Backstop

Abstract

To provide a backstop capable of preventing interference between a spacer and surrounding members.SOLUTION: A rear-side jib backstop 60 of a crane 1 has an outer cylinder 60A, an inner cylinder 60B, a spacer 70, a spacer holder 80, and a lock mechanism 90. The spacer holder 80 pivotably supports the spacer 70. When the rear-side jib backstop 60 changes its posture while a boom 16 is erected, the spacer 70 is fitted to the inner cylinder 60B to prevent the rear-side jib backstop 60 from contracting. The lock mechanism 90 can lock the spacer 70 so as to prevent the spacer 70 from swinging around a swing center axis CT in a state in which the spacer 70 is separated from the outer peripheral surface of the inner cylinder 60B.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a backstop mounted on a crane.

Background Art

[0002] Patent Document 1 discloses a crane including a crane body, a boom rotatably supported by the crane body in the hoisting direction, a jib rotatably supported by the tip of the boom in the hoisting direction, and a strut rotatably supported by the base end of the jib on the rear side of the jib and supporting the jib from the rear. The crane further includes a jib backstop for preventing the strut and the jib from falling backward with respect to the boom.

[0003] The jib backstop includes an outer cylinder, an inner cylinder relatively movable axially with respect to the outer cylinder, and a spacer. The jib backstop expands and contracts by the relative movement of the inner cylinder with respect to the outer cylinder. The base end of the outer cylinder is rotatably supported by the strut, and the tip of the inner cylinder is rotatably supported by the tip of the boom. The spacer has a shape that can be fitted to the outer peripheral surface of the inner cylinder and is rotatably supported by the tip of the outer cylinder. When the boom and the jib stand up with respect to the crane body during the assembly of the crane, if the posture of the jib backstop changes in conjunction with this movement, the spacer fits onto the outer peripheral surface of the inner cylinder and prevents the jib backstop from further contracting. As a result, the jib backstop supports the strut from the rear and prevents further rotation of the strut and the jib, that is, prevents the strut and the jib from falling backward.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the technology described in Patent Document 1, when the spacer rotates due to vibration or impact and interferes with surrounding members during disassembly or transportation of the crane, the spacer is damaged, and it becomes difficult for the backstop to stably support the strut during crane operation.

[0006] The present invention has been made in view of the above problems, and an object thereof is to provide a backstop capable of preventing interference between a spacer and surrounding members during assembly and disassembly of a crane.

Means for Solving the Problems

[0007] Provided by the present invention is a backstop that is attached to a crane including a fuselage, a boom that is supported by the fuselage so as to be able to rise and fall, and a strut, and is interposed between the boom and the strut and can support the strut. The boom includes a boom base end portion and a boom tip end portion. The boom base end portion is rotatably attached to the fuselage. The boom tip end portion is disposed on the opposite side of the boom base end portion and includes a strut support portion and a backstop support portion disposed behind the strut support portion. The strut includes a strut base end portion, a strut tip end portion, and a backstop connection portion. The strut base end portion is supported by the strut support portion of the boom tip end portion so as to be rotatable in the rising and falling direction around a horizontal reference rotation center axis. The strut tip end portion is disposed on the opposite side of the strut base end portion. The backstop connection portion is disposed between the strut base end portion and the strut tip end portion. The backstop includes an outer cylinder, an inner cylinder, a spacer, a spacer holder, and a locking mechanism. The outer cylinder includes an outer cylinder base end portion connected to the backstop connection portion of the strut so as to be rotatable around a first rotation center axis parallel to the reference rotation center axis, and an outer cylinder tip end portion disposed on the opposite side of the outer cylinder base end portion. The inner cylinder includes an inner cylinder base end portion supported by the backstop support portion of the boom tip end portion so as to be rotatable around a second rotation center axis parallel to the reference rotation center axis, and an inner cylinder tip end portion disposed on the opposite side of the inner cylinder base end portion and inserted into the outer cylinder through the outer cylinder tip end portion. Further, the inner cylinder relatively moves axially with respect to the outer cylinder so as to allow the distance between the backstop support portion and the backstop connection portion to change as the strut rotates around the reference rotation center axis with respect to the boom. The spacer has a semi-cylindrical inner peripheral surface having a predetermined dimension in the axial direction and capable of fitting on the outer peripheral surface of the inner cylinder along a direction orthogonal to the axial direction. When both ends of the spacer in the axial direction abut against the outer cylinder tip end portion and the inner cylinder base end portion, respectively, the spacer prevents the backstop from contracting so that the outer cylinder tip end portion approaches the inner cylinder base end portion by a distance corresponding to the dimension.The spacer holder is attached to the outer cylinder of the backstop and supports the spacer so as to be swingable about a swing center axis orthogonal to the axial direction. The spacer holder supports the spacer such that as the boom stands up with respect to the airframe in a state where the boom supports the strut, the spacer can swing about the swing center axis by its own weight and fit into the inner cylinder. The locking mechanism is capable of changing its state between a locked state and an unlocked state. The locked state is a state in which the locking mechanism locks the spacer so as to prevent the spacer from swinging about the swing center axis in a state where the spacer is separated from the outer peripheral surface of the inner cylinder. The unlocked state is a state in which the spacer is allowed to swing about the swing center axis.

[0008] According to this configuration, when the locking mechanism is in the locked state, the locking mechanism can lock the spacer so as to prevent the spacer from swinging about the swing center axis in a state where the spacer is separated from the outer peripheral surface of the inner cylinder. Therefore, it is possible to prevent the spacer from moving freely during the assembly and disassembly of the crane, and to prevent interference between the spacer and surrounding members and the accompanying damage. Thus, the operator can perform the work without having to pay attention to interference or damage of the spacer during the disassembly work or transportation work of the crane including the backstop. On the other hand, at the time of assembling the crane, by setting the locking mechanism to the unlocked state, the spacer can swing, and the length of the backstop can be restricted by the spacer.

[0009] The outer cylinder and the inner cylinder each have a cylindrical shape having a center line extending along the axial direction. The spacer holder supports the spacer so that it can swing around the swing center axis such that in the boom collapsed state, the spacer assumes a hanging posture, and as the boom stands up from the boom collapsed state with respect to the machine body, the spacer approaches the outer peripheral surface of the inner cylinder along the vertical plane passing through the center line of the outer cylinder from the hanging posture. The boom collapsed state is a state in which the boom supports the strut and lies down with respect to the machine body. The hanging posture is a posture in which the spacer intersects the vertical plane passing through the center line and hangs down from the swing center axis due to the weight of the spacer. The locking mechanism locks the spacer by connecting the spacer and the outer cylinder that are in the opposed postures to each other. The opposed posture is desirably a posture of the spacer in which the spacer swings so as to be farther from the outer peripheral surface of the inner cylinder than in the hanging posture and the outer peripheral surface of the spacer faces the outer cylinder.

[0010] According to this configuration, since the spacer can be locked in a state where it is separated from the inner cylinder and faces the outer cylinder, it is possible to prevent the spacer from approaching the inner cylinder due to vibrations during transportation or the like. Further, compared with the case where the locking mechanism locks the spacer in a posture extending in a direction orthogonal to the center line of the jib backstop, the backstop can be made more compact and the space occupied by the backstop during transportation can be reduced.

[0011] In the above configuration, it is desirable that the spacer holder is attached to the outer cylinder so as to be relatively rotatable in the circumferential direction with respect to the outer cylinder, and the locking mechanism connects the spacer and the outer cylinder to each other and locks the spacer in a state where the spacer holder rotates relative to the outer cylinder in the circumferential direction and the spacer detaches from the vertical plane when the spacer is in the opposed posture.

[0012] According to this configuration, an operator can move and lock the spacer so that it separates from the vertical plane passing through the backstop by rotating the spacer holder relative to the outer cylinder, thereby preventing the spacer from interfering with other members located directly above or below the backstop during transportation.

[0013] In the above configuration, the outer cylinder includes a cylindrical outer cylinder body and an outer cylinder fixing portion. The outer cylinder body includes the outer cylinder base end portion and the outer cylinder tip end portion, supports the spacer holder, and receives the inner cylinder therein. The outer cylinder fixing portion is disposed on the outer peripheral surface of the outer cylinder body at a position farther from the spacer holder than the spacer when viewed from the spacer in the hanging posture, and a first pin hole is formed in the outer cylinder fixing portion along a direction orthogonal to the axial direction. The spacer includes a semi-cylindrical spacer body and a spacer supported portion. The spacer body includes an inner peripheral surface that can be fitted to the outer peripheral surface of the inner cylinder. The spacer supported portion extends from the spacer body in the axial direction and is swingably supported by the spacer holder around the swing center axis. A second pin hole is formed in a portion of the spacer supported portion closer to the spacer body than the swing center axis along a direction orthogonal to the axial direction. The locking mechanism includes a locking pin. It is desirable that the locking pin is inserted into the first pin hole and the second pin hole in a state where the spacer is in the facing posture, thereby connecting the spacer supported portion of the spacer and the outer cylinder fixing portion of the outer cylinder to each other and locking the spacer.

[0014] According to this configuration, an operator can easily lock the spacer in the facing posture by inserting a locking pin into the pin holes formed in the spacer supported portion and the outer cylinder fixing portion, respectively.

[0015] In the above configuration, the spacer holder includes a holder cylindrical portion, a holder support portion, and a holder fixing portion. The holder cylindrical portion is externally fitted to the outer peripheral surface of the outer cylinder so as to be relatively rotatable in the circumferential direction with respect to the outer cylinder. The holder support portion is disposed on the outer peripheral surface of the holder cylindrical portion and supports the spacer supported portion of the spacer so as to be swingable around the swing center axis. The holder fixing portion is disposed so as to project from the holder cylindrical portion toward the base end portion of the outer cylinder at a position different from the holder support portion in the circumferential direction on the outer peripheral surface of the holder cylindrical portion. A third pin hole is formed in the holder fixing portion along a direction orthogonal to the axial direction. In a state where the spacer is in the hanging posture, the lock pin is inserted into the first pin hole and the third pin hole, respectively, and the lock pin connects the holder fixing portion of the spacer holder and the outer cylinder fixing portion of the outer cylinder to each other, so that the lock pin restrains the spacer in the circumferential direction of the outer cylinder. It is desirable that the position of the outer cylinder fixing portion is set.

[0016] According to this configuration, by connecting the lock pin to the holder fixing portion and the outer cylinder fixing portion to each other, the spacer can be prevented from moving in the circumferential direction. Therefore, during the assembly work of the crane, it is possible to prevent the spacer from detaching from the vertical plane passing through the center line of the backstop, and it is possible to prevent the occurrence of poor fitting of the spacer to the inner cylinder.

[0017] In the above configuration, it is desirable that the rotational angle of the spacer holder in the circumferential direction with respect to the outer cylinder is set so that the outer cylinder can be arranged to overlap the strut when the spacer detaches from the space between the strut and the backstop.

[0018] According to this configuration, when disassembling and transporting the crane, it is possible to load the backstop on the strut without being affected by the spacer and move the two integrally.

Effects of the Invention

[0019] According to the present invention, it is possible to provide a backstop that can prevent interference between a spacer and surrounding members during assembly and disassembly of a crane and damage associated therewith.

Brief Description of the Drawings

[0020]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

Figure 18

Figure 19

Figure 20

Figure 21

Figure 22

Mode for Carrying Out the Invention

[0021] Hereinafter, each embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a side view of a crane 1 (working machine) according to an embodiment of the present invention. In the following, the directions of "up", "down", "left", "right", "front" and "rear" are shown in each figure. However, these directions are shown for convenience in explaining the structure and assembly method of the crane 1 according to the present embodiment, and do not limit the moving direction of the crane according to the present invention or the usage mode of the backstop.

[0022] The crane 1 includes an upper slewing body 12, a lower traveling body 14, a boom 16, a jib 18, a lower spreader 19A, an upper spreader 19B, a pair of left and right boom guy lines 20, a gantry 21, a boom hoist rope 22, a boom hoist winch 30, a main winch 34, a supplementary winch 35, a counterweight 40, and a pair of left and right boom backstops 45. Further, the crane 1 includes a main hoist rope 51, a supplementary hoist rope 52, a main hook 53, a supplementary hook 54, a pair of left and right struts 55, a pair of left and right rear jib guy lines 56, a pair of left and right front jib guy lines 57, a pair of left and right rear jib backstops 60, and a pair of left and right front jib backstops 61. In the following description, for the pair of left and right members as described above, since the left and right structures are the same, the structure of either the left or the right will be described.

[0023] The upper slewing body 12 constitutes the crane body (airframe) of the crane 1 and is supported by the lower traveling body 14 so as to be rotatable around a swivel center axis extending in the vertical direction. The lower traveling body 14 can travel on a traveling surface such as the ground G.

[0024] The boom 16 is supported by the upper slewing body 12 so as to be able to undulate. Specifically, the boom 16 has a boom base end portion 16P and a boom tip end portion 16Q. The boom base end portion 16P is supported by the upper slewing body 12 so as to be rotatable in the undulating direction about a horizontal boom rotation center axis. The boom tip end portion 16Q is disposed on the side opposite to the boom base end portion 16P in the longitudinal direction. In the present embodiment, a boom foot 16S provided at the boom base end portion 16P is rotatably supported by a shaft support portion (not shown) of the upper slewing body 12. Further, the boom tip end portion 16Q has a jib support portion 161 (strut support portion) described later and a backstop support portion 162 disposed behind the jib support portion 161. Note that the boom 16 shown in FIG. 1 is a so-called lattice type and is configured by connecting a plurality of boom members to each other. The structure of the boom 16 is not limited to this, and a box type structure, a telescopic structure, or the like may be used. A pair of left and right backstops 45 are supported on the back surface of the boom 16. These backstops 45 abut against the upper slewing body 12 in the upright posture of the boom 16 (the working posture of the crane 1). By this abutment, the boom 16 is restricted from being blown backward by strong wind or the like.

[0025] The jib 18 is supported by the boom tip end portion 16Q of the boom 16 so as to be rotatable in the undulating direction about a horizontal rotation center axis. The jib 18 includes a lower jib 18A described later.

[0026] The lower spreader 19A is connected to the tip end portion of the gantry 21 and has a lower sheave block (not shown). A plurality of sheaves are arranged in the width direction (left - right direction) on the lower sheave block.

[0027] The upper spreader 19B is disposed in front of the lower spreader 19A at a predetermined interval. The upper spreader 19B is connected to the boom tip end portion 16Q via a boom guy line 20. The upper spreader 19B has an upper sheave block (not shown). A plurality of sheaves are arranged in the width direction (left - right direction) on the upper sheave block.

[0028] The boom guide lines 20 are arranged at intervals in the left - right direction orthogonal to the plane of the paper in FIG. 1. The rear end of each boom guide line 20 is connected to the upper spreader 19B, and the front end of each guide line 20 is detachably connected to the boom tip 16Q. The boom guide line 20 may have any structure such as a guy link (a metal plate), a guy rope, or a guy wire (a metal wire).

[0029] The gantry 21 is supported by the upper slewing body 12 behind the boom 16. As shown in FIG. 1, the gantry 21 is composed of two structures (compression member 21A and tension member 21B) that form a substantially triangular shape with the upper slewing body 12. The tension member 21B extends substantially vertically upward from the rear end of the upper slewing body 12. The compression member 21A connects the upper end of the tension member 21B and the front part of the upper slewing body 12 along an oblique direction. The gantry 21 supports the boom 16 from the rear so that the boom 16 can be raised and lowered.

[0030] The boom hoisting rope 22 is drawn out from the boom hoisting winch 30, wound around a sheave arranged at the tip of the tension member 21B, and then wound around a plurality of times between the lower sheave block of the lower spreader 19A and the upper sheave block of the upper spreader 19B. The tip of the boom hoisting rope 22 after being wound around the lower sheave block and the upper sheave block is fixed to the tip (upper end) of the gantry 21.

[0031] The boom hoisting winch 30 is arranged on the upper slewing body 12. By winding and unwinding the boom hoisting rope 22, the boom hoisting winch 30 changes the distance between the lower sheave block of the lower spreader 19A and the upper sheave block of the upper spreader 19B, and raises and lowers the boom 16 while rotating the boom 16 relative to the gantry 21.

[0032] The main hoist winch 34 winds up and pays out the suspended load by means of the main hoist rope 51 (Fig. 1). Regarding this main hoist, a main hoist guide sheave (not shown) is rotatably provided at the boom tip 16Q of the boom 16, and a main hoist sheave block in which a plurality of main hoist point sheaves are arranged in the width direction is provided at a position adjacent to the main hoist guide sheave. A main hook 53 for the suspended load is connected to the main hoist rope 51 suspended from the main hoist sheave block. Then, the main hoist rope 51 pulled out from the main hoist winch 34 is successively hung on the main hoist guide sheave, and is stretched between the sheaves of the main hoist sheave block and the sheaves of the sheave block provided on the main hook 53. Therefore, when the main hoist winch 34 winds up or pays out the main hoist rope 51, the main hook 53 is wound up or wound down.

[0033] Similarly, the auxiliary hoist winch 35 winds up and pays out the suspended load by means of the auxiliary hoist rope 52. Regarding this auxiliary hoist, an auxiliary hoist guide sheave (not shown) is rotatably provided at the tip of the jib 18, and an auxiliary hoist sheave block in which a plurality of auxiliary hoist point sheaves are arranged in the width direction is provided at a position adjacent to the auxiliary hoist guide sheave. An auxiliary hook 54 for the suspended load is connected to the auxiliary hoist rope 52 suspended from the auxiliary hoist sheave block. Then, the auxiliary hoist rope 52 pulled out from the auxiliary hoist winch 35 is successively hung on the auxiliary hoist guide sheave via the sheave of the strut 55, and is stretched between the sheaves of the auxiliary hoist sheave block and the sheaves of the sheave block provided on the auxiliary hook 54. And when the auxiliary hoist winch 35 winds up or pays out the auxiliary hoist rope 52, the auxiliary hook 54 for the suspended load connected to the end of the auxiliary hoist rope 52 is wound up or wound down.

[0034] Also, the counterweight 40 is loaded at the rear of the upper slewing body 12 to adjust the balance of the crane 1.

[0035] The strut 55 is rotatably supported in the undulating direction at the boom base end portion 18P of the jib 18 (Figs. 2 and 3). The strut 55 functions as a support column that supports the jib 18 from the rear. The tip end portion of the strut 55 (the strut tip end portion 55T described later) is connected to the longitudinal center portion of the boom 16 by the rear jib guy line 56 and is connected to the jib tip end portion 18Q of the jib 18 by the front jib guy line 57.

[0036] The rear jib backstop 60 connects the strut 55 and the boom tip end portion 16Q (the boom head 16T described later) of the boom 16. That is, the rear jib backstop 60 is interposed between the boom 16 and the strut 55 and can support the strut 55. Further, the front jib backstop 61 connects the strut 55 and the jib 18. That is, the front jib backstop 61 is interposed between the jib 18 and the strut 55 and can support the jib 18. As a result, the rear jib backstop 60 and the front jib backstop 61 prevent the strut 55 and the jib 18 from being blown by the wind or the like and falling during the operation of the crane 1. These jib backstops have a telescopic cylinder structure.

[0037] Figs. 2 and 3 are a side view and an enlarged perspective view, respectively, of a state in which the strut 55 is placed on the lower jib 18A of the crane 1 according to the present embodiment. Figs. 4 and 5 are an enlarged plan view and an enlarged cross-sectional view, respectively, of a state in which the strut 55 is placed on the lower jib 18A of the crane 1 according to the present embodiment. Fig. 5 corresponds to a cross-section at the position of arrow V-V in Fig. 2.

[0038] The boom 16 has a boom head 16T disposed at its tip (Fig. 9). The boom head 16T is the member disposed at the foremost tip among the plurality of boom members and constitutes the aforementioned boom tip 16Q. The boom head 16T has a jib support portion 161 and a backstop support portion 162 (see Fig. 9). When the boom 16 stands upright with respect to the upper slewing body 12, the backstop support portion 162 is disposed behind the jib support portion 161. When the boom 16 lies down with respect to the upper slewing body 12, the backstop support portion 162 is disposed behind and above the jib support portion 161.

[0039] The lower jib 18A (Fig. 2) is a member constituting the base end portion of the jib 18 and is detachably attached to the boom tip 16Q of the boom 16. When the crane 1 is assembled and disassembled, as shown in Fig. 2, the lower jib 18A of the jib 18 is detached from the boom 16, and with a strut 55 loaded thereon, the lower jib 18A and the strut 55 can be transported integrally. At this time, the rear jib backstop 60 is held on the strut 55, and the front jib backstop 61 is held on the lower jib 18A.

[0040] The strut 55 has a strut base end portion 55S, a strut tip portion 55T, a backstop connection portion 55Q, and a backstop holding portion 55R.

[0041] The strut base end portion 55S is the base end portion of the strut 55 and is supported by the boom tip portion 16Q via the jib base end portion 18P so as to be rotatable in the undulating direction about the horizontal reference rotation center axis (CL). The strut tip portion 55T is the tip portion of the strut 55 disposed on the side opposite to the strut base end portion 55S. The backstop connection portion 55Q is disposed between the strut base end portion 55S and the strut tip portion 55T in the longitudinal direction of the strut 55. Specifically, the backstop connection portion 55Q is disposed on the upper surface portion of the strut 55 and substantially at the center in the longitudinal direction of the strut 55 in a state where the strut 55 is loaded on the lower jib 18A. The backstop connection portion 55Q is connected to the fulcrum portion 60S of the rear jib backstop 60 and rotatably supports the fulcrum portion 60S. The backstop holding portion 55R is disposed at a position closer to the strut base end portion 55S than the backstop connection portion 55Q. The backstop holding portion 55R detachably holds the tip portion 60T of the rear jib backstop 60.

[0042] The rear jib backstop 60 (backstop) has a fulcrum portion 60S and a tip portion 60T. The fulcrum portion 60S is the base end portion of the rear jib backstop 60 and is rotatably supported by the strut 55. The tip portion 60T is the tip portion of the rear jib backstop 60 on the side opposite to the fulcrum portion 60S and is rotatably connected to the backstop support portion 162 of the boom tip portion 16Q described above. In FIGS. 2 to 4, the direction in which the rear jib backstop 60 extends long (the front-rear direction in each figure) is referred to as the axial direction of the rear jib backstop 60.

[0043] Further, the rear jib backstop 60 has an outer cylinder 60A, an inner cylinder 60B, a spacer 70, a spacer holder 80, and a locking mechanism 90. The rear jib backstop 60 can be expanded and contracted by the relative movement of the inner cylinder 60B with respect to the outer cylinder 60A.

[0044] The outer cylinder 60A has a cylindrical shape having a center line extending in the axial direction of the rear jib backstop 60. The outer cylinder 60A includes an outer cylinder base end portion supported by the backstop connection portion 55Q of the strut 55 so as to be rotatable about a first rotation center axis (C1) parallel to the reference rotation center axis CL, and an outer cylinder tip portion disposed on the side opposite to the fulcrum portion 60S. The outer cylinder base end portion of the outer cylinder 60A constitutes the fulcrum portion 60S of the rear jib backstop 60.

[0045] The inner cylinder 60B has a cylindrical shape having a center line (the same center line as the outer cylinder 60A) extending in the axial direction of the rear jib backstop 60. The outer diameter of the inner cylinder 60B is set to be slightly smaller than the inner diameter of the outer cylinder 60A. The inner cylinder 60B includes an inner cylinder base end portion supported by the backstop holding portion 55R so as to be rotatable about a second rotation center axis C2 parallel to the reference rotation center axis CL, and an inner cylinder tip portion disposed on the side opposite to the inner cylinder base end portion and inserted into the outer cylinder 60A through the outer cylinder tip portion of the outer cylinder 60A. The inner cylinder 60B is capable of moving axially relative to the outer cylinder 60A so as to allow the distance between the backstop support portion 162 and the backstop connection portion 55Q to change as the strut 55 rotates about the reference rotation center axis CL with respect to the boom 16. The inner cylinder base end portion of the inner cylinder 60B constitutes the tip portion 60T of the rear jib backstop 60.

[0046] In FIG. 2, the tip portion 60T (inner cylinder base end portion) of the rear jib backstop 60 is held by the backstop holding portion 55R as described above. However, when the tip portion 60T is detached from the backstop holding portion 55R, it can be attached to the backstop support portion 162 of the boom tip portion 16Q.

[0047] The spacer 70 has a predetermined dimension along the axial direction of the rear jib backstop 60 and has a semi-cylindrical inner peripheral surface that can be fitted to the outer peripheral surface of the inner cylinder 60B along a direction orthogonal to the axial direction (see FIGS. 5 to 8). Both end portions of the spacer 70 in the axial direction abut against the outer cylinder tip portion of the outer cylinder 60A and the inner cylinder base end portion of the inner cylinder 60B, respectively, so that the spacer 70 can prevent the rear jib backstop 60 from contracting such that the outer cylinder tip portion approaches the inner cylinder base end portion by a distance corresponding to the dimension of the spacer 70. That is, the spacer 70 prevents the rear jib backstop 60 from contracting to a predetermined length or less in the erected state of the boom 16, and prevents the strut 55 and the jib 18 from tilting backward. In another embodiment, one end portion of the spacer 70 in the axial direction may abut against the tip portion of the spacer holder 80 instead of the outer cylinder tip portion of the outer cylinder 60A. In this case, the tip portion of the spacer holder 80 can be said to constitute a part of the outer cylinder tip portion of the outer cylinder 60A.

[0048] The spacer holder 80 is attached to the tip portion of the outer cylinder 60A of the rear jib backstop 60. The spacer holder 80 supports the spacer 70 so as to be swingable about a swing center axis CT orthogonal to the axial direction. Specifically, when the boom 16 stands up with respect to the upper swing body 12 while supporting the strut 55, the spacer 70 swings about the swing center axis CT by its own weight, and the spacer holder 80 supports the spacer 70 so that it can be fitted to the inner cylinder 60B. In the present embodiment, the spacer holder 80 is attached to (supported by) the outer cylinder 60A so as to be relatively rotatable in the circumferential direction with respect to the outer cylinder 60A.

[0049] The locking mechanism 90 is detachably attached to the rear jib backstop 60 and the spacer 70, and is a member capable of locking the spacer 70 so as to prevent the spacer 70 from swinging about the swing center axis CT regardless of the posture of the strut 55 with respect to the boom 16. More specifically, the locking mechanism 90 can change its state between a locked state and an unlocked state. The locked state is a state in which the locking mechanism 90 locks the spacer 70 so that the spacer 70 is separated from the outer peripheral surface of the inner cylinder 60B and the spacer 70 is prevented from swinging about the swing center axis CT. Further, the unlocked state is a state in which the locking mechanism 90 allows the spacer 70 to swing about the swing center axis CT. Note that the locking mechanism 90 only needs to be detachable from at least one of the rear jib backstop 60 and the spacer 70.

[0050] FIGS. 6, 7, and 8 are perspective views showing a state in which the spacer 70 is fitted into the inner cylinder 60B of the rear jib backstop 60 of the crane 1 according to the present embodiment. Next, the detailed structures of the above-described respective members will be further described.

[0051] The outer cylinder 60A of the rear jib backstop 60 includes an outer cylinder main body 60K and an outer cylinder fixing portion 60H (see FIG. 18).

[0052] The outer cylinder main body 60K is the main body portion of the outer cylinder 60A, and is a cylindrical member including the outer cylinder base end portion and the outer cylinder tip end portion. The outer cylinder main body 60K supports the spacer holder 80 and can receive the inner cylinder 60B therein.

[0053] The outer cylinder fixing portion 60H is a plate-like portion disposed on the outer peripheral surface of the outer cylinder main body 60K and protruding radially from the outer peripheral surface. A first pin hole 60HS is formed in the outer cylinder fixing portion 60H along a direction orthogonal to the axial direction of the rear jib backstop 60. Note that the outer cylinder fixing portion 60H is disposed at a position farther from the spacer holder 80 than the spacer 70 when viewed from the spacer 70 in a state where the spacer 70 is in a hanging posture described later (see FIG. 18).

[0054] Further, the spacer 70 includes a spacer main body 70A and a spacer supported portion 70B (FIG. 6).

[0055] The spacer main body 70A is a main body portion of the spacer 70 and is a semi-cylindrical member including an inner peripheral surface that can be fitted to the outer peripheral surface of the inner cylinder 60B.

[0056] The spacer supported portion 70B extends from the spacer main body 70A along the longitudinal direction (axial direction) of the spacer main body 70A and is swingably connected (supported) to the spacer holder 80 around the swing center axis CT. In the present embodiment, the spacer supported portion 70B is composed of two plate members arranged at intervals from each other. In each of the plate members of the spacer supported portion 70B, second pin holes 70T (FIGS. 6 to 8) are formed along a direction orthogonal to the axial direction at portions closer to the spacer main body 70A than the swing center axis CT.

[0057] Further, the spacer holder 80 has a holder cylindrical portion 81, a holder fixing portion 82, and a holder support portion 83 (FIG. 6).

[0058] The holder cylindrical portion 81 is a main body portion of the spacer holder 80 and is externally fitted (supported) to the outer peripheral surface of the outer cylinder 60A so as to be relatively rotatable in the circumferential direction with respect to the outer cylinder 60A (outer cylinder main body 60K).

[0059] The holder support portion 83 is disposed on the outer peripheral surface of the holder cylindrical portion 81 and swingably supports the spacer supported portion 70B of the spacer 70 around the swing center axis CT. The holder support portion 83 protrudes radially from the outer peripheral surface.

[0060] The holder fixing portion 82 is arranged to project axially from the holder cylindrical portion 81 toward the outer cylinder base end portion of the outer cylinder 60A at a position different from the holder support portion 83 in the circumferential direction on the outer peripheral surface of the holder cylindrical portion 81. A third pin hole 82S is formed in the holder fixing portion 82 along a direction orthogonal to the axial direction. Further, the holder fixing portion 82 can be gripped by an operator when rotating the spacer holder 80 and functions as a gripping portion.

[0061] Also, in the present embodiment, the locking mechanism 90 includes a fixing pin P1 and a spring pin P2 (see FIG. 15). These pins have a function of restraining (locking) the position and posture of the spacer 70 or the spacer holder 80 as described later. The fixing pin P1 can be inserted into the above-described first pin hole 60HS, second pin hole 70T, and third pin hole 82S (FIGS. 16 and 18). The spring pin P2 is attached to the tip of the fixing pin P1 and functions as a so-called retaining pin.

[0062] Next, with reference to FIGS. 6 to 8, the basic functions of the spacer 70 will be described.

[0063] When disassembling and assembling the crane 1, during the raising and lowering operation (relative attitude change) of the boom 16 and the strut 55 with respect to the upper slewing body 12, the rear jib backstop 60 rotates about the tip 60T (the second rotation center axis C2) as a fulcrum. At this time, as shown in FIG. 6, with the protruding amount of the inner cylinder 60B with respect to the outer cylinder 60A being larger than the dimension in the axial direction of the spacer 70, the spacer 70 swings about the swing center axis CT from the posture extending vertically downward due to its own weight, and the cylindrical inner peripheral surface of the spacer body 70A of the spacer 70 approaches the outer peripheral surface of the inner cylinder 60B (FIG. 7). Eventually, as shown in FIG. 8, after the spacer body 70A of the spacer 70 fits onto the outer peripheral surface of the inner cylinder 60B, when the inner cylinder 60B contracts relative to the outer cylinder 60A, the tip 70A1 of the spacer body 70A abuts against the flange portion formed at the base end of the inner cylinder 60B along the axial direction, and the base end 70A2 of the spacer body 70A abuts against the tip of the outer cylinder 60A along the axial direction. As a result, the tip of the outer cylinder 60A is further prevented from approaching the base end side of the inner cylinder 60B, and the length of the rear jib backstop 60 is fixed. Therefore, as shown in FIG. 1, the rear jib backstop 60 supports the strut 55 from below, and can prevent the strut 55 and the jib 18 from swaying backward. Note that regarding the fitting between the spacer 70 and the inner cylinder 60B, there may be a predetermined gap between the inner peripheral surface of the spacer 70 and the outer peripheral surface of the inner cylinder 60B.

[0064] Next, through the assembly operation of the crane 1, the state in which the spacer 70 fits into the inner cylinder 60B of the rear jib backstop 60 as described above will be further described. FIGS. 9 and 10 are side views showing a state in which the lower jib 18A and the strut 55 are connected to the boom head 16T of the crane 1 according to the present embodiment. FIG. 11 is a side view showing a state in which the strut 55 is caused with respect to the lower jib 18A of the crane 1. FIG. 12 is a side view showing a state in which the strut 55 is caused in the crane 1. FIG. 13 is an enlarged side view showing a state in which the front jib backstop 61 is caused in the crane 1. FIG. 14 is an enlarged side view showing a state in which the rear jib backstop 60 is connected to the boom head 16T in the crane 1.

[0065] In the assembly work of the crane 1, as an example, as shown in FIGS. 2 and 3, with the strut 55 placed on the lower boom 18A of the boom 18, it is integrally carried into the work site by a transport vehicle such as a trailer. At this time, as shown in FIGS. 3 and 5, due to the rotation function of the spacer holder 80 with respect to the outer cylinder 60A of the rear boom backstop 60, the spacer 70 is disposed so as to be separated to the left and right outer sides with respect to the space between the strut 55 and the outer cylinder 60A. Therefore, the spacer 70 does not get in the way, and the rear boom backstop 60 can be stably loaded on the strut 55.

[0066] As shown in FIG. 9, the lower boom 18A and the strut 55 are lifted from the trailer by an auxiliary lifting device 100 (auxiliary crane, accompanying machine) and moved toward the boom head 16T of the boom 16 installed in advance on the ground G. The boom head 16T of the boom 16 is installed on the ground G via a support H (support stand).

[0067] Eventually, as shown in FIG. 10, when the boom foot 18S of the lower boom 18A is aligned with the boom support portion 161 of the boom head 16T, a connecting pin (not shown) is inserted into the pin holes formed in both of them, and the lower boom 18A is rotatably supported by the boom head 16T of the boom 16.

[0068] Next, as shown in FIG. 11, the operator assembles the boom 18 by connecting other boom members (intermediate boom, upper boom) to the tip of the lower boom 18A. Also, the operator connects one end of the rear boom guy line 56 and the front boom guy line 57 to the tip of the strut 55, respectively. Note that the other end of the front boom guy line 57 is fixed to the boom tip 18Q of the boom 18 (FIG. 1). Also, the ropes of the auxiliary hoisting device 100 are connected to the strut suspended portions 55P of the left and right struts 55 (FIGS. 2 to 4), respectively. Then, as shown in FIG. 12, the strut 55 is lifted toward the boom head 16T by the auxiliary hoisting device 100, and as shown by the arrow in FIG. 13, the front boom backstop 61 is lifted with the fulcrum portion 61S as a fulcrum, and the tip 61T of the front boom backstop 61 is connected to the connection location provided on the strut 55.

[0069] Next, as shown in FIG. 14, the operator removes the tip 60T of the rear boom backstop 60 from the backstop holding portion 55R of the strut 55 (FIG. 2), rotates the rear boom backstop 60 backward with the fulcrum portion 60S as a fulcrum, and connects the tip 60T to the backstop support portion 162 of the boom head 16T with a pin (not shown). As a result, the tip 60T of the rear boom backstop 60 is supported by the backstop support portion 162 so as to be rotatable about the second rotation center axis C2 (see FIG. 20). The strut 55 is supported by the boom 16 (boom head 16T) and the boom 18 (lower boom 18A) via the rear boom backstop 60 and the front boom backstop 61.

[0070] FIGS. 15 to 18 are perspective views showing a state in which the spacer 70 of the crane 1 according to the present embodiment is changed from the stored posture to the hanging posture.

[0071] In the state shown in FIG. 14 (the same applies during transportation), as shown in FIG. 15, the spacer 70 (spacer main body 70A) is in a posture where it is turned over around the swing center axis CT so that the outer peripheral surface of the spacer 70 faces the outer cylinder 60A (opposing posture). Further, a fixing pin P1 is inserted through the second pin hole 70T of the spacer 70 and the first pin hole 60HS (FIG. 18) formed in the outer cylinder fixing portion 60H of the outer cylinder 60A, and a spring pin P2 is attached to the tip of the fixing pin P1, thereby preventing the swing of the spacer 70 around the swing center axis CT and the circumferential relative movement (rotation) of the spacer holder 80 with respect to the outer cylinder 60A (the storage posture of the spacer 70, the locked state of the locking mechanism 90). In particular, in the present embodiment, as shown in FIG. 15, the outer cylinder fixing portion 60H of the outer cylinder 60A is inserted between the two spacer supported portions 70B of the spacer 70 so as to be sandwiched, and the fixing pin P1 is inserted through each second pin hole 70T (FIGS. 7 and 8) and the first pin hole 60HS (FIG. 8). Therefore, the spacer 70 can be fixed more stably. Note that the fixing method of the spacer 70 is not limited to the present embodiment. For example, the spacer supported portion 70B may be a single member.

[0072] Therefore, in the state of FIGS. 14 and 15, the operator sequentially removes the spring pin P2 and the fixing pin P1, and swings the spacer 70 downward around the swing center axis CT as shown by the arrow in FIG. 16. That is, the spacer 70 is in a state of hanging with respect to the spacer holder 80. In this state, since the spacer 70 extends outward in the left-right direction from the spacer holder 80, the operator relatively rotates the spacer holder 80 holding the spacer 70 inward in the left-right direction with respect to the outer cylinder 60A as shown in FIG. 17. As a result, the spacer 70 is arranged so as to intersect the vertical plane passing through the center of the rear jib backstop 60 (so that the center line of the spacer 70 is included in the vertical plane) as shown in FIG. 18. At this time, the spacer 70 is arranged vertically below the outer cylinder 60A (the hanging posture of the spacer 70, the unlocked state of the locking mechanism 90).

[0073] Next, the operator inserts the fixing pin P1 removed earlier into the first pin hole 60HS of the outer cylinder fixing portion 60H and the third pin hole 82S of the holder fixing portion 82 in sequence. Then, a spring pin P2 is attached to the tip of the fixing pin P1 to prevent the fixing pin P1 from coming off. As a result, the rotation of the spacer holder 80 with respect to the outer cylinder 60A is blocked, so that the spacer 70 can swing around the swing center axis CT while being prevented from moving left and right. Thus, in the present embodiment, the fixing pin P1 and the spring pin P2 can be commonly used between the operation of the crane 1 and the disassembly / transportation.

[0074] FIG. 19 is a side view showing a state in which the rear jib guy line 56 is connected to the boom 16 in the crane 1 according to the present embodiment. When the preparation of the spacer 70 is completed as described above, the operator connects the other end of the rear jib guy line 56 to the guy line connection portion 16H provided on the back surface of the boom 16 while lifting it by the auxiliary lifting device 100.

[0075] FIGS. 20 to 22 are enlarged side views showing a state in which the spacer 70 fits into the inner cylinder 60B of the rear jib backstop 60 as the boom 16 is erected in the crane 1 according to an embodiment of the present invention.

[0076] From the state of FIG. 19, the operator erects the boom 16 by winding up the boom hoist rope 22 by the boom hoist winch 30 of FIG. 1. As a result, as shown in FIGS. 20, 21, and 22, the boom head 16T, the lower jib 18A, and the strut 55 of the boom 16 change their postures. At this time, the fulcrum portion 60S and the tip portion 60T of the rear jib backstop 60 rotate around the first rotation center axis C1 and the second rotation center axis C2, respectively, while the inner cylinder 60B of the rear jib backstop 60 moves relative to the outer cylinder 60A, and the rear jib backstop 60 expands and contracts.

[0077] In FIGS. 20 and 21, the spacer 70 hanging down via the spacer holder 80 with respect to the outer cylinder 60A of the rear jib backstop 60 is fitted into the inner cylinder 60B from above by its own weight in response to the change in the posture of the rear jib backstop 60 so as to extend obliquely rearward as shown in FIG. 22 (see FIGS. 6 to 8). As a result, the spacer 70 prevents further contraction of the rear jib backstop 60, and the strut 55 is held in a preset posture with respect to the boom 16. Therefore, the rear jib backstop 60 can cooperate with the front jib backstop 61 to prevent the strut 55 and the jib 18 from falling backward and being swayed.

[0078] When disassembling the crane 1, the reverse process of the above is executed in order. At this time, when the boom 16 falls from the posture of FIG. 22, in the process in which the rear jib backstop 60 is changed from the posture extending obliquely rearward to the posture extending obliquely forward via the posture extending vertically upward (FIG. 21), the spacer 70 swings around the swing center axis CT by its own weight and detaches from the inner cylinder 60B of the rear jib backstop 60, and can return to the posture of hanging down from the spacer holder 80 at a position away from the inner cylinder 60B (hanging posture).

[0079] As described above, in the present embodiment, when the locking mechanism is in the locked state, the locking mechanism 90 (fixed pin P1, spring pin P2) can lock the spacer 70 so as to prevent the spacer 70 from swinging around the swing center axis CT while being separated from the outer peripheral surface of the inner cylinder 60B. For this reason, when assembling and disassembling the crane 1 or transporting members including the rear jib backstop 60, the spacer 70 can be prevented from moving freely, and interference between the spacer 70 and peripheral members can be prevented. As a result, damage to the spacer 70 and peripheral members can be prevented. Therefore, the operator can perform the work of disassembling and transporting the crane 1 including the rear jib backstop 60 without paying attention to interference and damage of the spacer 70, so that the workability can be improved. On the other hand, when assembling the crane 1, by setting the locking mechanism 90 to the unlocked state, the spacer 70 can swing, and the length of the rear jib backstop 60 can be restricted by the spacer 70.

[0080] In particular, in the present embodiment, the spacer 70 is not in a complete cylindrical shape but has a semi-cylindrical (semi-tube) shape and can be fitted to the outer peripheral surface of the inner cylinder 60B along a direction orthogonal to the axial direction of the rear jib backstop 60. For this reason, it is not necessary to remove the rear jib backstop 60 from the strut 55 when attaching the spacer 70 as in the case of externally fitting another spacer having a complete cylindrical shape to the inner cylinder 60B along the axial direction, and the spacer 70 can be easily attached and detached.

[0081] Further, in the present embodiment, the spacer holder 80 supports the spacer 70 so as to be swingable about the swing center axis CT such that in the boom collapsed state, the spacer 70 assumes a hanging posture, and as the boom 16 stands up from the boom collapsed state with respect to the upper swing body 12, the spacer 70 approaches the outer peripheral surface of the inner cylinder 60B along the vertical plane passing through the center line of the rear jib backstop 60 from the hanging posture. The boom collapsed state is a state in which the boom 16 supports the strut 55 and lies down with respect to the upper swing body 12. Further, the hanging posture is a posture of the spacer 70 with respect to the outer cylinder 60A in which the spacer 70 intersects the vertical plane and hangs down from the swing center axis CT due to its own weight with respect to the outer cylinder 60A. Further, the lock mechanism 90 locks the spacer 70 by connecting the spacer 70 and the outer cylinder 60A that are in the opposed posture to each other. The opposed posture is a posture of the spacer 70 with respect to the outer cylinder 60A in which the spacer 70 swings away from the outer peripheral surface of the inner cylinder 60B more than in the hanging posture and the outer peripheral surface of the spacer 70 faces the outer cylinder 60A.

[0082] According to such a configuration, since the spacer 70 can be locked in a posture separated from the inner cylinder 60B, it is possible to prevent the spacer 70 from approaching the outer cylinder 60A and the inner cylinder 60B due to vibrations during transportation or the like. Further, compared with the case where the spacer 70 is locked in a posture extending in a direction substantially orthogonal to the center line of the rear jib backstop 60, the rear jib backstop 60 becomes more compact, and the space occupied by the rear jib backstop 60 during transportation can be reduced.

[0083] Furthermore, in the present embodiment, the spacer holder 80 is attached to the outer cylinder 60A so as to be relatively rotatable in the circumferential direction with respect to the outer cylinder 60A, and the lock mechanism 90 locks the spacer 70 by connecting the spacer 70 and the outer cylinder 60A to each other in a state where the spacer 70 is in the opposed posture and the spacer holder 80 rotates relatively in the circumferential direction with respect to the outer cylinder 60A and the spacer 70 is detached from the vertical plane.

[0084] According to such a configuration, since the spacer 70 is detached from the vertical plane passing through the rear jib backstop 60 in a state of being folded so as to face the outer cylinder 60A, it is possible to prevent the spacer 70 from interfering with other members located directly above or below the rear jib backstop 60 during transportation.

[0085] Further, in the present embodiment, the locking mechanism 90 includes a fixing pin P1 (locking pin) that connects the spacer supported portion 70B of the spacer 70 and the outer cylinder fixing portion 60H of the outer cylinder 60A to each other and locks the spacer 70 by inserting the spacer 70 into the first pin hole and the second pin hole in this order in a state where the spacer 70 is in the facing posture.

[0086] According to such a configuration, by inserting the fixing pin P1 into the pin holes formed in the spacer supported portion 70B and the outer cylinder fixing portion 60H respectively, the spacer 70 can be easily locked in the facing posture.

[0087] Further, in the present embodiment, in a state where the spacer 70 is in the hanging posture, the fixing pin P1 is inserted into the first pin hole 60HS and the third pin hole 82S respectively, and the position of the outer cylinder fixing portion 60H is set so that the fixing pin P1 restrains the spacer 70 in the circumferential direction of the outer cylinder 60A by connecting the holder fixing portion 82 of the spacer holder 80 and the outer cylinder fixing portion 60H of the outer cylinder 60A to each other.

[0088] According to such a configuration, by connecting the holder fixing portion 82 and the outer cylinder fixing portion 60H with the fixing pin P1, it is possible to easily prevent the spacer 70 from moving in the circumferential direction. Therefore, it is possible to suppress the spacer 70 from detaching from the vertical plane passing through the center line of the rear jib backstop 60 during the assembly work of the crane 1, and prevent the occurrence of a fitting failure of the spacer 70 with respect to the inner cylinder 60B.

[0089] In addition, in the present embodiment, in the spacer holder 80, since the holder fixing portion 82 and the holder support portion 83 are arranged at different positions in the circumferential direction, as the spacer holder 80 rotates relative to the outer cylinder 60A, the state in which the spacer supported portion 70B faces the outer cylinder fixing portion 60H and the state in which the holder fixing portion 82 faces the outer cylinder fixing portion 60H are switched. In other words, the state in which the fixing pin P1 can be inserted into the first pin hole 60HS and the second pin hole 70T and the state in which the fixing pin P1 can be inserted into the first pin hole 60HS and the third pin hole 82S are switched. More specifically, the hanging posture (fitting posture) of the spacer 70 in which the spacer 70 can be fitted into the inner cylinder 60B and the posture in which the spacer 70 retracts from the inner cylinder 60B and faces the outer cylinder 60A while detaching from the space between the strut 55 and the outer cylinder 60A (storage posture) can be switched.

[0090] And in the present embodiment, the rotational angle of the spacer holder 80 in the circumferential direction with respect to the outer cylinder 60A is set so that the spacer 70 can be detached from the space between the strut 55 and the rear jib backstop 60 and the outer cylinder 60A can be arranged to overlap the strut 55.

[0091] According to such a configuration, during the operation of the crane 1, the length of the rear jib backstop 60 can be restricted by the spacer 70 being positioned directly below the inner cylinder 60B of the rear jib backstop 60. On the other hand, by rotating the spacer holder 80 that supports the spacer 70, during disassembly and transportation, the rear jib backstop 60 can be loaded on the strut 55 and the two can be moved integrally. In particular, when the rear jib backstop 60 is folded with the fulcrum portion 60S as a fulcrum, the tip portion 60T of the rear jib backstop 60 can be attached to the backstop holding portion 55R of the strut 55 without the spacer 70 getting in the way. Therefore, it is possible to stably prevent the rear jib backstop 60 from falling off the strut 55 during transportation.

[0092] The crane 1 including the rear jib backstop 60 (backstop) according to an embodiment of the present invention has been described above. Note that the present invention is not limited to these forms. In the present invention, the following modified embodiments are possible.

[0093] (1) In the above embodiment, the rear jib backstop 60 that supports the strut 55 is used as the backstop to which the spacer 70 is attached. However, the present invention is also applicable to backstops provided on other struts. In this case, the strut 55 is not limited to the form of one strut, and the crane 1 may have two struts such as a front strut and a rear strut. Further, the strut 55 is not limited to being rotatably supported by the jib base end portion 18P of the jib 18. The strut 55 may be directly rotatably supported by the boom tip portion 16Q (boom head 16T) of the boom 16. In the above embodiment as well, the strut 55 is indirectly rotatably supported by the boom tip portion 16Q of the boom 16 via the jib base end portion 18P and the jib support portion 161.

[0094] (2) Further, in the above embodiment, the spacer holder 80 has been described in a manner that is relatively rotatable with respect to the outer cylinder 60A. However, the spacer holder 80 may be fixed to the outer cylinder 60A. In this case, the spacer holder 80 may be a part of the outer cylinder 60A.

[0095] (3) Further, in the above embodiment, the crane 1 shown in FIG. 1 has been used for the description. However, the present invention is not limited to this, and is also applicable to cranes having other structures. That is, the crane to which the present invention is applied may include a lattice mast, a box mast, or the like instead of the gantry 21.

Explanation of Reference Numerals

[0096] 1 Crane 100 Auxiliary Hoisting Device 12 Upper Swing Body 14 Lower Traveling Body 16 Boom 161 Jib support part 162 Backstop support part 16H Guy line connection part 16P Boom base end part 16Q Boom tip end part 16S Boom foot 16T Boom head 18 Jib 18A Lower jib 55 Strut 55Q Backstop connection part 55P Strut suspended part 55R Backstop holding part 55S Strut base end part 55T Strut tip end part 56 Rear side jib guy line 57 Front side jib guy line 60 Rear side jib backstop 60A Outer cylinder 60B Inner cylinder 60H Outer cylinder fixing part 60K Outer cylinder body 60S Fulcrum part 60T Tip end part 61 Front side jib backstop 70 Spacer 70A Spacer body 70B Spacer supported part 70S Spacer fulcrum part 70T Spacer hole part 80 Spacer holder 81 Holder cylindrical part 82 Holder fixing part 82S Hole part 83 Holder support part 90 Lock mechanism C1 First rotation center axis C2 Second rotation center axis CL Reference center axis CT Oscillation center axis G Ground H Support P1 Fixed pin P2 Spring pin

Claims

1. It has a body, a boom that is supported by the body so as to be able to undulate, and a strut. The boom includes a boom base end portion that is rotatably attached to the body, and a boom tip portion on the side opposite to the boom base end portion, the boom tip portion including a strut support portion and a backstop support portion disposed behind the strut support portion. The strut is attached to a crane including a strut base end portion supported by the strut support portion of the boom tip portion so as to be rotatable in the undulating direction around a horizontal reference rotation center axis, a strut tip portion disposed on the side opposite to the strut base end portion, and a backstop connection portion disposed between the strut base end portion and the strut tip portion. A backstop that is interposed between the boom and the strut and can support the strut, An outer cylinder including an outer cylinder base end portion connected to the backstop connection portion of the strut so as to be rotatable around a first rotation center axis parallel to the reference rotation center axis, and an outer cylinder tip portion disposed on the side opposite to the outer cylinder base end portion, An inner cylinder including an inner cylinder base end portion supported by the backstop support portion of the boom tip portion so as to be rotatable around a second rotation center axis parallel to the reference rotation center axis, and an inner cylinder tip portion disposed on the side opposite to the inner cylinder base end portion and inserted into the outer cylinder through the outer cylinder tip portion. The inner cylinder is axially relatively movable with respect to the outer cylinder so as to allow the distance between the backstop support portion and the backstop connection portion to change as the strut rotates around the reference rotation center axis with respect to the boom, A spacer having a semi-cylindrical inner peripheral surface that has a predetermined dimension in the axial direction and can be fitted to the outer peripheral surface of the inner cylinder along a direction orthogonal to the axial direction. Both ends of the spacer in the axial direction abut against the outer cylinder tip portion and the inner cylinder base end portion respectively, so that the backstop can be prevented from contracting so that the outer cylinder tip portion approaches the inner cylinder base end portion by a distance corresponding to the dimension, A spacer holder that is attached to the outer cylinder of the backstop and supports the spacer so as to be swingable about a swing center axis orthogonal to the axial direction, the spacer holder supporting the spacer such that as the boom stands up with respect to the aircraft while supporting the strut, the spacer swings about the swing center axis under its own weight and can be fitted into the inner cylinder. A lock mechanism that can be changed in state between a locked state and an unlocked state, the locked state being a state in which the spacer is locked so as to prevent the spacer from swinging about the swing center axis in a state where the spacer is separated from the outer peripheral surface of the inner cylinder, and the unlocked state being a state in which the spacer is allowed to swing about the swing center axis. A backstop comprising the above.

2. The outer cylinder and the inner cylinder each have a cylindrical shape having a center line extending along the axial direction. In a boom-down state where the boom supports the strut and lies down with respect to the aircraft, the spacer holder supports the spacer so as to be swingable about the swing center axis such that the spacer intersects a vertical plane passing through the center line and hangs down from the swing center axis by its own weight with respect to the outer cylinder, and as the boom stands up from the boom-down state with respect to the aircraft, the spacer approaches the outer peripheral surface of the inner cylinder along the vertical plane from the hanging-down posture. The backstop according to claim 1, wherein the lock mechanism locks the spacer by connecting the spacer, which is in an opposed posture in which the outer peripheral surface of the spacer faces the outer cylinder and the spacer swings so as to be separated from the outer peripheral surface of the inner cylinder more than in the hanging-down posture, to the outer cylinder.

3. The spacer holder is attached to the outer cylinder so as to be relatively rotatable in the circumferential direction with respect to the outer cylinder. The lock mechanism locks the spacer by connecting the spacer and the outer cylinder to each other in a state where the spacer holder rotates relative to the outer cylinder in the circumferential direction with the spacer in the opposed posture and the spacer has detached from the vertical plane. The backstop according to claim 2.

4. The outer cylinder includes a cylindrical outer cylinder body that includes the base end portion and the tip end portion of the outer cylinder, supports the spacer holder, and can receive the inner cylinder therein, and an outer cylinder fixing portion disposed on the outer peripheral surface of the outer cylinder body at a position farther from the spacer holder than the spacer in the hanging posture, the outer cylinder fixing portion having a first pin hole formed along a direction orthogonal to the axial direction. has The spacer includes a semi-cylindrical spacer body having an inner peripheral surface that can be fitted to the outer peripheral surface of the inner cylinder, and a spacer supported portion that extends along the axial direction from the spacer body and is swingably connected to the spacer holder about the swing center axis, and a second pin hole is formed along a direction orthogonal to the axial direction in a portion of the spacer supported portion closer to the spacer body than the swing center axis. has The lock mechanism includes a lock pin that locks the spacer by connecting the spacer supported portion of the spacer and the outer cylinder fixing portion of the outer cylinder to each other by being inserted into the first pin hole and the second pin hole in sequence with the spacer in the opposed posture. The backstop according to claim 3.

5. The spacer holder includes a holder cylindrical portion that is externally fitted to the outer peripheral surface of the outer cylinder so as to be rotatable relative to the outer cylinder in the circumferential direction, and a holder support portion that is disposed on the outer peripheral surface of the holder cylindrical portion and swingably supports the spacer supported portion of the spacer about the swing center axis. A holder fixing portion disposed so as to project from the holder cylindrical portion toward the base end portion of the outer cylinder at a position different from the holder support portion in the circumferential direction on the outer peripheral surface of the holder cylindrical portion, wherein a third pin hole is formed in the holder fixing portion along a direction orthogonal to the axial direction. having In a state where the spacer is in the hanging posture, the lock pin is inserted into the first pin hole and the third pin hole, respectively, and the lock pin connects the holder fixing portion of the spacer holder and the outer cylinder fixing portion of the outer cylinder to each other, so that the position of the outer cylinder fixing portion is set such that the lock pin restrains the spacer in the circumferential direction of the outer cylinder. The backstop according to claim 4.

6. The rotational angle of the spacer holder in the circumferential direction with respect to the outer cylinder is set so that the outer cylinder can be arranged to overlap the strut when the spacer is detached from the space between the strut and the backstop. The backstop according to any one of claims 3 to 5.

Images