AUTOMATICALLY FOLDING AND UNFOLDING TOWER CRANE

Abstract

An automated collapsible tower crane comprising a mast with telescopic portions, a boom with boom sections articulated with each other by respective rotary joints, a boom folding system to unfold and fold the boom by the rotary joints wherein each proximal and distal rotary joint is associated with at least one hydraulic actuator to unfold and fold boom sections, a mast folding system to fold the mast down, wherein in the transport position the boom sections are folded down one on top of the other and on the mast, and the boom folding and unfolding system acts independently of the folding and telescoping system of the mast, and comprises hydraulic actuators to fold and unfold the boom sections.

Claims

1-7 (canceled)

8. An automated collapsible tower crane movable between a transport position and a working position, comprising: a telescopically extending mast with at least an upper telescopic portion with an upper end part, and a lower telescopic portion with a lower part rotatably anchored in a vertical plane to a lower base platform of the tower crane; a mast locking mechanism to lock the lower telescopic portion in a locked position in a substantially vertical plane with respect to a lower base platform of the tower crane; a telescoping system of the mast to telescopically extend and retract the mast between a retracted vertical position in which the mast is in a non-extended vertical position and an extended vertical position in which the mast extends upwards, the telescoping system comprising a combination of cable and pulleys driven by a winch; a boom comprising a plurality of boom sections articulated in respective rotary joints along respective rotation angles limited to substantially 180° around respective horizontal axes to stiffen the boom when it is extended, the boom sections including a first boom section articulated with the upper end part of the upper telescopic portion of the mast and at one end of the proximal portion of a second boom section; a boom folding system for unfolding and folding the boom by the rotary joints between a folded position and at least one linearly unfolded working position along a substantially horizontal plane, a mast folding system for moving the mast between a folded transport position and an unfolded position along a substantially vertical plane, the mast folding system comprising a bracing sling anchored to: the lower base platform; a first superiorly articulated vertically rotatable support strut of a proximal portion of the first boom section; a second vertically rotatable support strut articulated posteriorly of the proximal portion of the first boom section; and at least a third superiorly articulated vertically rotatable support strut of a distal portion of the first boom section of the boom; wherein: the sling is connected to the support struts; in the transport position the boom sections are folded down over one another and on the mast in folding planes; the boom folding and unfolding system acts independently of the combination of cables and pulleys driven by the winch of the mast folding and telescoping system, and comprises hydraulic actuators hydraulically powered by hydraulic equipment for folding and unfolding the boom sections; and wherein each proximal and distal rotary joint is associated with at least one hydraulic actuator arranged to unfold and fold boom sections relative to one another.

9. The automated collapsible tower crane, according to claim 8, wherein: the first boom section and the second boom section are articulated by a proximal rotary joint; the proximal rotary joint further comprises a joint body further comprising: a first lower end part in which a first lower horizontal axis is arranged and on which one end of the distal portion of the first boom section is rotatably coupled; a second lower end part in which a second lower horizontal axis is arranged and on which one end of the proximal portion of the second boom section is rotatably coupled; a first upper part with a first upper horizontal axis which is articulated with a distal end of a first hydraulic actuator, the first hydraulic actuator further comprising a proximal end articulated with an upper point in the distal portion of the first boom section; and a second upper part with a second upper horizontal axis articulated at a proximal end of a second hydraulic actuator, the second hydraulic actuator further comprising a distal end articulated at an upper point in the proximal portion of the second boom section; and wherein the lower horizontal axes are further apart from each other than the upper horizontal axes.

10. The automated collapsible tower crane according to claim 9, wherein the distal boom section is articulated at the preceding boom section by a distal rotary hinge joint further comprising: a primary horizontal joint axis that articulates the proximal portion of the distal section with the distal portion of the preceding boom section; a fixed lever arm immobilised on the proximal portion of the distal boom section and presenting a free end with a secondary joint axis; a rotary angle arm with a first leg articulated with the primary horizontal joint axis and a second leg articulated with the secondary joint axis; and an intermediate part between the legs of the rotary angle arm in which the distal end of the hydraulic actuator is articulated and wherein the proximal end of the hydraulic actuator is articulated in the distal portion of the preceding boom section.

11. The automated collapsible tower crane according to claim 8, wherein the second boom section constitutes a distal boom portion with a free distal end.

12. The automated collapsible tower crane according to claim 11, further comprising an auxiliary support arranged at the free distal end of the distal boom portion in such a way that the auxiliary support rests on the ground when the boom is in a maintenance position in which the boom) extends vertically inclined from the first rotary joint.

13. The automated collapsible tower crane according to claim 12, wherein the auxiliary support rests on the ground when the boom is unfolded and the mast is between its retracted vertical position and its extended vertical position.

14. The automated collapsible tower crane according to claim 13, wherein: the first boom section and the second boom section are articulated by a proximal rotary joint; the proximal rotary joint further comprises a joint body further comprising: a first lower end part in which a first lower horizontal axis is arranged and on which one end of the distal portion of the first boom section is rotatably coupled; a second lower end part in which a second lower horizontal axis is arranged and on which one end of the proximal portion of the second boom section is rotatably coupled; a first upper part with a first upper horizontal axis which is articulated with a distal end of a first hydraulic actuator, the first hydraulic actuator further comprising a proximal end articulated with an upper point in the distal portion of the first boom section; and a second upper part with a second upper horizontal axis articulated at a proximal end of a second hydraulic actuator, the second hydraulic actuator further comprising a distal end articulated at an upper point in the proximal portion of the second boom section; and wherein the lower horizontal axes are further apart from each other than the upper horizontal axes.

15. The automated collapsible tower crane according to claim 14, wherein the distal boom section is articulated at the preceding boom section by a distal rotary hinge joint further comprising: a primary horizontal joint axis that articulates the proximal portion of the distal section with the distal portion of the preceding boom section; a fixed lever arm immobilised on the proximal portion of the distal boom section and presenting a free end with a secondary joint axis; a rotary angle arm with a first leg articulated with the primary horizontal joint axis and a second leg articulated with the secondary joint axis; and an intermediate part between the legs of the rotary angle arm in which the distal end of the hydraulic actuator is articulated and wherein the proximal end of the hydraulic actuator is articulated in the distal portion of the preceding boom section.

16. The automated collapsible tower crane, according to claim 11, wherein: the first boom section and the second boom section are articulated by a proximal rotary joint; the proximal rotary joint further comprises a joint body further comprising: a first lower end part in which a first lower horizontal axis is arranged and on which one end of the distal portion of the first boom section is rotatably coupled; a second lower end part in which a second lower horizontal axis is arranged and on which one end of the proximal portion of the second boom section is rotatably coupled; a first upper part with a first upper horizontal axis which is articulated with a distal end of a first hydraulic actuator, the first hydraulic actuator further comprising a proximal end articulated with an upper point in the distal portion of the first boom section; and a second upper part with a second upper horizontal axis articulated at a proximal end of a second hydraulic actuator, the second hydraulic actuator further comprising a distal end articulated at an upper point in the proximal portion of the second boom section; and wherein the lower horizontal axes are further apart from each other than the upper horizontal axes.

17. The automated collapsible tower crane according to claim 16, wherein the distal boom section is articulated at the preceding boom section by a distal rotary hinge joint further comprising: a primary horizontal joint axis that articulates the proximal portion of the distal section with the distal portion of the preceding boom section; a fixed lever arm immobilised on the proximal portion of the distal boom section and presenting a free end with a secondary joint axis; a rotary angle arm with a first leg articulated with the primary horizontal joint axis and a second leg articulated with the secondary joint axis; and an intermediate part between the legs of the rotary angle arm in which the distal end of the hydraulic actuator is articulated and wherein the proximal end of the hydraulic actuator is articulated in the distal portion of the preceding boom section.

18. The automated collapsible tower crane according to claim 8, wherein: the second boom section is an intermediate boom portion; from its connection to the first support strut, the sling is divided into a first branch and a second branch; the first branch is connected to a distal portion of the first boom section of the boom while the second branch is connected to a distal portion of the second boom section of the boom; the boom comprises a third boom section with a proximal portion articulated with the distal portion of the second boom section; and the third boom section constitutes a distal boom portion with a free distal end.

19. The automated collapsible tower crane according to claim 18, further comprising an auxiliary support arranged at the free distal end of the distal boom portion in such a way that the auxiliary support rests on the ground when the boom is in a maintenance position in which the boom) extends vertically inclined from the first rotary joint.

20. The automated collapsible tower crane according to claim 19, wherein the auxiliary support rests on the ground when the boom is unfolded and the mast is between its retracted vertical position and its extended vertical position.

21. The automated collapsible tower crane according to claim 20, wherein: the first boom section and the second boom section are articulated by a proximal rotary joint; the proximal rotary joint further comprises a joint body further comprising: a first lower end part in which a first lower horizontal axis is arranged and on which one end of the distal portion of the first boom section is rotatably coupled; a second lower end part in which a second lower horizontal axis is arranged and on which one end of the proximal portion of the second boom section is rotatably coupled; a first upper part with a first upper horizontal axis which is articulated with a distal end of a first hydraulic actuator, the first hydraulic actuator further comprising a proximal end articulated with an upper point in the distal portion of the first boom section; and a second upper part with a second upper horizontal axis articulated at a proximal end of a second hydraulic actuator, the second hydraulic actuator further comprising a distal end articulated at an upper point in the proximal portion of the second boom section; and wherein the lower horizontal axes are further apart from each other than the upper horizontal axes.

22. The automated collapsible tower crane according to claim 21, wherein the distal boom section is articulated at the preceding boom section by a distal rotary hinge joint further comprising: a primary horizontal joint axis that articulates the proximal portion of the distal section with the distal portion of the preceding boom section; a fixed lever arm immobilised on the proximal portion of the distal boom section and presenting a free end with a secondary joint axis; a rotary angle arm with a first leg articulated with the primary horizontal joint axis and a second leg articulated with the secondary joint axis; and an intermediate part between the legs of the rotary angle arm in which the distal end of the hydraulic actuator is articulated and wherein the proximal end of the hydraulic actuator is articulated in the distal portion of the preceding boom section.

23. The automated collapsible tower crane according to claim 18, wherein: the first boom section and the second boom section are articulated by a proximal rotary joint; the proximal rotary joint further comprises a joint body further comprising: a first lower end part in which a first lower horizontal axis is arranged and on which one end of the distal portion of the first boom section is rotatably coupled; a second lower end part in which a second lower horizontal axis is arranged and on which one end of the proximal portion of the second boom section is rotatably coupled; a first upper part with a first upper horizontal axis which is articulated with a distal end of a first hydraulic actuator, the first hydraulic actuator further comprising a proximal end articulated with an upper point in the distal portion of the first boom section; and a second upper part with a second upper horizontal axis articulated at a proximal end of a second hydraulic actuator, the second hydraulic actuator further comprising a distal end articulated at an upper point in the proximal portion of the second boom section; and wherein the lower horizontal axes are further apart from each other than the upper horizontal axes.

24. The automated collapsible tower crane according to claim 23, wherein the distal boom section is articulated at the preceding boom section by a distal rotary hinge joint further comprising: a primary horizontal joint axis that articulates the proximal portion of the distal section with the distal portion of the preceding boom section; a fixed lever arm immobilised on the proximal portion of the distal boom section and presenting a free end with a secondary joint axis; a rotary angle arm with a first leg articulated with the primary horizontal joint axis and a second leg articulated with the secondary joint axis; and an intermediate part between the legs of the rotary angle arm in which the distal end of the hydraulic actuator is articulated and wherein the proximal end of the hydraulic actuator is articulated in the distal portion of the preceding boom section.

25. The automated collapsible tower crane according to claim 11, wherein the distal boom section is articulated at the preceding boom section by a distal rotary hinge joint further comprising: a primary horizontal joint axis that articulates the proximal portion of the distal section with the distal portion of the preceding boom section; a fixed lever arm immobilised on the proximal portion of the distal boom section and presenting a free end with a secondary joint axis; a rotary angle arm with a first leg articulated with the primary horizontal joint axis and a second leg articulated with the secondary joint axis; and an intermediate part between the legs of the rotary angle arm in which the distal end of the hydraulic actuator is articulated and wherein the proximal end of the hydraulic actuator is articulated in the distal portion of the preceding boom section.

26. The automated collapsible tower crane according to claim 18, wherein the distal boom section is articulated at the preceding boom section by a distal rotary hinge joint further comprising: a primary horizontal joint axis that articulates the proximal portion of the distal section with the distal portion of the preceding boom section; a fixed lever arm immobilised on the proximal portion of the distal boom section and presenting a free end with a secondary joint axis; a rotary angle arm with a first leg articulated with the primary horizontal joint axis and a second leg articulated with the secondary joint axis; and an intermediate part between the legs of the rotary angle arm in which the distal end of the hydraulic actuator is articulated and wherein the proximal end of the hydraulic actuator is articulated in the distal portion of the preceding boom section.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Embodiments of the invention will be described below on the basis of figures, wherein

[0019] FIG. 1 is a side elevation view of an embodiment of a rotating tower crane according to the invention in its working position;

[0020] FIG. 1A is an enlarged view corresponding to the rectangle A marked in FIG. 1;

[0021] FIG. 1B is an enlarged view of the area around joint 15B of the crane illustrated in FIG. 1;

[0022] FIG. 1C is an enlarged top perspective view of the area around joint 15B of the crane illustrated in FIG. 1B;

[0023] FIG. 1D is an enlarged view of the area near the joint 15C of the crane illustrated in FIG. 1;

[0024] FIG. 1E is an enlarged perspective view of the area near the joint 15B of the crane illustrated in FIG. 1D;

[0025] FIG. 2 is a side elevation view of the crane illustrated in FIG. 1 in a transport position;

[0026] FIG. 3 is a front elevation view of the crane in the transport position illustrated in FIG. 2;

[0027] FIG. 4 is a front perspective view of the lower part of the crane of FIG. 1 in a deployment phase from the transport position towards its working position in which the mast is unfolded towards a vertical position while the boom it not unfolded;

[0028] FIG. 4A is a schematic view of an embodiment of the telescoping system applicable to the crane according to the invention;

[0029] FIG. 5 is a side elevation view of the crane according to the invention in a phase of its erection from the transport position illustrated in FIG. 2 towards its working position;

[0030] FIG. 6 is a side elevation view of the crane according to the invention in a phase of its erection from the position illustrated in FIG. 5 towards its working position;

[0031] FIG. 7 is a side elevation view of the crane according to the invention in a following phase of its erection from the position illustrated in FIG. 6 towards its working position;

[0032] FIG. 8 is a side elevation view of the crane according to the invention in a following phase of its erection from the position illustrated in FIG. 7 towards its working position;

[0033] FIG. 7A is an enlarged side elevation view of the area near the joint 15B of the crane illustrated in FIG. 7;

[0034] FIG. 8A is an enlarged side elevation view of the area near the joint 15B of the crane illustrated in FIG. 8;

[0035] FIGS. 9-11 are side elevation views respectively showing successive phases of deployment of the boom from the position illustrated in FIG. 7 towards its working position;

[0036] FIG. 9A is an enlarged side elevation view of the area near the joint 15B of the crane illustrated in FIG. 9;

[0037] FIG. 10A is an enlarged side elevation view of the area near the joint 15B of the crane illustrated in FIG. 10;

[0038] FIG. 11A is an enlarged side elevation view of the area near the joint 15B of the crane illustrated in FIG. 11;

[0039] FIGS. 12-13 are side elevation views respectively showing successive phases of deployment of the boom from the position illustrated in FIG. 11 towards its working position;

[0040] FIG. 12A is an enlarged side elevation view of the area near the joint 15B of the crane illustrated in FIG. 12;

[0041] FIG. 12B is an enlarged side elevation view of the area near the joint 15C of the crane illustrated in FIG. 12;

[0042] FIG. 13A is an enlarged side elevation view of the area near the joint 15C of the crane illustrated in FIG. 13;

[0043] FIG. 14 is a side elevation view of the crane according to the invention in a maintenance position;

[0044] FIG. 14A is an enlarged view corresponding to rectangle B marked in FIG. 14;

[0045] FIG. 14B is an enlarged side elevation view of the area near the joint 15B of the crane illustrated in FIG. 14;

[0046] FIG. 14C is an enlarged side elevation view of the area near the joint 15C of the crane illustrated in FIG. 14.

[0047] Reference signs appear in the figures that identify the following elements:

[0048] S ground

[0049] α, β rotation angles

[0050] 1 mast

[0051] 1.1 lower telescopic portion

[0052] 1.2 upper telescopic portion

[0053] 1.2a upper end part

[0054] 2 boom

[0055] 2.1 first boom section

[0056] 2.1a proximal portion

[0057] 2.1b distal portion

[0058] 2.2 second boom section

[0059] 2.2a proximal portion

[0060] 2.2b distal portion

[0061] 2.3 third boom section

[0062] 2.3a proximal portion

[0063] 2.3b free distal end

[0064] 3 auxiliary support

[0065] 3a base

[0066] 3b vertical wings

[0067] 4 first hydraulic actuator

[0068] 4a proximal end

[0069] 4b distal end

[0070] 5 second hydraulic actuator

[0071] 5a proximal end

[0072] 5b distal end

[0073] 6 third hydraulic actuator

[0074] 6a proximal end

[0075] 6b distal end

[0076] 7 base platform

[0077] 8 sling

[0078] 8a first branch

[0079] 8b second branch

[0080] 9 counterload

[0081] 10 hydraulic equipment

[0082] 11 motor equipment

[0083] 12 carriage

[0084] 13 hoist hook

[0085] 14 hoist rope

[0086] 15A first rotary joint

[0087] 15B proximal rotary joint,

[0088] 15C distal rotary hinge joint

[0089] 4, 5, 6 hydraulic actuators

[0090] 16A first support strut

[0091] 16B second support strut

[0092] 16C third support strut

[0093] 17a first lower horizontal axis

[0094] 17b second lower horizontal axis

[0095] 17c first upper horizontal axis

[0096] 17d upper horizontal axis

[0097] 18 joint body

[0098] 18a proximal part

[0099] 18b distal part

[0100] 18c connector mechanism

[0101] 19 telescoping system

[0102] 19a winch

[0103] 19b cable

[0104] 19c, 19d, 19e, 19f pulleys

[0105] 20a primary horizontal joint axis

[0106] 20b tilting angle arm

[0107] 20c a secondary joint axis

[0108] 20d fixed lever arm (20d)

DETAILED DESCRIPTION

[0109] FIGS. 1 and 1A illustrate an embodiment of a rotating tower crane in its working position. In this embodiment, the automated assembly collapsible tower crane shown between a transport position and a working position, comprises a mast (1), a mast (1) locking mechanism to lock the lower telescopic portion (1.1) in a locked position in a substantially vertical plane with respect to a rotating lower base platform (7) of the tower crane and a boom (2). The lower base platform (7) receives a counterload (9) when the tower crane is in the working or maintenance operating configuration.

[0110] The mast (1) is telescopically extending and comprises an inner upper telescopic portion (1.2) with an upper end part (1.2a), vertically movable in an outer lower telescopic portion (1.1) with a lower part rotatably anchored in a vertical plane to a lower base platform (7) of the tower crane. The upper telescopic portion (1.2) can be moved vertically inside the lower telescopic portion by means of a telescoping system (19) (see FIG. 4A) to telescopically extend and retract the mast (1) between a retracted vertical position in which the mast (1) is in its non-extended vertical position and an extended vertical position in which the mast (1) extends upward. The telescoping system (19) comprises a combination of cable (19b) and pulleys (19c, 19d, 19e, 19f) driven by a winch (19a) (see FIG. 4a).

[0111] The boom (2) comprises a plurality of boom sections (2.1, 2.2, 2.3) articulated in respective rotary joints (15A, 15B, 15C), namely, a first rotary joint (15A), a proximal rotary joint (15B) and a distal rotary joint (15C). The proximal and distal rotary joints (15B, 15C) are capable of being rotated along respective rotation angles (β, β) limited to substantially 180° around respective horizontal axes to stiffen the boom (2) when extended.

[0112] The boom sections are a first boom section (2.1) articulated with the upper end part (1.2a) of the upper telescopic portion (1A) of the mast (1) and with one end of the proximal portion (2.2a) of a second boom section (2.2) that forms an intermediate boom portion, and a third boom section (2.3) with a proximal portion (2.3a) articulated with the distal portion (2.2b) of the second boom section (2.2) that forms a distal boom portion with a free distal end (2.3b).

[0113] The tower crane further comprises a mast (1) folding system for moving the mast (1) between a folded transport position and an unfolded position along a substantially vertical plane. The mast (1) folding system comprises a bracing sling (8) anchored to the base platform (7) as well as to a first superiorly articulated vertically rotatable support strut (16A) of a proximal portion (2.1a) of the first boom section (2.1), a second posteriorly articulated vertically rotatable support strut (16B) of the proximal portion (2.1a) of the first boom section (2.1), and a third superiorly articulated vertically rotatable support strut (16C) of a distal portion (2.1b) of the first boom section (2.1) of the boom (2). The sling (8) is connected to the support struts (16A, 16B, 16C). From its connection to the first support strut (16A), the sling (8) is divided into a first branch (8a) and a second branch (8b). The first branch (8a) is connected to a distal portion (2.1b) of the first boom section (2.1) of the boom (2) while the second branch (8b) is connected to a distal portion (2.2b) of the second boom section (2.2) of the boom (2).

[0114] The crane is provided with a boom (2) folding system for unfolding and folding the boom (2) by the rotary joints (15A, 15B, 15C) between a folded position and at least one linearly unfolded working position along a substantially horizontal plane.

[0115] The boom (2) folding and unfolding system acts independently of the combination of cables and pulleys driven by the winch (19a) of the mast (1) folding system, and comprises hydraulic actuators (4, 5, 6) hydraulically powered by hydraulic equipment (11) to fold and unfold the boom sections (2.1, 2.2, 2.3), for which each proximal and distal rotary joint (15B, 15C) is associated with at least one hydraulic actuator (4, 5, 6) arranged to unfold and fold boom sections (2.1, 2.2, 2.3) relative to each other.

[0116] The tower crane further comprises a hoist cable (14) at the free end of which a hoist hook (13) is coupled, which is guided by an electric carriage (12), powered by motor equipment (11). The carriage 12 can move along the boom (2) for which the boom sections (2.1, 2.2, 2.3) are provided with guide rails (not detailed in the figures) that are flush with each other when the boom (2) is unfolded in its working position.

[0117] In FIGS. 1B and 1C, the elements associated with the proximal rotary joint (15B) can be seen in more detail. Thus, it can be seen that the proximal rotary joint (15B) comprises a joint body (18) with a first lower end part in which a first lower horizontal axis (17a) is arranged in which one end of the distal portion (2.1b) of the first boom section (2.1) is rotatably coupled, as well as a second lower end part in which a second lower horizontal axis (17b) is arranged in which one end of the proximal portion (2.2a) of the second boom section (2.2) is rotatably coupled.

[0118] The joint body (18) is composed of a proximal part (18a) arranged in the distal portion (2.1b) of the first boom section (2.1) and a distal part (18b) arranged in the proximal portion (2.2A) of the second boom section (2.2). Said proximal (18a) and distal (18b) parts are joined on one side by means of a hinge mechanism (not shown in FIGS. 1B and 1C) and on the opposite side by means of a connector mechanism (18c). These mechanisms allow the second boom section (2.2) to be rotated with respect to the first boom section (2.1) in an initial phase of boom (2) deployment and a final phase of boom (2) retraction.

[0119] The joint body (18) further comprises a first upper part with a first upper horizontal axis (17c) in which it is articulated with a distal end (4b) of a first hydraulic actuator (4), the first actuator (4) comprising a proximal end (4a) articulated with an upper point in the distal portion (2.1b) of the first boom section (2.1), and a second upper part with a second upper horizontal axis (17d) articulated with a proximal end (5a) of a second hydraulic actuator (5), the second hydraulic actuator (5) comprising a distal end (5b) articulated with an upper point in the proximal portion (2.2a) of the second boom section (2.2). The lower horizontal axes (17a, 17b) are further apart from each other than the upper horizontal axes (17c, 17d).

[0120] FIGS. 1D and 1E show in more detail the elements associated with the distal rotary joint (15C). The distal boom section (2.3) is articulated with the second boom section (2.2) by means of the distal rotary hinge joint (15C) comprising a primary horizontal joint axis (20a), a fixed lever arm (20d) as well as a rotary angle arm (20b).

[0121] The primary horizontal joint axis (20a) articulates the proximal portion (2.3a) of the distal section (2.3) with the distal portion (2.2b) of the second boom section (2.2) while the fixed lever arm (20d) is made up of two parallel side plates and immobilised in the proximal portion (2.3a) of the distal boom section (2.3) and has a free end with a secondary joint axis (20c).

[0122] The tilting angle arm (20b) comprises two parallel side plates that together make up a first leg articulated with the primary horizontal joint axis (20a) and a second leg articulated with the secondary joint axis (20c). The distal end (6b) of the hydraulic actuator (6) is articulated with the tilting angle arm (20b), while the proximal end (6a) of the hydraulic actuator is articulated in the distal portion (2.2b) of the second boom section (2.2).

[0123] FIGS. 2 and 3 show the tower crane in its transport position, wherein the tower (1) is folded down and the boom sections are folded over the folded down tower.

[0124] FIG. 4 illustrates the crane with the tower (1) in a vertical erection phase and the folded boom sections and not yet unfolded before the second boom section (2.2) has been bent (in the direction of the arrow) on the first boom section (2.1) and before the proximal and distal parts (18a, 18b) of the joint body (18) have been brought together and locked to form the joint body.

[0125] In FIG. 4A, a telescoping system (19) comprising a winch (19a), a cable (19b), a set of pulleys (19c, 19d) arranged as a hoist in the upper telescopic portion and guiding pulleys (19c, 19f), arranged in the lower telescopic portion (1.1) of the mast (1) can be seen.

[0126] FIG. 5 shows the tower crane in a phase of erection of the mast (1) towards its vertical position (in the direction of the arrow), in which the boom sections are still folded over the mast (1).

[0127] FIG. 6 shows the tower crane in a following phase in which the mast (1) is in its vertical position, in which the boom sections are still folded over the mast (1) before the second boom section (2.2) has been bent over the first boom section (2.1) and the proximal and distal parts (18a, 18b) of the joint body (18) have been brought together and locked to form the joint body.

[0128] FIG. 7 shows the tower crane in a following phase in which the mast (1) is in its vertical position, in which the boom sections remain folded over the mast (1) after the second boom section (2.2) has been bent over the first boom section (2.1) and the proximal and distal parts (18a, 18b) of the joint body (18) have been brought together and locked to form the joint body (18) (see FIG. 7A). As can be seen in FIG. 7A, in this phase the hydraulic actuators (4, 5) are in their retracted positions so that the boom sections (2.1, 2.2) remain folded over one another.

[0129] FIG. 8 shows the tower crane in a following assembly phase in which the boom sections (2.1, 2.2) gradually unfold (see FIG. 8A). As can be seen in FIG. 8A, in this phase the first hydraulic actuator (4) has been extended and has forced the joint body (18) to rotate with respect to the first boom section (2.1), so that the second boom section (2.2) has started to unfold.

[0130] FIG. 9 illustrates a following phase of the deployment of the boom sections (2.1, 2.2), in which the tower has been telescopically extended in its vertical position, the first boom section (2.1) is unfolded to its horizontal position, the second boom section (2.2) is in a partially unfolded position towards its working position, and the third boom section (2.3) is still folded over the second boom section (2.2). As can be seen in FIG. 9A, the first hydraulic actuator (4) remains in the extended position and the second hydraulic actuator (5) remains in the retracted position, shown in FIGS. 8 and 8A.

[0131] FIG. 10 illustrates a following phase of the deployment of the boom sections (2.1, 2.2), in which the first boom section (2.1) is unfolded to its horizontal position, the second boom section (2.2) is in a more unfolded position towards its working position, and the third boom section (2.3) remains folded over the second boom section (2.2). As can be seen in FIG. 10A, the first actuator (4) has been fully extended forcing the joint body (18) into a first alignment position in which the lower part of the joint body (18) is aligned with the lower part of the first boom section (2.1). In addition, in this phase, the third support strut (16C) has rotated to its unfolded working position in which it is positioned orthogonally to the first boom section (2.1).

[0132] FIG. 11 illustrates a following phase of the deployment of the boom sections (2.1, 2.2), in which the first boom section (2.1) is unfolded to its horizontal position, the second boom section (2.2) is in an even more unfolded position towards its working position, and the third boom section (2.3) remains folded over the second boom section (2.2). As can be seen in FIG. 11, in this phase the second hydraulic actuator (5) has been partially extended so that it is forcing the second boom section (2.2) to rotate with respect to the joint body (18).

[0133] FIG. 12 illustrates a following phase in the deployment of the third boom section (2.3) and in which the first and second boom sections (2.1, 2.2) are unfolded to their horizontal position, and the third boom section (2.3) has started its deployment of the second boom section (2.2). As can be seen in FIG. 12A, in this phase the hydraulic actuators (4, 5) are fully extended so that the joint body (18) is fully aligned with the boom sections (2.1, 2.2). On the other hand, FIG. 12B shows that in this phase the third boom section (2.3) remains folded on the second boom section (2.2).

[0134] FIG. 13 illustrates a following phase of the deployment of the section of the third boom section (2.3) in which the first and second boom sections (2.1, 2.2) are unfolded to their horizontal position, and the third boom section (2.3) continues with its deployment of the second boom section (2.2). As can be seen in FIG. 13A, in this phase the third hydraulic actuator has started to extend forcing the third boom section (2.3) to unfold from the second boom section (2.2). The further extension of the third hydraulic actuator (6) will lead the second and third boom sections (2.2, 2.3) to adopt the alignment position that can be seen in FIGS. 1D and 1E.

[0135] In the deployment phases of the boom (2) illustrated in FIGS. 8-13, the bracing sling (8) confers stability on the deployment.

[0136] FIG. 14 illustrates the tower crane according to the invention in its maintenance position. It can be seen that the auxiliary support (3) is arranged at the free distal end (2.3b) of the third boom portion (2.3) such that the auxiliary support (3) rests on the ground (S) when the boom (2) is in a maintenance position in which the boom (2) extends vertically inclined from the first rotary joint (15A) and, in turn, the mast (1) is in an intermediate extension position between its retracted vertical position and its extended vertical position. In this maintenance position, the operator can access the boom (2) and its elements to carry out maintenance and repair work on the boom (2) by simply climbing up the boom (2) without needing hoisting means to lift the operator to the boom (2).

[0137] As can be seen in FIG. 14A, the auxiliary support (3) comprises two vertical wings (3b) joined at their lower ends by a base (3a), and is fixed to the respective side parts of the free distal end (2.3b) of the third boom section (2.2). FIGS. 14B and 14C show that in the maintenance position the boom sections (2.1, 2.2, 2.3) are in the same positions as those shown in FIGS. 1, 1A, 1C, 1D and 1E.