Method for assembling a crane and method for operating a crane

Abstract

A method for assembling a crane that comprises erecting an upright ballast mast with a back mast top slide that is movable along the ballast mast and constructing a back mast using the upright ballast mast. This comprises the steps of providing a back mast upper section, multiple back mast intermediate sections, and a back mast lower section. The method also comprises connecting a part of the back mast including at least the back mast upper section, and possibly further including one or more pre-connected intermediate sections, to the back mast top slide. The part of the back mast that has been connected to the back mast top slide is stepwise extended by attaching further back mast intermediate sections and the back mast lower section. During the extension of the back mast the back mast top slide is stepwise raised along the upright ballast mast.

Claims

1. A method for assembling a crane, which crane comprises a main boom, a back mast and a ballast mast, said back mast having in an assembled state a foot end and a ballast mast end, said main boom having in an assembled state a foot end and a load end, wherein both the main boom foot end and the back mast foot end are pivotably connected to a mast foot assembly, and wherein the ballast mast end of the back mast is pivotably connected to the ballast mast, which method comprises the following steps: erecting the ballast mast with a back mast top slide that is movable along the ballast mast and which back mast top slide is fixable in a plurality of positions relative to the ballast mast, constructing the back mast using the ballast mast, which comprises the following steps: providing a back mast upper section, which has a length that is shorter than the final length of the back mast, and which back mast upper section has a ballast mast side end and a back mast side end, providing multiple back mast intermediate sections, which each have a length that is shorter than the final length of the back mast, and each have a first end and a second end, providing a back mast lower section, which has a length that is shorter than the final length of the back mast, and which back mast lower section has a foot side end and a back mast side end, connecting a part of the back mast including at least the back mast upper section, and further including one or more pre-connected intermediate sections, to the back mast top slide, stepwise extending the part of the back mast that has been connected to the back mast top slide by attaching further back mast intermediate sections and the back mast lower section, and stepwise raising the back mast top slide along the ballast mast during the extending of the back mast.

2. The method according to claim 1, wherein during the extending of the back mast, the part of the back mast connected to the back mast top slide is also held by a surface based crane.

3. The method according to claim 1, wherein the extending of the part of the back mast connected to the back mast top slide by a further intermediate section involves making a pivotal connection of said further intermediate section to said part of the back mast and then raising the back mast top slide along the upright ballast mast so as to align the further intermediate section with said part of the back mast and then fixing said intermediate section to said part of the back mast.

4. The method according to claim 1, wherein the back mast lower section is pivotally connected to the part of the back mast connected to the back mast top slide and also to the mast foot assembly, of the crane, where after the back mast top slide is raised along the ballast mast, so that the back mast lower section is aligned with said part of the back mast, where after the back mast lower section is fixed to said part of the back mast.

5. The method according to claim 1, wherein the back mast top slide is moved a step upwards along the upright ballast mast after pivotably connecting the back mast upper section to the back mast top slide, but before further extending the back mast by connecting a further back mast intermediate section to the back mast side end of the back mast upper section.

6. The method according to claim 1, wherein during the stepwise raising of the back mast top slide, said slide is periodically fixed relative to the ballast mast in positions thereof along the ballast mast.

7. The method according to claim 6, wherein the back mast top slide comprises a fastening pin and the ballast mast comprises holes at differing heights to receive the fastening pin therein.

8. The method according to claim 1, wherein erecting said ballast mast comprises the following steps: arranging a ballast mast support on a surface on which the crane is assembled, placing ballast on said arranged ballast mast support, providing a first ballast mast section, which first ballast mast section has a length which is shorter than the final length of the ballast mast to be constructed, arranging the first ballast mast section on top of the ballast mast support in an upright position, providing a second ballast mast section, which second ballast mast section has a section length which is shorter than the length of the ballast mast to be constructed, fixing the second ballast mast section on top of the first ballast mast section in an upright direction, providing one or more further ballast mast sections, and stepwise extending the ballast mast until a desired length of the ballast mast has been obtained.

9. The method according to claim 8, wherein use is made of an auxiliary climbing crane to lift a ballast mast section onto the top of the ballast mast, said climbing crane stepwise climbing upwards as the ballast mast is extended.

10. The method according to claim 1, wherein the method comprises the assembling of the main boom which comprises the following steps: providing a main boom lower section, which has a length that is shorter than the final length of the main boom, and which main boom lower section has a foot side end and a main boom side end, providing multiple main boom intermediate sections, which each have a length that is shorter than the final length of the main boom, and which main boom intermediate sections each have a first end and a second end, providing a main boom top section, which has a length that is shorter than the final length of the main boom, and stepwise completing the main boom by interconnection of said lower, intermediate, and top sections of the main boom.

11. The method according to claim 10, wherein assembling of the main boom comprises the use of a mast section guide that is held by and extends along the completed back mast, said mast section guide having an upper end and a lower end, wherein main boom sections are successively made to engage with said mast section guide at one of said upper end and lower end thereof, and are displaced there along towards the other end so as to stack said main boom sections end to end, said main boom sections being fixed to each other so as to complete the main boom.

12. The method according to claim 11, wherein the lower main boom section is connected pivotably to a mast foot assembly of the crane, and wherein further main boom sections are engaged with the mast section guide via the upper end of the mast section guide, said further main boom sections being connected to the lower main boom section.

13. The method according to claim 12, wherein said further main boom sections are engaged with the mast section guide via the upper end of the mast section guide using an auxiliary crane mounted on the ballast mast.

14. The method according to claim 11, wherein the main boom section is engaged with the mast section guide via the lower end of the mast section guide.

15. The method according to claim 11, wherein the completely assembled main boom is released from the mast section guide or the mast section guide is released from the back mast whilst remaining connected to the main boom, and wherein the main boom is tilted away from the back mast into an operation main boom position.

16. The method according to claim 11, wherein the main boom section is engaged with the mast section guide via the lower end of the mast section guide using a surface based auxiliary crane.

17. The method according to claim 11, wherein the main boom section is engaged with the mast section guide via the lower end of the mast section guide, the lower end of the mast section guide comprising an actuator device adapted to push main boom sections upward along the mast section guide.

18. The method according to claim 1, wherein the back mast and the main boom are of the same shape and of the same length.

19. The method according to claim 1, wherein the ballast mast comprises triangular cross-section mast sections, each having an elongated element at a corner of said triangular cross-section, wherein the back mast top slide moves along a top slider guide section that forms or is secured to one or said elongated elements.

20. The method according to claim 19, wherein said top slider guide section is adapted to act as a tensile force connection between said back mast top slide and a ballast.

21. The method according to claim 19, wherein said top slider guide section is adapted to act as a tensile force connection between the back mast top slide and a ballast, the top slider guide section forming the primary or sole tensile connector between the back mast top slide and the ballast.

22. The method according to claim 1, wherein use is made of a climbing device between the ballast mast and the back mast top slide in order to displace the back mast top slide along the ballast mast, and wherein, said climbing device is operated to lift the ballast mast.

23. The method according to claim 1, wherein use is made of a climbing device between the ballast mast and the back mast top slide in order to displace the back mast top slide along the ballast mast, and wherein, said climbing device is operated to lift the ballast mast when the ballast mast is detached from the ballast mast support in a process of relocating the ballast mast.

24. A method for assembling a crane, which crane comprises a main boom and a back mast, wherein the main boom and the back mast are each pivotably connected to a mast foot assembly of the crane, which method comprises the following steps: arranging the back mast at an incline relative to a surface on which the crane is assembled, said back mast being provided with a mast section guide that extends along and is held by the back mast, said mast section guide having an upper end and a lower end, providing a main boom lower section, which has a length that is shorter than the final length of the main boom, and which main boom lower section has a foot side end and a main boom side end, providing multiple main boom intermediate sections, which each have a length that is shorter than the final length of the main boom, and which main boom intermediate sections each have a first end and a second end, and providing a main boom top section, has a length that is shorter than the final length of the main boom, wherein main boom sections are successively made to engage with said mast section guide at one of said upper end and lower end of the mast section guide, and are displaced along said mast section guide so as to stack said main boom sections end to end, said main boom sections being fixed to each other so as to complete the main boom.

25. The method according to claim 24, wherein the lower main boom section is connected pivotally to the mast foot assembly of the crane, and wherein further main boom sections are engaged with the mast section guide via the upper end of said mast section guide, said further main boom sections being connected to the lower main boom section.

26. The method according to claim 24, wherein the main boom section is engaged with the mast section guide via the lower end of said mast section guide.

27. The method according to claim 26, wherein the main boom is extended beyond the top end of the back mast so as to assemble the main boom longer than said back mast.

28. The method according to claim 24, wherein the completed main boom is released from the mast section guide or the mast section guide is released from the back mast whilst remaining connected to the main boom, and wherein the main boom is tilted away from the back mast into an operational main boom position.

29. The method according to claim 24, wherein the lower main boom section is connected pivotably to the mast foot assembly of the crane, and wherein further main boom sections are engaged with the mast section guide via the upper end of said mast section guide by using an auxiliary crane mounted on a ballast mast that supports the back mast at a top end of the back mast, said further main boom sections being connected to the lower main boom section.

30. The method according to claim 24, wherein the lower main boom section is connected pivotably to the mast foot assembly of the crane, and wherein further main boom sections are engaged with the mast section guide via the upper end of said mast section guide by using a climbing crane in assembly of the back mast, the further main boom sections being connected to the lower main boom section.

31. The method according to claim 24, wherein the main boom section is engaged with the mast section guide via the lower end of said mast section guide by using a surface based auxiliary crane.

32. The method according to claim 24, wherein the main boom section is engaged with the mast section guide via the lower end of said mast section guide, an actuator device arranged near the lower end of said mast section guide, the actuator device adapted and operated to push main boom sections upward along the mast section guide.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The various aspects of the invention will be described in more detail below with reference to the figures, in which in a non-limiting manner exemplary embodiments of the invention will be shown.

(2) FIG. 1: schematically illustrates an example of a crane which can be assembled by the first and/or second aspect of the invention, and which can be used in accordance with the third aspect of the invention,

(3) FIG. 2-FIG. 7: schematically illustrate subsequent stages in an exemplary embodiment of the method according to the first aspect of the invention,

(4) FIG. 8-FIG. 12: schematically illustrate further subsequent stages in an exemplary embodiment of the method according to the first aspect of the invention, in which an exemplary embodiment of the second aspect of the invention is used,

(5) FIG. 13-FIG. 15: schematically illustrate subsequent stages of an example of an alternative method for assembling a main boom which can be used in combination with the method according to the first aspect of the invention,

(6) FIG. 16: schematically illustrates an exemplary embodiment a crane which can be used in an exemplary embodiment of a method according to the third aspect of the invention,

(7) FIG. 17: schematically illustrates a first stage in an exemplary embodiment of a method according to the third aspect of the invention,

(8) FIG. 18: schematically illustrates a subsequent stage in the exemplary embodiment as shown in FIG. 17,

(9) FIG. 19: schematically illustrates an alternative embodiment of the method according to the third aspect of the invention,

(10) FIG. 20: schematically illustrates an example in which a load is lifted with the first anchor connection being connected to the secondary anchor,

(11) FIG. 21: schematically illustrates the example of FIG. 21, with the load arranged at the first load position,

(12) FIG. 22: schematically illustrates a further possible embodiment of the method according to the third aspect of the invention,

(13) FIG. 23A and FIG. 23B schematically illustrate a ballast mast according to the invention and a detail thereof on a larger scale,

(14) FIG. 24 schematically illustrates in side view the ballast mast of FIG. 23A and FIG. 23B, the associated back mast slider, the top end of the back mast, and the connection of the guy wires,

(15) FIG. 25 schematically illustrates in horizontal cross section the ballast mast of FIG. 23A and FIG. 23B and an embodiment of the associated back mast slider,

(16) FIG. 26 schematically illustrates in horizontal cross section the ballast mast of FIG. 23A and FIG. 23B and an alternative embodiment of the associated back mast slider,

(17) FIG. 27A-FIG. 27E illustrate schematically a method of assembly of a subsection of a mast, e.g. back mast, and/or boom, of a crane,

(18) FIG. 28A-FIG. 28D illustrate schematically an operational method and preferred or optional details of a crane according to the invention,

(19) FIG. 29 illustrates schematically an A-shaped back mast or main boom of a crane according to the invention,

(20) FIG. 30 illustrates schematically a single leg back mast or main boom of a crane according to the invention,

(21) FIG. 31-FIG. 33 illustrate schematically an alternative embodiment of a ballast container in accordance with the invention for a crane, e.g. to be used in combination with a crane as described herein.

DETAILED DESCRIPTION OF THE INVENTION

(22) FIG. 1 schematically illustrates an example of a crane 1 which can be assembled by the first and/or second aspect of the invention, and which can be used in accordance with the third aspect of the invention.

(23) The crane 1 as shown in FIG. 1 comprises an upright or generally vertically arranged ballast mast 2. The crane 1 further comprises a back mast 3 and a main boom 5.

(24) The crane 1 has been assembled on a surface 12. The surface 12 is for example the ground, most common, or a floating vessel, e.g. a barge, a heavy lifting vessel.

(25) The ballast mast 2 is connected to a primary anchor which in this example is a ballast 6.

(26) For example the ballast 6 is composed of stacked ISO containers 6a filled with ballast material, e.g. sand and/or gravel, as is known in the art. An alternative embodiment of the ballast 6 will be discussed with reference to FIG. 31-FIG. 33.

(27) The ballast mast 2 is mounted on a ballast mast support 16, which, as is preferred also supports and/or is integrated with the ballast 6.

(28) As shown in FIG. 2 the ballast mast support 16 may comprise a ballast supporting floor 16a that rests on the surface 12, e.g. stationary and immobile or in a mobile manner, e.g. on a (skid) rail track, wheeled with surface engaging wheels, etc. The ballast, here in containers 6a, rests on said floor 16a. One or more, preferably at least three, columns 16b extend upward from the floor 16a, and are connected via a ballast mast connector assembly 16c to the lower end of the ballast mast 2.

(29) As is preferred the ballast mast connector assembly 16c includes a bearing that allows for at least a rotation of the ballast mast 2 around its, generally vertical, axis. Preferably the ballast mast connector assembly 16c also allows for pivotal motion of the ballast mast 2 around one or more horizontal axes, e.g. allowing for gimballing of the ballast mast 2. For example the assembly 16c comprises a ball joint or a Cardan joint to allow for such gimballing motion of the ballast mast 2. This allows to avoid undue loads during operation of the crane on the ballast mast and/or the connection at the lower end thereof. The vertical rotation bearing and/or gimbal device are denoted with reference numeral 16d. The gimballing may be restricted to a limit angular range, e.g. a few degrees relative to vertical.

(30) As is preferred the ballast mast connector assembly 16c also comprises a fixation device 16e that is embodied to temporarily fixate the lower end of the ballast mast 2, e.g. so that its rotation around the vertical axis thereof and/or any gimballing motion is selectively blocked.

(31) During construction of the back mast 2 and/or or main boom 5 and/or during hoisting operations performed after the crane 1 has been assembled, the ballast mast 2 may be rotated, or allowed to rotate, around a vertical axis, and/or optionally be moved into an inclined position.

(32) Preferably during construction of the ballast mast 2, the ballast mast 2 is retained in a fixed orientation, e.g. relative to ballast 6, e.g. by temporary locking by means of device 16d at the lower end of the ballast mast 2.

(33) The back mast 3 is for example a single leg mast, or it may for example have an A-shape, an inverted Y-shape, a shape with two parallel masts (e.g. an H-shape) or a V-shape.

(34) The main boom 5 too, can for example be of a linear design, or it may for example have an A-shape, an inverted Y-shape, an H-shape or a V-shape.

(35) It is preferred for the back mast 3 and the main boom 5 to both have an A-frame shape, each with two legs joined at or near their upper ends and diverging at their lower ends, e.g. with one or more intermediate bracing between the legs. The A-frame design provides for optimal stability of the respective back mast 3 and main boom 5 at a relatively low weight thereof.

(36) The ballast mast 2 is preferably a single mast or one legged mast, that is assembled from multiple ballast mast sections 20, 21, 22 that are stacked on top of one another and interconnected.

(37) Onto the ballast mast 2, a back mast top slide 4 is arranged. The back mast top slide 4 is movable along the length or height of the ballast mast 2, thus in axial direction of the ballast mast 2.

(38) As is preferred the back mast top slide 4 is fixable in a plurality of positions relative to the ballast mast 2.

(39) The back mast 3 is at its top pivotable connected to the back mast top slide 4, e.g. at least around a horizontal pivot axis. As is preferred the slide 4 is connected to the mast 2 such that some pivotal motion around another horizontal axis, perpendicular to the vertical median plane of the back mast 3, is possible. The same mobility may be achieved by a Cardan joint between the back mast 3 and the slide 4.

(40) At its lower end, the back mast 3 is pivotable connected to a mast foot assembly 7 around a horizontal back mast pivot axis. The lower end of the main boom 5 is also pivotable connected to the mast foot assembly 7.

(41) In an embodiment the mast foot assembly is immobile relative to the surface 12. In another, more preferred, embodiment, the mast foot assembly is of a mobile design allowing for displacement over the surface, e.g. rotation and/or linear displacement, e.g. along a rail or another track.

(42) The mast foot assembly 7 preferably, as here, includes a left-hand and right-hand foot device. Here the left-hand leg of the back mast 3 and main boom 5 are each hinged to the left-hand footy device and the right-hand legs of the back mast 3 and the main boom are each hinged to the right-hand foot device.

(43) Each foot device may, as is preferred, comprise one or more vertical adjusters, e.g. hydraulic adjusters, e.g. to compensate for irregularities in the supporting surface 12 or other supporting structure, e.g. skid rail track, for ground deformation. The vertical adjusters may alternatively be arranged at another location in the mast foot structure.

(44) Each foot device may, as is preferred, comprise a skid displacement device, e.g. including one or more hydraulic skid jacks, e.g. horizontal skid jacks, to allow for controlled displacement of the foot device, e.g. over a skid rail structure with one or more skid rails.

(45) The mast foot assembly 7 may contain a rotation device, e.g. a vertical axis bearing, possibly with a rotation actuator, which device is adapted to allow for and/or cause rotation of a respective foot device around a vertical rotation axis.

(46) The exemplary embodiment of the crane 1 as shown in FIG. 1 further comprises, optionally, a temporary guy-line, rod or tube 8 for temporarily stabilizing the main boom 5 relative to the surface.

(47) The crane 1 may comprise a boom stop 9 to avoid undesired contact between the main boom 5 and the back mast 3 during booming operations.

(48) The exemplary embodiment of the crane 1 as shown in FIG. 1 further comprises, optionally, a main load hoisting system 10 comprising a hoisting member, e.g. a hook 10a, which is moveable and suspended from the main boom 5 via one or more hoisting lines 10b, e.g. hoisting cables. The main hoisting device for example further comprises hoisting winches or strand jacks 10c.

(49) The exemplary embodiment of the crane 1 as shown in FIG. 1 further comprises one or more guy-lines 11 between the top of the back mast 3 and the main boom 5.

(50) As depicted in FIG. 2-FIG. 4 it is envisaged, in an embodiment, that the ballast mast 2 is assembled using a climbing auxiliary crane 15 that has capacity to lift a section 21, 22 of the mast 2 and place it on top of the already construed part of the mast 2. Then the crane 15 is made to move up the extended mast 2 to repeat the lifting and assembly step until the mast 2 reaches the desired height. This approach using a climbing crane 15 allows to assemble the mast 2 on a minimal foot print, and allows to dispense with the need for a surface based major height crane. The auxiliary or climbing crane 15 may remain on the back mast 2 as shown here above the slide 4. In another embodiment the crane 15 is embodied so as to allow for the lowering thereof after assembly of the mast 2 or after the later assembly of the back mast 3 using the ballast mast 2 as will be explained. The crane 15 can be embodied to slide along the same structural components of the mast 2 as the slide 4, but one can also envisage that the crane 15 is mobile along an opposite side of the mast 2 relative to the side where the slide 4 moves.

(51) If desired a further auxiliary crane 15b can be mounted on top of the main boom 5, e.g. to assist in the placement of one or more strand jack devices on the top of the main boom 5.

(52) In FIG. 1, the exemplary embodiment of the crane is shown in a situation in which it carries a load 18, e.g. a vessel to be used in the (petro-)chemical industry, a power plant vessel, a module of an FPSO vessel to be placed on deck of such a vessel, etc.

(53) FIG. 2-FIG. 12 show a possible embodiment of the method according to the first aspect of the invention.

(54) In the first portion of the exemplary method in accordance with the first aspect of the invention as shown in FIG. 2-FIG. 12, the upright ballast mast 2 is assembled.

(55) FIG. 2 shows a first stage in a possible embodiment of the method according to the first aspect of the invention.

(56) In this step, a first ballast 6 is provided. A ballast mast support 16 is adapted to support the ballast mast 2. The ballast mast support 16 is placed on the surface 12 and the one or more ballast container 6 are placed on or connected to the support 16.

(57) During operation of the crane 1, the ballast 6 may be moveable relative to surface 12.

(58) FIG. 2 shows that a first ballast mast section 20 is provided. The first ballast mast section 20 has a length which is shorter than the final length of the ballast mast 2 to be constructed. In the step shown in FIG. 2, the first ballast mast section 20 is arranged on top of the ballast mast support 16 in an upright position, e.g. by means of a mobile crane.

(59) In the embodiment shown in FIG. 2-FIG. 12, an auxiliary or climbing crane 15 is arranged on the ballast mast 2. The auxiliary crane 15 moves upward along the ballast mast 2 while the ballast mast is constructed. This concept is known from common methods of erecting tower cranes.

(60) FIG. 3 shows a later stage in a possible embodiment of the method according to the first aspect of the invention.

(61) A second ballast mast section 21 has been provided. The second ballast mast section 21 has a section length which is shorter than the length of the ballast mast 2 to be constructed. The second ballast mast section 21 has been fixed on top of the first ballast mast section 20 in an upright direction.

(62) FIG. 3 shows that a further ballast mast section 22 is provided. The further ballast mast section 22 has a section length which is shorter than the length of the ballast mast 2 to be constructed.

(63) The further ballast mast section 22 will be stacked on top of the second ballast mast section 21.

(64) Additional further ballast mast sections are added until a desired length of the upright ballast mast 2 has been obtained.

(65) In the exemplary embodiment of FIG. 2-FIG. 12, the second ballast mast section 21 and the further ballast mast sections 22 are lifted into position by an auxiliary crane 15 which is arranged on the ballast mast 2. In an alternative embodiment that is not shown in the drawings, they can be arranged into position by a separate crane which is arranged in the vicinity of the ballast 6, e.g. on the support surface 12 on which the crane is assembled.

(66) The ballast mast 2 remains fixed in the upright position by means of temporal fixation, e.g. by device 16e, at least until the mast 2 has been complete, preferably at least until the back mast 3 has been constructed.

(67) Optionally, at least one of a first ballast mast section 20, a second ballast mast section 21, and a further ballast mast section 22 is constructed from elongate elements that are releasably connected to each other, for example by pen-slot connections. Optionally, such elongate elements have a length such that they fit in the space of standard size road containers or standard size sea containers. The elongate elements can for example be tubes, e.g. tubes with an octagonal cross section, or beams.

(68) Optionally, the assembly of at least one of a first ballast mast section 20, a second ballast mast section 21 and a further ballast mast section 22 takes place on the site where the crane 1 is assembled.

(69) FIG. 4 shows a subsequent stage in a possible embodiment of the method according to the first aspect of the invention.

(70) The ballast mast 2 has now been completed. It comprises a first ballast mast section 20, a second ballast mast section 21 and multiple further ballast mast sections 22.

(71) Now the ballast mast 2 has been completed, or earlier, a back mast top slide 4 is arranged on the ballast mast 2. The back mast top slide 4 is movable along the ballast mast 2 in the axial direction of the ballast mast 2 and the back mast top slide 4 is fixable, e.g. in a plurality of pre-determined positions, relative to the ballast mast 2.

(72) FIG. 5 shows a subsequent stage in a possible embodiment of the method according to the first aspect of the invention.

(73) After the ballast mast 2 has been constructed, the back mast 3 will be assembled.

(74) The back mast 3 may for example be of a linear or single legged design, or it may for example have an A-shape, an inverted Y-shape, a shape with two parallel masts (e.g. an H-shape), etc.

(75) The construction of the back mast comprises providing a back mast upper section 30. The back mast upper section 30 has a length that is shorter than the final length of the back mast 3. It has a ballast mast side end 31 and a back mast side end 32. The back mast upper section 30 will form the upper part of the back mast 3 of the assembled crane 1. For example a pair of upper sections 30 is arranged side by side, diverging according to the A-frame shape back mast 3 to be assembled.

(76) Optionally, the back mast upper section 30 is constructed from elements that are releasably connected to each other, e.g. including elongated chords along respective corners of a four sided element with diagonal trusses between chords. Connections between adjoining elements of the back mast may for example be pen-slot connections.

(77) Optionally, such elongate elements have a length such that they fit in the space of standard size road containers or standard size sea containers. The elongate elements can for example be tubes, e.g. tubes with an octagonal cross section, or beams. Optionally, the assembly of the back mast upper section 30 takes place on the site where the crane 1 is assembled.

(78) The back mast upper section 30 is pivotable connected to the back mast top slide 4.

(79) Preferably the back mast top slide 4 is brought into a lowered position thereof to connect the upper section or sections 30 to it, e.g. using a relatively small surface based crane. As is preferred the connection is pivotal around a horizontal pivot axis and is held or fixed in a first or lower position along the ballast mast 2 when the back mast upper section 30 is connected to it. In the example shown in FIG. 5, the back mast top slide 4 is in a position which is high enough to allow the back mast upper section 30 to become attached to the back mast top slide 4, but low enough to allow further upward movement of the back mast top slide 4 along the ballast mast 2.

(80) Optionally, after connecting the back mast upper section 30 to the back mast top slide 4, the back mast upper section 30 is pivotable around at least two pivot axis relative to the back mast top slide 4.

(81) The back mast upper section 30 is connected to the back mast top slide 4. In the example of FIG. 5, this is achieved by fixing the back mast top slide 4 at such a position on the ballast mast 2 that the back mast upper section 30 finds itself above the support surface 12 on which the crane is assembled when the back mast upper section 30 is connected to the back mast top slide 4. The back mast side end of the back mast upper section 30 is supported and lifted by a crane hook or other suitable lifting means 17.

(82) Alternatively, not shown in the drawings, when connecting the back mast upper section 30 to the back mast top slide 4, the back mast top slide 4 is fixed to the ballast mast 2 in a relatively low position, at a distance from the support surface 12 which is smaller than the length of the back mast upper section 30, so the back mast end 32 of the back mast upper section 30 still rests on the support surface 12 on a base structure. The back mast top slide 4 is then moved upwards along the ballast mast 2 after the back mast upper section 30 is connected to the back mast top slide 4.

(83) In the example of FIG. 5 the back mast side end 32 of the back mast upper section 30 is supported and lifted by a crane 17 or elevating construction (not shown). Alternatively, in an embodiment not shown in the drawings, the back mast side end 32 of the back mast upper section 30 may still rest on the support surface 12.

(84) The back mast upper section 30 can be lifted to the back mast top slide 4 for connection to the back mast top slide 4 by means of an auxiliary crane 15 that is arranged on top of the ballast mast, or by a separate crane that is arranged in the vicinity of the ballast mast 2.

(85) FIG. 6 shows a subsequent stage in a possible embodiment of the method according to the first aspect of the invention.

(86) A back mast intermediate section 34 is provided and connected to the back mast upper section.

(87) The back mast intermediate section 34 has a length that is shorter than the final length of the back mast 3. The back mast intermediate section 34 has a first end 35 and a second end.

(88) The first end 35 of the back mast intermediate section 34 is connected to the back mast side end 32 of the back mast upper section 30.

(89) In the embodiment of the first method according to the invention as shown in FIG. 2-FIG. 12, the back mast intermediate section 34 is assembled by stepwise addition of multiple back mast subsections 36. In this example, the back mast top slide 4 is moved upwardly along the ballast mast 2 after and/or before the addition of a subsequent back mast subsection 36.

(90) Each back mast subsection 36 has a length that is shorter than the final length of the back mast intermediate section 34. Each back mast subsection has a primary connection end 37 and a secondary connection end 38.

(91) FIG. 6 shows the connection of the first back mast subsection 36 to the back mast end 32 of the back mast intermediate section 30. The primary connection end 37 of this back mast subsection 36 forms the first end 35 of the back mast intermediate section 36. The secondary connection end of the back mast subsection that is arranged on the opposite end of the back mast intermediate section will form the second end of the back mast intermediate section once the back mast intermediate section has been completed. In this example, the primary connection end 37 of the back mast subsection 36 lifted towards the back mast side end 32 of the back mast upper section 30 by a separate crane 17 (partly shown in FIG. 6). Alternatively, the auxiliary crane 15 with extended boom on top of the ballast mast 2 can be used for this.

(92) The back mast intermediate section 34 is constructed by stepwise adding a predetermined number of back mast subsections 36.

(93) In the example as shown in FIG. 6, first, a plurality of back mast subsections 36 is provided. Then, the primary connection end 37 of a first back mast subsection 36 is connected to the back mast side end 32 of the back mast upper section 30. Herewith, the primary connection end 37 becomes the first end 36 of the back mast intermediate section 34.

(94) It can be seen in FIG. 6 that in this stage of this exemplary embodiment, the back mast subsection 36 does not yet extend in line with the axial direction of the back mast upper section 30. To achieve such an alignment, in this exemplary embodiment the back mast top slide 4 is moved upwards along the ballast mast 2, allowing the back mast subsection 36 to rotate around the connection to the back mast upper section 30. Therewith, the first back mast subsection 36 can come to extend in line with the axial direction of the back mast upper section 30 with the secondary connection end 38 of the first back mast subsection 36 facing downwards. Once this relative position has been obtained, the first back mast subsection 36 can be fixed to the back mast upper section 30.

(95) The back mast intermediate section 34 is then further constructed by adding further back mast subsections.

(96) This is for example carried out by subsequently connecting the primary connection end of a further back mast subsection to the secondary connection end of the first back mast subsection. Then, the back mast top slide 4 is moved upwards along the ballast mast 2. Therewith, the further back mast subsection can come to extend in line with the axial direction of the first back mast subsection 36 with the secondary connection end of the further back mast subsection facing downwards. The further back mast subsection is then fixed to the first back mast subsection. So, the further back mast subsection is connected to, aligned with and fixed to the first back mast subsection in the same way as the first back mast subsection 36 has been connected to, aligned with and fixed to the back mast upper section.

(97) Then, in this exemplary embodiment, the primary connection end of a subsequent further back mast subsection is connected to the secondary connection end of the previous further back mast subsection. The back mast top slide 4 is again moved upwards along the ballast mast 2 the subsequent further back mast subsection is made to come to extend in line with the axial direction of said previous further back mast subsection with the secondary connection end of the subsequent further back mast subsection facing downwards. The subsequent further back mast subsection is then fixed to said previous first back mast subsection. This is repeated by adding further subsequent back mast subsections until a desired length of the back mast intermediate section is obtained.

(98) The secondary connection end of the last back mast subsection that is applied forms the second end of the back mast intermediate section.

(99) Optionally, a back mast subsection is constructed from elongated elements that are releasably connected to each other, for example by pen-slot connections. Optionally, such elongate elements have a length such that they fit in standard size road containers or standard size sea containers. The elongate elements can for example be tubes, e.g. tubes with an octagonal cross section, or beams.

(100) Optionally, a back mast subsection is constructed on the site where the crane is assembled in accordance with the first aspect of the invention.

(101) As a preparation for the subsequent stages of the method according to the first aspect of the invention, a mast foot assembly 7 is provided.

(102) FIG. 7 shows a subsequent stage in a possible embodiment of the method according to the first aspect of the invention.

(103) The back mast intermediate section 34 has now been completed. It has been constructed from multiple back mast subsections 36 as described above.

(104) The secondary connection end of the back mast subsection that is arranged on the lower end of the back mast intermediate section 34 forms the second end 39 of the back mast intermediate section 34.

(105) The back mast intermediate section 34 extends in line with the axial direction of the back mast upper section 30, and the back mast intermediate section 34 is fixed to the back mast upper section 30. In the fixed position, the back mast intermediate section 34 extends in line with the axial direction of the back mast upper section 30.

(106) Now, a back mast lower section 40 is provided. The back mast lower section 40 has a length that is shorter than the final length of the back mast 3. The back mast lower section has a foot side end 42 and a back mast side end 41.

(107) As is shown in FIG. 7, the back mast side end 41 of the back mast lower section 40 is connected to the second end 39 of the back mast intermediate section 34.

(108) The foot side end 42 of the back mast lower section 40 is pivotably connected to the mast foot assembly 7. This may take place before or after the back mast lower section 40 is connected to the back mast intermediate section 34.

(109) The mast foot assembly 7 may be a fixed, that is, immobile, mast foot assembly, which has a fixed position on the support surface onto which the crane is assembled, or a moveable mast foot assembly, which can travel on the support surface onto which the crane is assembled, either freely or along a track. The mast foot assembly 7 comprises multiple mast feet. The mast foot assembly 7 contains a rotation device, which is adapted to allow the main boom and the back mast to rotate around a vertical rotation axis.

(110) The back mast lower section 40 is made to come to extend in line with the axial direction of the back mast intermediate section 30. Then, the back mast intermediate section is fixed to the back mast lower section. In the fixed position, the back mast lower section 40 extends in line with the axial direction of the back mast intermediate section 34. This alignment and/or fixing may take place either after or before the foot side end 42 of the back mast lower section 40 is connected to the mast foot assembly 7.

(111) Making the back mast lower section 40 to come to extend in line with the axial direction of the back mast intermediate section 34 optionally involves moving the back mast top slide 4 upwards along the ballast mast 2 and fixing the back mast top slide 4 at a higher position than the position it had on the ballast mast 2 when the back mast lower section 40 was connected to the back mast intermediate section 34.

(112) Making the back mast lower section 40 to come to extend in line with the axial direction of the back mast intermediate section 34 optionally involves moving the mast foot assembly 7 closer to the ballast mast 2 and lifting (climbing) the back mast top slide 4.

(113) After assembly of the back mast and the connection of the back mast to the mast foot assembly, the ballast mast that has up to now been fixed to the ballast, is allowed to move, e.g. with some restriction and/or damping, around one or more horizontal axes and a vertical axis.

(114) Now, the ballast mast and the back mast have been constructed. As a next phase in the assembly of the crane in accordance with the first aspect of the invention, a main boom 5 is assembled, which main boom 5 is pivotably connected to the mast foot assembly 7. The main boom 5 may for example be of a linear design, or it may for example have an A-shape, an inverted Y-shape, a shape with two parallel masts (e.g. an H-shape) or a V-shape.

(115) The main boom may be assembled in many different ways. In the embodiment shown in FIG. 2 to FIG. 12, the main boom is assembled in accordance with the second aspect of the invention. Alternatively, a different way of assembling the main boom and pivotably connecting the main boom to the mast foot assembly may be used in the method according to the first aspect of the invention.

(116) The method of assembling the main boom in accordance with the second aspect of the invention may be applied in combination with the method in accordance with the first aspect of the invention. It may however also be applied to assemble a main boom using the method in accordance with the second aspect of the invention. The back mast of the crane may in this case be provided in any way considered suitable.

(117) FIG. 8 shows a subsequent stage in a possible embodiment of the method according to the first aspect of the invention, in which now an exemplary embodiment of the method according to second aspect of the invention is applied.

(118) For the assembly of the main boom 5, a main boom lower section 50 is provided. The main boom lower section 50 has a length that is shorter than the final length of the main boom 5. The main boom lower section 50 has a foot side end 51 and a main boom side end 52.

(119) The foot side end 51 of the main boom lower section 50 is pivotably connected to the mast foot assembly 7. However, before this is done, preferably the ballast mast 2 is allowed to pivot relative to the ballast 6 and the position of the mast foot assembly 7 is fixed in position relative to the ballast mast 2, e.g. using temporary tubes that can absorb tensile as well as compressive forces. Then, the main boom lower section 50 is pivoted upwardly relative to the mast foot assembly 7.

(120) FIG. 9 shows a subsequent stage in a possible embodiment of the method according to the first aspect of the invention, in which now an exemplary embodiment of the method according to second aspect of the invention is applied.

(121) In this stage, the main boom lower section 50 has been pivoted upwardly relative to the mast foot assembly 7. In this example, it now rests against the back mast lower section 40.

(122) In the next phase, a main boom intermediate section 55 is provided. The main boom intermediate section 55 has a length that is shorter than the final length of the main boom 5. The main boom intermediate section has a first end and a second end.

(123) The first end of the main boom intermediate section 55 is provided upon the main boom side end 52 of the main boom lower section 50.

(124) In the embodiment shown in FIG. 9, the main boom intermediate section is constructed by stacking multiple main boom subsections 55 on top of each other.

(125) In the embodiment shown in FIG. 9, a mast section guide 45 is provided along the back mast 3. Each main boom subsection 55 is lifted to the top of the back mast 3, for example by the auxiliary crane 15 which is arranged on top of the ballast mast 2.

(126) The mast section guide also allows the main boom to be assembled by adding main boom sections, e.g. main boom intermediate sections, to the foot side end of a main boom section already provided against the mast guide sections. The main boom section to be added is pushed upwards by suitable pushing or lifting means. The main boom may thus be constructed by addition of main boom sections at the bottom or by addition of main boom sections at the top thereof.

(127) If the entire main boom intermediate section is arranged on the main boom lower section in one go, the main boom intermediate section is lifted to the top of the back mast 3. A separate crane may be provided for this.

(128) FIG. 10 shows a subsequent stage in a possible embodiment of the method according to the first aspect of the invention, in which now an exemplary embodiment of the method according to second aspect of the invention is applied.

(129) Each main boom subsection 55 is now lowered onto the main boom lower section 5 along the mast section guide 45. This way, a main boom intermediate section is assembled onto the main boom lower section 50 by stepwise addition of multiple main boom subsections 55.

(130) FIG. 11 shows a subsequent stage in a possible embodiment of the method according to the first aspect of the invention, in which now an exemplary embodiment of the method according to second aspect of the invention is applied.

(131) The main boom intermediate section 65 has now been constructed using multiple main boom subsections 55 which have been stacked on top of one another.

(132) On top of the main boom intermediate section 65, a main boom upper section 60 is now arranged. It is aligned relative to the main boom intermediate section preferably using the mast section guide 45. The main boom upper section 60 is in the example lifted into place by the auxiliary crane 15 which is arranged on top the ballast mast 2, but alternatively a separate crane can be used.

(133) The main boom upper section 60 is fixed onto the main boom intermediate section 65.

(134) FIG. 12 shows a subsequent stage in a possible embodiment of the method according to the first aspect of the invention, in which now an exemplary embodiment of the method according to second aspect of the invention is applied.

(135) The main boom intermediate section 65 with the connected main boom upper section 60 are now pivoted around the connection of the main boom intermediate section 65 and the main boom lower section 50. In this way the main boom intermediate section 65 with the attached main boom upper section 60 become aligned with the axial direction of the main boom lower section 50.

(136) The main boom intermediate section 65 is then fixed to the main boom lower section 50.

(137) Further elements of the crane 1 may be added or made operational, such as a guy-line 11 and a main hoisting system 10.

(138) FIG. 13 shows a first stage of an example of an alternative method for assembling a main boom which can be used in combination with the method according to the first aspect of the invention.

(139) In this example of the alternative embodiment, the main boom 5 is constructed along with the construction of the back mast 3.

(140) In this example, a main boom upper section 60 is provided. The main boom upper section 60 has a length that is shorter than the final length of the main boom 5. The main boom upper section 60 has a main boom side end 61.

(141) Then, before connecting the back mast intermediate section 34 to the back mast upper section 30, the main boom upper section 60 is arranged adjacent to the back mast upper section 30. The main boom upper section 60 is then connected to the back mast upper section 30 by connection element 59. This is shown in FIG. 13.

(142) The main boom upper section 60 will therewith generally be retained at least by this connection element 59. Optionally, the main boom upper section 60 comes to rest against back mast upper section 30.

(143) FIG. 14 shows a subsequent stage of an example of an alternative method for assembling a main boom which can be used in combination with the method according to the first aspect of the invention.

(144) In this stage, a first back mast subsection 36 of a back mast intermediate section is connectedand preferably also aligned with and fixedto the back mast upper section 30. The back mast top slide 4 is moved upwardly along the ballast mast 2 after connecting the main boom upper section 60 to the back mast upper section 30 but before connecting the back mast subsection 36 to the back mast upper section 30. Preferably, after this upward movement, the back mast top slide 4 is fixed in position relative to the ballast mast 2.

(145) Instead of a back mast subsection, the entire back mast intermediate section can be connected to the back mast upper section in this stage.

(146) FIG. 15 shows a subsequent stage of an example of an alternative method for assembling a main boom which can be used in combination with the method according to the first aspect of the invention.

(147) After connecting a back mast subsection 36 or the entire back mast intermediate section to the back mast upper section, a main boom subsection 65 or the entire main boom intermediate section is connected toand preferably also aligned with and fixed tothe main boom upper section 60. Optionally, the main boom intermediate section or main boom subsection 65 comes to rest against back mast intermediate section or back mast subsection 36, respectively.

(148) So, a possible variant of this embodiment, the back mast intermediate section and the main boom intermediate section are assembled by stepwise addition of multiple back mast subsections and main boom subsections, respectively. Optionally, the back mast top slide is moved upwardly along the ballast mast after and/or before the addition of a subsequent subsection, e.g. before the addition of each subsequent back mast subsection and/or before the addition of each subsequent main boom subsection.

(149) Then, after connecting the back mast lower section to the back mast intermediate section, a main boom lower section is connected toand preferably also aligned with and fixed tothe main boom intermediate section. Optionally, the main boom lower section comes to rest against back mast lower section.

(150) Then, the main boom lower section is connected to the mast foot assembly. Optionally, the main boom is then pivoted away from the back mast.

(151) FIG. 16 schematically illustrates an exemplary embodiment a crane which can be used in an exemplary embodiment of a method according to the third aspect of the invention.

(152) A crane 101 which can be used in the method according to the third aspect of the invention comprises a first anchor connection 102, e.g. a first ballast mast, an anchor chain, an anchor cable or a set of anchor chains and/or anchor cables.

(153) The crane further comprises a primary anchor 106 and a secondary anchor 126 (see FIG. 17), which are located at a distance from each other. Before operating the crane in accordance with the third aspect of the invention, the first anchor connection 102 is connected to the primary anchor 106.

(154) The primary anchor 106 and/or the secondary anchor 126 can for example be a ballast, for example made from stacked heavy objects such as metal weights or containers, for example sea containers filled with sand. Alternatively, the primary anchor 106 and/or the secondary anchor 126 can be a heavy object, for example a heavy object that is fixed to the ground, or an anchor e.g. in the form of a hook or ring that is fixed to the world, e.g. to a rock.

(155) The crane further comprises a back mast 103. The back mast 103 has a back mast lower section 140 which is pivotably connected to a mast foot assembly 107 and a back mast upper section 130 which is in two directions pivotably connected to the first anchor connection 102. The anchor connection 102, which can rotate around its vertical axis, provides a connection, e.g. a flexible connection, between the primary anchor 106 and the back mast upper section 130.

(156) The crane further comprises a main boom 105. The main boom 105 has a main boom lower section 150 which is pivotably connected to the mast foot assembly 107, and a main boom upper section 160.

(157) The crane further comprises a main load hoisting system 110 comprising a hoisting member 117, which is moveable and suspended from the main boom via one or more hoisting lines 118. The crane also comprises a guy-line 111 which connects the back mast upper section and the main boom upper section.

(158) In the example shown in FIG. 16, the first anchor connection 102 is a first ballast mast. The crane further comprises a back mast top slide 104 which is arranged on the first ballast mast. The back mast top slide 104 is movable along the first anchor connection 102 in the axial direction of the first anchor connection 102. The back mast top slide 104 is fixable in a plurality of positions relative to the first anchor connection 102.

(159) In the example shown in FIG. 16, the crane comprises a main boom stop 109 which is adapted to prevent undesired pivoting of the main boom, in particular in the direction towards the back mast.

(160) In the example shown in FIG. 16, auxiliary cranes 115 are provided on the top of the back mast 103 or on the top of the first anchor connection 102, and on the top of the main boom 105.

(161) The crane which is used in the third aspect of the invention can be a crane that is assembled in accordance with the first aspect of the invention and/or the second aspect of the invention, but this is not necessary.

(162) In the example of FIG. 16, the crane is arranged on surface 112, adjacent to a building 114.

(163) FIG. 17 schematically illustrates a first stage in an exemplary embodiment of a method according to the third aspect of the invention.

(164) In this embodiment, the method according to the first aspect of the invention starts from the situation that is shown in FIG. 16.

(165) In this first stage in the example shown in FIG. 17, the main boom 105 is fixed relative to the mast foot assembly 107 such that pivoting of the main boom 105 relative to the mast foot assembly 107 towards and away from the back mast 103 is prevented. To achieve this, the hoisting line 117 is connected to a main boom anchor 120. The main boom anchor 120 can for example be a ballast, for example made from stacked heavy objects such as metal weights or containers, for example sea containers filled with sand. Alternatively, the main boom anchor 120 can be a heavy object, for example a heavy object that is positioned on the ground, or an anchor e.g. in the form of a hook or ring that is fixed to the world, e.g. to a rock. In this example, the fixing of the main boom is carried out by fixing the length of the hoisting line 117 between the main boom anchor 120 and the top of the main boom 105, and by providing a guy-line 121 that connects between the side of the back mast away from the main boom and the ballast 106.

(166) As a subsequent step the back mast upper section 130 is disconnected from the primary anchor 106.

(167) There are several ways in which this can be carried out. For example, the first anchor connection can be disconnected from the primary anchor, or the back mast top slide can be disconnected from the first anchor connection, or the back mast upper section can be disconnected from the back mast top slide.

(168) In the embodiment shown in FIG. 17, the first anchor connection 102 is a first ballast mast, and the disconnecting of the back mast upper section 130 from the primary anchor 106 is carried out by disconnecting the first ballast mast from the primary anchor 106.

(169) As a subsequent step, the back mast upper section 130 is moved, e.g. rotated, towards the secondary anchor 126. It is not necessary that the back mast upper section 130 is brought all the way to the secondary anchor 126. In the embodiment shown in FIG. 17, at the end of the movement the back mast upper section 130 is at a distance from the secondary anchor 126. For example, at the end of the movement, the back mast upper section 130 is located at a distance above the secondary anchor 126, optionally at a distance straight above the secondary anchor 126.

(170) In the embodiment of FIG. 17, the distance from the primary anchor 106 to the mast foot assembly 107 is shorter than the distance from the secondary anchor 126 to the mast foot assembly 107, at least in this step of the exemplary embodiment. In this particular embodiment, the secondary anchor 126 is located on the other side of the building 114 compared to the primary anchor 106.

(171) As a subsequent step, which is shown in FIG. 18, the back mast upper section 130 is connected to the secondary anchor 126. This can be carried out in several ways, depending on how the back mast upper section 130 was disconnected from the primary anchor 106.

(172) In the embodiment shown in FIG. 18, the back mast upper section 130 is connected to the secondary anchor 126 by connecting the first ballast mast 102 to the secondary anchor 126.

(173) Optionally, in this embodiment, after the first ballast mast has been disconnected from the primary anchor but before the first ballast mast is connected to the secondary anchor, the first ballast mast is moved upwardly relative to the back mast top slide 104 and away from the primary anchor and then the first ballast mast is moved downwardly relative to the back mast top slide 104 and towards the secondary anchor. This may help to lift the first ballast mast over any obstacles that are present in the path, e.g. building 114, of the first ballast mast 102 between the primary anchor 106 and the secondary anchor 126.

(174) As can be seen in FIG. 18, the distance from the primary anchor 106 to the back mast top slide 104 when the first ballast mast 102 is connected to the primary anchor 106 is longer than the distance from the primary anchor 126 to the back mast top slide 104 when the first ballast mast 102 is connected to the secondary anchor 126.

(175) Optionally, as shown in FIG. 17, the first ballast mast 102 is moved to the secondary anchor 126 while maintaining the first ballast mast 102 in a substantial vertical position.

(176) As next steps, shown in FIG. 18, the hoisting line 117 is disconnected from the main boom anchor 120 and guy-line 121 is removed, so that the fixing of the main boom 105 relative to the mast foot assembly 107 is released, thereby allowing pivoting of the main boom 105 relative to the mast foot assembly 107 again.

(177) The crane is now ready for hoisting a load.

(178) In a variant of this embodiment, not shown in the drawing, the first anchor connection 102 is a primary anchor cable, a primary anchor chain or a set of primary anchor chains and/or primary anchor cables, or a combination of one or more primary anchor cables or one or more primary anchor chains with a fall back tube. In this variant, optionally an additional boom stop and/or additional cables are provided to prevent undesired motions of the back mast.

(179) In this variant, the primary anchor cable, a primary anchor chain or a set of primary anchor chains and/or primary anchor cables, or a combination of one or more primary anchor cables or one or more primary anchor chains with a fall back tube is disconnected from the primary anchor 106, and then optionally hoisted up towards the back mast upper section 130. Then, the back mast upper section 130 is moved towards the secondary anchor 126. Then, a primary anchor chain or a set of primary anchor chains and/or primary anchor cables or a combination of one or more primary anchor cables or one or more primary anchor chains with a tube is optionally, if necessary, lowered again towards the secondary anchor 126 so that it can be connected to the secondary anchor 126.

(180) FIG. 19 shows an alternative embodiment of the method according to the third aspect of the invention.

(181) In this embodiment, disconnecting the back mast upper section 130 from the primary anchor 106 is carried out by disconnecting the first anchor connection 102 from the back mast upper section 130. In the embodiment shown in FIG. 19, the first anchor connection 102 is a first ballast mast with a back mast top slide 104, but alternatively it can be a primary anchor cable, a primary anchor chain or a set of primary anchor cables and/or anchor chains.

(182) The back mast upper section 130 is then moved, e.g. rotated, towards the secondary anchor 126.

(183) Then, in this embodiment, the back mast upper section 130 is connected to the secondary anchor 126 by connecting the back mast upper section 130 to a second anchor connection 102*. This second anchor connection 102* is connected to the secondary anchor 126. In the embodiment shown in FIG. 19, the second anchor connection 102* is a second ballast mast but alternatively, it can be for example a second anchor cable, a second anchor chain or a second set of anchor cables and/or anchor chains.

(184) As shown in FIG. 19, optionally, the first anchor connection 102 is moved away from a line that extends between the mast foot assembly 107 and the secondary anchor 126 after disconnecting the back mast upper section 130 from the primary anchor 106 but before moving the back mast upper section 130 towards the secondary anchor 126.

(185) In the embodiment shown in FIG. 19, the first anchor connection 102 is moved downwards by pivoting around a horizontal pivot axis after disconnecting the back mast upper section 130 from the primary anchor 106 but before moving the back mast upper section 130 towards the secondary anchor 126.

(186) FIG. 20 shows an example in which a load 150 is lifted with the first anchor connection 102 being connected to the secondary anchor 126.

(187) In order to be able to lift the load 150, the main boom 105 and the hoisting cable of the main hoisting system 110 are moved to the load 150. The hoisting cable is then connected to the load 150, and the load can be moved, e.g. lifted, to a first load position 160, which is for example relatively close to the mast foot assembly 107. This is shown in FIG. 21.

(188) Starting from the situation shown in FIG. 21, the first anchor connection can be switched again to the primary anchor 106, for example to allow rotating the crane 101 around a vertical axis in a small space, for example between buildings and arrange the load 150 at a second load location. The crane 101 could for example rotate around the mast foot assembly 107 or around the primary anchor 106.

(189) If the load 150 is heavy enough and it can be anchored securely to the world, the load can serve as a main boom anchor 120. By using the load 150 as main boom anchor, the back mast upper section 130 can be connected again to another anchor, for example the primary anchor 106.

(190) To this end, the following steps are then taken: fixing the main boom 105 relative to the mast foot assembly 107 such that pivoting of the main boom 105 relative to the mast foot assembly 107 towards and away from the back mast 103 is prevented, disconnecting the back mast upper section 130 from the secondary anchor 126, moving the back mast upper section 130 towards the primary anchor 106, and connecting the back mast upper section 130 to the primary anchor 106.

(191) In a variant of this embodiment, it is possible that the back mast upper section 130 is connected to a further, e.g. a tertiary, anchor 136 to move the load to a third load position. To that end, optionally the following steps may be performed: fixing the main boom 105 relative to the mast foot assembly 107 such that pivoting of the main boom 105 relative to the mast foot assembly 107 towards and away from the back mast 103 is prevented, disconnecting the back mast upper section 130 from the primary anchor 106, moving the back mast upper section 130 towards a tertiary anchor 136, connecting the back mast upper section 130 to the tertiary anchor 136, releasing the fixing of the main boom 105 relative to the mast foot assembly 107, thereby allowing pivoting of the main boom 105 relative to the mast foot assembly 107 again, rotating the crane around the tertiary anchor 136 or around the mast foot assembly 107, and arranging the load at a third load position.

(192) FIG. 22 shows a further possible embodiment of the method according to the third aspect of the invention. In this embodiment, a moveable anchor 146 is provided, e.g. in the form of a moveable ballast. The moveable anchor 146 is moveable between a primary anchor position 106* and a secondary anchor position 126*. In this embodiment, the moveable anchor 146 is the primary anchor when it is in the primary anchor position 106* and the moveable anchor 146* is the secondary anchor when it is in the secondary anchor position 126*.

(193) Optionally, the back mast top section remains connected to the moveable anchor during the movement of said anchor from the primary anchor position to the secondary anchor position or vice versa. This will require that the length of the first anchor connection 102 is changed during this movement of the moveable anchor 146.

(194) An advantageous embodiment and advantageous details of a ballast mast are described with reference to FIG. 23-FIG. 24.

(195) As described with reference to FIG. 3-FIG. 4 in a possible embodiment the ballast mast 2 comprises multiple vertically stackable further ballast mast sections 22.

(196) FIG. 23 shows a further ballast mast section 22 embodied as a triangular tower mast section. Each tower mast section comprises two main elongate elements each embodied as a corner tube section 201, a back mast top slider guide section 202 and multiple connector elongate elements embodied as connector tubes 203. The back mast top slide guide section 202 is provided parallel to and at a distance, preferably an equal distance, from both vertical corner tube sections 201, thereby spanning a volume having a triangular base, preferably an equilateral triangular base. The connector tubes 203 interconnect the two corner tube sections and the back mast top slide guide. By stacking further ballast mast sections a strong, yet light-weight, tower mast is provided.

(197) The connector tubes 203 may be connected to and disconnected from the corner tube sections and back mast top slide guide section by means of connector elements 204. In FIG. 24 said connector elements are embodied as connector pins. The connector elements 204 allow for disassembly of the ballast mast section 22 into its two corner tube sections 201, back mast top slide guide section 202, connector tubes 203 and connector elements 204, e.g. for transport. Preferably the corner tube sections, back mast top slide guide section, connector tubes and connector elements fit in standard size road or sea containers.

(198) The back mast top slide guide sections 202 are connected end-to-end to form the back mast top slide guide. The back mast top slide guide guides the back mast top slide 4 in its motion along the ballast mast 2. In this embodiment of FIG. 23 and FIG. 24 the load during hoisting is to a large extent, presumably even fully, carried by the back mast top slide guide. The other elements of the tower mast provide support and stability, e.g. when the ballast mast is out of the vertical and when the back mast is going to lean against or onto the ballast mast.

(199) The back mast top slide guide will, especially during hoisting, be exposed to large tensile forces. To pass the tensile force between back mast top slide guide sections 202 a ridge 205 is provided to the lower end of each back mast top slide guide section and a groove 206 is provided to the upper end of each back mast top slide guide section. The ridge 205 of an upper back mast top slide guide section is inserted into a groove 206 of a back mast top slide section provided below said upper back mast top slide guide section. The upper back mast top slide guide sections are subsequently fastened to each other.

(200) The back mast top slide guide section 202 may be embodied in various ways. For instance, the guide section may be rack of a rack-and-pinion actuator or may be the leg chord rack of the jacking system of U.S. Pat. No. 6,231,269.

(201) An advantageous embodiment of the back mast top slide guide section and back mast top slide 4 is described with reference to FIG. 23-FIG. 26.

(202) The back mast top slide guide section 202 is embodied as steel strip bundle section comprising multiple, here four, parallel and adjoining steel strips 207. The back mast top slide guide comprises multiple steel strip bundle sections connected end-to-end as described in the foregoing description of the back mast top slide guide. Each steel strip 207 has a front side 208 that extends vertically and horizontally substantially parallel to the connector tubes that interconnect the two corner tube sections. The normal direction of the steel strip front side points away from said connector tubes that interconnect the two corner tube sections. Steel strips 207 adjoin with their front side to a back side of a neighboring steel strip so as to provide a steel strip bundle section with a front side 209 that corresponds to the front side 208 of the foremost steel strip 207. The side planes 211 of the strip bundle section extend vertically and horizontally substantially perpendicular to the connector elements that interconnect the two corner tube sections. The steel strip comprises multiple climbing holes 210 that each extend through the multiple steel strips from the front side to the back side of the strip bundle.

(203) The back mast top slide 4 comprises a housing 213 that can be provided around said front side 209, side planes 211 and a portion of the back side 212 of a portion of a strip bundle section 202. The housing 213 thus has, seen from above, substantially a C-shape with the two ends of said C-shape provided adjacent the back side of the strip bundle. The front portion 213a of the housing is provided adjacent the front side of the strip bundle, the side portions 213b of the housing adjacent the sides of the strip bundle, and the back portions of the housing provided adjacent the back 213c of the strip bundle. Bearing shoes 214 are provided onto one or more interior sides of the housing 213 that face the strip bundle. Said bearing shoes 214 are provided against said strip bundle so as to allow said housing 213 to move along the strip bundle. A clearance is provided between the side faces of the steel strip bundle and side faces of the housing, so as to allow the housing to assume a slightly tilted orientation with respect to the strip bundle. Moreover, a front pin hole 215 equal in size to a climbing hole 209 of the strip bundle extends through the front portion of the housing. The front pin hole 215 is provided such that at the positions of the strip bundle 202 where a climbing hole 209 is provided, the front pin hole 215 is aligned with said climbing hole 209.

(204) The back mast top slide furthermore comprises two trunnions 216. Each trunnion is provided to a side portion 213b of the housing. The ballast mast side end 31 of the back mast and an end of the guy line 11 are attached to said trunnions 216 in such a way as to allow a rotation of said mast side end 31 and guy line end around said trunnions 216.

(205) The back mast top slide furthermore comprises a fastening pin 217. The fastening pin 217 can be moved by a suitable actuator (not shown), e.g. a hydraulic cylinder provided in said locking pin, from a withdrawn position to a locking position and vice versa. In the withdrawn position, shown in FIG. 25, the fastening pin 217 is provided to the front of the front side 209 of the strip bundle, allowing the back mast top slide to move vertically along the strip bundle. In the locking position the fastening pin 217 is provided through the front pin hole 215 and through the climbing hole 209. In this way the back mast top slide 4, the ballast mast side end 31 and guy line 11 attached to it are locked in position with respect to the ballast mast 2.

(206) The housing 213, trunnions 216 and fastening pin 217 together form a gimbal.

(207) Furthermore, the back mast top slide 4 comprises a hydraulic climbing device (not shown), preferably a step-wise hydraulic climbing device, that provides the movement of the back mast top slide along the strip bundle. Such a hydraulic climbing device and step-wise hydraulic climbing device are known in the art. A possible embodiment of a step-wise hydraulic climbing device comprises an upper and a lower connector compartment each comprising a connection pin. Said connection pin can be inserted and removed from said climbing holes by a suitable actuator mechanism. Said step-wise hydraulic climbing device moreover comprises in between said lower and upper compartment one or more hydraulic cylinders, e.g. cylinders with a stroke of 1-3 meters. In operation the connection pin of the lower connector compartment is provided into a climbing hole for support. The hydraulic cylinder is then extended, such that the upper connector compartment can reach a higher climbing hole, into which the connection pin of the upper connector compartment is provided. The connection pin of the lower connector department is withdrawn, after which the cylinder of the hydraulic cylinder with attached lower connector department is pulled upwards. The above cycle is then repeated.

(208) The back mast top slide guide and back mast top slide 4 as described above allows the lifting, e.g. step-wise lifting, of the one or more back mast subsections during the assembly of said back mast subsections as described in the foregoing FIG. 5-FIG. 7.

(209) During hoisting of a load with the crane 1 said back mast top slide passes the load on the guy line 11 to the strip bundle. Said strip bundles than passes said load to the ballast 6.

(210) Optionally the back mast top slide further comprises a movable closure part 218. Said movable closure part is provided to and movable, e.g. pivotable or slidable, with respect to the housing 213 between an open position and a closed position. The movable closure part 218 comprises a back pin hole 219 that is equal in size to the front pin hole 215 and climbing hole 209. The movable closure part 218 may also comprise bearing shoes 214 at a side thereof that in the closed position faces the strip bundle. The bearing shoes 214 are in the closed position provided against said strip bundle. In the open position the movable closure part 218 allows the back mast top slide 4 to move past connector tubes 203 and connector elements 204 that are connected to the back mast top slide guide. In the closed position the closure part 218 extends adjacent the back side 212 of the strip bundle between the two ends of the C-shaped housing 213, so that the housing 213 and movable closure part 218 together encircle the strip bundle. In the closed position the back pin hole 219 is provided such that at the positions of the back mast top slide guide where a climbing hole 209 is provided, the back pin hole 219 is aligned with said climbing hole 209. When the fastening pin 217 is moved to the lock position it is supported by the housing 213 around the front pin hole 215, by the strip bundle around climbing hole 209 and the movable closure part around back pin hole 219, so as to provide a locking that can withstand a high load. In the embodiment of FIG. 26 the movable closure part 218 is embodied as a movable closure part pivotable with respect to housing around a vertical axis 220 so as to provide a door-like movable closure part.

(211) Alternative to or in combination with said movable closure part the housing 213 may extend to the front of the strip bundle around said pin 217 as shown in FIG. 25 and FIG. 26. This embodiment also provides further support to the fastening pin when said fastening pin has been moved to the lock position.

(212) An embodiment of the back mast 3 and a method of assembly of the back mast subsections 36 is described with reference to FIG. 27A-FIG. 27E. The embodiment and method of assembly apply to a main boom subsection 55 as well. Main boom subsections 55 and back mast subsections 36 are envisioned to contain the same type of components. However, the dimensions of said components or details of their construction may vary.

(213) The back mast 3 comprises multiple back mast subsections 36. Each back mast subsection 36 is first assembled and then provided in place, e.g. provided on top of or below another back mast subsection 36 in a manner described in the foregoing.

(214) The back mast subsection comprises four main elongate elements embodied as corner tube sections 301, four connector elongate elements embodied as side connector tubes 302, and one or more diagonal elongate elements embodied as connector tubes 303. The corner tube section may have a circular or polygonal, e.g. octagonal, cross-section. The side connector tubes have a length between 3 and 11 meters, e.g. 8 meters. Preferably the corner tube sections, back mast top slide guide section, connector tubes and diagonal connector tubes fit in standard size road containers or standard size sea containers. Thus, a crane comprising a back mast and/or main boom assembled as described here may be a containerized crane.

(215) In an assembled state, the corner tube sections 301 are provided parallel to each other and at a distance from each other. The four side connector tubes 302 interconnect the parallel corner tube sections 301 at one end of said corner tube sections so as to provide a back mast subsection 36 with a square ground plane. Optionally connector tubes 302 may also be provided between the vertical corner tube sections 301 at the other end of said vertical tube sections 301. The diagonal connector tubes 303 interconnect two corner tube sections 301 across a diagonal. The connection points of said diagonal connector tubes 303 to the two corner tube sections 301 are preferably offset along the length of the corner tube sections 301. Multiple, e.g. two, three or four diagonal connector tubes 303 may be provided. When two diagonal connector tubes 303 are used, a first diagonal connector tube 303 may interconnect two corner tube sections 301, while the second diagonal connector tube 303 may interconnect the other two corner tube sections 301.

(216) The back mast subsection 36 is assembled using a suitable assembly device 304. Said assembly device comprises four parallel and offset elongated supports 305 onto which the corner tube sections can be provided. The upper surface of the outer elongated supports 305 are preferably lower than the upper surface of the inner elongated supports 305. A sliding surface 306 is provided between each outer and adjacent inner support 305. Connector tubes 302 are provided between each of the adjacent corner tube sections. The connector tubes 302 provided between an outer and an inner elongated support 305 are pivotally connected to the corner tube sections provided on the inner elongated supports. Said pivotal connection is pivotable around an axis parallel to the main axis of the corner tube section. A diagonal connector tube 303 is provided to one of the corner tube sections 301 provided on the inner elongated supports 305. The system of corner tube sections 301 and connector tubes 302, 303 is then lifted. The corner tube sections 301 on the outer elongated supports 305 preferably slide along the sliding surface 306 to a position below the corner tube sections 301 that were previously provided on the inner elongated supports 305. The free end of the diagonal connector tube 303 is connected to a lower corner tube section 301. Another connector tube 302 is provided on two additional supports 305 and connected to the lower corner tube sections 301. The back mast subsection 36 is now assembled and may be included in the crane 1.

(217) In this embodiment the back mast subsection 36 has a square ground plane. With a method similarly to that presented here back mast subsections with differently shaped polygonal ground planes, e.g. rectangular or triangular, may be provided.

(218) An embodiment of the crane comprising a movable mast foot assembly 7 and skidding tracks 401, 402 is described under reference to FIG. 28A-FIG. 28D.

(219) In an advantageous embodiment the crane is provided with a circular skidding track 402 around the ballast mast 2 and one or more linear skidding tracks 401 extending from the ballast mast 2. Moreover, the mast foot assembly 7 comprises two mast feet provided at a distance from each other. Each of the feet may comprise multiple mast feet parts, said mast feet parts preferably being distant from each other in a direction perpendicular to the direction in which the two mast feet are distant. This double-split mast feet structure may provide a most stable mast foot assembly 7. Said mast feet part may for instance comprise skid shoes or wheels. Said mast foot assembly 7, and therefore the back mast and main boom are provided onto circular skidding track 402 or linear skidding track 401. The linear skidding track 401 intersects the circular skidding track 402 and the mast foot assembly 7 is adapted to skid on both the linear skidding track 401 and the circular skidding track 402. The circular skidding track 402 provides to the crane 1 additional flexibility in use, as it can now for instance transfer loads 18 from one side of the ballast mast 2 to the other side thereof. By means of said one or more linear skidding tracks 401 the distance between ballast mast 2 and mast foot assembly 7 can be varied.

(220) The combination of a linear skidding track 401 and circular skidding track 402 allows the mast foot assembly 7 first to be moved along the linear skidding track 401 to a position relatively far away from the ballast mast 2, allowing it to pick up a load 18 at a distant position, while keeping the ends of the back mast 3 and the main boom 5 at the same elevation. This is shown in FIG. 28A. The main boom 5 is subsequently hailed, thereby lifting the load 18, as shown in FIG. 28B. Next, shown in FIG. 28C, the mast foot assembly 7 is moved to a position closer to the ballast mast 2 where the linear skidding track 401 intersects the circular skidding track 402, thereby erecting the back mast 3. If desired, the load 18 can now be rotated with respect to the ballast mast 2 by further movement of the mast foot assembly 7, back mast 3 and main boom 5 around the ballast mast 2. The rotation is shown in FIG. 28D. The rotational motion is performed relatively close to the ballast mast 2, so that the free area required for said rotation is reduced.

(221) Side views of an A-shaped ballast mast 3 or main boom 5 and a side view of a single leg shaped ballast mast 3 or main boom 5 are provided in FIG. 29 and FIG. 30 respectively.

(222) FIG. 31-FIG. 33 illustrate schematically an alternative embodiment of a ballast for a crane, e.g. to be used in combination with a crane as described herein. FIG. 31 is a vertical cross section, FIG. 32 a top view, and FIG. 33 a side view.

(223) The ballast comprises a floor 300, a column 301 connected to and raised from said floor 300, and a circumferential wall 302 that forms together with said floor 300 a ballast container that is to be filled with ballast material, e.g. with sand, gravel, etc.

(224) For reference the depicted ballast may have a wall 302 that is about 12 meters high with a diameter of about 14 meters.

(225) The column 301 is arranged centrally with the ballast container and, as preferred, a ballast mast is connectable to the top end of the column 301, e.g. as described herein.

(226) The column 301 is preferably stabilized by diagonal braces 303 that extend to the floor 300.

(227) The floor 300 preferably is composed of a framework and floor panels placed over the framework.

(228) As is preferred the ballast container has a volume that exceeds 1000 cubic meter, e.g. is able to retain more than 1500 tons of sand.

(229) As is preferred the wall 302 is assembled from wall panels 302a, e.g. in a polygonal arrangement, wherein each wall panel fits within an ISO container, e.g. has a length of less than 12 meters and a width of at most 2.40 meters. The wall panels 302a can be interconnected in various manners, e.g. pairs being hinged to one another.

(230) In an embodiment tension rods or cables extend diametrically across the wall 302 and/or to the central column.

(231) In an embodiment doors 304 or the like are provided in multiple of the wall panels 302a, e.g. along the lower edge of the wall 302, e.g. so as to allow for discharge of ballast material when the crane is to be disassembled.