A jib attachment/detachment mechanism to mount a jib on a boom head includes a guide mechanism including a guide roller and a guide support configured to guide engaging portions of a jib support to positions of engagement with shaft pins of a boom head when the jib support is pulled up with a wire by using a winch and to prevent change of a state of the wire pulled up by the winch when the jib support is rotated around the shaft pins by contracting a cylinder.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from Japanese Patent Application No. 2013-117247 filed on Jun. 3, 2013, the disclosure of which is herein incorporated by reference.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a jib attachment/detachment mechanism for detachably attaching a jib on a tip portion of a boom.

Description of the Related Art

Conventionally, an attachment/detachment mechanism for detachably mounting a jib support provided to a rear portion of a jib main body on a boom head provided to a tip of a boom has been known (see Japanese Patent Application Publication No. 2000-153992).

In such an attachment/detachment mechanism, a cylinder for attachment and detachment is provided to the jib, a movable sheave is provided to a movable side of the cylinder for attachment and detachment, and a fixed sheave is provided to a base end portion of the jib. When the cylinder for attachment and detachment extends, the movable sheave is moved in the extension direction to pull wires. Thus, the fixed sheave is pulled up, and the jib is mounted onto a tip portion of the boom.

However, the attachment/detachment mechanism has a problem of requiring provision of a dedicated attachment/detachment cylinder for mounting the jib support on the boom head.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a jib attachment/detachment mechanism which eliminates the need for a dedicated attachment/detachment cylinder.

To accomplish the above object, a jib attachment/detachment mechanism according to one embodiment of the present invention includes:

a first connecting portion provided to an upper portion of a tip of a boom head;

a second connecting portion provided to an upper portion of a rear end of a jib support provided rotatably in a rear portion of a jib main body, the second connecting portion configured to be detachably connected to the first connecting portion;

a locking portion provided to one of a lower portion of the tip of the boom head and a lower portion of the rear end of the jib support; and

an engaging portion provided to the other one of the lower portions and configured to engage with the locking portion.

A jib is mounted on the boom head such that the engaging portion or the locking portion provided to the lower portion of the jib support is engaged with the locking portion or the engaging portion provided to the lower portion of the tip of the boom head by lying the jib main body with a cylinder for luffing the jib main body being extended, and pulling up the jib support, together with the rear portion of the jib main body, with a wire by using a winch, and then the second connecting portion is connected to the first connecting portion by contracting the cylinder to rotate the jib support around the locking portion by a predetermined amount.

The jib attachment/detachment mechanism includes a guide mechanism configured to guide the engaging portion or the locking portion of the jib support to a position of engagement with the locking portion or the engaging portion of the boom head when the jib support is pulled up with the wire by using the winch, and to prevent change of a state of the wire being pulled up by the winch when the jib support is rotated around the locking portion by contracting the cylinder.

DETAILED DESCRIPTION OF THE EMBODIMENT

Hereinafter, description is given of an embodiment of an attachment/detachment mechanism for detachably mounting a jib on a tip portion of a telescopic boom of a turnable boom operation machine according to the present invention on the basis of the drawings.

FIG. 1shows an all terrain crane10in which a jib50is mounted at a tip of a tip boom16C.

The all terrain crane10(hereinafter referred to as crane) includes a carrier11being a main body portion of a vehicle and capable of traveling, a pair of left and right front outriggers12provided in a front side of the carrier11, and a pair of left and right rear outriggers13provided in a rear side of the carrier11, a turn table14horizontally turnably attached to an upper portion of the carrier11, a cabin20provided to the turn table14, a bracket15fixed to the turn table14, a telescopic boom16attached to the bracket15, and the like.

The telescopic boom16has a base end portion attached by a supporting shaft (not illustrated), and is capable of luffing around the supporting shaft. A luffing cylinder18is set between the bracket15and the telescopic boom16, and the telescopic boom16is luffed by extension or contraction of the luffing cylinder18.

The telescopic boom16has multiple booms including a base boom16A, multiple intermediate booms16B, and the tip boom16C, which are nested in the base boom16A in this order from the outside to the inside. The telescopic boom16is configured to extend and contract by an extension cylinder (not illustrated).

As shown inFIGS. 2 to 4, the tip boom16C is provided with a boom head30, and the boom head30is provided with multiple sheaves31ato31d.

An end plate32is provided to a tip of the boom head30, and connecting portions (first connecting portions)33and34are provided on both sides in an upper portion (inFIG. 4) of the end plate32. Each of the connecting portions33and34includes a pair of connecting plates33A and33B or34A and34B, each pair of which face each other, and pin-insertion holes33Aa,33Ba,34Aa, and34Ba are formed in the connecting plates33A,33B,34A, and34B, respectively.

Likewise, shaft holding portions35and36are provided on both sides in a lower portion of the end plate32. Each of the shaft holding portions35and36includes a pair of shaft holding plates35A and35B or36A and36B, each pair of which face each other, and pin insertion holes35Aa,35Ba,36Aa, and36Ba are formed in the shaft holding plates35A,35B,36A, and36B, respectively. Shaft pins (locking portions) P1and P1described later are to be inserted through the pin insertion holes35Aa,35Ba,36Aa, and36Ba of the shaft holding plates35A,35B,36A, and36B.

In addition, a holding portion37for holding a guide roller (guided member)70described later is provided to a center portion of the lower portion of the end plate32. The holding portion37has a tubular portion (second tubular portion)37A and a supporting wall37B fixing the tubular portion37A to the end plate32. As shown inFIG. 5, a supporting rod71of the guide roller70is to be inserted into the tubular portion37A to detachably hold the guide roller70by the holding portion37.

As shown inFIG. 6, the jib50has a jib main body51, a jib support60provided rotatably to a rear of the jib main body51, and a cylinder52for luffing the jib main body51with respect to the jib support60.

An extension or contraction operation of the cylinder52causes the jib main body51to rotate around a shaft53with respect to the jib support60and luff with respect to the jib support60.FIG. 6shows a state where the cylinder52is extended. When the cylinder52contracts from this state, the jib main body51rotates with respect to the jib support60around the shaft53in the direction of the arrow.

As shown inFIGS. 7 to 9, the guide roller70is detachably attached to one side portion of the jib support60, and a guide support (guide unit)100is provided in a rear end of the jib support60.

Here, the guide roller70and the guide support100constitute a guide mechanism.

As shown inFIGS. 7 and 8, the jib support60has a tubular bearing portion (first tubular portion)62held by a bracket63provided on a sidewall61.

The supporting rod71of the guide roller70is detachably inserted into the bearing portion62to hold the guide roller70by the bearing portion62.

Connecting portions (second connecting portions)64and65to be connected to the connecting portions33and34of the boom head30are provided on both ends of an upper wall portion60A in the rear end of the jib support60.

As shown inFIGS. 7, 9, and 10, the connecting portion64has three connecting plates64A to64C arranged at predetermined intervals. Pin insertion holes64Aa to64Ca are formed in the connecting plates64A to64C, respectively.

In addition, the connecting plate33A of the connecting portion33of the boom head30is to be inserted between the connecting plate64A and the connecting plate64B, and the connecting plate33B of the connecting portion33is to be inserted between the connecting plate64B and the connecting plate64C.

Meanwhile, as shown inFIGS. 7, 9, and 10, the connecting portion65has three connecting plates65A to65C arranged at predetermined intervals. Pin insertion holes65Aa to65Ca are formed in the connecting plates65A to65C, respectively.

In addition, the connecting plate34A of the connecting portion34of the boom head30is to be inserted between the connecting plate65A and the connecting plate64B, and the connecting plate34B of the connecting portion34is to be inserted between the connecting plate65B and the connecting plate65C.

Engaging portions66and67are provided on both ends in a lower wall portion60B in the rear end of the jib support60. The engaging portion66has three engaging plates66A to66C arranged at predetermined intervals. Recessed portions66Aa to66Ca opening upward are formed in the engaging plates66A to66C, respectively. One of the shaft pins P1described later is to engage with the recessed portions66Aa to66Ca.

The shaft holding plate35A of the shaft holding portion35of the boom head30is to be inserted between the engaging plate66A and the engaging plate66B, and the shaft holding plate35B of the shaft holding portion35of the boom head30is to be inserted between the engaging plate66B and the engaging plate66C.

Likewise, the engaging portion67has three engaging plates67A to67C arranged at predetermined intervals. Recessed portions67Aa to67Ca opening upward are formed in the engaging plates67A to67C, respectively. The other one of the shaft pins P described later is to engage with the recessed portions67Aa to67Ca.

The shaft holding plate36A of the shaft holding portion36of the boom head30is to be inserted between the engaging plate67A and the engaging plate67B, and the shaft holding plate36B of the shaft holding portion36is to be inserted between the engaging plate67B and the engaging plate67C.

As shown inFIGS. 7 and 10, hooks68and69are provided outside the engaging portions66and67rotatably around shafts68J and69J. When the shaft pins P1engage with the recessed portions66Aa to66Ca and67Aa to67Ca of the engaging plates66A to66C and67A to67C, the hooks68and69are rotated around the shafts68J and69J. Thus, the recessed portions68aand69aof the hooks68and69are engaged with the shaft pins P1to prevent detachment of the shaft pins P1from the recessed portions66Aa to66Ca and67Aa to67Ca of the engaging plates66A to66C and67A to67C.

The attachment/detachment mechanism of the jib50is constituted by the connecting portions33and34and the shaft holding portions35and36of the boom head30, and the connecting portions64and65and the engaging portions66and67of the jib support60.

As shown inFIGS. 11 to 13, the guide roller70has a guide roller main body72, a holding frame73rotatably holding the guide roller main body72, the supporting rod71provided to a bottom plate73A of the holding frame73, and the like.

The guide roller main body72has a circular guide groove (circular groove)72A formed in a center portion of a circumferential surface along a circumferential direction, circumferential surface portions72B and72B formed on both sides of the guide groove72A along the circumferential direction and each having a predetermined width, and step portions72C and72C formed outside the circumferential surface portions72B and72B to be higher than the circumferential surface portions72B and72B by a step.

In addition, a shaft hole72H extending in a direction of an axis of the circumferential surface portions72B is formed in the guide roller main body72.

The holding frame73has a shaft portion73J inserted in the shaft hole72H of the guide roller main body72, side plate portions73B and73B holding both end portions of the shaft portion73J, the bottom plate73A connecting the side plate portions73B and73B to each other, and a reinforcing plate73K arranged above the bottom plate73A.

An upper portion of the supporting rod71is fixed to the reinforcing plate73K. The supporting rod71penetrates the bottom plate73A, and is fixed to the reinforcing plate73K and the bottom plate73A. Thus, the guide roller main body72is in a state of being supported by the holding frame73which is, in turn, supported by the supporting rod71.

In addition, the guide roller main body72is rotatable around the shaft portion73J.

Protruding portions74and74are formed in upper portions of the side plate portions73B and73B. A rod75is set between the protruding portions74and74. A connection member76having a hole76A to which a wire is tied is provided to the rod75.

As shown inFIGS. 14A and 14B, the guide support100has a pair of guide walls (guide members)101and101facing each other at a predetermined interval, a holding member110holding the guide walls101and101, and a wire102arranged between the guide walls101and101.

A right (inFIG. 14B) end surface101A of one of the guide walls101serves as a guide surface, and an upper portion of the end surface101A is formed to extend vertically and serves as a vertical guide surface101Aa. A portion above the vertical guide surface101Aa is formed as an upper guide surface101As inclined obliquely upward. In addition, a portion below the vertical guide surface101Aa is formed as an inclined guide surface101Ab inclined obliquely frontward (to the left inFIG. 14B). The structure of the other guide wall101is the same, and description thereof is omitted.

A connection shaft103is fixed to lower portions of the guide walls101and101, and a lower portion104A of a cable end fitting104is rotatably attached to the connection shaft103. An end portion of the wire102is inserted into the cable end fitting104, and the end portion is fixed inside the cable end fitting104.

The guide walls101and101are connected by multiple pins105to107. As shown inFIG. 14B, a cover wall108is arranged on a left side and a cover wall109is arranged on a right side between the guide walls101and101.

The cable end fitting104is made almost parallel with the inclined guide surfaces101Ab of the guide walls101by the cover wall108and the pin107. In addition, the cover wall109, the pin105, and an upper portion of the cover wall108are configured to guide the wire102upward.

The cover wall108is set so that the wire102and leg members111described later can be aligned on a straight line when the wire102is pulled upward, as shown inFIG. 14B.

The holding member110has a pair of the leg members111and111extending downward, and upper portions of the guide walls101and101are fixed to upper portions of the leg members111and111. As shown inFIGS. 7, 9, and 10, lower end portions111A and111A of the leg members111and111are fixed by shaft members113and113to supporting plates60S and60S provided to a lower wall portion60B of the jib support60. The leg members111are symmetrical with respect to the guide walls101and101.

Lower portions of the leg members111and111and lower portions of the guide walls101and101are connected and fixed to each other by connecting members114and114.

The positions of the shaft members113and113are set near the axis of the shaft pins P1and P1being in a state of engaging with the recessed portions66Aa to66Ca and67Aa to67Ca (seeFIG. 10) of the engaging plates66A to66C and67A to67C.

In addition, one (on the right side inFIGS. 9 and 10) of the leg members111is connected by connecting a connection member112provided to the leg member111and a connection member60F provided on a supporting-column wall portion60C in the rear end of the jib support60by a pin P5. By the connecting and the like, the guide support100is fixed to the rear end of the jib support60, as shown inFIGS. 7 to 10.

Next, a method for mounting the jib50configured as described above onto the boom head30is described.

First, as shown inFIG. 15, the jib50is laid on the ground with the cylinder52of the jib50being extended to maximize an angle of the jib main body51luffed with respect to the jib support60. Note that, as shown inFIG. 7, the supporting rod71of the guide roller70is inserted into the bearing portion62of the jib support60to hold the guide roller70by the bearing portion62.

Next, while the telescopic boom16of the crane10is kept in a folded state, the crane10is moved so that the boom head30of the telescopic boom16can be positioned near an area above the jib support60, as shown inFIG. 16. In addition, the shaft pins P1(illustrated in onlyFIG. 16) are inserted into the pin insertion holes35Aa,35Ba,36Aa, and36Ba of the shaft holding plates35A,35B,36A, and36B (seeFIG. 4) of the boom head30.

A tip portion of a wire (not illustrated) is tied to the connection member76of the guide roller70, and the wire is pulled up by a winch (not illustrated) of the crane10. Thus, the guide roller70is detached from the bearing portion62of the jib support60shown inFIG. 7.

The guide roller70detached from the bearing portion62is pulled up by the wire, and the supporting rod71of the guide roller70is inserted into the tubular portion37A of the boom head30shown inFIG. 16. The supporting rod71is inserted into the tubular portion37A by letting the wire out by the winch to move the guide roller70downward.

By inserting the supporting rod71of the guide roller70into the tubular portion37A of the boom head30, the guide roller70is held by the tubular portion37A of the boom head30as shown inFIG. 17.

Since the tubular portion37A is provided to a lower portion of the boom head30, the guide roller30is mounted at a low position. Hence, the mounting operation is safe. In addition, the guide roller30is pulled up from the bearing portion62of the jib support60by the wire of the crane. Hence, it is unnecessary to provide a winch dedicated to the guide roller30.

After that, the wire tied to the connection member76of the guide roller70is detached, and the wire is rewound until a tip portion Wa of the wire W (seeFIG. 17) reaches an upper surface of the tip boom16C.

Next, the wire102of the guide support100is inserted into the guide groove72A (seeFIG. 11) of the guide roller main body72of the guide roller70shown inFIG. 17, and further set on the sheave31b(seeFIG. 2) of the boom head30. Then, a rear end portion of the wire102and a tip portion of the wire W are connected to each other by a joint member120as shown inFIG. 17.

Then, by winding up the wire W with the winch, the wire102is pulled up. With the pulling-up of the wire102, the jib support60is pulled up together with the rear portion of the jib main body51. Here, since the wire102is inserted into the guide groove72A of the guide roller main body72, shift of the jib support60in a left-right direction (a width direction of the telescopic boom16) with respect to the boom head30is corrected, and the jib support60is moved to a predetermined position in the left-right direction of the boom head30.

When the jib support60is pulled up to a predetermined height, as shown inFIG. 18, the upper guide surfaces101As and101As of the guide walls101and101of the guide support100come into contact with the circumferential surface portions72B and72B (seeFIG. 11) of the guide roller main body72. Moreover, as the wire102is pulled up, the vertical guide surfaces101Aa and101Aa of the guide walls101and101come into contact with the circumferential surface portions72B and72B of the guide roller main body72. After that, as shown inFIG. 19, the inclined guide surfaces101Ab and101Ab of the guide walls101and101come into contact with the circumferential surface portions72B and72B of the guide roller main body72.

The upper guide surfaces101As and101As, the vertical guide surfaces101Aa and101Aa, and the inclined guide surfaces101Ab and101Ab of the guide walls101and101are reliably brought into contact with the circumferential surface portions72B and72B of the guide roller main body72, because the wire102is inserted into the guide groove72A of the guide roller main body72, and guided by the guide groove72A.

In addition, since the inclined guide surfaces101Ab and101Ab of the guide walls101and101come into contact with the circumferential surface portions72B and72B of the guide roller main body72, the jib support60is guided to a predetermined position shown inFIGS. 20 and 21.

Specifically, as shown inFIG. 21, at a position where the circumferential surface portions72B and72B of the guide roller main body72are in contact with lower portions of the inclined guide surfaces101Ab and101Ab of the guide walls101and101, the recessed portions66Aa to66Ca and67Aa to67Ca (seeFIG. 7) of the engaging plates66A to66C and67A to67C of the jib support60are positioned below the shaft pins P1and P1inserted into the pin insertion holes35Aa,35Ba,36Aa, and36Ba (seeFIG. 4) of the shaft holding plates35A,35B,36A, and36B of the boom head30.

When the jib support60at this position is pulled up, the engaging portions66and67of the jib support60engage with the shaft pins P1and P1of the shaft holding portions35and36of the boom head30.

In other words, the guide walls101and101of the guide support100are guided by the guide roller main body72of the guide roller70, and thus the jib support60is guided to the above-described position.

As the jib support60in the state shown inFIG. 21is further lifted up with the pulling-up by the wire102, the shaft pin P1is inserted into the recessed portion67Aa of the engaging plate67A, as shown inFIG. 22A.

In other words, as shown inFIG. 22B, the shaft pins P1of the shaft holding portions35and36of the boom head30are inserted into the recessed portions66Aa to66Ca and67Aa to67Ca of the engaging plates66A to66C and67A to67C of the jib support60.

Then, by further pulling up the wire102, the shaft pin P1is engaged with the recessed portion67Aa of the engaging plate67A as shown inFIG. 23. In other words, the shaft pins P1and P1of the shaft holding portions35and36of the boom head30are engaged with the recessed portions66Aa to66Ca and67Aa to67Ca of the engaging plates66A to66C and67A to67C of the jib support60.

As shown inFIG. 22B, this engagement is conducted as follows. Specifically, the shaft holding plate35A of the shaft holding portion35of the boom head30is inserted between the engaging plate66A and the engaging plate66B of the engaging portion66, and the shaft holding plate35B of the shaft holding portion35of the boom head30is inserted between the engaging plate66B and the engaging plate66C. Likewise, the shaft holding plate36A of the shaft holding portion36of the boom head30is inserted between the engaging plate67A and the engaging plate67B of the engaging portion67, and the shaft holding plate36B of the shaft holding portion36is inserted between the engaging plate67B and the engaging plate67C.

The insertion thereof can be conducted reliably because the wire102is inserted in the guide groove72A of the guide roller main body72, so that the shift of the jib support60in the right-left direction with respect to the boom head30is prevented.

After the shaft pins P1and P1are engaged with the recessed portions66Aa,66Ba,67Aa, and67Ba (seeFIG. 23) of the engaging plates66A,66B,67A, and67B, the operation of the winch is stopped. After that, as shown inFIG. 24A, the hook69is rotated to engage the recessed portion69aof the hook69with the shaft pin P1. Likewise, the recessed portion68aof the hook68(seeFIG. 10) is engaged with the shaft pin P1.

Next, as the cylinder52of the jib50is operated to contract, a force acts to rotate the jib main body51around the shaft53in a direction of the arrow, as shown inFIG. 24B. Since the sheave55in the tip portion of the jib main body51is in a state of being in contact with the ground, the shaft53comes up. Because of the coming-up of the shaft53, the jib support60of the jib50rotates clockwise around the shaft pins P1and P1, as shown inFIG. 25.

As the jib support60rotates to a position indicated by the dot and dash line shown inFIG. 25, the connecting plate34A of the connecting portion34of the boom head30is inserted, as shown inFIG. 26, between the connecting plate65A and the connecting plate65B of the connecting portion65of the jib support60, and the connecting plate34B of the connecting portion34is inserted between the connecting plate65B and the connecting plate65C. Likewise, the connecting plate33A of the connecting portion33of the boom head30is inserted between the connecting plate64A and the connecting plate64B of the connecting portion64of the jib support60, and the connecting plate33B of the connecting portion33is inserted between the connecting plate64B and the connecting plate64C.

After the insertion is completed, the operation of the winch is stopped. In addition, a pin P3is inserted into the pin insertion holes64Aa to64Ca of the connecting plates64A to64C and the pin insertion holes33Aa and33Ba of the connecting plates33A and33B, and a pin P4is inserted into the pin insertion holes65Aa to65Ca of the connecting plates65A to65C and the pin insertion holes34Aa and34Ba of the connecting plates34A and34B. Thus, the connecting plates64A to64C and65A to65C of the connecting portions64and65of the jib support60and the connecting plates33A,33B,34A, and34B of the connecting portions33and34of the boom head30are connected, so that the jib support60is mounted on the boom head30. In other words, the jib50is mounted on the boom head30.

Since detachment of the jib50from the boom head30can be achieved by conducting the above-described operations in a reversed manner, description of the detachment is omitted.

As described above, by the contraction operation of the cylinder52for luffing the jib main body51, the connecting portions64and65of the jib support60can be moved to the connecting positions to the connecting portions33and34of the boom head30. Hence, there is no need for a cylinder dedicated to the mounting of the jib support60on the boom head30.

As shown inFIG. 25, with the contraction operation of the cylinder52, the jib support60rotates clockwise around the shaft pins P1. Here, the position H1of each of the shaft members113and113fixing the lower end portions111A and111A of the leg members111and111of the guide support100is set near the axis of the shaft pins P1. Hence, even when the jib support60is rotated from the position shown inFIG. 24Ato the position indicated by the dot and dash line inFIG. 25, the positions H1of the shaft members113and113hardly change. For this reason, this rotation does not change the tension of the wire102, and the jib support60is prevented from falling down due to such a change in tension of the wire102.

Since the positions H1of the shaft members113and113do not change, the state of tension of the wire102does not change. For this reason, a problem which would otherwise occur because of an excessive force applied on the wire102by the contraction operation of the cylinder52is not caused.

In addition, when the jib support60is pulled up by the wire102, the cover wall108aligns the wire102and the leg members111of the guide support100on the straight line, as shown inFIG. 14B. Hence, a portion above the leg members111and111is lifted up in this state. Accordingly, as shown inFIG. 14A, an isosceles triangle is formed by connecting the position F1above the leg members111and111and points of the shaft members113and113of the lower end portions111A and111A of the leg members111. Since the vertex (F1) of the isosceles triangle is lifted up in this state, the jib support60can be lifted up in a stable state.

The guide support100and the guide roller70are housed between the boom head30and the jib support60mounted on the boom head30. Hence, the size of the crane10does not increase.

In the above-described embodiment, the shaft holding portions35and36(seeFIG. 4), to which the shaft pins P1are attached, are provided to the boom head30, and the engaging portions66and67(seeFIG. 7), which engage with the shaft pins P1, are provided to the jib support60. However, those portions are interchangeable with each other. Moreover, the shaft members113and113of the lower end portions111A and111A of the leg members111are provided at the positions shifted from the positions of the axis of the shaft pins P1and P1. Hence, when the shaft pins P1and P1are detached to detach the jib50from the boom head30, the shaft members113and113do not interfere in the detachment of the shaft pins P1and P1in the axial direction.

In addition, the guide roller70is used in the above-described embodiment. However, the present invention is not limited to the guide roller70, and, for example, a roller does not have to be used, as long as a member made of a material with low frictional resistance is used. In addition, the guide roller70is detachably held by the holding portion37(seeFIG. 4) of the boom head30. However, the guide roller70may be fixed to the holding portion37.

In the above-described embodiment, the attachment/detachment mechanism for mounting the jib50on the boom head30of the telescopic boom16of the crane10is described. However, the present invention is not limited to this mechanism, and the mechanism may be an attachment/detachment mechanism for mounting a jib on a tip portion of a boom of a fixed operation machine.

The present invention is not limited to the above-described embodiment, and alteration, addition, and the like of the design are acceptable, unless the gist of the invention according to each claim in Scope of Claims is departed.