Crane attachments

Abstract

To provide a crane attachment capable of preventing the damage of a connection link of a jib support line and a connection link of a strut support line and capable of Improving workability of attaching / detaching the jib support line to the connection link of the jib support line and of attaching / detaching the strut support line to connection link of the strut support line.SOLUTION: A crane attachment 3 comprises a jib support device 8 for supporting a jib 6 from the rear, the jib assuming a forward-tilted orientation relative to a boom 5 when the boom 5 assumes an upright orientation. The jib support device 8 has a link restraint 30 configured so as to be capable of restraining a jib support line connection link 27 when in a jib support line connection link securing orientation, which is a prescribed turning orientation relative to a strut distal-end part 37, and restraining a strut support line connection link 28 when in a strut support line connection link securing orientation, which is another prescribed turning orientation relative to the strut distal-end part 37.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a crane attachment. [Background technology]

[0002] BACKGROUND ART Crane attachments that are attached to a crane body to perform crane work of suspending a load have been known in the past. For example, Patent Document 1 listed below discloses an example of such a crane attachment.

[0003] Specifically, the crane attachment disclosed in Patent Document 1 below includes a boom mounted on an upper rotating body as the crane body so as to be able to be raised and lowered, a fixed jib having a jib base end attached to the tip of the boom so as to be rotatable about an axis extending in the width direction of the boom, a strut extending from the tip of the boom to the rear thereof and having a strut base end attached to the tip of the boom so as to be rotatable about an axis extending in the width direction of the boom, a guy line stretched linearly between the tip of the fixed jib and the tip of the strut, and another guy line stretched linearly between the tip of the strut and an intermediate portion of the boom in the extension direction. With this crane attachment, the strut and two guy lines support the fixed jib, which is tilted forward relative to the upright boom, from behind, and fix the fixed jib in the tilted forward position. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-162344 Summary of the Invention [Problem to be solved by the invention]

[0005] The strut tip is generally provided with a jib support line connection link for connecting the end of a jib support guy line stretched between the tip of the jib and the tip of the strut to the tip of the strut, and a strut support line connection link for connecting the end of a strut support guy line stretched between the tip of the strut and the middle of the boom to the tip of the strut. The jib support line connection link and strut support line connection link are attached to the tip of the strut so as to be rotatable about an axis extending parallel to the rotation axis of the base end of the strut.

[0006] However, because the jib support line connection link and the strut support line connection link are rotatable, there is a risk that the jib support line connection link and / or the strut support line connection link may be damaged when the crane is disassembled, transported, or assembled, and that the workability of attaching and detaching the jib support guy line to the jib support line connection link and the strut support guy line to the strut support line connection link may be reduced.

[0007] Specifically, when transporting a crane, the crane is disassembled and each constituent unit is loaded onto a transport vehicle such as a trailer for transport, and the transported constituent units are then assembled at the destination to complete the crane. If the jib support line connection link and the strut support line connection link are rotatable relative to the tip of the strut, there is a risk that the jib support line connection link and / or the strut support line connection link will rotate unintentionally during disassembly, transportation, and assembly of such a crane, and will collide with surrounding components, etc., resulting in damage to the jib support line connection link and / or the strut support line connection link.

[0008] Furthermore, if the jib support line connection link is rotatable relative to the tip of the strut, the jib support line connection link will move when attaching or detaching the jib support line to or from the jib support line connection link, making the attachment and detachment work difficult.Similarly, if the strut support line connection link is rotatable relative to the tip of the strut, the strut support line connection link will move when attaching or detaching the strut support line to or from the strut support line connection link, making the attachment and detachment work difficult.

[0009] The object of the present invention is to provide a crane attachment that can prevent damage to the jib support line connection link and the strut support line connection link during disassembly, assembly, and transportation of the crane, and that can improve the workability of attaching and detaching the jib support line to the jib support line connection link and the strut support line to the strut support line connection link. [Means for solving the problem]

[0010] The present invention provides a crane attachment for attaching to a crane main body for crane operation to hoist a load. This crane attachment comprises a boom having a boom base end attached to the crane main body and a boom tip end opposite the boom base end, a jib having a jib base end at one end rotatable about an axis extending in the width direction of the boom and separably attached to the boom tip end, and a jib tip end at the other end opposite the jib base end, and a jib support device that supports from behind the jib, which is tilted forward relative to the boom when the boom base end is attached to the crane main body and the boom is in an upright position. The jib support device comprises a jib support line having one end connected to the jib tip and the other end opposite to it; a strut attached to an attachment portion which is either the jib base end or the boom tip and positioned so as to extend from the attachment portion behind it when the jib assumes the forward tilting position, and supporting the other end of the jib support line at a position away from the attachment portion behind it so that the jib support line extends and is taut from the jib tip; and a strut support line having one end connected to the strut and preventing the strut from falling in a direction along the jib. The strut comprises a strut body having a strut base end, which is one end attached to the attached portion so as to be rotatable around an axis parallel to the rotation axis of the jib base end, and a strut tip end, which is the end opposite to the strut base end; a jib support line connection link, which is rotatably attached to the strut tip end about an axis parallel to the rotation axis of the strut base end, and to which the other end of the jib support line is connected; and a strut support line connection link, which is rotatably attached to the strut tip end about an axis parallel to the rotation axis of the strut base end, and to which one end of the strut support line is connected.The jib support device further has a link restraint device configured to restrain the jib support line connection link in a jib support line connection link fixed position, which is a predetermined rotational position relative to the strut tip, and to restrain the strut support line connection link in a strut support line connection link fixed position, which is a predetermined rotational position relative to the strut tip.

[0011] In this crane attachment, the jib support device has a link restraint device configured to restrain the jib support line connection link in the jib support line connection link fixed position and the strut support line connection link in the strut support line connection link fixed position, so that when a crane to which the crane attachment is applied is assembled, disassembled, or transported, the link restraint device restrains the jib support line connection link in the jib support line connection link fixed position and the strut support line connection link in the strut support line connection link fixed position, thereby preventing unintended rotation of the links.This prevents the jib support line connection link and the strut support line connection link from colliding with surrounding components, etc., and being damaged when the crane is assembled, disassembled, or transported.

[0012] In addition, when attaching or detaching the jib support line to or from the jib support line connection link, and when attaching or detaching the strut support line to or from the strut support line connection link, the link restraint device restrains the jib support line connection link in the jib support line connection link fixed position and the strut support line connection link in the strut support line connection link fixed position, so that the jib support line and the strut support line can be attached or detached without moving those links. This improves the workability of attaching or detaching the jib support line to or from the jib support line connection link and the strut support line to or from the strut support line connection link.

[0013] Therefore, this crane attachment can prevent damage to the jib support line connection link and the strut support line connection link when the crane is disassembled, assembled, or transported, and can improve the workability of attaching and detaching the jib support line to the jib support line connection link and the strut support line to the strut support line connection link.

[0014] It is preferable that the jib has a plurality of jib members arranged in a line in its extension direction and detachably connected to each other, the plurality of jib members including a lower jib member which is a jib member having the jib base end, and the strut is configured to be capable of assuming a storage position which is a rotational position centered on the rotation axis of the strut base end and is arranged along the back surface of the lower jib member.

[0015] With this configuration, the strut base end is attached to the jib base end, and the strut can be placed in the stored position, and the strut can be loaded onto a transport vehicle together with the lower jib member for transport.

[0016] The jib support line connection link has a line connection point where the other end of the jib support line is connected, and it is preferable that the jib support line connection link fixed position is a position in which the line connection point is positioned behind and away from the back surface of the lower jib member when the strut takes the stored position.

[0017] With this configuration, when the other end of the jib support line is attached or detached to or from the line connection point of the jib support line connection link with the strut in the stored position, the other end of the jib support line can be attached or detached at a position away from the back surface of the lower jib member and behind it where it is not interfered with by the lower jib member, thereby improving the workability of attaching and detaching the other end of the jib support line.

[0018] It is preferable that the jib support line connection link has a link pressing portion that abuts against the strut support line connection link when the jib support line connection link is rotated in a direction away from the back surface of the lower jib member and behind it when the strut is in the stored position, and pushes the strut support line connection link toward the strut support line connection link fixed position.

[0019] With this configuration, simply by rotating the jib support line connection link in a direction away from the back surface of the lower jib member to the rear thereof in order to cause the jib support line connection link to assume the jib support line connection link fixed position, the link pressing portion of the jib support line connection link can push the strut support line connection link toward the strut support line connection link fixed position. This simplifies the work of causing the jib support line connection link to assume the jib support line connection link fixed position and the work of causing the strut support line connection link to assume the strut support line connection link fixed position.

[0020] The strut body has a link receiving portion that receives the strut support line connection link when the strut support line connection link is pressed by the link pressing portion and placed in the strut support line connection link fixed position, and it is preferable that the jib support line connection link fixed position is the rotational position of the jib support line connection link in a state where the link pressing portion of the jib support line connection link presses the strut support line connection link and the strut support line connection link is received by the link receiving portion.

[0021] With this configuration, by rotating the jib support line connection link until it is received by the link receiver and then pressing the strut support line connection link with the link pressing portion, the strut support line connection link can be placed in the strut support line connection link fixed position and the jib support line connection link can be placed in the jib support line connection link fixed position. Therefore, the worker can perform the work of placing the strut support line connection link and the jib support line connection link in their respective fixed positions without paying particular attention to whether the rotated position of the strut support line connection link has reached the strut support line connection link fixed position or whether the rotated position of the jib support line connection link has reached the jib support line connection link fixed position, thereby reducing the workload on the worker.

[0022] It is preferable that the strut support line connection link has a pressed portion that is pressed by the link pressing portion when the jib support line connection link is rotated in a direction away from the back surface of the lower jib member toward the rear thereof, and that one of the link pressing portion and the pressed portion has a recessed portion that can accept the other portion, and that the other portion has a shape that can fit into the recessed portion.

[0023] With this configuration, when the link pressing portion of the jib support line connection link presses the pressed portion of the strut support line connection link, the stability of the state in which the link pressing portion presses the strut support line connection link can be increased by the engagement between the recessed portion of one part of the link pressing portion and the pressed portion and the other part.

[0024] It is preferable that the link restraint device is a fastening device that connects a predetermined location of the strut to the jib support line connection link, and is configured to pull the jib support line connection link so that when the strut is in the stored position, the jib support line connection link rotates in a direction away from the back of the lower jib member and behind it, thereby fastening the jib support line connection link in a fixed position.

[0025] With this configuration, the strut support line connection link and the jib support line connection link can be placed in their respective fixed positions and simultaneously restrained in those fixed positions simply by having the link pressing portion of the jib support line connection link press against the strut support line connection link and then using the lashing device to pull the jib support line connection link until the strut support line connection link is received by the link receiving portion. This reduces the workload compared to when the work of rotating the strut support line connection link and the jib support line connection link to their respective fixed positions and the work of restraining those links in their respective fixed positions are performed separately. [Effects of the Invention]

[0026] As described above, according to the present invention, a crane attachment is provided that can prevent damage to the jib support line connection link and the strut support line connection link when the crane is disassembled, assembled, or transported, and that can improve the workability of attaching and detaching the jib support line to the jib support line connection link and the strut support line to the strut support line connection link. [Brief explanation of the drawings]

[0027] [Figure 1] 1 is a side view of a crane to which a crane attachment according to an embodiment of the present invention is applied. [Figure 2] FIG. 2 is a partially enlarged view showing the strut tip, jib support line connecting link, strut support line connecting link, and guy lines connected to these links of the crane attachment shown in FIG. 1. [Figure 3] This is a side view showing the state in which the lower jib member of the jib of the crane attachment has been separated and the struts have been placed in a stored position relative to the lower jib member, and the figure also shows the state in which the jib support line is connected to the jib support line connection link and the strut support line is connected to the strut support line connection link. [Figure 4]4 is a view of the lower jib member and the strut shown in FIG. 3 as viewed from the direction IV in FIG. 3. [Figure 5] 10 shows the state before the rotational posture of the jib support line connecting link is restrained. [Figure 6] This figure shows the state in which the strut support line connection link is placed in a strut support line connection link fixed position and the jib support line connection link is placed in a jib support line connection link fixed position and is restrained in these fixed positions. [Figure 7] FIG. 10 is a cross-sectional view of the strut support line connection link and the jib support line connection link when the links and the strut are positioned in their respective fixed positions. [Figure 8] FIG. 1 is a front view of the jib support line connecting link. [Figure 9] FIG. 1 is a perspective view of a jib support line connecting link. [Figure 10] FIG. 10 is a front view of the strut support line connecting link. [Figure 11] FIG. 10 is a perspective view of a strut support line connecting link. [Figure 12] FIG. 10 is a diagram showing the assembly process of the crane attachment, showing the state in which the jib base end is connected to the boom tip. [Figure 13] 13 is a diagram showing a state in which the strut is raised from the state shown in FIG. 12. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0028] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0029] A crane attachment 3 according to one embodiment of the present invention is applied to a crane 100 as shown in Fig. 1 to perform crane work of lifting a load. This crane 100 comprises a self-propelled running body 1 and a rotating body 2 rotatably mounted on the running body 1. The rotating body 2 is an example of a crane main body according to the present invention.

[0030] The crane attachment 3 according to this embodiment is detachably attached to the rotating bed 2. The crane attachment 3 has a boom 5, a jib 6, a pair of jib connecting pins 7, a jib support device 8, and a pair of support pins 9.

[0031] The boom 5 is attached so as to be able to be raised and lowered to the rotating body 2. The boom 5 has a boom body 11 having a linearly extending lattice structure, and a boom-side line connection point 12 attached to the boom body 11.

[0032] The boom body 11 has a boom base end 14 which is one end in the extension direction, and a boom tip end 15 which is the end opposite to the boom base end 14. The boom base end 14 is attached to the revolving unit 2 so as to be rotatable about a rotation axis which extends in the left-right direction of the revolving unit 2 (the width direction of the boom 5). By attaching the boom base end 14 to the revolving unit 2 in this manner, the boom 5 can be raised and lowered with the rotation axis of the boom base end 14 as a fulcrum. The boom base end 14 is detachable from the revolving unit 2.

[0033] 1, the boom main body 11 has a boom ventral surface 11a that faces forward when the boom 5 is upright, and a boom back surface 11b that faces rearward in that state. The boom ventral surface 11a faces downward when the boom 5 is lowered, and the boom back surface 11b faces upward in the same state.

[0034] The boom-side line connection point 12 is a portion to which an end of a strut support line 23 (described later) of the jib support device 8 is detachably connected. The boom-side line connection point 12 is located at a predetermined distance from the boom tip 15 toward the boom base end 14, and is provided on the boom back surface 11b.

[0035] The jib 6 has a lattice structure and extends linearly. The jib 6 has a jib base end 17, which is one end in the extension direction, and a jib tip end 18, which is the end opposite to the jib base end 17. The jib 6 has multiple jib members arranged side by side in the extension direction and connected to each other. Specifically, the jib 6 has a lower jib member 6A including the jib base end 17, an intermediate jib member 6B, and an upper jib member 6C including the jib tip end 18. The jib 6 may also have multiple intermediate jib members. It is also possible to omit the intermediate jib member 6B.

[0036] 1, the jib 6 has a jib belly surface 6a that faces forward when raised together with the boom 5, and a jib back surface 6b that faces rearward in that state. The jib belly surface 6a faces downward when the jib 6 is lowered, and the jib back surface 6b faces upward in the same state.

[0037] The jib base end 17 is attached to the boom tip 15 so as to be rotatable about an axis extending in the left-right width direction of the boom 5. In other words, the jib base end 17 is attached to the boom tip 15 so as to be rotatable about an axis parallel to the rotation axis of the boom base end 14. The jib base end 17 is detachable from the boom tip 15. Specifically, the jib base end 17 has a jib first base end 17a and a jib second base end 17b that are spaced apart from each other in the width direction of the jib 6 along the rotation axis of the jib base end 17 (see FIG. 4). The jib first base end 17a and the jib second base end 17b are each connected to the boom tip 15 by a corresponding jib connecting pin 7. By removing the corresponding jib connecting pins 7 from the jib first base end portion 17a and the jib second base end portion 17b, the jib base end portion 17 can be separated from the boom tip portion 15. The jib connecting pins 7 that connect the jib first base end portion 17a to the boom tip portion 15 and the jib connecting pins 7 that connect the jib second base end portion 17b to the boom tip portion 15 are arranged coaxially. The jib base end portion 17 is designed to rotate relative to the boom tip portion 15 around these jib connecting pins 7.

[0038] The jib base end 17 also has a pair of strut supports 19 that support a pair of strut base ends 36, which will be described later. One of the pair of strut supports 19 is provided so as to protrude rearward from the jib first base end 17a, and the other of the pair of strut supports 19 is provided so as to protrude rearward from the jib second base end 17b. Each of the pair of strut supports 19 is provided with a through-hole (not shown) through which a support pin 9 is inserted. Each strut support 19 supports a pair of strut base ends 36, which will be described later, via the support pin 9 inserted through the through-hole.

[0039] The jib tip 18 has a jib side line connecting portion 18a (see FIG. 1) to which one end of a jib support line 22 (described later) of the jib support device 8 is detachably connected.

[0040] The jib support device 8 supports the jib 6 from behind, which assumes a predetermined forward tilting position relative to the boom 5 when the boom base end 14 is attached to the rotating bed 2 and the boom 5 assumes an upright position, thereby maintaining the forward tilting position of the jib 6. The jib support device 8 includes a pair of jib support lines 22, a pair of strut support lines 23, a plurality of connecting pins 24, 25, a strut 26, a pair of link restraints 30, a front stopper 31, and a rear stopper 32. Note that the drawings (FIGS. 1, 2, 12, and 13) showing the jib support lines 22 and the strut support lines 23 are views from a direction in which the pair of jib support lines 22 and the pair of strut support lines 23 appear to overlap, and therefore, only one of the pair of jib support lines 22 and only one of the pair of strut support lines 23 are shown in these drawings.

[0041] The jib support line 22 and the strut support line 23 are so-called guy lines, guy cables, or guy links.

[0042] The pair of jib support lines 22 are laid between the jib tip 18 and a pair of strut tips 37 described below, connecting the jib tip 18 to the pair of strut tips 37. Each of the pair of jib support lines 22 has a jib support line one end 22a, which is one end connected to the jib side line connection point 18a of the jib tip 18, and a jib support line other end 22b, which is the opposite end, connected to the strut tip 37 via a jib support line connection link 27 (see Figure 2), described below.

[0043] The pair of strut support lines 23 are installed between a pair of strut tips 37 described below and a pair of boom-side line connection points 12, connecting the pair of strut tips 37 to the pair of boom-side line connection points 12, and prevent the struts 26, which are in an upright position extending from the jib base end 17 to the rear thereof, from falling in a direction along the jib 6. Each of the pair of strut support lines 23 has a strut support line one end 23a connected to the strut tip 37 via a strut support line connection link 28 (see Figure 2) described below, and a strut support line other end 23b on the opposite end thereof which is connected to the boom-side line connection point 12 (see Figure 1).

[0044] The struts 26 are attached to the jib base end 17, which is the mounting portion, and are arranged in an upright position extending from the jib base end 17 to the rear when the jib 6 assumes the predetermined forward tilting position, and support the other ends 22b of the pair of jib support lines 22 at a position away from the pair of jib base ends 17 and behind them so that the pair of jib support lines 22 extend taut in a straight line diagonally downward and rearward from the jib tip end 18. The struts 26, together with the pair of jib support lines 22 taut in this way and the pair of strut support lines 23, support the jib 6 in the predetermined forward tilting position relative to the boom 5.

[0045] The strut 26 has a strut body 26a, a pair of jib support line connecting links 27, and a pair of strut support line connecting links 28.

[0046] The strut body 26a is attached to a pair of strut supports 19 at the jib base end 17 so as to be rotatable about an axis parallel to the rotation axis of the jib base end 17. The strut body 26a has a pair of strut main columns 33 arranged at a distance from each other in the width direction of the strut body 26a along the rotation axis, and a plurality of beam members 34 connecting the pair of strut main columns 33. Each of the pair of strut main columns 33 has a strut base end 36 which is one end of the strut main column 33 in the extension direction, and a strut tip end 37 which is the end opposite to the strut base end 36.

[0047] Each strut base end 36 of the pair of strut main columns 33 is attached to a corresponding one of the pair of strut support parts 19 of the jib base end 17 so as to be rotatable around an axis parallel to the rotation axis of the jib base end 17. Specifically, each strut base end 36 is provided with a through hole (not shown) through which a support pin 9 is inserted, and each strut base end 36 is attached to the corresponding strut support part 19 via the support pin 9 inserted through the through hole and through hole of the strut support part 19. Each strut base end 36 is rotatable relative to the corresponding strut support part 19 around the support pin 9 inserted through the through hole.

[0048] Furthermore, each strut base end 36 of the pair of strut main columns 33 is detachable from the corresponding one of the pair of strut supports 19 at the jib base end 17. Specifically, each strut base end 36 can be separated from the corresponding strut support 19 by removing the support pins 9 inserted through the through holes of each strut base end 36 and the corresponding strut support 19 from those through holes.

[0049] Each strut tip 37 of the pair of strut main columns 33 is provided with an insertion hole 37a through which a pivot pin 39 is inserted. A jib support line connecting link 27 and a strut support line connecting link 28 are attached to each strut tip 37 via the pivot pin 39.

[0050] The strut body 26a also has a pair of link receiving portions 26b (see Figures 4 and 7) that receive the pair of strut support line connection links 28 on the opposite side of the link pressing portions 56 when the pair of strut support line connection links 28 are pressed by the link pressing portions 56 of the corresponding jib support line connection links 27 and placed in the strut support line connection link fixed position, as will be described later. Each of the pair of link receiving portions 26b is provided at a location on the pair of strut main columns 33 adjacent to the strut base end portion 36 side relative to the strut tip end portion 37.

[0051] The beam members 34 are arranged at intervals in the extension direction of the strut main post 33. Each beam member 34 extends in the width direction of the strut body 26a.

[0052] The strut 26 also has a pair of restraint attachment portions 29 to which the pair of link restraints 30 are respectively attached. The pair of restraint attachment portions 29 are installed at predetermined locations on the strut 26 between the strut tip end 37 and the strut base end 36, specifically on the beam member 34 closest to the strut tip end 37 among the multiple beam members 34.

[0053] The strut 26 can rotate about the pivot axis (support pin 9) of the strut base end 36, taking two positions: an upright position (see FIG. 1) in which it stands upright and extends behind the jib base end 17, and a stowed position (see FIG. 3) in which it is positioned along the jib back surface 6b of the lower jib member 6A. When the crane 100 is disassembled and transported, the strut 26 is transported integrally with the lower jib member 6A, and at that time, it is transported in the stowed position. Furthermore, when attaching and detaching the pair of jib support lines 22 to and from the pair of jib support line connection links 27, and when attaching and detaching the pair of strut support lines 23 to and from the pair of strut support line connection links 28, these attachments and detachments are performed with the strut 26 in the stowed position.

[0054] Each of the pair of jib support line connection links 27 is rotatably attached to the corresponding one of the pair of strut tip ends 37 around an axis parallel to the pivot axis of the strut base end 36. To each of the pair of jib support line connection links 27, the other end 22b of each of the pair of jib support lines 22 is separably connected.

[0055] Each jib support line connecting link 27 has a pair of side plates 52, a one-side erection portion 53, an other-side erection portion 54, a locked portion 55, and a link pressing portion 56 (see Figures 8 and 9).

[0056] The pair of side plates 52 are arranged side by side in a direction along the rotation axis of the jib support line connection link 27. The pair of side plates 52 are fixed with a gap between them by a one-side installation portion 53 installed on one side edge of the pair of side plates 52 facing one side in the rotation direction of the jib support line connection link 27, and a other-side installation portion 54 installed on the side edge opposite to the one side edge of the pair of side plates 52. Each side plate 52 is provided with a pivot pin insertion hole 52a and a line connection hole portion 52b that penetrate the side plate 52.

[0057] An axle pin 39 inserted into the insertion hole 37a of the strut tip 37 is inserted into the axle pin insertion hole 52a of each side plate 52. The pair of side plates 52 are rotatable relative to the strut tip 37 around this axle pin 39, thereby allowing the jib support line connecting link 27 to rotate relative to the strut tip 37.

[0058] The line connection hole 52b is a portion to which the other end 22b of the jib support line is connected. Specifically, a connection pin 24 is inserted into the line connection hole 52b, and the other end 22b of the jib support line is connected to the jib support line connection link 27 via this connection pin 24. The line connection hole 52b is an example of a line connection point in the present invention.

[0059] The locked portion 55 is the portion to which the link side locking portion 30b of the link restraint device 30 is locked. The locked portion 55 is fixed to one of the pair of side plates 52. The locked portion 55 protrudes from one side edge of the side plate 52 facing in the direction in which the jib support line connecting link 27 rotates away from the back surface of the lower jib member 6A and behind it when the strut 26 is in the stored position. This locked portion 55 is hook-shaped.

[0060] The link pressing portion 56 is a portion that abuts against the strut support line connection link 28 when the jib support line connection link 27 is rotated away from the back surface of the lower jib member 6A to the rear thereof with the strut 26 in the stowed position, and presses the strut support line connection link 28 toward the strut support line connection link fixed position, which will be described later. The link pressing portion 56 is in the shape of a round bar, and is installed between one side edge of the pair of side plates 52 that faces in the direction in which the jib support line connection link 27 rotates away from the back surface of the lower jib member 6A to the rear thereof with the strut 26 in the stowed position. The link pressing portion 56 has a shape that can fit into a recessed portion 64 of a pressed portion 63, which will be described later, of the strut support line connection link 28.

[0061] When the lower jib member 6A is lowered and the struts 26 are in the stowed position, and when the jib support line connection link 27 is not restrained by the link restraint device 30, it takes a pivoted position in which it protrudes downward from the strut tip 37, as shown in Figure 5, and is positioned so that the line connection hole 52b overlaps with the main pillar material 70 on the back side of the lower jib member 6A when viewed from the direction along the pivot axis of the jib support line connection link 27. On the other hand, when each jib support line connection link 27 is restrained by the corresponding link restraint device 30 as described below with the struts 26 in the stowed position, it takes a jib support line connection link fixed position (see Figure 6), which is a pivoted position in which the line connection hole 52b is positioned at a position away from the back side of the lower jib member 6A. The fixed posture of the jib support line connection link is the rotational posture of the jib support line connection link 27 when the link pressing portion 56 of the jib support line connection link 27 presses the strut support line connection link 28 and the strut support line connection link 28 is received by the link receiving portion 26b of the strut body 26a.

[0062] Each of the pair of strut support line connection links 28 is attached to the corresponding one of the pair of strut tip ends 37 so as to be rotatable about an axis parallel to the rotation axis of the strut base end 36. In other words, each of the pair of strut support line connection links 28 is attached to the strut tip end 37 so as to be rotatable about the same axis as the rotation axis of the jib support line connection link 27 that is attached to the strut tip end 37 to which that strut support line connection link 28 is attached. Each strut support line connection link 28 and the corresponding jib support line connection link 27 are rotatable relative to each other. To each of the pair of strut support line connection links 28, one end portion 23a of each of the pair of strut support lines 23 is separably connected.

[0063] Each strut support line connecting link 28 is inserted into the gap between a pair of side plates 52 of the corresponding jib support line connecting link 27. Each strut support line connecting link 28 has a shaft pin insertion hole 62 b and the line connection hole portion 62 a (See FIGS. 10 and 11).

[0064] Axle pin insertion hole 62 b An axle pin 39 is inserted into the strut support line connection link 28, which is in turn inserted into the insertion hole 37a of the strut tip end 37 and the axle pin insertion hole 52a of the side plate 52 of the jib support line connection link 27. The strut support line connection link 28 is rotatable around this axle pin 39 relative to the strut tip end 37. The strut support line connection link 28 and the jib support line connection link 27 are also rotatable relative to each other around the axle pin 39.

[0065] Line connection hole 62 a is the portion to which the strut support line one end 23a is connected. a A connection pin 25 is inserted through the strut support line 23 , and one end 23 a of the strut support line is connected to a strut support line connection link 28 via the connection pin 25 .

[0066] In addition, each strut support line connection link 28 has a pressed portion 63 that is pressed by the link pressing portion 56 of the corresponding jib support line connection link 27 when the corresponding jib support line connection link 27 is rotated in a direction away from the back surface of the lower jib member 6A toward the rear thereof. The pressed portion 63 has a recessed portion 64 that can receive the link pressing portion 56 that approaches when the corresponding jib support line connection link 27 is rotated in the direction described above.

[0067] Each strut support line connection link 28 takes a strut support line connection link fixed position (see Figure 6), which is a predetermined rotational position, when restrained as described below by the corresponding link restraint device 30. Specifically, each strut support line connection link 28 is restrained in the strut support line connection link fixed position when the corresponding jib support line connection link 27 is restrained in the jib support line connection link fixed position by the corresponding link restraint device 30, and the link pressing portion 56 of that jib support line connection link 27 is pressed against the link receiving portion 26b, thereby restraining the strut support line connection link 28 in the strut support line connection link fixed position.

[0068] Each of the pair of link restraint devices 30 is configured to restrain the corresponding jib support line connection link 27 in the jib support line connection link fixed position relative to the strut tip 37, and to restrain the corresponding strut support line connection link 28 in the strut support line connection link fixed position relative to the strut tip 37. The pair of link restraint devices 30 are intended to restrain the corresponding jib support line connection link 27 and strut support line connection link 28 in their respective fixed positions so that they do not rotate when the strut 26 and lower jib member 6A are transported together, and when the other end 22b of the jib support line is attached to or detached from the jib support line connection link 27 and the strut support line one end 23a is attached to or detached from the strut support line connection link 28.

[0069] In this embodiment, each link restraint device 30 connects the restraint device mounting portion 29 of the strut 26 to the jib support line connection link 27, and is configured to pull the jib support line connection link 27 so that the jib support line connection link 27 rotates away from the back surface of the lower jib member 6A toward the rear thereof when the strut 26 is in the stored position, thereby securing the jib support line connection link in a fixed position. More specifically, a chain block, which is an example of a lashing device, is used as each link restraint device 30.

[0070] Each link restraint 30 has a fixed-side locking portion 30a attached to the corresponding restraint-device mounting portion 29, and a link-side locking portion 30b locked to the locked portion 55 of the corresponding jib support line connection link 27. When the link restraint 30 is a chain block as in this embodiment, the fixed-side locking portion 30a is a hook connected to the main body of the chain block and is attached by being hooked onto the restraint-device mounting portion 29, and the link-side locking portion 30b is a hook connected from the main body of the chain block via a chain and is hooked onto the locked portion 55 of the jib support line connection link 27 to be locked. The link restraint 30 is configured so that the link-side locking portion 30b can be pulled toward the fixed-side locking portion 30a.

[0071] When the jib support line connecting link 27 is restrained by each link restraining device 30, the fixed side locking portion 30a is Restraint attachment part 29 and the link-side locking portion 30b is locked to the corresponding locked portion 55 of the jib support line connection link 27, and in this state, the link pressing portion 56 of the jib support line connection link 27 abuts against the pressed portion 63 of the strut support line connection link 28 and fits into the recessed portion 64 of the pressed portion 63, and the link-side locking portion 30b is pulled toward the fixed-side locking portion 30a until the strut support line connection link 28 is received by the link receiver 26b. As a result, the jib support line connection link 27 is fastened and restrained to the restraining-device mounting portion 29 by the link restraint device 30 in the jib support line connection link fixed position, and the strut support line connection link 28 is pressed against the link receiver 26b by the link pressing portion 56 of the jib support line connection link 27 and restrained in the strut support line connection link fixed position.

[0072] The front stopper 31 is interposed between the strut 26 and the jib 6 when the strut 26 is in an upright position as shown in FIG. 1, and prevents the strut 26 from falling forward.

[0073] The rear stopper 32 is interposed between the strut 26 and the boom tip 15 when the strut 26 is in an upright position, and prevents the strut 26 from falling backward.

[0074] Furthermore, the crane 100 to which the crane attachment 3 of this embodiment is applied further includes a boom raising device 110, a main hoisting winch 112, a main hook 113, an auxiliary hoisting winch 114, and an auxiliary hook 115, as shown in FIG.

[0075] The boom hoisting device 110 is a device that raises and lowers the boom 5. The boom hoisting device 110 has a boom mast 118, a pendant rope 120, a mast-side sheave 122, a rotating body-side sheave (not shown), and a hoisting winch 124.

[0076] The boom mast 118 is used to raise and lower the boom 5, and is disposed behind the boom 5. The boom mast 118 is attached to the rotating unit 2 so as to be rotatable about an axis parallel to the rotation axis of the boom 5 (the rotation axis of the boom base end 14). Specifically, the boom mast 118 has a boom mast base end which is one end in the longitudinal direction of the boom mast, and a boom mast tip end 126 which is the opposite end thereof, and the boom mast base end is attached to the rotating unit 2 so as to be rotatable about an axis parallel to the rotation axis of the boom 5. Note that the boom mast 118 may be a so-called gantry.

[0077] The pendant rope 120 connects the boom mast tip 126 to the boom tip 15 .

[0078] The mast side sheave 122 is attached to the boom mast tip 126 so as to be rotatable around an axis extending parallel to the rotation axis of the boom mast base end.

[0079] The unillustrated rotating body side sheave is attached to the rear end of the rotating body 2 so as to be rotatable around an axis extending in the left-right direction of the rotating body 2 .

[0080] The hoisting winch 124 is mounted on the rotating unit 2 and raises and lowers the boom 5 by winding in and out the hoisting rope 128. The hoisting winch 124 has a hoisting drum around which the hoisting rope 128 is wound. The hoisting rope 128 is pulled out from the hoisting drum and is looped around the mast-side sheave 122 and the rotating unit-side sheave (not shown). The hoisting winch 124 rotates the hoisting drum in the forward direction to wind in the hoisting rope 128, thereby pulling the mast-side sheave 122 toward the rotating unit-side sheave and rotating the boom mast 118 rearward. As a result, the boom mast 118 pulls the boom tip 15 rearward via the pendant rope 120, raising the boom 5. Meanwhile, the boom hoisting winch 124 allows the boom mast 118 to rotate forward by rotating the boom hoisting drum in the reverse direction and letting out the boom hoisting rope 128, thereby lowering the boom 5 while the boom mast 118 supports the boom tip 15 via the pendant rope 120.

[0081] The main hoisting winch 112 raises and lowers the main hook 113 suspended from the jib tip 18 via the main hoisting rope 132 by winding and unwinding the main hoisting rope 132.

[0082] The auxiliary winch 114 raises and lowers the auxiliary hook 115 suspended from the boom tip 15 via the auxiliary rope 134 by winding and unwinding the auxiliary rope 134.

[0083] Next, a method for assembling the crane attachment 3 according to this embodiment will be described.

[0084] In this assembly method, the boom base end 14 of the boom 5 is connected to the revolving bed 2 in a collapsed state. Then, as shown in Figure 12, the jib base end 17 of the lower jib member 6A is connected to the boom tip 15 of the boom 5, and the intermediate jib member 6B is connected to the lower jib member 6A, and further, although not shown in Figure 12, the upper jib member 6C is connected to the intermediate jib member 6B. The jib 6 consisting of the lower jib member 6A, intermediate jib member 6B, and upper jib member 6C is positioned so that it extends forward from the boom tip 15 in a collapsed state.

[0085] At this time, the strut 26 is positioned in a stored position along the back surface of the lower jib member 6A. Furthermore, each jib support line connection link 27 and each strut support line connection link 28 of this strut 26 is restrained in its respective fixed position by a corresponding link restraint device 30 (see Figures 3 and 6). In this state, the other end 22b of the jib support line 22 of the corresponding jib support line is connected to each jib support line connection link 27, and one end 23a of the strut support line 23 of the corresponding strut support line is connected to each strut support line connection link 28.

[0086] Specifically, a connection pin 24 is inserted into the line connection hole 52b of each jib support line connection link 27, and the other end 22b of the jib support line is connected to the jib support line connection link 27 via the connection pin 24. Also, a connection pin 25 is inserted into the line connection hole 62b of each strut support line connection link 28, and one end 23a of the strut support line is connected to the strut support line connection link 28 via the connection pin 25.

[0087] Thereafter, the restraint of each jib support line connection link 27 by each link restraint device 30 is released. This allows each jib support line connection link 27 to rotate relative to the strut tip end 37, and at the same time, each strut support line connection link 28 that was pressed and fixed by the link pressing portion 56 of each jib support line connection link 27 also becomes able to rotate relative to the strut tip end 37.

[0088] Then, one end 22a of each jib support line 22 is connected to the jib side line connection point 18a of the jib tip 18, and the other end 23b of each strut support line 23 is connected to the boom side line connection point 12 of the boom 5.

[0089] 12 and 13, the strut 26 is then raised from the stowed position to the erected position by the auxiliary crane 101. Then, the front stopper 31 is interposed between the lower jib member 6A and the strut 26, and the rear stopper 32 is interposed between the boom tip 15 and the strut 26.

[0090] Thereafter, the boom 5 is raised by the boom raising / lowering device 110.

[0091] In this manner, the crane attachment 3 according to this embodiment is assembled. The crane attachment 3 according to this embodiment can be disassembled by reversing the assembly procedure described above.

[0092] In the crane attachment 3 according to this embodiment, the jib support device 8 has a link restraint device 30 configured to restrain the jib support line connection link 27 in a jib support line connection link fixed position and the strut support line connection link 28 in a strut support line connection link fixed position. Therefore, when assembling, disassembling, or transporting a crane 100 to which the crane attachment 3 is applied, the link restraint device 30 restrains the jib support line connection link 27 in a jib support line connection link fixed position and the strut support line connection link 28 in a strut support line connection link fixed position, thereby preventing unintended rotation of the links 27, 28. This prevents the jib support line connection link 27 and the strut support line connection link 28 from colliding with surrounding components and being damaged when assembling, disassembling, or transporting the crane 100.

[0093] Furthermore, when attaching or detaching the jib support line 22 to the jib support line connection link 27 and the strut support line 23 to the strut support line connection link 28, the jib support line connection link 27 is restrained in a jib support line connection link fixed position by the link restraint device 30, and the strut support line connection link 28 is restrained in a strut support line connection link fixed position by the link restraint device 30, so that the jib support line 22 and the strut support line 23 can be attached or detached without moving the links 27, 28. This improves the workability of attaching or detaching the jib support line 22 to the jib support line connection link 27 and the strut support line 23 to the strut support line connection link 28.

[0094] Therefore, the crane attachment 3 of this embodiment can prevent damage to the jib support line connection link 27 and the strut support line connection link 28 when the crane 100 is disassembled, assembled, or transported, and can improve the workability of attaching and detaching the jib support line 22 to the jib support line connection link 27 and the strut support line 23 to the strut support line connection link 28.

[0095] Furthermore, in the crane attachment 3 according to this embodiment, the strut base end 36 is rotatably attached to the strut support 19 of the jib base end 17, and the strut 26 is configured to be able to assume a stowed position, which is a rotational position around the rotation axis of the strut base end 36 and a rotational position in which the strut 26 is positioned along the lower jib member 6A. Therefore, with the strut base end 36 attached to the jib base end 17, the strut 26 can be placed in the stowed position, and the strut 26 can be loaded onto a transport vehicle together with the lower jib member 6A for transportation.

[0096] Furthermore, in this embodiment, the jib support line connection link fixed position is a position in which the line connection hole 52b of the jib support line connection link 27 is positioned behind and away from the back surface of the lower jib member 6A when the strut 26 is in the stowed position. Therefore, when attaching or detaching the other end 22b of the jib support line to or from the line connection hole 52b of the jib support line connection link 27 via the connection pin 24 while the strut 26 is in the stowed position, the other end 22b of the jib support line can be attached or detached (the connection pin 24 can be inserted or detached from the line connection hole 52b) at a position away from and behind the lower jib member 6A. This improves the workability of attaching or detaching the other end 22b of the jib support line.

[0097] Furthermore, in this embodiment, the jib support line connection link 27 has a link pressing portion 56 that abuts against the strut support line connection link 28 and presses the strut support line connection link 28 toward the strut support line connection link fixed position when the jib support line connection link 27 is rotated in a direction away from the back surface of the lower jib member 6A toward its rear while the strut 26 is in the stowed position. Therefore, simply by rotating the jib support line connection link 27 in a direction away from the back surface of the lower jib member 6A toward its rear in order to cause the jib support line connection link 27 to assume the jib support line connection link fixed position, the link pressing portion 56 of the jib support line connection link 27 can press the strut support line connection link 28 toward the strut support line connection link fixed position. This simplifies the process of placing the jib support line connection link 27 and the strut support line connection link 28 in their respective fixed positions.

[0098] Furthermore, in this embodiment, the jib support line connection link fixed posture is the rotational posture of the jib support line connection link 27 in a state where the link pressing portion 56 of the jib support line connection link 27 is pressing the strut support line connection link 28 and the strut support line connection link 28 is received by the link receiving portion 26b of the strut body 26a. Therefore, by rotating the jib support line connection link 27 until the strut support line connection link 28 is received by the link receiving portion 26b and pressing the strut support line connection link 28 with the link pressing portion 56, it is possible to place the strut support line connection link 28 in the strut support line connection link fixed posture and the jib support line connection link 27 in the jib support line connection link fixed posture. Therefore, the worker can perform the work of placing the strut support line connection link 28 and the jib support line connection link 27 in their respective fixed positions without paying particular attention to whether the rotational position of the strut support line connection link 28 has reached the strut support line connection link fixed position, or whether the rotational position of the jib support line connection link 27 has reached the jib support line connection link fixed position, thereby reducing the workload on the worker.

[0099] Furthermore, in this embodiment, the pressed portion 63 of the strut support line connection link 28 has a recessed portion 64, and the link pressing portion 56 of the jib support line connection link 27 is in the shape of a round bar that can fit into the recessed portion 64. Therefore, when the link pressing portion 56 of the jib support line connection link 27 presses the pressed portion 63 of the strut support line connection link 28, the recessed portion 64 of the pressed portion 63 fits into the link pressing portion 56, thereby increasing the stability of the state in which the link pressing portion 56 presses the pressed portion 63 of the strut support line connection link 28.

[0100] In this embodiment, the link restraint 30 is a lashing device that connects the jib support line connection link 27 to a predetermined location of the strut 26 that is located closer to the strut base end 36 than the strut tip end 37, and is configured to pull the jib support line connection link 27 and secure it in a jib support line connection link fixed position so that the jib support line connection link 27 rotates away from the back surface of the lower jib member 6A toward the rear of the lower jib member 6A when the strut 26 is in the stowed position. Therefore, the link pressing portion 56 of the jib support line connection link 27 presses the strut support line connection link 28, and the link restraint 30 (lashing device) simply pulls the jib support line connection link 27 until the strut support line connection link 28 is received by the link receiving portion 26b of the strut body 26a, thereby placing the strut support line connection link 28 and the jib support line connection link 27 in their respective fixed positions and simultaneously restraining them in those fixed positions. This reduces the workload compared to the case where the work of rotating the strut support line connection link 28 and the jib support line connection link 27 to their respective fixed positions and the work of restraining those links 28, 27 in their respective fixed positions are performed separately.

[0101] (Variation) The crane attachment according to the present invention is not necessarily limited to the above-described configuration. For example, the following techniques can be employed for the crane attachment according to the present invention.

[0102] (1) The link restraint device is not necessarily limited to a fastening device such as the chain hoist used in the above embodiment, as long as it can restrain the rotational position of the jib support line connection link relative to the strut tip in a jib support line connection link fixed position and can restrain the rotational position of the strut support line connection link relative to the strut tip in a strut support line connection link fixed position. For example, the link restraint device may be a fixing pin that pins the jib support line connection link, which is positioned in the jib support line connection link fixed position, and the strut support line connection link, which is positioned in the strut support line connection link fixed position, to the strut tip. In this case, the strut tip may have an insertion hole through which the fixing pin is inserted when restraining the jib support line connection link and the strut support line connection link, and the jib support line connection link and the strut support line connection link may each have an insertion hole that overlaps with the insertion hole of the strut tip when positioned in their respective fixed positions and through which the fixing pin inserted through the insertion hole is inserted.

[0103] (2) Furthermore, even if the link restraint device is a fastening device, the fastening device is not necessarily limited to a chain block, but may be a cord-like member such as a sling or rope, and such a cord-like member may be used to connect a predetermined point of the strut to the jib support line connection link, thereby fastening the jib support line connection link in a fixed position.

[0104] (3) The crane attachment according to the present invention may be not only a fixed jib type in which the angle of the jib relative to the boom is fixed, but also a luffing jib type in which the angle of the jib relative to the boom is changeable.

[0105] (4) The attachment point to which the strut is attached, more specifically, the attachment point to which the strut base end is attached, may be the boom tip instead of the jib base end. In this case, when the jib is tilted forward, the strut is attached to the boom tip and is positioned so that it extends behind the boom tip, holding the jib support line connection link and the strut support line connection link in a position spaced apart from the boom tip and behind it.

[0106] In this case, when transporting the crane, the strut may be removed from the boom tip and placed in a stowed position along the lower jib member, and transported integrally with the lower jib member. Alternatively, the strut may be removed from the boom tip and transported separately. If the strut is transported separately, when assembling the crane (when assembling the crane attachment), the strut is hoisted by an assist crane and the base end of the strut is attached to the boom tip of the lowered boom, and then the strut is placed along the lowered lower jib member, connected to the boom tip and extending forward from the boom tip. The crane attachment can then be assembled using the same steps as those in the method for assembling a crane attachment in the above embodiment, from the steps of connecting the other end of the jib support line to the jib support line connection link and connecting one end of the strut support line to the strut support line connection link onward. [Explanation of symbols]

[0107] 2 Rotating body (crane body) 3 Crane attachments 5. Boom 6 Jib 6A Lower jib member 8 Jib support device 14 Boom base end 15 Boom tip 17 Jib base end 18 Jib tip 22 Jib support line 22a Jib support line one end 22b Other end of jib support line 23 Strut support line 23a Strut support line one end 26 Strut 26a Strut body 26b Link receiving part 27 Jib support line connecting link 28 Strut support line connecting link 30 Link Restraints 36 Strut base end 37 Strut tip 52b Line connection hole (line connection point) 56 Link pressing part 63 Pressed part 64 Recess

Claims

1. A crane attachment that is attached to a crane body to perform crane work of lifting a load, a boom having a boom base end attached to the crane body and a boom tip end at the end opposite to the boom base end; a jib having a jib base end portion which is one end rotatable about an axis extending in the width direction of the boom and separably attached to the boom tip portion, and a jib tip portion which is an end opposite to the jib base end portion; a jib support device that supports the jib from behind, the jib being tilted forward relative to the boom when the boom base end is attached to the crane body and the boom is in an upright position, The jib support device comprises: a jib support line having one end connected to the jib tip and the other end opposite thereto; a strut attached to an attachment portion which is either the jib base end or the boom tip and arranged in a position extending from the attachment portion behind it when the jib takes the forward tilting position, the strut supporting the other end of the jib support line at a position away from the attachment portion behind it so that the jib support line extends taut from the jib tip; and a strut support line having one end connected to the strut and preventing the strut from falling in a direction along the jib. The strut comprises a strut body having a strut base end which is one end attached to the attached portion so as to be rotatable about an axis parallel to the rotation axis of the jib base end and a strut tip end which is the end opposite to the strut base end, a jib support line connection link which is rotatably attached to the strut tip end about an axis parallel to the rotation axis of the strut base end and to which the other end of the jib support line is connected, and a strut support line connection link which is rotatably attached to the strut tip end about an axis parallel to the rotation axis of the strut base end and to which one end of the strut support line is connected, The jib support device is an attachment for a crane, and further has a link restraining device configured to restrain the jib support line connection link in a jib support line connection link fixed position, which is a predetermined rotational position relative to the strut tip, and to restrain the strut support line connection link in a strut support line connection link fixed position, which is a predetermined rotational position relative to the strut tip.

2. The jib has a plurality of jib members arranged side by side in the extension direction thereof and separably connected to each other, The plurality of jib members includes a lower jib member that is a jib member having the jib base end portion, 2. A crane attachment as described in claim 1, wherein the strut is configured to be capable of taking a storage position, which is a rotational position around the rotation axis of the strut base end and in which the strut is positioned along the back surface of the lower jib member.

3. The jib support line connection link has a line connection point where the other end of the jib support line is connected, 3. A crane attachment as described in claim 2, wherein the jib support line connection link fixed position is a position in which the line connection point is positioned behind and away from the back surface of the lower jib member when the strut is in the stored position.

4. 4. A crane attachment as described in claim 2 or 3, wherein the jib support line connection link has a link pressing portion that abuts against the strut support line connection link when the jib support line connection link is rotated in a direction away from the back surface of the lower jib member toward the rear of the lower jib member while the strut is in the stored position, and presses the strut support line connection link toward the strut support line connection link fixed position.

5. the strut body has a link receiving portion that receives the strut support line connection link when the strut support line connection link is pressed by the link pressing portion and placed in the strut support line connection link fixed position, 5. A crane attachment as described in claim 4, wherein the jib support line connection link fixed posture is a rotational posture of the jib support line connection link in a state where the link pressing portion of the jib support line connection link presses the strut support line connection link and the strut support line connection link is received by the link receiving portion.

6. The strut support line connection link has a pressed portion that is pressed by the link pressing portion when the jib support line connection link is rotated in a direction away from the back surface of the lower jib member toward the rear thereof, 6. The crane attachment according to claim 5, wherein one of the link pressing portion and the pressed portion has a recessed portion capable of receiving the other portion, and the other portion has a shape that can fit into the recessed portion.

7. A crane attachment as described in any one of claims 4 to 6, wherein the link restraint device is a fastening device that connects a predetermined location of the strut to the jib support line connection link, and is configured to pull the jib support line connection link so that the jib support line connection link rotates in a direction away from the back surface of the lower jib member toward the rear of the lower jib member when the strut is in the stored position, thereby securing the jib support line connection link in a fixed position.

Images