Crane

A crane includes: a boom; a jib; a front post that is swingably attached to a tip end side of the boom; a rear post that is swingably attached to the tip end side of the boom; a post-side pendant member, with one end of the post-side pendant member being attached to a tip end of the rear post; a boom-side pendant member, with one end of the boom-side pendant member being attached to another end of the post-side pendant member, and another end of the boom-side pendant member being attached to the boom; and a post driving device having a link mechanism that rotates the rear post in a range including a position at which the rear post is swung down to the front post side and a position at which the rear post is swung down to the boom side, while the boom is held down in a horizontal position.

INCORPORATION BY REFERENCE

The disclosure of the following priority application is herein incorporated by reference: Japanese Patent Application No. 2015-107238 filed May 27, 2015

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a crane.

2. Description of Related Art

A crane is provided with rear post support members (for example, cables) that support a rear post in a crane task (cargo-handling task). Japanese Laid-Open Patent Publication No. H8-48489 describes a method of mounting rear post support cables, in which a hydraulic cylinder is interposed between a rear post and a boom of a crane in such a manner that the rear post is rotatable, and rear post support cables that has been divided in two are connected to each other and are installed in the crane.

In the method described in the aforementioned publication, the rear post and a front post are attached to a boom head of a tower boom that has been rotated to lie down in a horizontal position. One end of one rear post support cable is engaged to a tip end of the rear post, while one end of the other rear post support cable is engaged to a cable mounting part of the tower boom. The other rear post support cable is laid on the tower boom so that the other end of this cable is arranged on the rear post side.

When the hydraulic cylinder is retracted, the rear post is rotated down to the tower boom side, so that two rear post support cables are coupled to each other. Thereafter, the hydraulic cylinder is extended so that the rear post raises up at a predetermined angle and the rear post support cables are installed.

SUMMARY OF THE INVENTION

In the method described in the aforementioned publication, it is necessary to generally vertically raise the rear post that is attached to the boom which has been swung down in a horizontal position, using an auxiliary crane (see Japanese Laid-Open Patent Publication No. H8-48489, Paragraph 0010 and FIG. 4).

A crane according to a first aspect of the present invention comprises: a boom; a jib that is attached to the boom so that the jib can be hoisted or lowered; a front post that is swingably attached to a tip end side of the boom and linked to the jib via a linking member; a rear post that is swingably attached to the tip end side of the boom, wherein a rope for hoisting or lowering the jip is wound between the rear post and the front post; a post-side pendant member, with one end of the post-side pendant member being attached to a tip end of the rear post; a boom-side pendant member, with one end of the boom-side pendant member being attached to another end of the post-side pendant member, and another end of the boom-side pendant member being attached to the boom; and a post driving device having a link mechanism that rotates the rear post in a range including a position at which the rear post is swung down to the front post side and a position at which the rear post is swung down to the boom side, while the boom is held down in a horizontal position.

DESCRIPTION OF EMBODIMENTS

A crane according to one embodiment of the present invention will be described with reference to the drawings. For the sake of convenience, front, back, right, left, up and down directions of the crane will be defined as shown in the figures.FIG. 1is a side schematic view showing an appearance of a tower crane. The tower crane (hereinafter referred to as the crane100) has a travel body101, a swing body (or revolving body)102that is swingably mounted on the travel body101, a tower boom (hereinafter referred to as a boom103) that is attached to a frame of the swing body102so that the boom103can be raised and lowered, and a tower jib (hereinafter referred to as a jib104) that is attached to a tip end of the boom103so that the jib can be raised and lowered.

A hook (hereinafter referred to as a jib hook105) for suspension by the jib is suspended from a tip end of the jib104, and a hook (hereinafter referred to as a boom hook106) for suspension by the boom is suspended from a tip end of the boom103.

A front winch110, a rear winch111, and a boom hoist winch112are attached to the swing body102. A front wire rope (hereinafter referred to as a front rope110a) is wound around the front winch110and the front rope110ais connected to the boom hook106over a top part of the boom103. Actuation of the front winch110causes the front rope110ato be wound up or fed out so that the boom hook106moves upwardly or downwardly, respectively.

A rear wire rope (hereinafter referred to as a rear rope111a) is wound around the rear winch111and the rear rope111ais connected to the jib hook105over the top part of the boom103and the tip end of the jib104. Actuation of the rear winch111causes the rear rope111ato be wound up or fed out so that the jib hook105moves upwardly or downwardly, respectively.

A mast107is rotatably supported on a front part of the swing body102, and the tip end of the mast107and the top part of the boom103are connected to each other with a pendant rope115. A wire rope for hoisting/lowering (hereinafter referred to as a boom hoist rope112a) is wound around the boom hoist winch112. The boom hoist rope112ais wound a plurality of times between sheaves121provided behind the boom hoist winch112and sheaves122provided in the tip end of the mast107. Actuation of the boom hoist winch112causes the boom hoist rope112ato be wound up or fed out so that the mast107rotates to hoist or lower the boom103via the pendant rope115.

A jib hoist winch113is provided on a back side of the boom103and a jib hoist rope113ais wound around the jib hoist winch113. A front post108and a rear post109are swingably or rotatably attached to the tip end of the boom103. The front post108is arranged between the jib104and the rear post109and linked to the tip end of the jib104via a pendant rope116(a linking member).

Sheaves123are provided at a tip end of the front post108and sheaves124are provided at a tip end of the rear post109. The jib hoist rope113afor hoisting/lowering the jib is wound a plurality of times between the sheaves123of the front post108and the sheaves124of the rear post109. Actuation of the jib hoist winch113causes the jib hoist rope113ato be wound up or fed out so that the front post108rotates with respect to the rear post109to hoist or lowers the jib104via the pendant rope116.

The tip end of the rear post109and a bracket139in the vicinity of a base end of the boom103are linked to each other with a rear post support pendant140that can be divided. The rear post support pendant140can be divided into a post-side pendant member141and a boom-side pendant member142.

The post-side pendant member141is rotatably attached, on one end, to a pin109b(seeFIG. 2) in the tip end of the rear post109. The other end of the post-side pendant member141is attached to one end of the boom-side pendant member142. The boom-side pendant member142is rotatably attached, on the other end, to the bracket139in the vicinity of the base end of the boom103.

It will be noted that the rear post support pendant140is constructed of components that are linked to one another, such as a plurality of rod-like pendant members (bar pendants) and/or pendant members formed of wire ropes (pendant ropes). In this embodiment, the post-side pendant member141is a rod-like bar pendant, and a component of the boom-side post pendant member142that is coupled to the post-side pendant member141is a rod-like bar pendant.

Generally, the boom103, the jib104, and other components are separately transported in a disassembled manner by a trailer to a working site and assembled to form the crane100in the working site. In the assembly task, an operator attaches the front post108and the rear post109to the tip end side of the boom103, while the boom103extends in a generally horizontal manner with respect to the ground.

After attaching the front post108and the post109to the boom103, the operator connects the post-side pendant member141which is connected to the rear post109and the boom-side pendant member142which is connected to the boom103. Thereafter, the operator attaches the jib104to the boom103with an auxiliary crane or the like.

A configuration of a post driving device150that is used for attaching the post-side pendant member141to the boom-side pendant member142will now be described in detail. The post driving device150is provided in the tip end of the boom103.

FIG. 2is a view showing the tip end of the boom103. It will be noted that outlines of components are schematically represented by solid lines in side schematic views shown inFIGS. 2 to 14, for the sake of convenience. As shown inFIG. 2, the boom103is provided with a boom head131that forms the tip end of the boom103. In the illustration ofFIG. 2, the boom103is swung down so that a ventral surface thereof faces to the ground and the boom103is generally horizontally arranged to extend in the front-back direction.

As shown inFIG. 2, a pair of right and left post fixing members132having a predetermined length is provided in the top part of the boom head131, extending from a base end of the front post108to a base end of the rear post109. The pair of right and left post fixing members132are coupled to each other at the center in the longitudinal direction with two support pipes166and167.

The front post108includes a pair of columns181that oppose to each other in the right-left direction and extend in the longitudinal direction, and a coupling member (not shown) that couples the pair of right and left columns181. The columns181are pivotably supported on one end (a lower end of the post fixing member132shown inFIG. 2) of the post fixing member132in a rotatable manner by a pin108athat extends in the right-left direction.

The rear post109includes a pair of columns191that oppose to each other in the right-left direction and extend in the longitudinal direction, and coupling members192that couple the pair of right and left columns191. The columns191are pivotably supported on the other end (an upper end of the post fixing member132shown inFIG. 2) of the post fixing member132in a rotatable manner by a pin109athat extends in the right-left direction.

As shown inFIG. 2, the post driving device150that drives the rear post109to rotate is provided between the rear post109and the boom head131. The post driving device150includes a link mechanism155that has a first link151and a second link152, and a hydraulic cylinder153(an extension/retraction actuator) that drives the link mechanism155.

The support pipes166and167that are bridged between the pair of right and left post fixing members132are provided with a generally triangular attaching plate165. The support pipe166and the support pipe167are inserted in the vicinity of respective ones of two vertexes on a base side of the generally triangular attaching plate165(a side in which the attaching plate165is attached to the post fixing member132).

In the vicinity of a vertex on a protruding side (on a tip end side) of the attaching plate165in the boom head131, a base end of the first link151is rotatably attached by a pin161that extends in the right-left direction. The pin161, which is a rotation pivot of the first link151, is arranged between the front post108and the rear post109. The structure of the first link151is such that a pair of right and left elongated longitudinal plates151aare coupled to each other by one elongated transverse plate151b.

Mounting brackets168are provided in a protruding manner on an upper surface of the base end side of the rear post109shown inFIG. 2. A pin162that extends in the right-left direction is bridged between the pair of right and left mounting brackets168in the rear post109. The base end of the second link152is rotatably attached by this pin162. The structure of the second link152is such that a pair of right and left elongated longitudinal plates152aare coupled to each other by one elongated transverse plate152b.

A cylinder support bracket169is provided in an upwardly protruding manner at a predetermined distance from the mounting bracket168of the rear post109toward the tip end side. The hydraulic cylinder153has a cylinder tube (hereinafter referred to as a tube153t) and a rod153rthat extends/retracts with respect to the tube153t.

The hydraulic cylinder153includes an oil chamber on the bottom side (hereinafter referred to as a bottom chamber) and an oil chamber on the rod side (hereinafter referred to as a rod chamber). The hydraulic cylinder153is configured to extend when hydraulic oil is supplied to the bottom chamber and retract when hydraulic oil is supplied to the rod chamber.

An end of the tube153tthat is one end of the hydraulic cylinder153is rotatably attached to the cylinder support bracket169of the rear post109by a pin163that extends in the right-left direction. A tip end (rod head) of the rod153rthat is the other end of the hydraulic cylinder153, the tip end of the first link151, and the tip end of the second link152are coupled by a coupling shaft160that extends in the right-left direction. In other words, the hydraulic cylinder153, the first link151, and the second link152are coupled to be rotatable relative to one another about the coupling shaft160as a rotation center.

The link mechanism155that is constructed of the first link151and the second link152is actuated by means of the extension/retraction operation of the hydraulic cylinder153, with a rotation radius restricted by the first link151. The rear post109is driven to rotate about a pin109aby actuation of the link mechanism155.

FIG. 3is a schematic view showing a rotating range of the rear post109that is rotated by the post driving device150. The link mechanism155is configured to rotate the rear post109in a range including a position (PL) at which the rear post109is swung down to the front post108side as represented by solid lines inFIG. 3and a position (BL) at which the rear post109is swung down to the boom103side as represented by long dashed double-short dashed lines inFIG. 3, while the boom103is swung down in a horizontal position. The position (PL) at which the rear post109is swung down is a position at which the rear post109is tilted to the front post108side beyond the vertical direction (V), and the position (BL) at which the rear post109is swung down is a position at which the rear post109is tilted to the boom103side beyond the vertical direction (V).

When a task of winding the jib hoist rope113abetween the sheaves123and the sheaves124is performed, it is preferable in view of workability to bring the sheaves124of the rear post109and the sheaves123of the front post108as close as possible to each other and bring the sheaves124of the rear post109closer to the ground. For this reason, the front post-side limit position (PL) of the rotating range S of the rear post109is set to a position at which the rear post109is tilted by approximately 10 degrees toward the front post108from a position at which the rear post109is arranged in parallel to the boom103, i.e., from the horizontal direction (H). The rear post109is in the front post-side limit position (PL) when the hydraulic cylinder153is retracted to the maximum extent, while the boom103is swung down in a horizontal position.

The boom-side limit position (130of the rotating range S of the rear post109is set so that the rear post109is swung down to the boom103side until one end of the boom-side pendant member142attached to the boom103and the other end of the post-side pendant member141attached to the tip part of the rear post109can be attached to each other. The rear post109is in the boom-side limit position (PL) when the hydraulic cylinder153is extended to the maximum extent, while the boom103is swung down in a horizontal position.

In this embodiment, the boom-side limit position (BL) of the rotating range S of the rear post109is set to a position at which the rear post109is tilted by approximately 45 degrees toward the boom103from a position at which the rear post109is arranged orthogonally to the boom103, i.e., from the vertical direction (V).

In this way, the rear post109is rotated by the post driving device150so as to go beyond the vertical direction (V), while the boom103is swung down in a horizontal position.

In this embodiment, the rotating range S is set to approximately 145 degrees in such a manner that the rotating range S includes at least a position (H) at which the rear post109extends in the horizontal direction and a position (V) at which the rear post109extends in the vertical direction. In this way, the rear post109can be rotated between a position at which a task of winding the jib hoist rope113abetween the sheaves123and the sheaves124can be performed, and a position at which a task of attaching the boom-side pendant member142to the post-side pendant member141can be performed.

A task of attaching the front post108and the rear post109to the boom103and a task of attaching the post-side pendant member141to the boom-side pendant member142, among assembly tasks of the crane100, will be described below. It will be noted that the boom-side pendant member142is disposed on the boom103as shown inFIG. 3so that a connecting end142athereof for connection to the post-side pendant member141is arranged on the rear post109side.

FIGS. 4A and 4Bare views explaining the task of attaching the front post108to the boom103. As shown inFIG. 4A, the operator actuates the boom hoist winch112to swing the boom103down so that the boom103is in a horizontal position, by operating a control lever for boom hoisting/lowering.

As shown inFIG. 4B, the operator uses an auxiliary crane to lift up the front post108so that the base end of the front post108is attached to the boom head131. Thereafter, the operator uses the auxiliary crane to lift up the rear post109. As shown in this figure, ropes R that are suspended from a hook F of the auxiliary crane are attached to both ends of the rear post109. It will be noted that the hydraulic cylinder153has been previously retracted to its shortest length. Additionally, the post-side pendant member141has been previously rotatably attached to the tip end of the rear post109by a pin109b(seeFIG. 3), on one end. The other end of the post-side pendant member141is fixed to the rear post109by a fixing device (not shown) so that the member141would not rotate with one end being as a rotation pivot.

FIGS. 5A and 5Bare views explaining a task of attaching the rear post109to the boom103. After lifting up the rear post109using the auxiliary crane, the operator attaches the base end of the rear post109to the post fixing member132of the boom head131(seeFIG. 2), as shown inFIG. 5A. Thereafter, the operator sets a fitting angle of the rear post109to an angle at which the rear post109is supported by the post driving device150, as shown inFIG. 5B.

FIGS. 6A and 6Bare views explaining a task of winding the jib hoist rope113aaround the sheaves123of the front post108and the sheaves124of the rear post109. After setting the fitting angle of the rear post109, the operator removes the ropes R that are suspended from the hook F of the auxiliary crane, as shown inFIG. 6A. At this time, the distance between the sheaves123of the front post108and the sheaves124of the rear post109and the distance between the sheaves124and the ground are shorter than that in the state ofFIG. 5A(the state where the rear post109is horizontally arranged).

As shown inFIG. 6B, the operator pulls the jib hoist rope113aout of the jib hoist winch113, using a reeving winch or the like (not shown). The operator guides the jib hoist rope113awhich is pulled out of the jib hoist winch113to the sheaves124, via a guide sheave133provided in the boom head131and a guide sheave134provided in the rear post109. Thereafter, the operator winds the jib hoist rope113abetween the sheaves124and the sheaves123a plurality of times, and then fixes an end of the jib hoist rope113aat a predetermined position on the rear post109or the front post108.

FIGS. 7 to 12are views explaining how the rear post109is driven to rotate by the post driving device150. Before the hydraulic cylinder153is driven, the hydraulic cylinder153and a hydraulic power source (not shown) are connected to each other. Between the hydraulic cylinder153and the hydraulic power source (not shown), a switching valve unit (not shown) that switches flow of hydraulic oil discharged from the hydraulic power source is provided. The operator can operate the switching valve unit (not shown) so as to supply the hydraulic oil discharged from the hydraulic power source to either the rod chamber or the bottom chamber of the hydraulic cylinder153.

The bottom chamber of the hydraulic cylinder153in its shortest state shown inFIG. 7is supplied with the hydraulic oil from the hydraulic power source (not shown), while the hydraulic oil is discharged from the rod chamber and guided to a tank (not shown). When the bottom chamber of the hydraulic cylinder153is supplied with the hydraulic oil, a cylinder thrust acts on each of the first link151and the second link152via the coupling shaft160, while a cylinder thrust acts on the rear post109via the pin163.

The cylinder thrust F1acting on the first link151is decomposed into a force F11that directs to the pin161, which is the rotation center of the first link151, and a force F12that urges the first link151to rotate. It will be noted that rotation of the first link151is restricted by the second link152even when the three F12acts on the first link151.

The cylinder thrust F2acting on the second link152is decomposed into a force F21that directs to the pin162, which is the rotation center of the second link152, and a force F22that urges the second link152to rotate. It will be noted that rotation of the second link152is restricted by the first link151even when the force F22acts on the second link152.

The force F21which directs to the rotation center of the second link152acts on the pin162. The force F21acting on the pin162is decomposed into a rotating force F211that acts to cause the rear post109to rotate about the pin109aas a rotation center, and a force F212that is orthogonal to the rotating force F211.

The cylinder thrust F3acting on the rear post109via the pin163is decomposed into a force F31that acts to cause the rear post109to rotate about the pin109aas a rotation center, and a force F32that is orthogonal to the rotating force F31.

Therefore, when the bottom chamber of the hydraulic cylinder153is supplied with the hydraulic oil, the rotating force F31and the rotating force F211which are generated by the thrust of the hydraulic cylinder153act on the rear post109, so that the rear post109rotates about the pin109aas a rotation center in a counterclockwise direction inFIG. 7. In other words, the position of the rear post109shifts from the position shown inFIG. 7to the position shown inFIG. 8, the position shown inFIG. 9, the position shown inFIG. 10, the position shown inFIG. 11, and the position shown inFIG. 12sequentially, so that the rear post109raises up.FIG. 12shows a state where the rear post109has raised up, extending in the vertical direction.

FIGS. 13A and 13Bare views explaining the task of attaching the post-side pendant member141to the boom-side pendant member142. From the state shown inFIG. 12, the rear post109swings (tilts) to the boom103side so as to shift its position to that shown inFIG. 13A, when the bottom chamber of the hydraulic cylinder153is further supplied with the hydraulic oil.

The operator releases the fixation of the bottom end of the post-side pendant member141to swing the post-side pendant member141about the pin109bas a rotation center, so that a connecting end141aof the post-side pendant member141is connected to the connecting end142aof the boom-side pendant member142via a metal connecting fitting143.

The connecting fitting143is a coupling member that is provided with through holes on both ends. As shown in an enlarged schematic view ofFIG. 12, a pin has been previously inserted and attached into one through hole of the connecting fitting143and a through hole of the connecting end141a so that the connecting fitting143is rotatably attached to the post-side pendant member141.

As shown inFIGS. 13A and 13B, the operator inserts and attaches a pin into the other through hole of the connecting fitting143and a through hole of the connecting end142ato rotatably couple the boom-side pendant member142to the connecting fitting143. Thereby, the post-side pendant member141and the boom-side pendant member142are linked to each other.

FIG. 14is a view explaining a task of stretching out (tensioning) the post-side pendant member141and the boom-side pendant member142. The operator operates the switching valve unit so that the hydraulic oil discharged from the hydraulic power source (now shown) is supplied to the rod chamber of the hydraulic cylinder153. The operator causes the hydraulic oil to be supplied to the rod chamber of the hydraulic cylinder153in order to retract the hydraulic cylinder153. Thereby, the rear post109, which has been swung down to the boom103side, raises up so that the post-side pendant member141and the boom-side pendant member142are tensioned as shownFIG. 14. Thereafter, the operator proceeds to a task of attaching the jib104to the boom103.

According to the embodiment described above, the following operational advantages can be achieved.

(1) There is provided the post driving device150having the link mechanism155that rotates the rear post109in a range including a position (PL) at which the rear post109is swung down to the front post108side and a position (BL) at which the rear post109is swung down to the boom side103, while the boom103is swung down in a horizontal position. Thereby, the rear post109that is attached to the boom103which has been swung down in a horizontal position can be raised up and further swung down to the boom103side without using the auxiliary crane. In this way, the rear post109that is attached to the boom103which has been swung down in a horizontal position, and that is swung down to the front post108side, can be raised up and further swung down to the boom103side without using the auxiliary crane. As a result, an improvement in the assembly and disassembly workability of the crane can be achieved.

(2) The post driving device150is provided so that the rear post109rotates in a range including a position (H) at which the rear post109is arranged in parallel to the boom103and a position (V) at Which the rear post109is arranged orthogonally to the boom103. Because the rear post109can be swung down to the front post108side beyond the position (H) at which the rear post109is arranged in parallel to the boom103, an improvement in the workability of winding the jib hoist rope113abetween the sheaves123and the sheaves124can be achieved.

The following variations are also within the scope of the present invention and one or more of the variations may be combined with the foregoing embodiment.

First Variation

In the foregoing embodiment, an example has been described in which the first link151and the second link152are connected or attached with the rod head of the hydraulic cylinder153in a rotatable manner about the coupling shaft160. However, the present invention is not limited to this. The first link151and the second link152may be connected or attached with the end of the tube153tof the hydraulic cylinder153in a rotatable manner about the coupling shaft160, and the rod head of the hydraulic cylinder153may be connected to the rear post109.

Second Variation

In the foregoing embodiment, an example has been described in which the front post108is rotatably attached to the boom head131. However, the present invention is not limited to this. For example, the bottom of the front post108may be attached to the base part of the jib104.

Third Variation

In the foregoing embodiment, an example has been described in which the hydraulic cylinder153is used as a driving power source of the post driving device150. However, the present invention is not limited to this. For example, a linear type extension/retraction actuator including an electric motor and a feed screw mechanism may be employed.

Fourth Variation

The post-side pendant member141and the boom-side pendant member142are not limited to be rod-like bar pendants, but may be formed of wire ropes.

Fifth Variation

In the foregoing embodiment, the movable crane100having the travel body101has been described. However, the present invention is not limited to this. A fixed crane may also be applied.

Although an embodiment and variations have been described above, the present invention is not limited to these forms. Other aspects that are conceivable within the scope of the technical idea of the present invention are also encompassed within the scope of the present invention.

According to the embodiment and variations of the present invention described above, the rear post that is attached to the boom which has been swung down in a horizontal position and that is swung down to the front post side, can be raised up and further swung down to the boom side without using the auxiliary crane.