the free end of the lifting cable so as to be able to pull on the free end of the lifting cable by means of the auxiliary cable.

[0020] 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.

[0021] 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.

[0022] 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 scrap metal. It also facilitates the distribution of the weight of the auxiliary cable and the weight of the lifting cable, making it easier to pull on the free end of the lifting cable.

[0023] In a particular embodiment, the auxiliary traction system includes a traction actuator coupled to the auxiliary cable, such as, for example, a winch.

[0024] In this embodiment, the auxiliary traction system is either an assisted or motorized system, enabling it to pull on the auxiliary cable and thus on the lifting cable via the traction actuator. This auxiliary traction system may, for example, incorporate a winch, a hoist, a capstan, or a jib crane.

[0025] 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 indeed be suitable for a small crane with a lifting cable of small cross-section and therefore manageable by hand, so that the traction would be carried out manually by the operator, preferably by providing one or more pulleys to redirect the traction cable, thus facilitating manual traction.

[0026] It is of course also possible to provide one or more return pulleys for the traction cable in an assisted system or a motorized system.

[0027] According to another possibility, the crane includes at least one accessory pulley mounted on the boom tip and positioned below and behind the main pulley. If so, this accessory pulley is positioned below the auxiliary pulley.

[0028] 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.

[0029] In a particular embodiment, the means set includes an anchoring device adapted to be fixed on the lifting cable, and at least one flexible link allowing 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.

[0030] Such an anchoring device thus makes it possible to create a fixed point on the lifting cable, in order to move the pulley block more easily during configuration changes, This is especially true when the pulley block has been placed on the support on the ground and the free end of the lifting cable has been manipulated / unhooked. The flexible link, meanwhile, supports the pulley block or the free end of the lifting cable.

[0031] It is also possible to have a flexible link which connects the anchoring element 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 element, to facilitate the handling of this free end by an operator.

[0032] The invention also relates to a pulley system for making pulley changes of the lifting cable of a luffing jib crane as described above, in which the pulley system comprises at least: - supporting the pulley by the support in a fixed position so as to be able to operate the lifting winch downwards to release the lifting cable while leaving the pulley in its fixed position; - pull the free end of the lifting cable using the auxiliary traction system or operate the lifting winch upwards in order to change the configuration of the lifting cable.

[0033] When switching from the single-strand configuration to the two-strand or three-strand configuration, the auxiliary traction system is used to pull on the free end of the lifting cable in order to pass under the pulley block and to 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).

[0034] When switching from the two-strand or three-strand configuration to the one-strand configuration, the lifting winch is operated upwards in order 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 one-strand configuration).

[0035] In a particular embodiment, the pulley system comprises 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 loosen the lifting cable while leaving the pulley block in its fixed position; - detach the free end of the lifting cable from the pulley, then pass the lifting cable under the pulley block; - to 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.

[0036] After supporting the pulley with the support and before unhooking the free end of the lifting cable from the pulley, it may be necessary to pull on the lifting cable in order to unhook its free end from the pulley.

[0037] Indeed, in some cases, the weight of the upstream lifting cable is such that it leaves the free end of the lifting cable in tension on the pulley block, even if the pulley block is supported and even if the lifting cable has been relaxed by operating the lifting winch downwards.

[0038] According to one possibility, the lifting cable is pulled with the following steps, called 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 activated 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.

[0039] In a first embodiment, the pulley block is supported by the support, which is a ground support, after the pulley block has been lowered to this ground support, and the pulley block method comprises: - after passing the lifting cable under the pulley block and before attaching 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).

[0040] It is therefore conceivable to have a flexible link which connects the anchoring element 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 element, to facilitate the taking of this free end by an operator.

[0041] According to one possibility, when attaching the anchoring device to the lifting cable: - either the anchoring device is fixed to a descending section of the lifting cable positioned 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 pulley then being suspended on the anchoring device via the flexible link during the raising of the pulley; - either the anchoring device is fixed on a terminal section of the lifting cable arranged between the pulley block and its free end, the anchoring device coming to a stop against the pulley block during the raising of the pulley block, and the flexible link is put in place to connect the free end of the lifting cable to the pulley block or to the anchoring device.

[0042] In a second embodiment, the pulley is supported by the support which includes at least one sling fixed to the arrowhead and to the pulley (possibly two slings fixed to the arrowhead and to the pulley), so that the pulley is suspended below the arrowhead.

[0043] In this second embodiment, the block is supported by at least one sling (possibly by two slings to balance the block) 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 arrowhead, 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 pulley block (possibly until both slings are taut and support the pulley block).

[0044] 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.

[0045] According to a second variant, the final configuration is the three-strand configuration, and in this case the auxiliary cable follows an auxiliary path which passes under an accessory pulley mounted on the arrowhead, then passes 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 onto the block to be in the three-strand configuration.

[0046] In this second embodiment, the anchoring member is not necessary.

[0047] 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 loosen the lifting cable while leaving the pulley block in its fixed position; - detach the free end of the lifting cable in accordance with 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 onto the pulley block in accordance with the single-strand configuration.

[0048] Regarding the step of detaching the free end of the lifting cable in accordance with the initial configuration: - either it consists of detaching the free end of the lifting cable from the anchor point provided on the arrow tip if the initial configuration is the two-strand configuration; - either it consists of unhooking the free end of the lifting cable from the pulley if the initial configuration is the three-strand configuration.

[0049] 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 relief steps described above can be implemented.

[0050] In a particular embodiment, the pulley block is supported by the support which includes at least one sling fixed to the arrowhead and to the pulley block, so that the pulley block is suspended below the arrowhead.

[0051] 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).

[0052] It is nevertheless conceivable to use an anchoring device associated with a ground support for changing the pulley system from the two-strand or three-strand configuration to the one-strand configuration.

[0053] 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 back the lifting cable, 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.

[0054] Thus, the auxiliary cable can accompany the lifting cable and support part of its weight, thereby securing the operation.

[0055] In another particular embodiment, the pulley system comprises at least the following steps for a pulley system change from the two-strand configuration to the three-strand configuration: - 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; - the lifting winch is operated downwards to slacken the lifting cable while leaving the pulley block in its fixed position; - the free end of the lifting cable is detached from the anchor point; - to 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 boom 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 on the block to be in the three-strand configuration; - detach the auxiliary cable from the free end of the lifting cable.

[0056] 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 relief steps described above can be implemented.

[0057] In another embodiment, the pulley system comprises at least the following steps for a pulley system change from the three-strand configuration to the two-strand configuration: - 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; - the lifting winch is operated downwards to slacken the lifting cable while leaving the pulley block in its fixed position; - the free end of the lifting cable is detached from 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 passing under an accessory pulley mounted on the end of the boom; - 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 hold the free end of the lifting cable; - fix the free end of the lifting cable to the anchor point provided on the arrow tip to be in the two-strand configuration; - detach the auxiliary cable from the free end of the lifting cable.

[0058] 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 relief steps described above can be implemented. Brief description of the drawings

[0059] 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:

[0060] [Fig-1] is a schematic and partial view of a luffing jib crane, with a zoom on the arrowhead (top right) and a zoom on the main pulley and the secondary pulley (bottom right);

[0061] [Fig.2] is a schematic view illustrating three steps (a1a) to (a3) ​​for a change of pulley systems, starting from a single-strand configuration to a two-strand configuration;

[0062] [Fig.3] is a schematic view illustrating three steps (a4) to (a6), following the three steps (al) to (a3) ​​of [Fig.2], for a change of pulley system from the single-strand configuration to the two-strand configuration;

[0063] [Fig.4] is a schematic view illustrating three steps (a7) to (a9), following the three steps (a4) to (a6) of [Fig.3], for a change of pulley system from the single-strand configuration to the two-strand configuration;

[0064] [Fig. 5] is a schematic view illustrating three steps (bl) to (b3) for a change of pulley system from the single-strand configuration to the two-strand configuration, according to a variant of the implementation compared to the implementation of Figures 2 to 4;

[0065] [Fig.6] is a schematic view illustrating three steps (b4) to (b6), following the three steps (bl) to (b3) of [Fig.5], for a reeving change from the single-strand configuration to the two-strand configuration;

[0066] [Fig.7] is a schematic view illustrating three steps (b7) to (b9), following the three steps (b4) to (b6) of [Fig.6], for a reeving change from the single-strand configuration to the two-strand configuration;

[0067] [Fig.8] is a schematic view illustrating a final step (blO), following of the three steps (b7) to (b9) of [Fig.7], for a change of pulley system from the single-strand configuration to the two-strand configuration;

[0068] [Fig.9] is a schematic view illustrating two steps (c1) and (c2) for a change of pulley system from the single-strand configuration to the two-strand configuration, according to another embodiment variant compared to the embodiment of Figures 2 to 4 and the embodiment of Figures 5 to 8;

[0069] [Fig. 10] is a schematic view illustrating three steps (c3) to (c5), following the two steps (cl) and (c2) of [Fig.9], for a reeving change from the single-strand configuration to the two-strand configuration;

[0070] [Fig. 11] is a schematic view illustrating three steps (c6) to (c8), following the three steps (c3) to (c5) of [Fig. 10], for a reeving change from the single-strand configuration to the two-strand configuration;

[0071] [Fig. 12] is a schematic view illustrating three steps (dl) to (d3) for a reeving change from the one-strand configuration to the three-strand configuration;

[0072] [Fig. 13] is a schematic view illustrating three steps (d4) to (d6), following the three steps (d1) to (d3) of [Fig. 12], for a reeving change from the one-strand configuration to the three-strand configuration;

[0073] [Fig. 14] is a schematic view illustrating three steps (d7) to (d9), following the three steps (d4) to (d6) of [Fig. 13], for a change of pulley system from the one-strand configuration to the three-strand configuration;

[0074] [Fig. 15] is a schematic view illustrating three steps (el) to (e3) for a reeving change from the two-strand configuration to the three-strand configuration;

[0075] [Fig. 16] is a schematic view illustrating three steps (e4) to (e6), following the three steps (e1) to (e3) of [Fig. 15], for a change of pulley system from the two-strand configuration to the three-strand configuration; and

[0076] [Fig. 17] is a schematic view illustrating three steps (e7) to (e9), following the three steps (e4) to (e6) of [Fig. 16], for a change of pulley system from the two-strand configuration to the three-strand configuration.

[0077] [Detailed description of several embodiments of the invention]

[0078] With reference to [Fig. 1], a luffing jib crane 1 includes a luffing jib 10 equipped with a jib tip 11 and a jib foot 12 articulated for 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.

[0079] 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.

[0080] The jib tip 11 is successively equipped 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, and over which the lifting cable 20 passes, depending on the length of the luffing jib 10.

[0081] The boom tip 11 is also equipped with a secondary pulley 35 (clearly illustrated only in [Fig. 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; therefore, it is not visible in Figures 2 to 17. This secondary pulley 35 is located below and in front of the upper pulley 31.

[0082] The arrowhead 11 has an anchor point 15 located at the rear of the main pulley 32 and below the upper pulley 31.

[0083] 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.

[0084] The luffing jib crane 1 includes a block 4 equipped with a hooking device 40 (conventionally 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-strand configuration, not described hereafter, the block 4 would include another pulley block.

[0085] Three pulley configurations are possible with this luffing jib crane 1, namely: - a single-strand configuration (visible in [Fig.1], [Fig.2] step (al1), [Fig.5] step (bl) and [Fig.9] step (cl)) in which, at the output of the main pulley 32, the free end 21 of the lifting cable 20 is fixed on the pulley 4 (and more precisely fixed on the upper attachment point 43) so that the pulley 4 is suspended by a single strand of the lifting cable 20; - a two-strand configuration (visible in [Fig.4] step (a9), [Fig.8] step (blO), [Fig.11] step (c8) and [Fig.15] step (el)) in which, at the exit of the main pulley 32, the lifting cable 20 passes under the pulley block 41 and its free end 21 is fixed on the anchor point 15 provided on the arrow point 11, so that the pulley block 4 is suspended by two strands of the lifting cable 20; - a three-strand configuration (visible in [Fig. 14] step (d9) and [Fig. 17] step (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.

[0086] The luffing jib crane 1 includes a set of means for operating changes in the lifting cable 20 between the three pulley configurations.

[0087] This assembly includes a support 50, 51 for holding the pulley block 4 in a fixed position so that the lifting winch 2 can be lowered to slacken the lifting cable 20 while leaving the pulley block 4 in its fixed position. Thus, with the pulley block 4 supported by the bracket to remain in its fixed position, it is possible to lower the lifting winch 2 without moving the pulley block 4 (which remains in its fixed position), and therefore the lifting cable 20 slackens and provides slack, allowing it to be manipulated to change its configuration.

[0088] In the embodiments illustrated in [Fig.2] steps (a2) and (a3) ​​and in [Fig.5] 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.

[0089] In the embodiments illustrated in [Fig. 10] steps (c3) to (c5), in [Fig. 12] step (d3), in [Fig. 13] steps (d4) to (d6), in [Fig. 15] step (e3) and in [Fig. 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.

[0090] Advantageously, the at least one sling 51 comprises two slings 51 of the same length which can be fixed on the arrowhead 11 and on the block 4; with a sling 51 on the right fixed on the right side of the block 4 and on the right side of the arrowhead 11, and a sling 51 on the left fixed on the left side of the block 4 and on the left side of the arrowhead 11, so as to balance the suspension of the block 4 to remain straight during operations.

[0091] Once the pulley block 4 is suspended by the sling(s) 51, it is possible to operate the lifting winch 2 downwards without moving the pulley block 4 (which remains suspended), and therefore the lifting cable 20 slackens and becomes loose. In certain situations, it may be advantageous and necessary to assist the lifting cable 20 by relieving it 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.

[0092] 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.

[0093] This set of means includes an auxiliary traction system 6 mounted on the luffing boom 10 and allowing 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 which is coupled to a traction actuator 61, such as a winch. In a manual variant, a traction actuator 61 may not be provided in order to pull the traction cable 60 by hand. The auxiliary cable 60 has a free end 62 which 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.

[0094] 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.

[0095] 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.

[0096] 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 may be in the form of a stirrup or a cleat 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.

[0097] The following description relates to the pulley system for making pulley changes of the lifting cable 20 of the luffing jib crane 1 described above, with several embodiment examples illustrated in Figures 2 to 17.

[0098] Figures 2 to 4 illustrate a first method for a reeving change from the single-strand configuration to the two-strand configuration, and which implements the following steps (al1) to (a9).

[0099] In a first step (al) illustrated in [Fig.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.

[0100] In a second step (a2) illustrated in [Fig. 2], the lifting winch is operated downwards to lower the pulley block 4 until the pulley block 4 is supported by the floor support 50 in a fixed position. Once the pulley block 4 is supported by the floor 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 floor support 50.

[0101] In a third step (a3) ​​illustrated in [Fig.2], the free end 21 of the lifting cable 20 is detached from the block 4, then the lifting cable 20 is passed under the block 41 and then comes out of the block 4. The lifting cable 20 thus has a terminal section 22 which protrudes from the block 4 and which is disposed between the block 41 and its free end 21.

[0102] In a fourth step (a4) illustrated in [Fig.3], the anchoring member 52 is fixed on the lifting cable 20, and more specifically the anchoring member 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 member 52).

[0103] In a fifth step (a5) illustrated in [Fig.3], the lifting winch is operated upwards to raise the pulley 4. During this raising of the pulley 4, the anchoring member 52 holds the pulley 4 held by the lifting cable 20. Indeed, the anchoring member 52 is in a butt against the frame 42 of the pulley 4 while the lifting winch pulls on the lifting cable 20 to raise the pulley 4.

[0104] In a sixth step (a6) illustrated in [Fig.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.

[0105] In a seventh step (a7) illustrated in [Fig. 4], the flexible link 53 is detached from the pulley block 4 (or alternatively from the anchoring member 52), while remaining attached at the end The free end 21 of the lifting cable 20 is then pulled. 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 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 accompany the movement.

[0106] In an eighth step (a8) illustrated in [Fig.4], the flexible link 53 is detached from the free end 21 of the lifting cable 20 and 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.

[0107] In a ninth step (a9) illustrated in [Fig.4], the anchoring member 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.

[0108] Figures 5 to 7 illustrate a second method for a reeving change from the single-strand configuration to the two-strand configuration, and which implements the following steps (bl) to (b 10).

[0109] In a first step (bl) illustrated in [Fig.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.

[0110] In a second step (b2) illustrated in [Fig. 5], the lifting winch is operated downwards to lower the pulley block 4 until the pulley block 4 is supported by the floor support 50 in a fixed position. Once the pulley block 4 is supported by the floor 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 floor support 50.

[0111] In a third step (b3) illustrated in [Fig. 5], the free end 21 of the lifting cable 20 is detached from the block 4, and then the lifting cable 20 is passed under the block and tackle pulley 41 and then exits the block 4. The lifting cable 20 thus has a terminal section 22 extending from the block 4 and located between the block and tackle pulley 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 and tackle pulley 41. Next, the anchoring device 52 is fixed to the lifting cable 20, and more specifically, the anchoring device 52 is fixed to the section descending 23, just above the pulley 4, and we put in place the flexible link 53 which connects the anchoring element 52 to the pulley 4; This flexible link 53 is in a slack state because it is longer than the distance between the pulley 4 and the anchoring device 52. The end section 22 is raised and fixed to the descending section 23 of the lifting cable 20 above the anchoring device 52 or is fixed to the anchoring device 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 device 52 or is fixed to the anchoring device 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 device 52 via another flexible link.

[0112] In a fourth step (b4) illustrated in [Fig.6], the lifting winch is operated upwards to raise the pulley 4. During this raising of the pulley 4, the anchoring member 52 holds the pulley 4 held by the lifting cable 20. Indeed, the pulley 4 is suspended from the anchoring member 52 by the flexible link 53.

[0113] In a fifth step (b5) illustrated in [Fig.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.

[0114] In a sixth step (b6) illustrated in [Fig.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 member 52; the terminal section 22 of the lifting cable 20 then passing into a slack state, while being held by the traction cable 60.

[0115] In a seventh step (b7) illustrated in [Fig. 7], the 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 in accordance with the two-strand configuration. While the traction cable 60 is pulling 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.

[0116] In an eighth step (b8) illustrated in [Fig.7], the auxiliary cable 60 is detached from the lifting cable 20.

[0117] In a ninth step (b9) illustrated in [Fig.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.

[0118] In a tenth step (blO) illustrated in [Fig.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.

[0119] Figures 9 to 11 illustrate a third method for a reeving change from the one-strand configuration to the two-strand configuration, and which implements the following steps (cl) to (c8).

[0120] In a first step (cl) illustrated in [Fig.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.

[0121] In a second step (c2) illustrated in [Fig.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.

[0122] In a third step (c3) illustrated in [Fig.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.

[0123] In a fourth step (c4) illustrated in [Fig. 10], once 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.

[0124] In a fifth step (c5) illustrated in [Fig. 10], the traction cable 60 is pulled, which 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 in accordance with the two-strand configuration. While the traction cable 60 is pulling 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.

[0125] 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.

[0126] In a sixth step (c6) illustrated in [Fig. 11], the auxiliary cable 60 is detached from the lifting cable 20.

[0127] In a seventh step (c7) illustrated in [Fig. 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.

[0128] In an eighth step (c8) illustrated in [Fig.11], at least one sling 51 is detached from the pulley 4 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.

[0129] Figures 12 to 14 illustrate a method for a reeving change from the one-strand configuration to the three-strand configuration, and which implements the following steps (d1) to (d9).

[0130] In a first step (dl) illustrated in [Fig. 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.

[0131] In a second step (d2) illustrated in [Fig.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.

[0132] In a third step (d3) illustrated in [Fig. 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.

[0133] In a fourth step (d4) illustrated in [Fig. 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.

[0134] In a fifth step (d5) illustrated in [Fig. 13], 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. The free end 62 of the traction cable 60 is then attached to the free end 21 of the lifting cable 20.

[0135] In a sixth step (d6) illustrated in [Fig. 13], 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 driven downwards to unwind the lifting cable 20 and thus accompany the movement.

[0136] In a seventh step (d7) illustrated in [Fig. 14], the auxiliary cable 60 is unhooked from the lifting cable 20 and the free end 21 of the lifting cable 20 is then hooked onto the pulley block 4, to be in the three-strand configuration.

[0137] In an eighth step (d8) illustrated in [Fig. 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.

[0138] In a ninth step (d9) illustrated in [Fig.14], at least one sling 51 is detached from the pulley 4 and 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.

[0139] Figures 15 to 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).

[0140] In a first step (el) illustrated in [Fig. 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 jib tip 11, in a given high position.

[0141] In a second step (e2) illustrated in [Fig.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.

[0142] In a third step (e3) illustrated in [Fig.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.

[0143] In a fourth step (e4) illustrated in [Fig. 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.

[0144] In a fifth step (e5) illustrated in [Fig.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.

[0145] In a sixth step (e6) illustrated in [Fig. 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 driven downwards to unwind the lifting cable 20 and thus accompany the movement.

[0146] In a seventh step (e7) illustrated in [Fig. 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 block 4, to be in the three-strand configuration.

[0147] In an eighth step (e8) illustrated in [Fig.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.

[0148] In a ninth step (e9) illustrated in [Fig.17], at least one sling 51 is detached from the pulley 4 and 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.

[0149] In general, to carry out the reverse configuration changes, it is sufficient to carry out the steps in reverse order.

[0150] A method for changing the pulley system from the two-strand configuration to the one-strand configuration can be described by referring to Figures 9 to 11, but this time read in reverse (for this reading, the arrows indicating cable movements should not be taken into account).

[0151] In a first step (c8) illustrated in [Fig. 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.

[0152] In a second step (c7) illustrated in [Fig. 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.

[0153] In a third step (c6) illustrated in [Fig.1 1], 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.

[0154] In a fourth step (c5) illustrated in [Fig. 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.

[0155] In a fifth step (c4) illustrated in [Fig.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.

[0156] In a sixth step (c3) illustrated in [Fig. 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 to the pulley block. 4 in accordance with the single-strand configuration, and the free end 62 of the traction cable 60 is detached from the lifting cable 20.

[0157] In a seventh step (c2) illustrated in [Fig.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.

[0158] In an eighth step (cl) illustrated in [Fig.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.

[0159] A method for changing the pulley system from the three-strand configuration to the one-strand configuration can be described by referring to Figures 12 to 14, but this time read in reverse (for this reading, the arrows indicating cable movements should not be taken into account).

[0160] In a first step (d9) illustrated in [Fig. 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.

[0161] In a second step (d8) illustrated in [Fig.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.

[0162] In a third step (d7) illustrated in [Fig. 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 put in place to follow an auxiliary path which passes first over the auxiliary pulley 63, then over the rear of the accessory pulley 64.

[0163] In a fourth step (d6) illustrated in [Fig. 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 4.

[0164] In a fifth step (d5) illustrated in [Fig. 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.

[0165] In a sixth step (d4) illustrated in [Fig. 13], the lifting winch is continued to be operated upwards to further 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 4 according to the single-strand configuration, and the free end 62 of the traction cable 60 is detached from the lifting cable 20.

[0166] In a seventh step (d3) illustrated in [Fig. 12], the traction cable 60 can be removed (but it can also remain in place, waiting).

[0167] In an eighth step (d2) illustrated in [Fig. 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.

[0168] In a ninth step (dl) illustrated in [Fig.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.

[0169] A method for changing the pulley system from the three-strand configuration to the two-strand configuration can be described by referring to Figures 15 to 17, but this time read in reverse (for this reading, the arrows indicating cable movements should not be taken into account).

[0170] In a first step (e9) illustrated in [Fig. 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 jib tip 11, in a given high position.

[0171] In a second step (e8) illustrated in [Fig.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.

[0172] In a third step (e7) illustrated in [Fig. 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.

[0173] In a fourth step (e6) illustrated in [Fig. 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 4.

[0174] In a fifth step (e5) illustrated in [Fig.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.

[0175] In a sixth step (e4) illustrated in [Fig. 16], the lifting winch is operated downwards to give slack, and then the free end 21 of the cable is fixed lifting 20 on anchor point 15 in accordance with the two-strand configuration, and the free end 62 of the traction cable 60 is detached from the lifting cable 20.

[0176] In a seventh step (e3) illustrated in [Fig. 15], the traction cable 60 can be removed (but it can also remain in place, waiting).

[0177] In an eighth step (e2) illustrated in [Fig.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.

[0178] In a ninth step (el) illustrated in [Fig.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. Demands 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 actuable in upward motion to raise the free end (21) of the lifting cable (20) and actuable in downward motion to lower the free end (21) of the lifting cable (20); - a lifting boom (10) equipped with a boom tip (11) on which are mounted a main pulley (32) over which passes the lifting cable (20) and a secondary pulley (35); - a pulley block (4) equipped with a hooking device (40) for hooking a load, in which said pulley block (4) is held by the lifting cable (20) and includes a pulley block (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 pulley block (41) and its free end is fixed on an anchor point (15) provided on the arrowhead (11), so that the pulley block (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 ascends to pass over the secondary pulley (35), and finally its free end (21) is fixed to the block and tackle (4), so that the block and tackle (4) is suspended by three strands of the lifting cable (20); in which the set of means comprises at least: - a support (50; 51) allowing the pulley (4) to be supported in a fixed position so that the lifting winch (2) can be operated downwards to release the lifting cable (20) while leaving the pulley (4) in its fixed position; - an auxiliary traction system (6) mounted at least in part on the lifting boom (10) and allowing to pull on the free end (21) of the lifting cable (20).

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 passes the auxiliary cable (60).

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 reeving method for performing reeving changes on the lifting cable (20) of a luffing jib crane (1) according to any one of the preceding claims, wherein the reeving method comprises at least: - support the pulley (4) by the support (50; 51) in a fixed position so that the lifting winch (2) can be operated downwards to relax the lifting cable (20) while leaving the pulley (4) in its fixed position; - pull the free end (21) of the lifting cable (20) by means of the auxiliary traction system (6) or operate 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 either a two-strand or a 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 block (4) is supported by the support, which is a ground support (50), after lowering the pulley block (4) to this ground support (50), and the pulley system comprises: - after passing the lifting cable (20) under the pulley block (41) and before securing the auxiliary cable (60), attaching an anchoring device (52) to the lifting cable (20) and installing at least one flexible link (53) that connects the anchoring device (52) to the pulley block (4) or that connects the free end (21) of the lifting cable (20) to the pulley block (4) or to the anchoring device (52), then operating the lifting winch (2) upwards to raise the pulley block (4), said device anchorage (52) being arranged to hold the pulley (4) held by the lifting cable (20); - once in the final configuration, detach and remove the anchorage (52) from the lifting cable (20).

11. A pulley system according to claim 10, wherein, when attaching the anchoring member (52) to the lifting cable (20): - either the anchoring member (52) is attached to a descending section of the lifting cable (20) disposed between the main pulley (32) and the pulley (41), the flexible link (53) is put in place to connect the anchoring member (52) to the pulley (4), and the free end (21) of the lifting cable (20) is attached to this descending section of the lifting cable (20) or to the anchoring member (52), the pulley (4) then being suspended on the anchoring member (52) via the flexible link (53) during the raising of the pulley (4);- either the anchoring device (52) is fixed on a terminal section of the lifting cable (20) arranged between the pulley block (41) and its free end, the anchoring device (52) coming to a stop against the pulley block (4) during the raising of the pulley block (4), and the flexible link (53) is put in place to connect the free end (21) of the lifting cable (20) to the pulley block (4) or to the anchoring device (52).;

12. A pulley system according to claim 9, wherein the pulley (4) is supported by the support which includes at least one sling (51) fixed to the arrowhead (11) and to the pulley (4), so that the pulley (4) is suspended below the arrowhead (11).

13. A pulley system according to claim 12, wherein the pulley (4) is supported by at least one sling (51) by operating as follows, starting from the single-strand configuration: - operate the lifting winch (2) upwards to a given high position; - fix at least one sling (51) between the pulley (4) and the jib tip (11), the high position being such that at least one sling (51) is slack in this high position; - operate the lifting winch (2) downwards at least until at least one sling (51) is taut and supports the pulley (4).

14. A pulley system according to any one of claims 9 to 13, 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), such 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 there in order to be in the two-strand configuration.

15. A pulley system according to any one of claims 9 to 13, 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 jib tip (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.

16. A pulley system according to any one of claims 8 to 15, comprising at least the following steps, for a pulley system change from an initial configuration which is the two-strand configuration or the three-strand configuration, to the single-strand configuration: - the pulley (4) being 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; - 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 (41); - fix the free end (21) of the lifting cable (20) on the pulley (4) in accordance with the single-strand configuration.

17. A pulley system according to claim 16, wherein the pulley (4) is supported by the support which includes at least one sling (51) fixed to the arrowhead (11) and to the pulley (4), so that the pulley (4) is suspended below the arrowhead (11).

18. A pulley system according to claim 17, wherein the pulley (4) is supported by at least one sling (51) by operating as follows, starting from the initial configuration: - operate the lifting winch (2) upwards to a given high position; - fix at least one sling (51) between the block (4) and the arrowhead (11), the high position being such that at least one sling (51) is slack in this high position; - operate the lifting winch (2) downward at least until at least one sling (51) is taut and supports the block (4).

19. A pulley system according to any one of claims 16 to 18, wherein: - before unhooking the free end (21) of the lifting cable (20) in accordance with the initial configuration, the free end (21) of the lifting cable (20) is attached to an auxiliary cable (60), said auxiliary cable (60) being integrated into the auxiliary traction system (6); - when the lifting winch (2) is operated upwards to bring back the lifting cable (20), the auxiliary traction system (6) allows the auxiliary cable (60) to run out to follow the lifting cable (20); - once in the single-strand configuration, the auxiliary cable (60) is unhooked from the free end (21) of the lifting cable (20).

20. A pulley system according to any one of claims 8 to 19, 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);- to attach an auxiliary cable (60) having 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 - to pull on the free end (21) of the lifting cable (20) by means of the auxiliary traction system (6), via the cable; auxiliary (60), to pass over the secondary pulley (35) and finally to be fixed on the pulley block (4) to be in the three-strand configuration; - unhook the auxiliary cable (60) from the free end (21) of the lifting cable (20).

21. A pulley system according to any one of claims 8 to 20, comprising at least the following steps for a pulley system change from the three-leg configuration to the 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 tip of the boom (il);- 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 arrowhead (11) to be in the two-strand configuration; - detach the auxiliary cable (60) from the free end (21) of the lifting cable (20).

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