DOUBLE JIB SLEWING PEDESTAL CRANE

Abstract

The present invention relates to a double jib slewing pedestal crane comprising a main jib and a secondary jib, and a secondary jib positioning device to support and position the secondary jib with respect to the main jib and actuate the pivotal movement of the secondary jib. The secondary jib positioning device comprises a secondary jib positioning cable; a spoke structure fixed to the secondary jib and extending radially outward; a tension chain connected at one end to the secondary jib positioning cable and at the other end to the secondary jib and/or to the spoke structure, wherein the spoke structure is adapted to support the tension chain.

Claims

1. Double jib slewing pedestal crane comprising: a stationary pedestal, preferably adapted to be mounted to a vessel; a crane housing that is mounted to the pedestal and adapted to slew relative to the pedestal about a vertical slew axis; a main jib comprising an outer end and an opposed inner end which is connected pivotably about a first horizontal pivot axis to the crane housing, allowing an up-and-down luffing movement of the main jib; a luffing assembly comprising a luffing winch and a luffing cable extending between the main jib and the crane housing; and a secondary jib comprising an outer end and an opposed inner end connected pivotably about a second horizontal pivot axis to the outer end of the main jib, allowing a pivotal movement of the secondary jib with respect to the main jib; an object suspension device to which an object is connectable; a hoist assembly comprising a hoist winch and an associated hoisting cable; wherein the secondary jib is provided with a hoist cable departing sheave at the outer end and a first mounting facility for a hoist cable retention device close to the inner end and a second mounting facility for a hoist cable retention device between the inner and the outer end, allowing the hoisting cable to extend from the hoist winch, via the departing sheave and via the object suspension device to a hoist cable retention device, such that the hoisting cable comprises one or more first suspension cable parts extending between the object suspension device and the departing sheave, and one or more second suspension cable parts extending between the object suspension cable device and the hoist cable retention device, such that the first and second suspension cable parts extend at a relatively large angle with respect to each other when the hoist cable retention device is mounted at the first mounting facility, and at a relatively small angle with respect to each other when the hoist cable retention device is mounted at the second mounting facility.

2. Double jib slewing pedestal crane according to claim 1, wherein the hoist cable retention device is provided on a trolley and the secondary jib is provided with a rail for the trolley, extending between the first and second mounting facility, allowing the hoist cable retention device to move along the secondary jib, thereby changing the angle between the first and second suspension cable parts.

3. Double jib slewing pedestal crane according to claim 1, wherein the hoisting cable has a dead end connected to the hoist cable retention device.

4. Double jib slewing pedestal crane according to claim 1, wherein the hoist cable retention device is embodied as a guide sheave.

5. Double jib slewing pedestal crane according to claim 1, wherein the hoist cable retention device is embodied as a second hoist winch.

6. Double jib slewing pedestal crane according to claim 1, wherein the second mounting facility is arranged half-way between the inner end and the outer end of the secondary jib.

7. Double jib slewing pedestal crane according to claim 1, wherein at least one of the first mounting facility and the second mounting facility is embodied as a hole or a set of holes.

8. Double jib slewing pedestal crane according to claim 7, wherein the hole or holes are provided in plates that form part of the secondary jib, which plates extend beyond a cross-sectional area of the secondary jib.

9. Vessel comprising a double jib slewing pedestal crane according to one of the preceding claims.

Description

[0074] The invention is further elucidated in the attached drawings, in which:

[0075] FIG. 1 shows a perspective view of a double jib slewing pedestal crane according to the present invention, wherein the secondary jib is positioned essentially in line with the main jib;

[0076] FIG. 2 shows a perspective view of the double jib slewing pedestal crane of FIG. 1, wherein the secondary jib includes a sharp angle with the main jib;

[0077] FIG. 3 shows a detail of the crane housing and hoisting cable of the double jib slewing pedestal crane of FIG. 1;

[0078] FIG. 4 shows a perspective top view of a detail of the double jib slewing pedestal crane in the position of FIG. 1;

[0079] FIG. 5 shows a perspective view from below of a detail of the double jib slewing pedestal crane in the position of FIG. 1;

[0080] FIG. 6 shows a perspective view of the double jib slewing pedestal crane of FIG. 1, wherein the secondary jib includes an even sharper angle with the main jib than shown in FIG. 2;

[0081] FIG. 7 shows a perspective view of the double jib slewing pedestal crane of FIG. 1, wherein the secondary jib includes an even sharper angle with the main jib than shown in FIG. 6.

[0082] In FIGS. 1-7 various positions and details of a double jib slewing pedestal crane according to both aspects of the present invention are shown. As all drawings relate to the same embodiment, the same reference numbers are used in all figures.

[0083] A double jib slewing pedestal crane 1 is shown in its entirety in FIGS. 1, 2, 6 and 7. The double jib slewing pedestal crane 1 according to both aspects of the invention comprises a stationary pedestal 2 which is adapted to be mounted to a vessel. On the pedestal 2, a hoisting cable guide 21 is provided, described in pending application NL 2009287.

[0084] A crane housing 3 is mounted to the pedestal 2 and adapted to slew relative to the pedestal 2 about a vertical slew axis R. The crane housing 3 of this embodiment is shaped as a closed vertical column tapering towards the top. The central axis of the crane housing 3 extends at a small angle of about 20 with respect to the vertical as visible in FIG. 2, to give room to the main jib 4. On the crane housing 3, an operator's cabin 22 is provided.

[0085] Attached to a lower portion of the crane housing 3 is the inner end of a main jib 4, which is connected pivotably about a first horizontal pivot axis 20 to the crane housing 3. The main jib 4 is here of a closed configuration, essentially box-shaped, including forked inner ends 4a and 4a, shown in detail in FIG. 3, and forked outer ends 4b and 4b, shown in detail in FIGS. 4 and 5. The main jib and the secondary jib may be of any possible configuration, e.g. one of them or both may have a truss-shaped framework, but alternatively it is also conceivable that one of them or both are formed as a closed box.

[0086] In order to position the main jib 4, a luffing assembly 12 is provided, extending between the outer end 4b, 4b of the main jib 4, here in particular in the vicinity of the second pivot axis 11, and the crane housing 3, here an upper end 3a of the crane housing. The luffing assembly 12 comprises a luffing winch (not visible) and a luffing cable 12b. In particular in FIG. 4 it is visible that two parallel sets of luffing cable 12b extend to the outer end 4b and the outer end 4b of the main jib respectively. The luffing winch is preferably provided inside the crane housing.

[0087] Between and slightly below the forked inner ends 4a and 4a winches are mounted to the crane housing 3, in particular damping winches 23 and 23 to which damping cables 24 and 24 are connected, respectively. These damping devices comprising winches and cables may be connected to the object suspension device 9, to dampen sea-state induced motions of the object suspension device 9.

[0088] Furthermore, a winch 26 is provided, which actuates hoist cable 26a which is connected to a hook 26b. This assembly is e.g. provided for additional hoisting capacity, but can alternatively also be provided to assist in motion-compensation.

[0089] The advantage of the forked inner ends 4a and 4a is in particular visible in FIG. 7, in which it is visible that two platforms 30 and 40 mounted on a central part 3b of the crane housing protrude between the forked inner ends 4a and 4a. The functions of these platforms 30, 40 will be explained later.

[0090] Between the two forked outer ends 4b and 4b a jib axle 10 extends defining a second horizontal pivot axis 11, indicated in FIG. 4.

[0091] A secondary jib 5 is provided, comprising a forked inner end defining a left-hand fork end 5b and a right-hand fork end 5b, which are connected pivotably to the jib axle 10. In particular, in the shown embodiment, the forked inner end of the secondary jib is connected to the jib axle 10 between the forked outer ends 4b and 4b of the main jib. The pivot connection of the secondary jib 5 allows a pivotal movement of the secondary jib 5 with respect to the main jib 4. The secondary jib 5 of the shown embodiment is also of a closed box-shaped configuration, similar to that of the main jib 4. Between the left-hand fork end 5b and the right-hand fork ends 5b of the secondary jib 5 a guide sheave 15 for a hoisting cable 16 is received on the jib axle 10. This will be explained in more detail below.

[0092] The double jib slewing pedestal crane 1 further comprises a hoist assembly comprising a hoist traction winch, provided within the pedestal 2 and not visible here, extending to a hoist wire storage winch 17 which is in the shown embodiment is provided below the pedestal 2, preferably below deck in the hull of a vessel (not shown). From the hoist wire storage winch 17 a hoisting cable 16 extends, which extends via a sheave 18 provided below the pedestal 2 into the crane housing 3. Heave compensation is indicated with reference number 13. Via a sheave 19 mounted onto the crane housing 3 the hoisting cable 16 extends to the jib axle 10, where guide sheave 15 is provided. Sheave 19, in detail shown in FIG. 3, is surrounded by a platform 30, which, in an upright position of the main jib 4, falls between the forked inner ends 4a, 4a of the main jib. From guide sheave 15, the hoisting cable 16 extends over the secondary jib 5 via a departure sheave 14 on the secondary jib 5, in particular provided at the outer end 5a of the secondary jib, to an object suspension device 9. From FIGS. 4 and 5 it is visible that the outer end 5a of the secondary jib 5 is also forked, as the departure sheave 14 of the shown embodiment is provided between these forked outer ends. Other configurations are also conceivable. The position of sheave 19 halfway the crane housing 3 is advantageous as it causes the hoist cable to enter the crane housing in the axis of rotation R of the crane housing, enabling the crane housing to slew without causing the hoisting cable to entangle or get twisted.

[0093] In order to position the secondary jib 5 with respect to the main jib 4, according to the first aspect of the invention a secondary jib positioning winch (not shown) cooperating with a secondary jib positioning cable 31 is provided, extending between the crane housing 3 and a tension chain 32. The secondary jib positioning winch is preferably positioned inside the crane housing. In the shown embodiment the secondary jib positioning cable 31 departs the crane housing at a central part 3b thereof, in particular via a sheave block 33 provided in a central part 3b of the crane housing 3. In the shown embodiment, as in particular visible in FIG. 3, a platform 40 is connected to the central part 3b of the crane housing adjacent the sheave block 33.

[0094] The shown secondary jib positioning cable 31 comprises a combination of cables and sheaves, which can be actuated via a winch (not shown) to vary in length.

[0095] The secondary jib positioning device of the first aspect of the invention further comprises a tension chain 32, embodied as a series of multiple articulated interconnected rods, one end of which is pivotably connected to the secondary jib positioning cable 31 about pivot 32b. Tension chain 32 is supported by a spoke structure 50, and extends to and is pivotably connected to this spoke structure 50 about pivot 32a.

[0096] The spoke structure 50 is fixed to the secondary jib 5 and extends radially outward from the jib axle 10, and is pivotable together with the secondary jib 5 about the second pivot axis 11. The spoke structure 50 of the shown embodiment comprises spokes 51, 52a, 52b, 53a and 53b, extending essentially in a quarter of a circle, defined between the upward perpendicular direction with respect to the secondary jib, and a direction essentially opposite the secondary jib. The spokes differ in length.

[0097] In the shown embodiment, first spoke 51 extends essentially in an upward perpendicular direction with respect to the secondary jib 5. In particular, spoke 51 includes a first angle 1, indicated in FIG. 6, with secondary jib 5. This angle 1 is preferably between 45-130, more preferably between 70-110, in particular between 80-100.

[0098] Parallel right-hand third spoke 53a and left-hand third spoke 53b extend in a direction essentially opposite the secondary jib 5, and includes a third angle 3, indicated in FIG. 6, with secondary jib 5. This angle 3 is preferably between 160-210.

[0099] Parallel right-hand and left-hand second spokes 52a, 52b are provided therebetween, and include a second angle 2, for clarity indicated not in FIG. 6 but in FIG. 7, with secondary jib 5. This second angle 2 is preferably between 110-180, in particular between 130-160.

[0100] The spokes 52, 53 of the spoke structure are composed of right-hand spokes 52a, 53a, attached to the right-hand fork end 5b, and left-hand spokes 52b, 53b, attached to the left-hand fork end 5b. Between the right-hand spokes 52a, 53a and the left-hand spokes 52b, 53b a space 55 is defined, indicated in FIG. 4, in which the guide sheave 15 is provided and through which the hoisting cable 16 extends. The right-hand spokes 52a, 53a are mutually connected via a strut 54a. Likewise, the left-hand spokes 52b, 53b are mutually connected via a strut 54b.

[0101] In the shown embodiment, the first spoke 51 has a forked inner end 51a, wherein the hoisting cable 16 extends between the forked ends from the guide sheave 15 to the departing sheave 14. In an alternative configuration, it is not required to provide such a forked inner end 51a.

[0102] In the shown embodiment, the tension chain 32 is pivotably connected at one end via pivot 32b to the secondary jib positioning cable 31 and is connected at the other end via pivot 32a to the spoke structure 50, in particular to the radial outer end 51b of the first spoke 51. In addition, a tension link 55 is provided between the radial outer end 51b of the first spoke 51 and the outer end 5a of the secondary jib 5. This tension link 55 is embodied similar to the tension chain 32. As in the shown embodiment the tension chain 32 is connected to the radial outer end 51b, the tension link 55 is a different part of the construction. In an alternative embodiment, the tension chain 32 is not connected to the spoke structure, but to the outer end 5a of the jib. In this case, the tension chain 32 comprises a link similar to tension link 55, which in this embodiment is thus part of the tension chain. The tension chain 32 is supported by the spoke structure.

[0103] In the shown embodiment, the radial outer ends of the second spokes 52a,b, as visible in particular in FIG. 4, are provided with seats 52a and 52b for receiving a pivot 32c of the tension chain. Adjacent the seats, guide plates 52a and 52b are optionally provided to guide and position the pivot 32c correctly onto the seats. This is in particular advantageous as the tension chain 32 is inherently susceptible to play, and hence the exact position of the pivot 32c is variable. At the radial outer ends 53 of the third spokes 53a,b guide plates 53a and 53b for pivot 32b of the tension chain 32 are visible in FIG. 4.

[0104] In the position of the main boom 4 and jib 5 of FIGS. 6 and 7, wherein the main jib 4 and the secondary jib 5 include an acute angle, tension chain 32 is supported by the first, second and third spokes 51, 52a,b and 53a,b. In the position shown in FIGS. 2 and 4, wherein the main jib 4 and the secondary jib 5 include an obtuse angle, the tension chain 32 is no longer supported by the third spokes 53a,b. In the position shown in FIG. 1, wherein the main jib 4 and the secondary jib 5 extend almost in line with each other, it can be discerned that the tension chain 32 is no longer supported by the third spokes 53a,b, and not by the second spokes 52a,b.

[0105] As indicated above, the main jib 4 has forked outer ends 4b, 4b, visible in detail in FIGS. 4 and 5. The length of these forked outer ends 4b, 4b of the main jib 4 is such that the gap between the forked outer ends of the main jib allows to pass at least a portion of the spoke structure, in the shown embodiment at least the third right-hand spoke 53a and third left-hand spoke 53b. This passing through is visible in particular in FIG. 1.

[0106] The combination of secondary jib positioning cable 31, tension chain 32 and spoke structure 50 enables an accurate control of the position of the secondary jib 5 at a range of different positions with respect to the main jib 4: from an extended position in which the tip of the secondary extends mainly forward from the main jib, as visible in FIG. 1, to a folded position in which the secondary jib is folded back, essentially parallel along the main jib, as is visible in FIGS. 6 and 7.

[0107] In the drawings, also the second aspect of the invention is also visible. It is noted that the secondary jib positioning device of the first aspect of the invention is not required for the second aspect of the invention.

[0108] According to this second aspect of the invention, the secondary jib 5 is provided with a hoist cable departing sheave 14 at the outer end 5a and a first mounting facility 61 for a hoist cable retention device 60 close to the inner end 5a and a second mounting facility 62 for a hoist cable retention device 60 intermediate, here half-way, between the inner end 5b and the outer end 5a.

[0109] In the shown embodiment, the hoisting cable 16 extends from the hoist winch 17, via the departing sheave 14 and via the object suspension device 9 to a hoist cable retention device 60, such that the hoisting cable 16 comprises one or more first suspension cable parts 16a extending between the object suspension device 9 and the departing sheave 14, and one or more second suspension cable parts 16b extending between the object suspension cable device 9 and the hoist cable retention device 60. The first and second suspension cable parts 16a, 16b may extend at a relatively large angle with respect to each other when the hoist cable retention device is mounted at the first mounting facility 61, as visible in FIGS. 1, 4 and 5, and at a relatively small angle with respect to each other when the hoist cable retention device 60 is mounted at the second mounting facility 62, as visible in FIG. 2. This angle is not only determined by the mounting location of the hoist cable retention device 60, but also by the position of the object suspension device 9. Hence, although the angle may be relatively small when the hoist cable retention device 60 is mounted to the second mounting facility 62, compared to when it would be mounted to the first mounting facility 61, the angle may still be large as visible in FIG. 2. On the other hand, the angle will be small when the hoist cable retention device 60 is mounted to the first mounting facility 61, when the object suspension device 9 is lowered into the water, in particular deep water.

[0110] In the shown embodiment, the mounting facilities are embodied as holes, provided in plates that form part of the secondary jib 5. These plates extend beyond the cross-sectional area of the jib, and are provided solely for the purpose of the mounting facility.

[0111] The hoist cable retention device in the shown embodiment is a dead end connector. Alternatively, the hoist cable retention device could also be embodied as a guide sheave.