JP7654986B2 - Backstop and crane equipped with same - Google Patents

Description

The present invention relates to a backstop and a crane equipped with the same.

Conventionally, cranes that include a crane body and a hoisting body such as a boom or mast are known. The hoisting body is supported by the crane body so that it can be raised or lowered around a horizontal central axis of rotation. In addition, such cranes are known that further include a pair of retractable backstops that are interposed between the hoisting body and the crane body to prevent the hoisting body from tipping backward. The base end of each backstop is supported by one of the structures of the hoisting body and the crane body, and the tip of each backstop extends toward the other structure of the hoisting body and the crane body. When the hoisting body is raised against the crane body in this state, the tip of each backstop eventually abuts against the backstop receiving portion provided on the other structure. As a result, the pair of backstops support the hoisting body, preventing further rotation of the hoisting body, i.e., preventing the hoisting body from tipping backward.

Patent Document 1 discloses a telescopic structure for a backstop that has the above-mentioned functions. The backstop has an outer cylinder supported by the crane body, a middle cylinder fitted into the outer cylinder via a first spring, and a support shaft fitted into the middle cylinder via a second spring. When the boom is raised, the tip of the support shaft abuts against a target on the boom side, compressing the first and second springs in turn, and the backstop supports the boom from the rear.

Japanese Patent Application Publication No. 9-86881

The technology described in Patent Document 1 has the problem that it is difficult to set the free length of the backstop without changing the compressed length of the backstop, and it is difficult for the backstop to simultaneously function to stably support the boom in the upright state and to assist the boom's collapse. Specifically, in the above backstop, the first spring is arranged to be expandable and contractable between the inner bottom of the outer cylinder and the tip surface of the middle cylinder, and the second spring is arranged to be expandable and contractable between a flange provided at the tip of the middle cylinder and a flange provided at the tip of the support shaft.

During normal crane operation, the boom is tilted backwards, extending diagonally backward from the crane body, and each backstop supports the boom from the rear with both the first and second springs in their most compressed state, i.e., at their full length. The overall length of the backstop in this state (compressed length of the backstop) is determined by the dimensions of each spring in its compressed state (full length).

On the other hand, when lowering a boom such as the one described above during disassembly of a crane, it is necessary to push the boom forward using the extension energy of each spring in the backstop until it reaches the collapse start angle, which is the angle at which the boom begins to collapse toward the ground under its own weight. For this reason, in order to reliably lower the boom, it is necessary to adjust the overall length of the backstop when each spring is at its free length (the free length of the backstop) and set the compression start angle, which is the angle at which each spring begins to compress when the boom is raised, to be equal to or less than the collapse start angle.

However, with the technology described in Patent Document 1, when attempting to appropriately set the free length of the backstop in accordance with the boom specifications, etc., the compressed length of the backstop also changes. For example, when attempting to set the free length of the backstop long in accordance with the boom collapse start angle, the compressed length of the backstop also becomes long, making it difficult to stably support the boom in an appropriate backward tilted position.

The present invention was made in consideration of the above problems, and aims to provide a backstop that allows the free length of the backstop to be set without changing the compressed length of the backstop, and a crane equipped with the same.

The backstop according to one embodiment of the present invention is a retractable backstop that is attached to a crane having a crane body and a hoisting body including a hoisting body base end supported on the crane body so as to be rotatable in the hoisting direction and a hoisting body tip end opposite the hoisting body base end, and supports the hoisting body standing upright against the crane body from behind. The backstop has a backstop base end, a backstop tip end, a cylindrical body, a movable part, a tip spring member, and a spring support part. The backstop base end is supported on one of the structures of the hoisting body and the crane body so as to be rotatable about a horizontal central axis of rotation. The backstop tip end is positioned on the opposite side to the backstop base end in the axial direction of the backstop, which is perpendicular to the central axis of rotation, and can abut against the other structure different from the one of the structures of the hoisting body and the crane body as the hoisting body stands upright against the crane body. The cylinder is a cylindrical member having a cylinder base end connected to the backstop base end and a cylinder tip end disposed on the opposite side of the cylinder base end in the axial direction, the cylinder having an internal space formed along the axial direction and a tip opening formed at the cylinder tip end that communicates with the internal space along the axial direction. The movable part is connected to the backstop tip end and is movable relative to the cylinder along the axial direction together with the backstop tip end, and has an abutment part that is disposed between the backstop tip end and the insertion part in the axial direction and is abuttable against the cylinder tip end along the axial direction. The spring support part is disposed in the internal space of the cylinder and is held by the cylinder so as to prevent movement of the spring support part in a base end direction, which is a direction from the backstop tip end to the backstop base end. The tip side spring member is disposed in the internal space so as to be interposed between the movable part and the spring support part in the axial direction, and is compressible and deformable between a free length and a tight length, the free length being the length of the tip side spring member when the elastic energy of the tip side spring member is released, and the tight length being the length of the tip side spring member when the tip side spring member is in the most contracted state. The abutment part abuts the tip of the cylindrical body so that the tip side spring member is compressed by the load received from the undulating body as the tip of the backstop abuts against the other structure, and the compression of the tip side spring member is restricted to a length between the free length and the tight length, while the distance in the axial direction from the tip opening to the spring support part is set so that the abutment part is separated from the tip of the cylindrical body by the restoring force of the tip side spring member as the tip of the backstop moves away from the other structure.

According to this configuration, the tip side spring member is accommodated in the portion of the internal space of the cylinder from the tip side opening to the spring support member (accommodation space), and the tip side spring member expands and contracts between the movable part and the spring support member. When the tip part of the backstop abuts against the other structure, the abutting part of the movable part abuts against the tip part of the cylinder before the tip side spring member is compressed to the tight length, so the compressed length of the backstop can be set according to the erection angle of the undulating body regardless of the tight length of the tip side spring member. On the other hand, when the tip part of the backstop moves away from the other structure, the restoring force of the tip side spring member causes the abutting part of the movable part to move away from the tip part of the cylinder, so the free length of the backstop can be set according to the angle at which the undulating body starts to collapse under its own weight, without changing the compressed length of the backstop.

In the above configuration, it is preferable that the cylinder body is an outer cylinder including the distal end of the cylinder body, in which the internal space is formed and a proximal end opening that communicates with the internal space along the axial direction is formed on the opposite side of the distal end of the cylinder body, an inner cylinder including the proximal end of the cylinder body, which is inserted into the internal space through the proximal end opening of the outer cylinder, and at least one proximal side spring member that is disposed between the outer cylinder and the inner cylinder and is expandable and contractible so that the inner cylinder moves relative to the outer cylinder along the axial direction.

With this configuration, the backstop can be expanded and contracted not only by the tip-end spring member but also by the base-end spring member of the cylinder, allowing the expansion and contraction stroke of the backstop to be set larger.

In the above configuration, the movable part further has an insertion part that is inserted into the internal space of the cylinder through the tip opening, and the insertion part has a long hole formed in it so as to extend along the axial direction, the insertion part has a first inner surface that defines the end of the long hole on the backstop base end side and a second inner surface that defines the end of the long hole on the backstop tip end side, the cylinder has a first pin that is inserted into the long hole in a direction perpendicular to the axial direction and is movable within the long hole along the axial direction, and the first pin abuts against the first inner surface after the abutment part moves away from the cylinder tip due to the restoring force of the tip side spring member as the backstop tip moves away from the other structure, thereby preventing the movable part from moving relative to the cylinder.

According to this configuration, when the tip-side spring member extends, the first pin abuts against the first inner surface, preventing the movable part from slipping out of the cylindrical body and preventing the movable part from rotating in the circumferential direction relative to the cylindrical body. In addition, because the long hole is formed on the insertion part side, the rigidity of the backstop when supporting the undulating body from behind can be increased compared to when the long hole is formed on the cylindrical body side.

In the above configuration, it is preferable that the cylinder further has a second pin that is inserted into the long hole along a direction perpendicular to the axial direction on the backstop tip side from the first pin and is movable within the long hole along the axial direction together with the first pin.

With this configuration, the second pin, together with the first pin, can guide the movement of the movable part and prevent the movable part from rotating relative to the cylindrical body in the circumferential direction.

In the above configuration, the cylinder is provided with a pair of pin holes that are spaced apart from each other in the axial direction and that pass through the cylinder so as to communicate between the outside of the cylinder and the internal space, and that can receive the first pin and the second pin, and it is desirable that the first pin and the second pin can be inserted into the long hole from the outside of the cylinder through the pair of pin holes.

With this configuration, the insertion part is inserted into the cylinder beforehand, and then the first and second pins are inserted into a pair of pin holes from the outside of the cylinder, respectively, so that the long holes and each pin can be engaged, allowing the movable part of the backstop to be easily assembled with the cylinder.

In the above configuration, the spring support portion has a dimension that allows it to be inserted into the internal space from the tip opening, and it is desirable to further include a fixing member that is fixed to the cylindrical body so as to be positioned in the internal space on the opposite side of the tip opening as viewed from the spring support portion, and that abuts against the spring support portion to prevent the spring support portion from moving in the base end direction.

With this configuration, the fixing member restrains the spring support part on the base end side of the backstop, so that the spring support part can be stably held within the internal space by the biasing force of the tip side spring member and the fixing member.

In the above configuration, it is preferable that the fixing member is a fixing pin having an outer peripheral surface capable of abutting against the spring support portion, the cylinder is provided with a fixing pin hole that penetrates the cylinder so as to connect the outside of the cylinder to the internal space, the fixing pin hole being capable of receiving the fixing pin, and the fixing pin can be attached to the cylinder so as to enter the internal space from the outside of the cylinder through the fixing pin hole.

With this configuration, the fixing pin is inserted into the fixing pin hole from the outside of the cylinder in advance, and the spring support part is inserted into the internal space of the cylinder from the tip opening, making it easy to hold the spring support part in the internal space.

A crane according to another aspect of the present invention comprises a crane body, a hoisting body including a base end of the hoisting body supported on the crane body so as to be rotatable in a hoisting direction and a tip end of the hoisting body opposite the base end of the hoisting body, and a backstop as described above that is capable of supporting the hoisting body erected against the crane body from behind and pushing the erected hoisting body forward until it reaches a position where it can be lowered under its own weight.

This configuration makes it possible to set the free length of the backstop without changing the compressed length of the backstop. Therefore, by setting the free length of the backstop according to the boom specifications, the backstop can simultaneously provide stable support for the boom in the upright position and assist in the collapse of the boom.

The present invention provides a backstop that allows the free length of the backstop to be set without changing the compressed length of the backstop, and a crane equipped with the backstop.

FIG. 1 is a side view of a crane with a backstop according to an embodiment of the present invention. FIG. 2 is a side view of a lower boom of a crane with a backstop according to one embodiment of the present invention and the backstop in a stowed position. FIG. 2 is a plan view of a lower boom of a crane with a backstop according to one embodiment of the present invention and the backstop in a stowed position. FIG. 2 is a side view of the lower boom of a crane with a backstop according to one embodiment of the present invention and the backstop in a supporting position. FIG. 1 is a side view of a crane equipped with a backstop according to one embodiment of the present invention, in which the backstop is in a supporting position and the boom is raised. FIG. 2 is a side view of a movable portion of the backstop according to one embodiment of the present invention. FIG. 2 is a side view of a backstop barrel according to one embodiment of the present invention. FIG. 2 is a side view for explaining the extension length of the backstop according to one embodiment of the present invention. FIG. 2 is a plan view of a backstop according to one embodiment of the present invention. FIG. 2 is a horizontal cross-sectional view of a backstop according to one embodiment of the present invention. FIG. 2 is a side cross-sectional view of a backstop according to one embodiment of the present invention.

Embodiments of the present invention will be described below with reference to the drawings. Figure 1 is a side view of a crane 10 (work machine) equipped with a backstop 45 according to one embodiment of the present invention. Note that although the directions of "up," "down," "front," and "rear" are shown in each figure hereafter, these directions are shown for the sake of convenience in explaining the structure and assembly method of the crane 10 according to this embodiment, and do not limit the direction of movement or the manner of use of a crane equipped with a backstop according to the present invention.

The crane 10 comprises an upper rotating body 12, which corresponds to the crane body, a lower running body 14 that rotatably supports the upper rotating body 12 and can run on the ground G, a boom 16 that functions as a raising and lowering body, a pair of left and right backstops 45, a lattice mast 17 that is a member for raising and lowering the boom, and a box mast 21.

The boom 16 has a boom base end 16P (base end of the boom) supported on the upper rotating body 12 so as to be rotatable in the hoisting direction, and a boom tip end 16Q (tip end of the boom) arranged on the opposite side of the boom base end 16P in the longitudinal direction. In this embodiment, a boom foot 16S provided on the boom base end 16P is rotatably supported on a shaft support (not shown) of the upper rotating body 12. The boom 16 shown in FIG. 1 is a so-called lattice type, and is composed of a lower boom 16A including a boom foot 16S, one or more (three in the illustrated example) intermediate booms 16B, 16C, 16D, and an upper boom 16E. A pair of left and right backstops 45 that can be extended and retracted are provided on the lower boom 16A. These backstops 45 each come into contact with the upper rotating body 12 when the boom 16 reaches the upright posture (working posture) shown in FIG. 1 relative to the upper rotating body 12. This contact allows the backstop 45 to support the boom 16 from the rear, preventing the boom 16 from being blown backward by strong winds, etc. The structure of the backstop 45 will be described in detail later.

The lattice mast 17 includes a mast base end 17P and a mast tip end 17Q. The mast base end 17P is attached to the upper rotating body 12 so that it can be raised and lowered around a rotation axis parallel to the rotation axis of the boom 16 at a position on the rear side of the boom 16. In other words, the lattice mast 17 can also rotate in the same direction as the raising and lowering direction of the boom 16. The mast tip end 17Q is the tip of the lattice mast 17 located on the opposite side of the mast base end 17P in the longitudinal direction. As shown in FIG. 1, a first mast sheave 171 and a second mast sheave 172 are located at the mast tip end 17Q of the lattice mast 17. A boom raising and lowering rope 22, which will be described later, is hung on the first mast sheave 171 and the second mast sheave 172. The lattice mast 17 serves as a support for the rotation of the boom 16. The lattice mast 17 is also made up of multiple mast members 17A, 17B, and 17C.

A pair of left and right backstops 46 are provided on the mast base end 17P side of the lattice mast 17. These backstops 46 each come into contact with the upper rotating body 12 when the lattice mast 17 reaches the upright position shown in FIG. 1. This contact prevents the lattice mast 17 from being blown backward by strong winds, etc.

The crane 10 further includes a lower spreader 18, an upper spreader 19, guy lines 20, a boom raising and lowering rope 22, and a boom raising and lowering winch 38.

The lower spreader 18 has a lower sheave block 181. The lower sheave block 181 has multiple sheaves arranged in the width direction (left-right direction).

The upper spreader 19 is disposed at a predetermined distance in front of the lower spreader 18. The upper spreader 19 is connected to the boom tip 16Q via guy lines 20. The upper spreader 19 has an upper sheave block 191. The upper sheave block 191 has multiple sheaves arranged in the width direction (left-right direction). A pair of guy lines 20 are disposed in the left-right direction perpendicular to the plane of the paper in FIG. 1. The rear end of the guy line 20 is connected to the upper spreader 19, and the front end of the guy line 20 is detachably connected to the boom tip 16Q. The guy lines 20 include guy links (metal plate material), guy ropes, guy wires (metal wire material), etc.

The boom hoisting rope 22 is pulled out from the boom hoisting winch 38 and hung around the first mast sheave 171 and the second mast sheave 172 of the mast tip 17Q, and then wound around the lower sheave block 181 and the upper sheave block 191 multiple times. After being hung around the lower sheave block 181 and the upper sheave block 191, the tip of the boom hoisting rope 22 is fixed to the mast tip 17Q of the lattice mast 17.

The boom hoist winch 38 is disposed on the mast base end 17P side of the lattice mast 17. The boom hoist winch 38 changes the distance between the lower sheave block 181 of the lower spreader 18 and the upper sheave block 191 of the upper spreader 19 by winding and unwinding the boom hoist rope 22, thereby raising and lowering the boom 16 while rotating the boom 16 relative to the lattice mast 17.

The box mast 21 has a base end and a rotating end (tip), and is rotatably connected to the upper rotating body 12 behind the lattice mast 17. The box mast 21 has a rectangular shape in cross section. The rotation axis of the box mast 21 is parallel to the rotation axis of the boom 16 and is located at approximately the same position as the rotation axis of the lattice mast 17. In other words, the box mast 21 can also rotate in the same direction as the raising and lowering direction of the boom 16.

The crane 10 further comprises guy lines 23, a mast hoisting rope 26, and a mast hoisting winch 30. A pair of guy lines 23 are arranged in the left-right direction perpendicular to the plane of the paper in FIG. 1. The guy lines 23 connect the mast tip 17Q of the lattice mast 17 to the rotating end of the box mast 21. This connection coordinates the rotation of the lattice mast 17 with the rotation of the box mast 21. The mast hoisting rope 26 is wound multiple times between a sheave block 24 arranged on the upper rotating body 12 and having multiple sheaves arranged in the width direction, and a sheave block 25 arranged on the rotating end of the box mast 21 and having multiple sheaves arranged in the width direction.

The mast hoisting winch 30 is positioned at the base end of the box mast 21. The mast hoisting winch 30 winds and pays out the mast hoisting rope 26. The winding and paying out operation of the mast hoisting winch 30 changes the distance between the sheave block 25 at the tip of the box mast 21 and the sheave block 24 at the rear end of the upper rotating body 12, and the box mast 21 and the lattice mast 17 rotate together relative to the upper rotating body 12, causing the lattice mast 17 to rise and fall.

In addition to the mast hoisting winch 30 and boom hoisting winch 38 mentioned above, the crane 10 is equipped with a main hoisting winch 34 and an auxiliary hoisting winch 36 for hoisting and lowering a load. In the crane 10 according to this embodiment, the main hoisting winch 34 and the auxiliary hoisting winch 36 are both installed on the lower boom 16A of the boom 16. The winches 34 and 36 of the crane 10 may be mounted on the upper rotating body 12.

The main winch 34 hoists and lowers the load using the main hoist rope 51 (Fig. 1). For 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 is provided adjacent to the main hoist guide sheave, with multiple main hoist point sheaves arranged in the width direction. A main hook 53 for the load is connected to the main hoist rope 51 suspended from the main hoist sheave block. The main hoist rope 51 drawn out from the main hoist winch 34 is hung in order on the main hoist guide sheaves, and is hung between the sheave of the main hoist sheave block and the sheave of the sheave block provided on the main hook 53. Therefore, when the main hoist winch 34 winds and unwinds the main hoist rope 51, the main hook 53 is hoisted and lowered.

Similarly, the auxiliary winch 36 hoists and lowers the load using the auxiliary hoist rope 52. This auxiliary hoisting has a structure (not shown) similar to that of the main hoist described above. When the auxiliary hoist winch 36 winds or unwinds the auxiliary hoist rope 52, the auxiliary hook for the load (not shown) connected to the end of the auxiliary hoist rope 52 is hoisted or lowered.

A counterweight 40 for adjusting the balance of the crane 10 is loaded on the rear of the upper rotating body 12, and a pallet weight 41 is also arranged behind the upper rotating body 12. The pallet weight 41 serves as a SHL (Super Heavy Lifting) weight provided for the crane 10 to lift heavy loads, and has the function of maintaining the balance of the crane 10. The pallet weight 41 is connected to the mast tip 17Q of the lattice mast 17 by a weight line 42.

Figures 2 and 3 are a side view and a plan view of the lower boom 16A and the backstop 45 when the boom 16 of the crane 10 according to this embodiment is in a lowered position. Figure 4 is a side view of the crane 10 according to this embodiment with the backstop 45 in a supporting position by the backstop lifting device 60 (backstop position changing device). Figure 5 is a side view of the crane 10 according to this embodiment with the backstop 45 in a supporting position by the backstop lifting device 60 and the boom 16 in an upright position.

Referring to Figures 2 to 5, when the boom 16 (lower boom 16A) is viewed in a state in which it is lowered relative to the upper rotating body 12, the lower boom 16A has a pair of left and right lower frames 160, a pair of left and right first main pipes 161, a pair of left and right second main pipes 162, a pair of left and right first connecting pipes 163, a pair of upper and lower second connecting pipes 164 (Figure 3), and a plurality of lattice pipes 165.

The pair of left and right first main pipes 161 and the pair of left and right second main pipes 162 are pipes that define the outer shape of the lower boom 16A, and extend from the vicinity of the boom foot 16S toward the tip side of the lower boom 16A so that the distance between them increases, as shown in FIG. 2 and other figures. The lower frame 160 is a plate-like member that connects the base ends of the first main pipes 161 and the second main pipes 162 to each other on both the left and right sides of the lower boom 16A. The pair of left and right first connecting pipes 163 connect the tips of the first main pipes 161 and the second main pipes 162 to each other. In addition, the pair of upper and lower second connecting pipes 164 connect the tips of the pair of left and right first main pipes 161 to each other and the tips of the pair of left and right second main pipes 162 to each other. The multiple lattice pipes 165 connect the first main pipe 161 and the second main pipe 162, the left and right pair of first main pipes 161, and the left and right pair of second main pipes 162 to each other at multiple locations.

The lower boom 16A further has a pair of left and right brackets 161S. The pair of left and right brackets 161S are disposed on the first main pipe 161 between the boom foot 16S and the tip of the first main pipe 161, more specifically, at a position close to the tip of the first main pipe 161. The brackets 161S rotatably support the backstop fulcrum portion 45S of the backstop 45 described below.

As described above, the crane 10 is equipped with a pair of left and right backstops 45. The crane 10 further includes a pair of left and right backstop lifting devices 60 that can be mounted between the backstops 45 and the boom 16 of the crane 10. Each backstop 45 is disposed on a pair of left and right first main pipes 161. The pair of left and right backstops 45 and the pair of left and right backstop lifting devices 60 have the same structure and function, so hereafter, only the backstop 45 and backstop lifting device 60 on the right side (the front side of the paper in FIG. 2) will be described.

Referring to FIG. 5, the upper rotating body 12 includes a rotating frame 120, which has a support portion 12S that rotatably supports the boom foot 16S, and a pair of left and right backstop receiving portions 121. Note that in FIG. 5, only the support portion 12S and backstop receiving portion 121 on the right side (the front side of the page) are visible.

The backstop lifting device 60 can change the position of the backstop 45 between the support position (FIG. 4) and the storage position (FIG. 2) by rotating the backstop 45 about the backstop fulcrum 45S as a fulcrum when the boom 16 is in a collapsed state relative to the upper rotating body 12. In the support position, the backstop 45 extends obliquely upward from the collapsed boom 16 (lower boom 16A) so that the backstop 45 can restrict the boom 16 from collapsing backward as the boom 16 rises from the collapsed state and the backstop abutment portion 45T described later of the backstop 45 abuts against the backstop receiving portion 121 of the upper rotating body 12 (see FIG. 4). On the other hand, in the storage position, the backstop abutment portion 45T of the backstop 45 is located closer to the lower boom 16A (boom 16) than in the support position. For this reason, as shown in Figures 2 and 4, the backstop lifting device 60 is placed in the space between the backstop 45 and the first main pipe 161 of the lower boom 16A.

Referring to FIG. 4, the backstop lifting device 60 has a first arm 61, a second arm 62, a pair of left and right stoppers 63, and a lifting cylinder 66.

The first arm 61 and the second arm 62 are connected so as to be able to bend and extend, and one end of the first arm 61 is rotatably connected to the backstop connection portion 451T of the backstop 45. Meanwhile, the other end of the first arm 61 and one end of the second arm 62 are rotatably connected to each other. The other end of the second arm 62 is rotatably connected to the first main pipe 161 of the lower boom 16A.

The lift cylinder 66 is disposed on the top of the second arm 62, as shown in FIG. 4. The lift cylinder 66 is composed of an extendable hydraulic cylinder. When the lift cylinder 66 extends, the tip of the lift cylinder 66 pushes up the first arm 61, causing it to stand up against the second arm 62. As a result, as shown in FIG. 4, the backstop 45 is changed to the support position. On the other hand, when the lift cylinder 66 contracts, the first arm 61 and the second arm 62 are bent under the weight of the backstop 45, and the backstop 45 is changed to the storage position as shown in FIG. 2.

The pair of left and right stoppers 63 connect the first arm 61 and the second arm 62 to each other when the backstop 45 is in the supporting position, and hold the backstop 45 in the supporting position. The pair of left and right stoppers 63 are detachable from the first arm 61 and the second arm 62.

<About the structure of the backstop>
Fig. 6 is a side view of the tip tube 456 of the backstop 45 according to this embodiment. Fig. 7 is a side view of the outer tube 451 of the backstop 45. Fig. 8 is a side view for explaining the extension length of the backstop 45. The upper view of Fig. 8 corresponds to the free length of the backstop 45, and the lower view corresponds to the compressed length of the backstop 45. Figs. 9, 10, and 11 are a plan view, a horizontal cross-sectional view, and a side cross-sectional view of the backstop 45, all of which show the state immediately before the backstop 45 reaches its most compressed length (compressed length).

The backstop 45 has a backstop fulcrum portion 45S (backstop base end portion), a backstop abutment portion 45T (backstop tip portion), an outer tube 451 (Fig. 2), an inner tube 452 (Fig. 2), a first spring 453 (base end side spring member), a spacer 454, a second spring 455 (base end side spring member), a tip tube 456 (movable portion), a third spring 457 (tip side spring member), and a spring support member 458 (spring support portion). In the following description, unless otherwise specified, the tip side means a portion relatively closer to the backstop abutment portion 45T, and the base side means a portion relatively closer to the backstop fulcrum portion 45S. In addition, in this embodiment, the outer tube 451, the inner tube 452, the first spring 453, the spacer 454, the second spring 455, and the multiple pins described below constitute the cylinder body 450 according to the present invention.

The backstop fulcrum 45S (Figure 2) is supported to be rotatable around a horizontal rotation center axis on the lower boom 16A (one of the structures) of the boom 16. In this embodiment, as described above, the backstop fulcrum 45S is supported on the bracket 161S provided on the lower boom 16A.

The backstop abutment portion 45T is disposed on the opposite side of the backstop fulcrum portion 45S in the axial direction of the backstop 45, which is perpendicular to the central axis of rotation. The backstop abutment portion 45T is capable of abutting against the upper rotating body 12 (the other structure different from the one structure) as the boom 16 stands up relative to the upper rotating body 12. In this embodiment, as described above, the backstop abutment portion 45T abuts against the backstop receiving portion 121 (FIG. 5) provided on the upper rotating body 12.

The outer cylinder 451 is the longest member among the members that make up the backstop 45. As shown in FIG. 7, the outer cylinder 451 is a cylindrical member that extends along the axial direction of the backstop 45. The outer cylinder 451 has an outer cylinder main body 451A, an outer cylinder flange 451B, and a backstop connection portion 451T.

The outer cylinder body 451A is the main body of the outer cylinder 451, and a cylindrical internal space is formed inside. In addition, both ends of the cylindrical space are open. The outer cylinder body 451A has an outer cylinder tip portion 451A1 and an outer cylinder base end portion 451A2. The outer cylinder tip portion 451A1 is the tip portion of the outer cylinder 451, and the outer cylinder base end portion 451A2 is the base end portion of the outer cylinder 451, which is disposed on the opposite side of the outer cylinder tip portion 451A1. The outer cylinder tip portion 451A1 has a tip opening in this embodiment, which is connected to the above-mentioned internal space along the axial direction of the backstop 45. Similarly, the outer cylinder base end portion 451A2 has a base opening in this embodiment, which is connected to the above-mentioned internal space along the axial direction. The outer cylinder tip portion 451A1 constitutes the cylinder body tip portion of the present invention.

The backstop connection part 451T is a roughly triangular plate material that is located roughly in the center of the outer tube body 451A in the axial direction and is fixed to the outer peripheral surface of the outer tube body 451A. A pin hole is formed in the backstop connection part 451T, and the tip of the first arm 61 of the backstop lifting device 60 described above is rotatably connected to the backstop connection part 451T by a pin (not shown).

The outer tube flange 451B is a flange disposed on the outer circumferential surface of the outer tube body 451A between the backstop connection portion 451T and the outer tube base end portion 451A2. In other words, the outer diameter of the outer tube flange 451B is set to be larger than the outer diameter of the other portions of the outer tube body 451A. The outer tube flange 451B abuts against the tip portion of the first spring 453 (Figs. 9 and 10).

Furthermore, the outer tube 451 has a pair of first holes 451P (pin holes), a pair of second holes 451Q (pin holes), a pair of third holes 451R (fixing pin holes), and a pair of fourth holes 451S. The holes are arranged on opposite sides of the outer tube 451 in the circumferential direction. For this reason, only the holes on the front side of the paper are shown in each figure, but similar holes are also formed on the opposite side of the paper. These holes are opened to communicate the outside of the outer tube 451 with the internal space and penetrate the outer tube 451 (outer tube main body 451A). As shown in FIG. 7, the first hole 451P and the second hole 451Q are arranged at an interval in the axial direction on the tip side of the backstop 45, and the second hole 451Q is arranged on the tip side of the first hole 451P. The third hole 451R is located closer to the base end of the backstop 45 than the first hole 451P, and closer to the tip end than the backstop connection part 451T. The fourth hole 451S is located between the backstop connection part 451T and the outer tube flange 451B. Each of the above holes is capable of receiving a pin, which will be described later.

The inner tube 452 (FIG. 8) is a cylindrical (tubular) member having a length approximately half that of the outer tube 451 in the axial direction. The inner tube 452 has an inner tube main body 452A, an inner tube flange 452C, and an inner tube tip portion 452D. The inner tube main body 452A is inserted into the internal space of the outer tube 451 through the outer tube base end portion 451A2 (base end opening) of the outer tube 451. A pair of long holes 452B (long holes) extending along the axial direction are opened on the tip side of the inner tube 452. The long holes 452B are arranged on opposite sides to each other in the circumferential direction of the inner tube 452. For this reason, only the long hole 452B on the front side of the paper is shown in each figure, but a similar long hole 452B is also formed on the opposite side of the paper. The long hole 452B is disposed opposite the inner peripheral surface of the outer cylinder body 451A in a direction perpendicular to the axial direction of the backstop 45 (a direction perpendicular to the plane of the paper in FIG. 8).

The inner tube flange 452C is a flange disposed on the outer circumferential surface of the inner tube body 452A at the base end side of the inner tube 452. In other words, the outer diameter of the inner tube flange 452C is set to be larger than the outer diameter of the other parts of the inner tube body 452A. The inner tube flange 452C abuts against the base end of the second spring 455 (Figures 8 and 10).

The inner tube tip 452D (Figure 8) is the tip of the inner tube 452 (inner tube body 452A) and is disposed in the internal space of the outer tube 451.

As shown in FIG. 8, the backstop fulcrum 45S is connected to the base end side of the inner tube flange 452C of the inner tube 452. The backstop fulcrum 45S is configured by forming a pin hole in a plate-like member connected to the inner tube flange 452C. In this embodiment, the backstop fulcrum 45S is configured integrally with the inner tube 452.

The spacer 454 is a cylindrical member supported on the outer circumferential surface of the inner tube body 452A of the inner tube 452. The spacer 454 is fitted onto the inner tube body 452A so as to be movable in the axial direction relative to the inner tube body 452A. The spacer 454 has a spacer flange portion 454A and a spacer tube portion 454B. The spacer flange portion 454A constitutes the tip side portion of the spacer 454 and has an outer diameter larger than the outer diameter of the outer tube body 451A of the outer tube 451. The spacer tube portion 454B constitutes the base end portion of the spacer 454 and is connected to the spacer flange portion 454A in the axial direction. The spacer tube portion 454B also has an inner diameter larger than the outer diameter of the inner tube body 452A of the inner tube 452.

The first spring 453 is a coil-shaped spring member that is disposed between the outer tube 451 and the spacer 454. Specifically, the tip end of the first spring 453 abuts against the outer tube flange 451B as described above. In addition, the base end of the first spring 453 abuts against the spacer flange portion 454A. As a result, the first spring 453 expands and contracts between the outer tube flange 451B and the spacer 454.

The second spring 455 is a coil-shaped spring member arranged so as to be interposed between the inner tube 452 and the spacer 454. Specifically, the tip end of the second spring 455 passes between the spacer tube portion 454B and the inner tube main body 452A in the radial direction and abuts against a portion of the spacer flange portion 454A opposite to the portion abutting against the first spring 453. In addition, the base end of the second spring 455 abuts against the inner tube flange 452C. As a result, the second spring 455 expands and contracts between the spacer 454 and the inner tube flange 452C.

Referring to FIG. 6, the tip tube 456 is connected to the backstop abutment portion 45T described above, and is movable along the axial direction relative to the outer tube 451 together with the backstop abutment portion 45T. The tip tube 456 has a tip tube main body 456A (insertion portion) and a tip flange 456C (abutment portion). In this embodiment, the tip tube 456 and the backstop abutment portion 45T are integrally configured.

The backstop abutment portion 45T is connected to the tip of the tip tube 456. The backstop abutment portion 45T is a plate material that is substantially circular in side view, and a pair of guide portions 45T1 are fixed to both sides of the backstop abutment portion 45T. As shown in Figures 9 and 10, the pair of guide portions 45T1 are arranged so that the distance between them increases toward the tip side, and have the function of guiding the backstop abutment portion 45T to the backstop receiver portion 121 in the left-right direction when the backstop abutment portion 45T abuts against the backstop receiver portion 121 (Figure 5).

The tip tube body 456A is the main body of the tip tube 456 and has a cylindrical shape extending in the axial direction. The tip tube body 456A has an outer diameter slightly smaller than the inner diameter of the outer tube 451 so that it can be inserted into the internal space through the tip opening of the outer tube 451. A lid portion 456S (Figure 6) is fixed to the base end of the tip tube body 456A, sealing the cylindrical portion of the tip tube body 456A. The lid portion 456S abuts against the tip portion of the third spring 457 described below.

Furthermore, the tip tube body 456A is formed with a pair of elongated holes 456B extending along the axial direction. The pair of elongated holes 456B are arranged on opposite sides of each other in the circumferential direction of the tip tube body 456A. Each elongated hole 456B penetrates the tip tube body 456A in a direction perpendicular to the axial direction. The tip tube body 456A has a long hole base end 456B1 (first inner surface) and a long hole tip end 456B2 (second inner surface). The long hole base end 456B1 defines the end on the base end side of the long hole 456B, and the long hole tip end 456B2 defines the end on the tip end side of the long hole 456B.

The tip flange 456C is disposed circumferentially between the backstop abutment portion 45T and the tip tube body 456A in the axial direction, and has an outer diameter larger than the outer diameter of the tip tube body 456A. The tip flange 456C is capable of abutting against the outer tube tip portion 451A1 (tube body tip portion) along the axial direction, as described below.

The third spring 457 is a coil-shaped spring member. The third spring 457 is disposed in the internal space of the outer tube 451 so as to be interposed between the tip tube body 456A (lid portion 456S) and the spring support member 458 in the axial direction, and is capable of compressive deformation between the free length and the tight length. Specifically, the tip end of the third spring 457 abuts against the lid portion 456S, and the base end of the third spring 457 abuts against the spring support member 458. The free length of the third spring 457 is the axial length of the third spring 457 in a state in which the elastic energy of the third spring 457 is released. The tight length of the third spring 457 is the axial length of the third spring 457 in a state in which adjacent loops of the wire material constituting the third spring 457 are in tight contact with each other in the axial direction, and the third spring 457 is in a most contracted state.

The spring support member 458 is disposed in the internal space of the outer tube 451 on the backstop fulcrum 45S side of the tip tube body 456A of the tip tube 456. The spring support member 458 is a cylindrical member with an outer diameter slightly smaller than the inner diameter of the outer tube 451. Therefore, the spring support member 458 can be inserted into the internal space from the tip opening formed in the outer tube tip 451A1 of the outer tube 451. In addition, the spring support member 458 is held by the outer tube body 451A of the outer tube 451 so as to prevent movement in the base end direction, which is the direction from the backstop abutment portion 45T toward the backstop fulcrum 45S.

The backstop 45 will be described based on the cylindrical body 450 according to this embodiment. As described above, the cylindrical body 450 has an outer tube 451, an inner tube 452, a first spring 453, a spacer 454, a second spring 455, a first pin 459P, a second pin 459Q, a third pin 459R (fixing member, fixing pin), and a fourth pin 459S. The cylindrical body 450 has a cylindrical base end 450A (FIG. 8) connected to the backstop fulcrum portion 45S and a cylindrical tip end 450B arranged on the opposite side of the cylindrical base end 450A in the axial direction. The cylindrical body 450 has an internal space formed along the axial direction, and a tip opening communicating with the internal space along the axial direction is formed in the cylindrical tip end 450B (outer tube tip end 451A1).

The spring support member 458 is disposed in the internal space of the tube 450, and is held by the tube 450 so as to prevent movement at least in the base end direction. The third spring 457 is disposed in the internal space so as to be interposed between the tip tube body 456A (lid portion 456S) of the tip tube 456 and the spring support member 458 in the axial direction, and is compressible and deformable between the free length and the contact length.

<Assembly of the tip portion of the backstop 45>
As shown in Fig. 8, a procedure for attaching the tip tube 456, the third spring 457, and the spring support member 458 to the outer tube 451 will be described. The third pin 459R is inserted from the outside of the outer tube 451 toward the internal space through one of the pair of third holes 451R (Fig. 7) formed in the outer tube body 451A of the outer tube 451, and a non-removal member (not shown) is attached to the third pin 459R in a state in which the tip of the third pin 459R protrudes outside the outer tube 451 through the other third hole 451R. In this state, when the spring support member 458 is inserted from the outer tube tip portion 451A1 into the internal space of the outer tube 451, the spring support member 458 abuts against the third pin 459R arranged in the internal space, thereby preventing the spring support member 458 from moving toward the base end side of the third pin 459R.

As described above, after the spring support member 458 is inserted into the outer tube 451, the third spring 457 and the tip tube 456 are inserted into the internal space in sequence, thereby constraining the axial position of the spring support member 458.

6, 8, and 9, the third spring 457 is inserted into the internal space of the outer tube 451 through the tip opening of the outer tube tip portion 451A1, and then the tip tube body 456A of the tip tube 456 is inserted into the internal space. Then, the rotation angle of the tip tube 456 is adjusted so that the pair of first holes 451P and the pair of second holes 451Q are aligned radially with the pair of long holes 456B. Furthermore, the first pin 459P is inserted from the outside of the outer tube 451 toward the internal space through one of the pair of first holes 451P (FIG. 7) formed in the outer tube body 451A of the outer tube 451, and a non-removal member (not shown) is attached to the first pin 459P with the tip of the first pin 459P protruding outside the outer tube 451 through the other first hole portion 451P. Similarly, the second pin 459Q is inserted from the outside of the outer tube 451 toward the internal space through one of the pair of second holes 451Q (FIG. 7) described above, and a retaining member (not shown) is attached to the second pin 459Q with the tip of the second pin 459Q protruding outside the outer tube 451 through the other second hole 451Q. As a result, as shown in FIGS. 8 and 9, the first pin 459P and the second pin 459Q are movable within the long hole 456B, and the tip tube 456 is attached to the outer tube 451 so as to be movable relative to the outer tube 451.

<Assembly of the base end portion of the backstop 45>
8, a procedure for attaching the inner tube 452, the first spring 453, the spacer 454, and the second spring 455 to the outer tube 451 will be described. With the first spring 453 fitted onto the outer tube body 451A of the outer tube 451 and the spacer 454 and the second spring 455 fitted onto the inner tube body 452A of the inner tube 452, the inner tube body 452A is inserted into the internal space of the outer tube 451 through the base end opening of the outer tube base end 451A2. Then, with the pair of elongated holes 452B and the pair of fourth hole portions 451S (FIG. 7) aligned, the fourth pin 459S is inserted from the outside of the outer tube 451 toward the internal space through one of the pair of fourth hole portions 451S, and with the tip of the fourth pin 459S protruding outside the outer tube 451 through the other fourth hole portion 451S, a retaining member (not shown) is attached to the fourth pin 459S. As a result, as shown in FIGS. 8 and 9, the inner tube 452 is attached to the outer tube 451 so as to be movable relative to the outer tube 451.

The method of attaching the first pin 459P, the second pin 459Q, the third pin 459R and the fourth pin 459S is not limited to the above, and other attachment structures may be used.

<About the boom raising and lowering operation>
Next, a description will be given of the behavior of the backstop 45 during the hoisting operation of the boom 16. As shown in Figure 4, with the backstop 45 in a supporting position relative to the lower boom 16A, the other boom members (16B to 16E) are connected to the lower boom 16A, and the boom hoist winch 38 in Figure 1 winds up the boom hoist rope 22, thereby raising the boom 16 relative to the upper rotating body 12. When the backstop abutment portion 45T of the backstop 45 eventually abuts against the backstop receiving portion 121 of the upper rotating body 12, compression of the backstop 45 begins.

In this embodiment, the three springs contract in the order of the third spring 457, the second spring 455, and the first spring 453. When the third spring 457 is compressed as the boom 16 is raised, the tip flange 456C abuts against the outer tube tip 451A1 before the third spring 457 reaches its tight length (its most compressed length), and the contraction of the third spring 457 stops. Furthermore, when the boom 16 is raised, the second spring 455 and the first spring 453 contract. Then, when the boom 16 hoisting angle reaches the upper limit angle (for example, 80 degrees) of the preset working angle range, the boom hoisting winch 38 automatically stops winding up the boom hoisting rope 22. If the boom 16 attempts to rise beyond the above upper limit angle due to the influence of wind, etc., a limit switch (not shown) detects the raising of the boom 16 and reliably stops the raising and lowering of the boom 16. In this embodiment, in this workable state, the first spring 453 and the second spring 455 are not completely contracted, and are both set to have a margin before the contact length. Note that FIG. 8 illustrates the difference between the free length of the backstop 45 and the compressed length of the backstop 45, that is, the expansion stroke LC of the backstop 45. In this embodiment, the backstop 45 is rarely used in a state in which the first spring 453 and the second spring 455 are both completely contracted (contact length) as shown in the lower diagram of FIG. 8, but at the same time that both spring members reach the length at which they are completely contracted, the outer tube base end 451A2 of the outer tube 451 abuts against the spacer flange portion 454A, and the base end of the spacer tube portion 454B of the spacer 454 abuts against the inner tube flange 452C as shown in the lower diagram of FIG. For this reason, the contact length of the first spring 453 and the second spring 455 is also set so as not to directly contribute to the compressed length of the backstop 45. In addition, during normal operation of the crane 10, the first spring 453 and the second spring 455 have sufficient compression to stably support the boom 16 from unintentionally tipping backward.

On the other hand, when the boom 16 is to be lowered, the boom hoist winch 38 in FIG. 1 pays out the boom hoist rope 22, releasing the restraining force on the boom 16, and the boom 16 is pushed forward by the restoring force of the three springs of the backstop 45. In this embodiment, the first spring 453, the second spring 455, and the third spring 457 extend toward their free length in this order until the boom 16 reaches an angle (the collapse start angle) at which it can be collapsed forward by its own weight, pushing the boom 16 forward. In order to impart the elastic force of each spring to the boom 16 up to the collapse start angle, the free length of the backstop 45 is set so that the springs of the backstop 45 start contracting at the collapse start angle when the boom 16 is raised.

As described above, in this embodiment, when the boom 16 is raised, the third spring 457 is compressed by the load received from the boom 16 as the backstop abutment portion 45T abuts against the backstop receiving portion 121 of the upper rotating body 12, and before the third spring 457 is compressed to the tight length, in other words, the tip flange 456C abuts against the outer tube tip portion 451A1 to prevent further compression of the third spring 457 so that the compression of the third spring 457 is restricted to the length between the free length and the tight length. On the other hand, when the boom 16 is lowered, the axial distance from the outer tube tip portion 451A1 (tip opening) to the spring support member 458 is set so that the tip flange 456C moves away from the outer tube tip portion 451A1 due to the restoring force of the third spring 457 as the backstop abutment portion 45T moves away from the backstop receiving portion 121.

According to this configuration, the third spring 457 is accommodated in the portion (accommodation space) of the internal space of the cylinder 450 from the outer cylinder tip 451A1 (tip side opening) to the spring support member 458, and the third spring 457 expands and contracts between the tip cylinder 456 and the spring support member 458. When the backstop abutment portion 45T abuts against the backstop receiving portion 121 of the upper rotating body 12, the tip flange 456C of the tip cylinder 456 abuts against the outer cylinder tip 451A1 before the third spring 457 is compressed to the tight length. Therefore, the tight length of the third spring 457 does not contribute to the compressed length of the backstop 45 when the boom 16 is raised, and the compressed length of the backstop 45 can be set according to the raising angle of the boom 16 regardless of the tight length of the third spring 457. On the other hand, when the boom 16 is lowered relative to the upper rotating body 12, when the backstop abutment portion 45T separates from the backstop receiving portion 121, the restoring force of the third spring 457 allows the tip flange 456C of the tip tube 456 to separate from the outer tube tip portion 451A1, and the free length of the backstop 45 can be set according to the angle at which the boom 16 begins to collapse under its own weight. Therefore, the third spring 457 can be used to set the compressed length and free length of the backstop 45 independently of each other. In other words, it is possible to set the free length of the backstop 45 according to the specifications of the boom 16 without changing the compressed length of the backstop 45.

For example, if it is desired to set the collapse start angle of the boom 16 small without changing the angle of the boom 16 in the rearward tilt posture according to the specifications (center of gravity) of the boom 16, a third spring 457 with a longer free length can be accommodated in the portion (accommodation space) of the internal space of the cylinder 450 from the outer cylinder tip 451A1 (tip side opening) to the spring support member 458. In this case, the free length of the backstop 45 becomes longer, so that the collapse start angle of the boom 16 can be set small. On the other hand, the compression length of the backstop 45 is regulated by the abutment between the tip flange 456C and the outer cylinder tip 451A1 regardless of the free length of the third spring 457, so that the angle of the boom 16 in the rearward tilt posture does not change. It is also possible to adjust the axial position of the spring support member 458 in order to adjust the elastic energy of the third spring 457.

In this embodiment, the tube body 450 has an outer tube 451, an inner tube 452, and a base end side spring member (a first spring 453, a second spring 455). The first spring 453 and the second spring 455 are disposed between the outer tube 451 and the inner tube 452, and are capable of expanding and contracting so that the inner tube 452 moves relative to the outer tube 451 in the axial direction.

With this configuration, the backstop 45 can be further expanded and contracted by the first spring 453 and the second spring 455 of the cylinder 450 in addition to the third spring 457, so that the expansion and contraction stroke of the backstop 45 can be set to be larger. Note that the base-end side spring member interposed between the outer cylinder 451 and the inner cylinder 452 may be a single spring member.

In this embodiment, a long hole 456B is formed in the tip tube 456, and the tube body 450 has a first pin 459P. Then, as the backstop abutment portion 45T moves away from the backstop receiving portion 121, the restoring force of the third spring 457 causes the tip flange 456C to move away from the outer tube tip portion 451A1, and the first pin 459P then abuts against the long hole base end portion 456B1, thereby preventing the tip tube 456 from moving relative to the outer tube 451 (tubular body 450).

This configuration can prevent the tip tube 456 from slipping out of the cylinder body 450, and can prevent the tip tube 456 from rotating in the circumferential direction relative to the cylinder body 450 (rotation prevention). As a result, the relative positions of the pair of guide parts 45T1 and the backstop receiving part 121 can be easily adjusted. In addition, with this configuration, since the long hole 456B is formed in the tip tube 456, the rigidity of the backstop 45 when supporting the boom 16 from the rear can be increased compared to when the long hole 456B is formed in the outer tube 451. Note that when the backstop 45 supports the boom 16, the tip flange 456C abuts against the outer tube tip 451A1, so the long hole 456B of the tip tube 456 does not significantly affect the rigidity of the backstop 45.

Furthermore, in this embodiment, the cylindrical body 450 has a second pin 459Q in addition to the first pin 459P.

With this configuration, the second pin 459Q, together with the first pin 459P, can guide the movement of the tip tube 456 and prevent the tip tube 456 from rotating circumferentially relative to the outer tube 451. Also, compared to when the tube body 450 has only the first pin 459P, the tip tube 456 can be prevented from tilting obliquely (twisting) with the first pin 459P as a fulcrum.

In addition, in this embodiment, the tip tube body 456A is inserted into the outer tube 451 (tubular body 450) in advance, and then the first pin 459P and the second pin 459Q are inserted into a pair of pin holes from the outside of the outer tube 451, so that the long hole 456B can be engaged with each pin, allowing the tip tube 456 of the backstop 45 to be easily assembled with the tubular body 450.

Furthermore, in this embodiment, the third pin 459R (fixed pin) is fixed to the cylinder 450 (outer cylinder 451) so as to be positioned in the internal space on the opposite side of the tip opening as viewed from the spring support member 458. The third pin 459R restrains the spring support member 458 on the backstop fulcrum portion 45S side, so that the spring support member 458 can be stably held in the internal space by the biasing force of the third spring 457 and the third pin 459R.

In addition, the third pin 459R can be inserted into the third hole 451R from the outside of the outer tube 451 in advance, and the spring support member 458 can be inserted into the internal space of the outer tube 451, so that the spring support member 458 can be easily held. Note that the third pin 459R is not limited to being inserted into the outer tube 451 as described above. The third pin 459R may be welded to the inner surface of the outer tube 451 in advance in the internal space of the outer tube 451.

The structure of the backstop 45 according to this embodiment changes the structure of the hoisting body (position of the center of gravity), for example when a jib (not shown) is further connected to the boom 16. In this case, the free length of the third spring 457 of the backstop 45 can be changed to stably support the hoisting body after the change in the upright position and assist the hoisting body in its collapse.

In this case, too, the contact length of the third spring 457 does not contribute to the compressed length of the backstop 45, so it is possible to change the free length of the backstop 45 without changing the compressed length. In other words, even if it is necessary to make the collapse start angle smaller, it is possible to increase the free length of the backstop 45 without changing the compressed length of the backstop 45.

The above describes the backstop 45 according to one embodiment of the present invention and the crane 10 equipped with the same. With such a crane 10, the free length of the backstop 45 can be set without affecting the compressed length of the backstop 45 by setting the free length of the third spring 457 according to the specifications of the boom 16 (elevating body). This allows the backstop 45 to both stably support the boom 16 in the upright position (prevent it from tipping backward) and assist the boom 16 in tipping forward. Note that the present invention is not limited to these forms. The following modified embodiments are possible with the present invention.

(1) In the above embodiment, the backstop fulcrum 45S is rotatably supported on the lower boom 16A, and the backstop receiving portion 121 is disposed on the upper rotating body 12, but the present invention is not limited to this. The backstop fulcrum 45S may be rotatably supported on the upper rotating body 12 (one of the structures), and as the boom 16 rises, the backstop abutment portion 45T abuts against a backstop receiving portion (not shown) of the lower boom 16A (the other structure), so that the backstop 45 supports the boom 16 from behind.

(2) In the above embodiment, the backstop 45 placed on the boom 16 was described, but the backstop 46 in FIG. 1 may have a structure similar to that of the backstop 45. In addition, the backstop according to the present invention may be one that maintains the posture of a jib, strut (elevating body), etc. (not shown).

(3) In the above embodiment, the crane 10 shown in FIG. 1 is used for the description, but the present invention is not limited to this and can be applied to cranes with other structures. That is, the crane to which the present invention is applied may be a general-purpose crane equipped with a gantry instead of the lattice mast, and the hoisting winch may be placed on the upper frame (rear side) of the upper rotating body 12. In addition, as a large crane, instead of the SHL structure, a structure in which the boom is hoisted by hoisting a box mast may be used. In this case, the sheave block may not be provided, and the tip of the box mast and the tip of the boom may be directly connected by a guy link. In addition, both the general-purpose crane and the large crane may have a jib or strut attached to the tip of the boom. In the above embodiment, the backstop of the boom is used for the description, but the present invention is also applicable to backstops provided on the mast (lattice mast), struts (rear strut, front strut), and jib.

(4) In the above embodiment, the tip tube body 456A of the tip tube 456 is inserted into the internal space of the external tube 451, but the present invention is not limited to this. The tip tube body 456A of the tip tube 456 may be formed of a cap structure that receives the external tube tip 451A1 without being inserted into the internal space of the external tube 451. In this case, the distance from the external tube tip 451A1 (tip opening) to the spring support member 458 may be set so that the bottom of the tip tube 456 abuts against the external tube tip 451A1 before the third spring 457 reaches the tight length. In this case, it is possible to set the compression length of the backstop 45 regardless of the tight length of the third spring 457, and the free length of the backstop 45 can be set based on the free length of the third spring 457. In other words, the free length of the backstop 45 can be set according to the specifications of the boom without changing the compression length of the backstop 45.

(5) In the above embodiment, the crane 10 is described as being equipped with the backstop lifting device 60, but the present invention is not limited to this. The crane 10 may not have the backstop lifting device 60. In addition, the structure of the backstop lifting device 60 is not limited to a bending and extending structure including the first arm 61 and the second arm 62 as in the above embodiment, but may be a cylinder structure or a rod-shaped support member that supports the backstop 45 along a direction perpendicular to the longitudinal direction of the backstop 45.

(6) In the above embodiment, the cylindrical body 450 has the first pin 459P and the second pin 459Q, but the present invention is not limited to this. The cylindrical body 450 may have only the first pin 459P. Furthermore, each pin that moves along the long hole 452B is not limited to being cylindrical. Each pin may have other shapes, such as a rectangular parallelepiped or plate shape that extends along the longitudinal direction of the long hole 452B.

10 Crane 12 Upper rotating body (crane body)
120 Swivel frame 121 Backstop receiving part 16 Boom (elevating body)
160 Lower frame 16A Lower boom 16S Boom foot 45 Backstop 450 Cylinder body 450A Cylinder base end 450B Cylinder tip 451 Outer cylinder 451A Outer cylinder main body 451A1 Outer cylinder tip 451A2 Outer cylinder base end 451B Outer cylinder flange 451P First hole (pin hole)
451Q 2nd hole (pin hole)
451R Third hole (fixing pin hole)
451S Fourth hole portion 451T Backstop connection portion 452 Inner cylinder 452A Inner cylinder main body 452B Long hole 452C Inner cylinder flange 452D Inner cylinder tip portion 453 First spring (base end side spring member)
454 Spacer 454A Spacer flange portion 454B Spacer tube portion 455 Second spring (base end side spring member)
456 Tip tube (movable part)
456A Tip tube body (insertion part)
456B Long hole (long hole)
456B1 Long hole base end (first inner surface)
456B2 Long hole tip (second inner surface)
456C Tip flange (contact part)
457 Third spring (tip side spring member)
458 Spring support member (spring support part)
459P: First pin 459Q: Second pin 459R: Third pin (fixing member, fixing pin)
459S 4th pin 45S Backstop fulcrum part (backstop base end part)
45T Backstop abutment part (backstop tip)
45T1 Guide portion 60 Backstop lifting device 61 First arm 62 Second arm 63 Stopper 66 Lifting cylinder

Claims (7)

A backstop is attached to a crane having a crane body and a hoisting body including a base end of the hoisting body supported on the crane body so as to be rotatable in a hoisting direction and a tip end of the hoisting body opposite to the base end of the hoisting body, and supports the hoisting body from behind when the hoisting body is erected relative to the crane body.
A backstop base end portion is supported rotatably around a horizontal rotation center axis on one of the structures of the elevation body and the crane body;
A backstop tip portion is disposed on the opposite side of the backstop base end portion in an axial direction of the backstop that is perpendicular to the pivot axis, and the backstop tip portion is capable of contacting the other structure of the crane body and the one structure of the crane body as the crane body stands upright against the crane body;
a cylindrical body having a base end connected to the base end of the backstop and a tip end disposed on the opposite side of the base end in the axial direction, the body having an internal space formed along the axial direction, and a tip opening formed at the tip end of the body that communicates with the internal space along the axial direction;
A movable part that is connected to the backstop tip portion and is movable relative to the cylindrical body along the axial direction together with the backstop tip portion, the movable part having an abutment portion that can abut against the cylindrical body tip portion along the axial direction;
A spring support portion disposed in the internal space of the cylindrical body, the spring support portion being held by the cylindrical body so as to prevent the spring support portion from moving in a base end direction, which is a direction from the backstop tip portion to the backstop base end portion;
a tip-side spring member that is disposed in the internal space so as to be interposed between the movable portion and the spring support portion in the axial direction, the tip-side spring member being compressively deformable between a free length and a tight length, the free length being the length of the tip-side spring member in a state in which elastic energy of the tip-side spring member is released, and the tight length being the length of the tip-side spring member in a state in which the tip-side spring member is most contracted;
having
the abutment portion abuts against the tip of the tubular body such that the tip side spring member is compressed by the load received from the undulating body as the tip of the backstop abuts against the other structure, and the compression of the tip side spring member is restricted by a length between the free length and the tight length, while the distance in the axial direction from the tip opening to the spring support portion is set such that the abutment portion moves away from the tip of the tubular body due to the restoring force of the tip side spring member as the tip of the backstop moves away from the other structure ,
The cylindrical body is
an outer cylinder including the cylindrical body distal end portion, the inner space being formed in the outer cylinder, and a base end opening communicating with the inner space along the axial direction being formed on a side of the outer cylinder opposite to the cylindrical body distal end;
an inner tube including a cylindrical body base end portion, the inner tube being inserted into the internal space through the base end opening of the outer tube;
At least one base end side spring member is disposed between the outer tube and the inner tube, and is expandable and contractible so that the inner tube moves relative to the outer tube along the axial direction;
A backstop. The movable portion further includes an insertion portion that is inserted into the internal space of the cylindrical body through the tip opening,
The insertion portion has a slot formed therein so as to extend along the axial direction, and the insertion portion has a first inner surface that defines an end portion of the slot on the base end side of the backstop and a second inner surface that defines an end portion of the slot on the tip end side of the backstop,
the cylindrical body has a first pin that is inserted into the long hole along a direction perpendicular to the axial direction and is movable within the long hole along the axial direction;
2. The backstop as described in claim 1, wherein the first pin prevents relative movement of the movable part with respect to the cylindrical body by abutting against the first inner surface after the abutment portion moves away from the cylindrical body tip due to the restoring force of the tip side spring member as the backstop tip moves away from the other structure. A backstop is attached to a crane having a crane body and a hoisting body including a base end of the hoisting body supported on the crane body so as to be rotatable in a hoisting direction and a tip end of the hoisting body opposite to the base end of the hoisting body, and supports the hoisting body from behind when the hoisting body is erected relative to the crane body.
A backstop base end portion is supported rotatably around a horizontal rotation center axis on one of the structures of the elevation body and the crane body;
A backstop tip portion is disposed on the opposite side of the backstop base end portion in an axial direction of the backstop that is perpendicular to the pivot axis, and the backstop tip portion is capable of contacting the other structure of the crane body and the one structure of the crane body as the crane body stands upright against the crane body;
a cylindrical body having a base end connected to the base end of the backstop and a tip end disposed on the opposite side of the base end in the axial direction, the body having an internal space formed along the axial direction, and a tip opening formed at the tip end of the body that communicates with the internal space along the axial direction;
A movable part that is connected to the backstop tip portion and is movable relative to the cylindrical body along the axial direction together with the backstop tip portion, the movable part having an abutment portion that can abut against the cylindrical body tip portion along the axial direction;
A spring support portion disposed in the internal space of the cylindrical body, the spring support portion being held by the cylindrical body so as to prevent the spring support portion from moving in a base end direction, which is a direction from the backstop tip portion to the backstop base end portion;
a tip-side spring member that is disposed in the internal space so as to be interposed between the movable portion and the spring support portion in the axial direction, the tip-side spring member being compressively deformable between a free length and a tight length, the free length being the length of the tip-side spring member in a state in which elastic energy of the tip-side spring member is released, and the tight length being the length of the tip-side spring member in a state in which the tip-side spring member is most contracted;
having
the abutment portion abuts against the tip of the tubular body such that the tip side spring member is compressed by the load received from the undulating body as the tip of the backstop abuts against the other structure, and the compression of the tip side spring member is restricted by a length between the free length and the tight length, while the distance in the axial direction from the tip opening to the spring support portion is set such that the abutment portion moves away from the tip of the tubular body due to the restoring force of the tip side spring member as the tip of the backstop moves away from the other structure,
The movable portion further includes an insertion portion that is inserted into the internal space of the cylindrical body through the tip opening,
The insertion portion has a slot formed therein so as to extend along the axial direction, and the insertion portion has a first inner surface that defines an end portion of the slot on the base end side of the backstop and a second inner surface that defines an end portion of the slot on the tip end side of the backstop,
the cylindrical body has a first pin that is inserted into the long hole along a direction perpendicular to the axial direction and is movable within the long hole along the axial direction;
The first pin prevents the movable part from moving relative to the cylindrical body by abutting against the first inner surface after the abutment part moves away from the cylindrical body tip due to a restoring force of the tip side spring member as the backstop tip moves away from the other structure,
The cylindrical body further has a second pin which is inserted into the long hole along a direction perpendicular to the axial direction on the backstop tip side further than the first pin and which is movable within the long hole along the axial direction together with the first pin. a pair of pin holes are formed in the cylindrical body, the pair of pin holes being spaced apart from each other in the axial direction and penetrating the cylindrical body so as to communicate between an outside of the cylindrical body and the internal space, the pair of pin holes being capable of receiving the first pin and the second pin,
The backstop according to claim 3 , wherein the first pin and the second pin can be inserted into the elongated hole from the outside of the cylindrical body through the pair of pin holes. A backstop is attached to a crane having a crane body and a hoisting body including a base end of the hoisting body supported on the crane body so as to be rotatable in a hoisting direction and a tip end of the hoisting body opposite to the base end of the hoisting body, and supports the hoisting body from behind when the hoisting body is erected relative to the crane body.
A backstop base end portion is supported rotatably around a horizontal rotation center axis on one of the structures of the elevation body and the crane body;
A backstop tip portion is disposed on the opposite side of the backstop base end portion in an axial direction of the backstop that is perpendicular to the pivot axis, and the backstop tip portion is capable of contacting the other structure of the crane body and the one structure of the crane body as the crane body stands upright against the crane body;
a cylindrical body having a base end connected to the base end of the backstop and a tip end disposed on the opposite side of the base end in the axial direction, the body having an internal space formed along the axial direction, and a tip opening formed at the tip end of the body that communicates with the internal space along the axial direction;
A movable part that is connected to the backstop tip portion and is movable relative to the cylindrical body along the axial direction together with the backstop tip portion, the movable part having an abutment portion that can abut against the cylindrical body tip portion along the axial direction;
A spring support portion disposed in the internal space of the cylindrical body, the spring support portion being held by the cylindrical body so as to prevent the spring support portion from moving in a base end direction, which is a direction from the backstop tip portion to the backstop base end portion;
a tip-side spring member that is disposed in the internal space so as to be interposed between the movable portion and the spring support portion in the axial direction, the tip-side spring member being compressively deformable between a free length and a tight length, the free length being the length of the tip-side spring member in a state in which elastic energy of the tip-side spring member is released, and the tight length being the length of the tip-side spring member in a state in which the tip-side spring member is most contracted;
having
the abutment portion abuts against the tip of the tubular body such that the tip side spring member is compressed by the load received from the undulating body as the tip of the backstop abuts against the other structure, and the compression of the tip side spring member is restricted by a length between the free length and the tight length, while the distance in the axial direction from the tip opening to the spring support portion is set such that the abutment portion moves away from the tip of the tubular body due to the restoring force of the tip side spring member as the tip of the backstop moves away from the other structure,
The spring support portion has a dimension that allows it to be inserted into the internal space from the tip opening,
A backstop further comprising a fixing member fixed to the cylindrical body so as to be positioned in the internal space on the opposite side of the spring support portion from the tip opening, the fixing member abutting against the spring support portion to prevent movement of the spring support portion in the base end direction. The fixing member is a fixing pin having an outer circumferential surface capable of contacting the spring support portion,
a fixing pin hole penetrating the cylindrical body so as to communicate an outside of the cylindrical body with the internal space, the fixing pin hole being capable of receiving the fixing pin;
The backstop of claim 5 , wherein the fixing pin can be attached to the barrel so as to enter the interior space from the outside of the barrel through the fixing pin hole. The crane body,
A hoisting body including a base end portion of the hoisting body supported on the crane body so as to be rotatable in a hoisting direction and a tip end portion of the hoisting body opposite to the base end portion of the hoisting body;
A backstop according to any one of claims 1 to 6, capable of supporting the hoisting body erected relative to the crane body from the rear and pushing the erected hoisting body forward until the hoisting body can be lowered by its own weight;
A crane equipped with