JPH07215672A - Crane with jib - Google Patents

Abstract

PURPOSE:To facilitate assembling and disassembling of a jib supporting device in a crane provided with a jib. CONSTITUTION:A distance maintaining member 43, which accommodates the front column 42 and the rear column 41 of a jib supporting device 4 in a lowered attitude on a boom side 2 respectively, and, while permitting both the columns 41, 42 to move toward each other, becomes tense when they are apart at a prescribed distance, is mounted between the front column 42 and the rear column 41. A strut member 8, which prevents both the columns 41, 42 from coming nearer in a condition where the distance maintaining member is tense between the rear column 41 and the front column 42, is mounted. The first expansion cylinder 6, which raises up the front column until the distance maintaining member 43 becomes tense, is mounted in the proximity of a boom top end part 2b. Then, the second expansion cylinder 7, which raises the rear column 41 to a desired position, is mounted. It is thus possible to assemble both the columns 41, 42 and the distance maintaining member 42 in a prescribed condition by extending the second expansion cylinder 7 after extending the first expansion cylinder 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a jib-equipped crane in which a base end portion of a jib is pivotally attached to a tip portion of a boom, and the jib can be undulated by a winch via a column provided at the tip portion of the boom. It is about.

[0002]

11 to 12 show a known crane with a jib of this type (Japanese Patent Laid-Open No. 3-25699).
7 publication). In this known crane with jib, FIG.
As shown in, the jib (roughing jib) 3 mounted on the boom tip 2b is supported by a jib support device 4 continuously provided on the back side of the jib 3 and the back side of the boom 2, and The jib 3 can be undulated in the vertical plane at the boom tip 2b by hoisting and lowering the winch 44 for hoisting the jib, which constitutes a part of the jib supporting device 4. A support 22 having a predetermined length is attached to the tip of the tip boom, and the tip of the support 22 is attached to the boom tip 2b.
Becomes Further, in this type of crane with a jib, the working radius and the lifting height can be increased as the length of the jib 3 is increased. However, when the length of the jib 3 is increased, the tension member for supporting the jib is increased. (Wire rope) 4
Since it is necessary to make a large angle between the axis of the jib 3 and the axis of the jib 3, the jib support device 4 uses columns 41 and 42 that project to the back side of the boom tip 2b. That is, the jib support device 4 includes two front and rear columns (a front column 42, which has an appropriate length (for example, 7 to 8 m) at the boom tip 2b.
A connecting rod 43 for pivotally attaching each base end portion of the rear support column 41) and for maintaining a space between each front end portion of the front and rear support columns 42, 41.
The jib tip 3b and the tip of the front strut 42 are connected by a tension member 48, and the rope 45 from the winch 44 for jib up and down installed on the swivel base 11 of the carriage is attached to the rear strut 41. It is configured to be connected to the tip of the. The base end of the rear column 41 is pivotally attached to the upper side of the boom tip 2b, while the tip of the front column 42 is pivotally attached to the lower part of the boom tip 2b. Also, the front support column 42
The rear support column 41 and the rear support column 41 are separated from each other by an angle of about 60 ° in the front-rear direction when the connection rod 43 holds the space. In this crane with a jib, the jib 3 can be raised up through the columns 41 and 42 by hoisting the winch 44 for hoisting the jib, and by lowering the winch 44, the jib 3 is chained. As shown in the figure, it can be laid down by its own weight.

Further, in this known crane with a jib, when assembling the jib supporting device 4, as shown in FIG. 12, the boom 2 is tilted to a substantially horizontal posture, and the boom tip 2b.
Is connected to the base end portion of the jib 3 (the jib is also held in a horizontal posture), and the rear strut 41 has the base end portion of the boom end 2b.
With it pivoted to, tilt it backward (boom top side),
On the other hand, the front strut 42 is tilted to the front side (upper side of the jib) with its base end pivotally attached to the boom tip 2b. In addition, in this known crane with a jib, it is not possible to tilt both the columns 41 and 42 toward the boom side. Then, the telescopic cylinder 10 for raising and lowering the support column provided at the tip of the boom is extended to raise the rear support column 41 up to near the vertical posture as shown by the chain line 41 ', and thereafter, the rope 45 from the winch 44 is used. Back post 41 'while applying back tension
Is tilted by its own weight toward the jib 3 side by a predetermined angle, and the tip end of the rear strut 41 ″ and the tip end of the front strut 42, which is installed on the upper surface of the base end of the jib in a lying posture, are connected by a connecting rod 43. In addition, in a general crane with a jib of this kind, when the jib support device 4 is assembled or disassembled, the columns 41 and 42 are moved from the retracted position along the boom upper surface or the jib upper surface. It is necessary to stand up to the assembleable position, fall down from the standing state to the retracted position, or attach / detach the connecting rod 43. However, since those members have a large weight, the column 41 , 42 and the connecting rod 43 are supported by another crane.

Prior to assembling the jib support device 4,
The sheave 51 provided on the rear support column 41 on the front side of the rope 14 unreeled from the loading winch 13 (FIG. 11),
Sheave 52 provided on front support 42 and jib tip 3b
Each of the sheaves 53 is guided to the lower end of the jib. When the rope 14 is passed through the sheave 51 and the sheave 52, respectively, the rope tip portion is provided between the disengagement prevention pins (154, 155) provided near the outer periphery of each sheave (51, 52) and the outer peripheral surface of the sheave. It takes place throughout. This rope threading operation is carried out by allowing a worker to pass the rope tip between the pin and the outer peripheral surface of the sheave and then pulling the rope tip forward in order. At that time, the rope 14 and the pin (154, At present, the rope pulling out work is considerably heavy due to friction with 155).

By the way, as described above, each of the columns 41, 42
In the crane with a jib in which the jib 3 is undulated via the support, each of the columns 41, 42, the connecting rod 43, the rope 45, and the like has a considerable weight, and the boom 2 in the maximum upright posture. , When the hook 15 raises the jib 3 upwards in an empty state, the center of gravity (rotational moment) of the total weight of the jib 3 and the jib support device 4 (excluding the winch 44) is changed from the front side of the boom 2. Move to the back side. When there is no safety device for rearward fall regulation with respect to the jib 3, when the center of gravity moves from the base end pivotal support position P of the jib 3 to the rear side of the boom, the jib and the jib support device are The combined rotational moment is the jib pivot 29
It works in the counterclockwise direction around the
The rotation moments of the motors 1, 42 cause them to fall to the rear side of the boom. In this known crane with jib, as described above, the stopper device 16 is provided to prevent the jib 3 from rotating backward relative to the boom 2 beyond the allowable elevation limit angle. The stopper device 16 has an abutment member 17 provided on the upper surface near the jib base end and a receiving member 18 provided on the front surface of the boom tip 2b, so that the jib 3 exceeds the allowable elevation limit angle. When attempting to stand up, the abutment member 17 on the jib abuts on the receiving member 18 on the boom side, and acts so that the jib 3 does not fall further rearward. In addition, in this crane with jib,
By removing one of the stopper devices 16 (for example, the abutting member 17) for restricting the raising and lowering angle of the jib or by positioning the stopper device 16 so that the two do not abut, the boom and the jib as shown in FIG. And can be located almost on a straight line.

Further, in a crane with a jib using this type of jib support device (especially one using long columns 41 and 42), the jib is hung from the rear side to the front side of the boom. A support device is required to pass through the jib hoisting rope used when swinging. An example of this type of supporting device is one used in a crane with a jib shown in FIG. 13 (Japanese Patent Laid-Open No. 63-180695). The rope support device 60 used in this known crane with a jib is configured by providing a sheave 62 on the upper end of a support 161 having a predetermined height provided on the back side of the boom tip 2b. Then, the rope 45 from the jib undulating winch 44 (the tip of which is connected to the tip of the rear column 41) is supported by the sheave 62, and the winch 44 is rolled up to operate the jib 3 by the reference numeral 3 '. As shown by, it is possible to stand upright in front of the boom 2.

[0007]

However, in the known crane with a jib shown in FIGS. 11 and 12, when the jib supporting device 4 is assembled (FIG. 12), the rear support column 41 is moved backward (boom 2 side). Tilt the other side of the front strut 42 forward (on the jib 3 side)
Each of them is attached to the boom tip 2b in a state of being tilted to the rear, and the rear support column 41 is placed at a predetermined front position (position 41 ").
It is necessary to connect (pin-connect) the rear support column 41 and the front support column 42 with the connection rod 43 in a state of being rotated up to.
Therefore, the connecting work between the connecting rod 43 and both columns 41, 42 (particularly the positioning of the pin hole at the end of the connecting rod 43 and the pin hole on the supporting column side) is troublesome, and the connecting work requires an operator. There was a problem that it was dangerous to work because it was necessary to climb to a high place. In addition, the rear column 41 and the front column 42
When connecting and with the connecting rod 43, the swinging operation of the supporting rod can be performed by the telescopic cylinder 10 for raising and lowering the supporting rod, but when the connecting rod 43 is heavy, the connecting rod 43 is supported or aligned. I had to use another crane to do this.

In the known crane with a jib shown in FIGS. 11 and 12, the jib 3 exceeds the allowable elevation limit angle with respect to the boom 2 between the boom tip 2b and the base end of the jib 3. The stopper device 16 is provided to prevent the rearward reversal of the stopper device 16.
For example, when the boom 2 and the jib 3 are arranged in a straight line as in the case of assembling the jib support device 4 as shown in FIG. 12, one of the stopper devices 16 (the abutting member 1
7 or the receiving member 18) must be removed or displaced to release the stopper function. However, in this known crane with a jib, since the worker manually changes the stopper function of the stopper device 16, there is a problem that the work is troublesome.

Further, in the jib-equipped crane using the jib supporting device 4 having the columns 41 and 42, when the jib 3 is raised from the suspended state to the front of the boom, for example, as shown in FIG. A rope support device 60 for passing the rope 45 is required, but the known rope support device 60 shown in FIG. 13 is fixed to the boom tip portion 2b, and moreover, a considerable height is provided on the boom rear surface (upper surface) side. Because of the protrusion, there is a problem that the rope support device 60 becomes an obstacle when the rope support device 60 is not used.

In view of the above-mentioned problems of the known crane with a jib, the present invention makes it easy to assemble and disassemble the jib support device in a crane with a jib using a jib support device having a front strut and a rear strut. To be able to
In addition, the sheave for passing the jib that is used when swinging up the jib suspended from the boom tip toward the front of the boom is retracted from the back side of the boom tip, so that the sheave interferes with the sheave when not in use. The mechanical stopper function prevents the jib from moving backwards and backwards beyond the allowable elevation limit angle with respect to the boom. The purpose is to be able to shift between a state and a non-functional state.

[0011]

The invention according to claim 1 of the present application is as follows.
The jib supported at the tip of the boom is supported by a jib support device, and the jib can be separated from the boom tip while the support by the jib support device is released. , Each of which has a base end pivotally attached to the boom front end and is mounted so as to be swingable in a jib undulation surface on the back side of the boom, and a space between the front and rear supports. And a tension member that connects the front end of the front strut and the proper position of the jib, a winch for raising and lowering the jib provided on the base end side of the boom, and a rear strut extended from the winch. In a crane with a jib, which comprises a rope directly or indirectly connected to the tip end of the space, the spacing member allows the front strut and the rear strut to move toward each other while the front strut and the front strut are separated from each other. rear When the support and the support are separated from each other by a predetermined distance, the support and the support are configured to be tensioned to prevent further separation of the support, and the rear support and the front support are connected to each other with the tension members released. While each base end is pivotally attached to the boom tip, it can be collapsed to a retracted position close to the rear side of the base end of the boom. A strut member is provided to prevent the column and the front column from approaching each other, and the column member is extended in the vicinity of the boom tip end to push the front column in the retracted posture in a non-fixed state so that the space retaining member acts on the front column. The first telescopic cylinder standing up to the tensioned range and the rear strut in the retracted position are pressed in a non-fixed state by extending the front strut and the rear strut in a state in which the strut members make the proximity operation impossible. do it Front strut rear strut is characterized in that the second telescopic cylinder capable of causing standing to a position capable of interposed a tension member respectively provided between the position of the jib and its distal end.

In the crane with a jib according to the first aspect of the present invention, each of the front support column and the rear support column forming a part of the jib supporting device has a considerable length. Further, it is preferable that each of the columns is provided on the left and right sides in terms of balance and strength. The base end portions of the front support column and the rear support column are pivotally attached to each other at a small distance from each other at an upper position of the boom tip end portion. Further, the front support pillar and the rear support pillar can individually swing within the jib undulation surface. Further, in a state in which the front strut and the rear strut are respectively housed on the boom side, the rear strut is on the lower side (inner side) and the front side strut is on the upper side (outer side) along the boom back side.

As the spacing member provided between the front support and the rear support, a member in which a plurality of link pieces are flexibly connected or a flexible member such as a rope can be used. Also, each end of this spacing member is always connected to the proper position of the front strut and rear strut (preferably near the tip of each strut), and the base end of each strut is connected to the boom tip. The front strut and the rear strut can be opened and closed within the length range of the spacing member in a pivotally attached state. Incidentally, in a state where both columns are maximally opened (a state in which the spacing member is tensioned), the angle between the columns is, for example, 60.
It is preferable to set it to about °.

The tension member for connecting the front end of the front strut and the proper position of the jib may be a rope or a rod, but the rope is preferable because it is more flexible when connecting the front strut and the proper position of the jib.

The rope extended from the jib undulating winch has its tip directly connected to the tip of the rear strut,
You may connect indirectly via a sheave.

As the bracing member for preventing the rear strut and the front strut from approaching each other, one link having a predetermined length may be used, or two links which can slide in the longitudinal direction with respect to each other are used. However, it is also possible to connect the both links in a stretched state by pin connection so that they cannot be bent and contracted. Further, it is preferable that the strut members are connected at positions near the base end portions of both columns.

The first telescopic cylinder provided at the tip of the boom pushes the front supporting column (located outside the boom from the rear supporting column) in the retracted position on the boom side from below to raise the front supporting column. Although it is for raising, the movable portion of the first telescopic cylinder is installed in a non-connected state (a state in which it can be simply pressed) with respect to the front support. Further, the first telescopic cylinder needs a stroke for raising (rotating) the front support pillar at least to the range where the space holding member is tensioned while the rear support pillar is laid down on the boom side.

The second telescopic cylinder provided at the tip of the boom pushes the rear strut from below with the tension member functioning between the front strut and the rear strut to push the rear strut together with the front strut. The second movable cylinder of the second telescopic cylinder is also installed in a non-connected state with respect to the rear support. In addition, the second telescopic cylinder needs a stroke that at least raises (rotates) the rear strut to a position where the tension member can be interposed between the front end strut and the jib proper position.

According to a second aspect of the present invention, in the crane with a jib according to the first aspect, on the movable side of the first telescopic cylinder,
It is characterized in that a support projecting outward from the back side of the boom tip portion is provided by the extension of the first telescopic cylinder, and a roller through which a jib hoisting rope is passed is provided in the support.

According to a third aspect of the present invention, in the crane with a jib according to the first aspect, the jib is backward-reversed between the upper end of the jib and the tip of the boom, exceeding the allowable elevation limit angle with respect to the boom. Is provided with a stopper device, and the stopper device includes an abutting member provided on an upper portion of the jib on the proximal end side,
And a support provided on the telescopic side of the first telescopic cylinder, so that the support is displaced between a position where the abutting member can be received and a position where the abutting member cannot receive by the expansion and contraction of the first telescopic cylinder. It is characterized by having done.

Further, according to the invention of claim 4, the jib mounted so as to be able to move up and down at the tip of the boom is supported by the jib support device, and the jib is released from the support by the jib support device. And the jib support device includes two front and rear jib supporting devices, each of which has a base end pivotally attached to the boom front end and is mounted so as to be swingable in the jib undulation surface on the back side of the boom. A pillar, a spacing member that holds the distance between the front pillar and the rear pillar, a tension member that connects the front end of the front pillar and the proper place of the jib, and a jib undulating provided on the base end side of the boom. In a crane with a jib that includes a winch and a rope that extends from the winch and is directly or indirectly connected to the tip of the rear strut, the spacing member includes a front strut and a rear strut that are close to each other. Do While the front strut and the rear strut are separated by a predetermined distance, they are tensioned to prevent further separation of the strut. With the tension members uncoupled, the base ends of both columns can be laid down to the retracted position close to the rear face of the boom base, while the base ends of the columns are pivotally attached to the boom tip, and near the boom tip, Expansion and contraction that allows the front strut in the retracted position to be pressed in a non-fixed state so as to erect the front strut to a position where a tension member can be provided between the front end of the front strut and the proper position of the jib. It is characterized by having a cylinder.

A crane with a jib according to claims 1 to 3 is
The front strut and the rear strut in the retracted position are individually raised by the first telescopic cylinder and the second telescopic cylinder, respectively. The telescopic cylinder allows the front column to stand up to a desired large angle range. That is, in the telescopic cylinder for raising the support column used in the invention of claim 4, at least the front support column can be raised up to a position where a tension member can be interposed between the front end portion and the proper position of the jib. Has a range of strokes.

In addition, in the crane with a jib according to claim 4, the crane with a jib according to any one of claims 1 to 3 is used to raise each of the front and rear columns from the retracted state to the desired angle range described above. The supporting member is not necessary, but the supporting member may be provided between both columns in a state where the jib supporting device is assembled.

[0024]

In the crane with a jib according to the first aspect of the present invention, while the distance maintaining member for maintaining the distance between the front strut and the rear strut allows the front strut and the rear strut to move close to each other. The front and rear stanchions are prevented from moving apart from each other by a predetermined distance or more, and the front and rear stanchions are close to the boom rear face with a space holding member interposed between the struts. It is possible to store them (at this time, the spacing member is in a non-tensioned state).

In order to assemble the jib supporting device, the ropes from the winch for jib raising and lowering are directly or indirectly connected to the front end of the rear strut in a state where both the props are stored (tilted) on the boom side, and then, The front strut stored on the boom side by the first telescopic cylinder until the spacing member is tensioned, and then the tension member is interposed between both strut, and then the boom is retracted on the boom side. By pressing the side strut with the second telescopic cylinder, the rear strut and the front strut are also pressed / rotated to the jib side, and both struts are erected to desired positions (positions where tension members can be interposed). Can be raised. Then, when the front end of the front column and the proper place of the jib are connected by a tension member, the assembling work of the jib supporting device is completed. In this way, by pressing the front strut and the rear strut in two steps by the first telescopic cylinder and the second telescopic cylinder, respectively, it is possible to use each telescopic cylinder having a relatively small stroke.

Further, as described above, the jib supporting device can be assembled in such a manner that each of the columns can be erected by the telescopic cylinder and the space holding member is interposed between the columns. Therefore, when assembling the jib supporting device, it is not necessary to use a separate crane for the work of raising each column and the work of connecting the spacing members. further,
Since both ends of the distance maintaining member are connected to each of the columns in advance, the work of connecting the distance maintaining members after opening both columns by a predetermined distance becomes unnecessary, and the worker does not climb to a high place by that much. Complete. Also, when the front support column is raised up to the first stage by the first telescopic cylinder, it is necessary for an operator to set a tension member between the two support columns. This tension member is located near the base end of each support column. Since it can be set to the lower position, for example, a ladder that is not so long can be set on the boom, and the tensioning member can be set while climbing the ladder. In addition, to disassemble the assembled jib support device,
The assembly work of the jib supporting device may be performed in the reverse order.

According to a second aspect of the invention, in the crane with a jib according to the first aspect, a support is provided on the movable side of the first telescopic cylinder, and a roller through which the jib hoisting rope is passed is provided on the support. The roller can be placed in the use position by extending the first telescopic cylinder, and the roller can be placed below by retracting the first telescopic cylinder when the roller is not in use.

According to a third aspect of the present invention, in the crane with a jib according to the first aspect, the support provided on the movable side of the first telescopic cylinder is reversed with the jib exceeding the allowable elevation limit angle with respect to the boom. It is used as a part of the stopper device (reception part that receives the abutting member on the jib side) that blocks the above. Further, since this support can be displaced between the position where the abutting member on the jib side can be received and the position where it cannot be received by expanding and contracting the first telescopic cylinder, the stopper device can be used and not used. The operation of changing to the state can be performed only by the extension / contraction operation of the first extension cylinder.

According to the invention of claim 4, as compared with the crane with a jib of claim 1, one telescopic cylinder allows the front support column of the two support columns stored (fallen) on the boom side to reach a desired large angle at a stretch. It can be raised, and thereby the rear strut can also be raised to the desired angle. Therefore, although a telescopic cylinder having a larger stroke than that in the case of claims 1 to 3 is required, one telescopic cylinder is sufficient to raise both columns, and both columns can be raised by one operation. it can.

[0030]

In the crane with a jib according to the first aspect of the present invention, the front support column stored on the boom side is raised by the first telescopic cylinder until the space holding member is tensioned, and then is stretched between the support columns. After the member is interposed, the second support cylinder stored on the boom side is pressed by the second telescopic cylinder, so that both support columns are held at a predetermined interval (tension). The member can be erected up to a position where the member can be interposed, whereby the jib supporting device can be assembled by a simple operation, and the jib supporting device in use can be disassembled by a similar simple operation. In addition, even if each of the columns and the spacing members are heavy,
There is an effect that another crane is unnecessary for assembling or disassembling them into a predetermined state, and work for climbing to a high place is unnecessary or reduced.

In the crane with a jib according to the invention of claim 2,
In addition to the effect of claim 1, since the roller for passing the jib hoisting rope used when swinging up the jib suspended from the boom tip portion to the front of the boom is provided on the movable side of the first telescopic cylinder, When the roller is unnecessary, the first
By contracting the telescopic cylinder of (1), it is possible to position the roller at a position that does not obstruct the lower part, and the operation of changing the roller between the use position and the non-use position is simply performed by the first telescopic cylinder. Since the operation can be performed by expanding and contracting, there is an effect that the work is extremely easy.

In the crane with a jib according to the invention of claim 3,
In addition to the effect of claim 1, a part of the stopper device (jib which prevents the support provided on the movable side of the first telescopic cylinder from reversing the jib with respect to the boom beyond the allowable elevation limit angle). Used as a receiving part for receiving the abutting member on the side,
Since the support can be displaced between the position where the abutting member on the jib side can be received and the position where the abutting member cannot be received by expanding and contracting the first telescopic cylinder, the stopper device can be used in The operation of changing to the unused state can be performed only by the expansion / contraction operation of the first expansion / contraction cylinder, and there is an effect that the operation of changing the use / non-use of the stopper device can be performed very easily.

In the crane with a jib according to the invention of claim 4,
With one telescopic cylinder, the front strut of the two strut retracted (falling down) on the boom side can be raised up to a desired large angle (a position where a tension member can be interposed) at a stretch, and thereby the rear strut Since it is also possible to stand up to a desired angle, a telescopic cylinder having a stroke larger than that in the case of claim 1 is required, but one telescopic cylinder is sufficient to stand up both columns. In addition, it is possible to raise both the columns by a single operation, and it is possible to reduce the number of members and to simplify the operation of raising the columns.

[0034]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to FIGS.
The crane with a jib of the first embodiment corresponding to
9 to 10 show a crane with a jib of a second embodiment corresponding to claim 4 of the present application.

First, the jib-equipped crane of the first embodiment shown in FIGS. 1 to 8 will be described. This jib-equipped crane is mounted on a carriage 1 and a swing mounted on the carriage 1 so as to be horizontally rotatable. A base 11, a boom 2 mounted on the swivel base 11 so as to be capable of hoisting in a vertical plane, a jib 3 mounted so as to be hoistable at a tip 2b of the boom 2, and the jib 3 is a boom tip. The jib support device 4 that supports the portion 2b at an arbitrary undulation angle is a basic configuration. The trolley 1 is provided with an outrigger device 12, which is used by the outrigger device 12 during crane work.
Can be supported and fixed.

In this embodiment, the boom 2 is of a multi-stage telescopic type (for example, a 5-stage telescopic type). In addition, the tip of the tip boom has a specified length (for example, about 4 to 5 m).
The support 22 having the above is attached, and in this embodiment, the tip of the support 22 serves as the boom tip 2b.

The boom 2 is lifted and lowered by a hoisting cylinder (hydraulic cylinder) 21 within a range of a substantially horizontal posture and a substantially vertical posture. Further, the boom 2 is telescopically operated by a telescopic cylinder incorporated in the boom.

The jib 3 is constructed by connecting a plurality of divided jibs 31 sequentially in a line. The jib 3 has a base end portion 3a at a tip end portion of the boom 2 (a tip end portion of the support 22) 2b.
Is pivotally supported by a shaft 29, and is mounted so as to be capable of undulating within the undulating surface of the boom 2.

Each of the jib supporting devices 4 has a base end portion 42.
a and 41a are pivotally attached to the boom tip 2b, and two front and rear struts 42 and 41, a spacing member 43 that holds the spacing between the front struts 42 and the rear struts 41, and the tip of the front struts 42. A tension member (wire rope) 48 that connects 42b and a proper place of the jib 3, a winch 44 for raising and lowering the jib mounted on the swivel 11, and a rope 45 for pulling up a strut extended from the winch 44. have.

In order to increase the angle formed by the tension member 48 and the jib 3, the front strut 42 and the rear strut 41 are
Each is quite long (for example, about 7-8m each)
It is composed of a rod-shaped body. In addition, the both columns 42, 41
As shown in FIG. 7, each has two left and right rod-shaped bodies. During the crane work, each pillar 41,
A large buckling pressure is applied to 42,
1, 42 must be strong enough to withstand the buckling pressure, and therefore the weight of each strut becomes considerably large. Further, in this embodiment, two rod-shaped members are used for the front and rear columns 42 and 41, respectively, but in other examples, one front column 42 and one rear column 41 are used. You can also

The front support column 42 and the rear support column 41 are connected to the boom tip 2b as follows. That is, the vicinity of the upper rear corner portion of the triangular connecting plate 49 having a small area is integrally fixed to the base end portion 41a of the rear supporting column 41, and the lower corner portion of the connecting plate 49 is attached to the boom. Tip 2
The shaft 56 is pivotally attached to the upper end position of b and the connecting plate 4
The base end portion 42 a of the front support column 42 is attached to the upper front corner of the shaft 9.
It is pivoted at 7. Therefore, the front strut 42 and the rear strut 41 can individually swing within the jib undulation surface on the back side of the boom 2 or the jib 3, respectively.
Further, as shown in FIG. 4, the two columns 41 and 42 can be laid down to a retracted posture in the vicinity of the rear surface of the boom 2 on the base end side, with each base end being pivotally attached to the boom tip 2b. It is like this. In addition, each of the columns 41 and 42 is attached to the boom 2
When stored in the side, along the back side of the boom,
Moreover, the rear support column 41 is on the lower side (inner side) and the front support column 42 is on the upper side (outer side).

Between the front support column 42 and the rear support column 41, there is provided a spacing member 43 (a pair of left and right) for retaining the spacing between the two support columns. In this embodiment, the front and rear two link pieces 43a and 43b are used as the space holding member 43.
3C is used so that it can be bent freely. Then, the spacing member 43 has its end portions at the front end portion 42b of the front support column 42 and the front end portion 41 of the rear support column 41, respectively.
The shaft 52a and 51a are pivotally attached to b and are permanently installed. Therefore, as shown in FIG. 2, the front support column 42 and the rear support column 41 are maximally opened in the state where the spacing member 43 extends in a straight line, and on the other hand, as shown in FIG.
When 3 is bent, the front strut 42 and the rear strut 41 come close to each other. It should be noted that both columns 41, 42 are fully opened (the spacing member 43 is in a tensioned state)
Then, the angle between the two columns is set to, for example, about 60 °. In this embodiment, the bendable link pieces 43a and 43b are used as the distance maintaining member 43, but in other embodiments, the distance maintaining member 43 is made of a flexible material such as rope. May be.

The tension member 48 is mounted with its base end portion fixed to the tip end portion 42b of the front strut 42, and its tip end portion fixed to a proper position near the tip end of the jib 3. The tension member 48 has a pair of left and right sides. Further, in this embodiment, a rope is used as the tension member 48, and a predetermined number of ropes are connected to form a predetermined length according to the length of the jib 3 used. Further, the base end side rope 48a of the tension member 48 has its base end portion always connected to the front side support column front end portion 42b, and when the front support column 42 is stored on the boom side as shown in FIG. The end rope 48a is stored in a vertically long space provided in the front support column 42. And this proximal end side rope 48a is
As shown in FIG. 6, when the front column 42 is tilted forward from the vertical posture, the rope automatically comes out of the vertically long space of the front column 42 due to the weight of the rope. In another embodiment, the tension member 48 may be a rod instead of the rope.

One end of a rope 47 having a predetermined length is connected to the front end portion 42b of the rear column 41, and a sheave 46 is attached to the other end of the rope 47. Then, after the rope 45 extending from the winch 44 for undulating the jib is wound around the sheave 46, the tip end portion of the rope is fixed to the swivel base 11 side. In this embodiment, the rope 45 extending from the winch 44 is indirectly connected to the tip portion 41b of the rear support column 41 via the sheave 46 and the sheave 46, but in other embodiments, the winch is used. Rope 4 from 44
The leading end of 5 may be directly connected to the leading end 41b of the rear column 41.

In the assembled state of the jib support device 4, when the winch 44 is operated in the winding direction, the rope 45 is wound around the winch 44, so that the rear support column 41, the spacing member 43, and the front support column. 42, and the jib tip 3b is pulled through the tension member 48,
When the jib 3 is caused to pivot in the rising direction and the winch 44 is actuated in the unwinding direction, the rope 45 is unwound from the winch 44, so that the jib 3 is pivoted in the falling direction by its own weight. Come to do.

Between the rear strut 41 and the front strut 42,
A tension member 8 is attached to the space holding member 43 so as to be disengageable so as to prevent the columns from approaching each other when the space holding member 43 is under tension. The bracing members 8 in this embodiment can slide longitudinally relative to each other, as best seen in FIG.
The links 8a and 8b of the book are used, and both links 8a and 8b are used.
Is connected by pin coupling (reference numeral 8c) in an extended state so that it cannot be bent and contracted. Also, the links 8a and 8b of the strut member 8 differ from each other in the outer end portions of the respective links by a predetermined distance from the base end pivotal support portions of the rear strut 41 and the front strut 42 at positions near the base end portions. The links 8a and 8b are connected to each other at positions, and when the columns 41 and 42 are opened and closed with the pin 8c connecting the links removed, the links 8a and 8b automatically slide and expand and contract. Then, in a state in which both the columns 41, 42 are opened until the spacing member 43 is tensioned (both links 8a, 8b are also extended), both links 8a, 8
By connecting b with a pin 8c, a striking action is generated between both columns.

The first telescopic cylinder 6 for raising the front support column 42 in the retracted posture is provided near the boom tip 2a.
And a second telescopic cylinder 7 for raising the rear support column 41 which is also in the retracted posture.
It should be noted that one first telescopic cylinder 6 is used at the middle portion in the left-right width direction of the boom tip portion 2b, and one second telescopic cylinder 7 is provided at each end portion in the left-right width direction of the boom tip portion 2b.
Book) used.

In the first telescopic cylinder 6, the base end portion of the tube located on the lower side is pivotally attached to the boom tip end portion 2b, and the rod thereof is vertically movable.
Further, a thin plate-shaped support (two on the left and right) 61 having an appropriate length is pivotally attached to the tip of the rod on the movable side near the tip. The support 61 is pivotally supported by a shaft 65 at an appropriate position near the base thereof on an upper end of a support member 64 fixed to the boom tip 2b. The support 61 can be vertically swung about the pivot shaft 65 by expanding and contracting the first expanding and contracting cylinder 6 in a plane parallel to the swinging surfaces of the columns 41 and 42. ing. The front end of the support 61 serves as a pressing portion 61a for pressing the front support column 42 from below, and the base end portion of the support 61 is a receiving portion 63 of a stopper device described later.
Is used as. The pressing portion 61a of the support 61
Comes into contact with the engaging portion 66 provided on the front strut 42 from the boom side in an unfixed state. Further, in FIG. 3, the support 61 is extended when the first telescopic cylinder 6 is extended most.
Is placed in the state shown by the solid line, and the support is placed in the state shown by the chain line (61 ') when the first telescopic cylinder is at the minimum contraction as shown by the reference numeral 6'. At this time, the roller provided on the support 61 'is at the position of reference numeral 62',
Further, the receiving portion of the stopper device is at the position 63 '.

In the fully contracted state of the first telescopic cylinder 6,
The pressing portion 61a of the support 61 is located below the front support column 42 in the storage posture shown in FIG. 4, and the support 61 is rotated by extending the first telescopic cylinder 6 from the state of FIG. The engaging portion 66 of the front strut 42 is pressed upward by the pressing portion 61a. And the first
When the telescopic cylinder 6 is fully extended, as shown in FIG. 5, the front support column 42 can be raised up at least until the spacing member 43 is tensioned with respect to the rear support column 41 in the retracted posture.

Second telescopic cylinder (two left and right) 7
In the above, the tip of the tube located on the lower side is pivotally attached to the boom tip 2b so that the rod can move up and down. Further, between the tip of the rod on the movable side and the connecting plate pivot shaft 56 at the boom tip 2b,
A swing link 71 is provided. Connecting plate pivot shaft 56
Serves as a swing center of the rear support column 41, and one end of a swing link 71 is pivotally mounted coaxially with the shaft 56. The second telescopic cylinder 7 has a rod tip portion that serves as a pressing portion 72 for pressing the rear support column 41 from below. When the second telescopic cylinder 7 extends and contracts, the pressing portion 7 is pressed.
2 moves in a circular arc up and down about the shaft 56. The pressing portion 72 comes into contact with the engaging portion 76 provided on the rear column 41 from the boom side in an unfixed state.

In the fully contracted state of the second telescopic cylinder 7,
The pressing portion 72 is located below the rear column 41 in the storage posture shown in FIGS. 4 and 5, and the pressing portion 7 is extended by extending the second telescopic cylinder 7 from the state of FIG.
In step 2, the engaging portion 76 of the rear column 41 is pressed upward. Then, when the second telescopic cylinder 7 is fully extended, as shown in FIG. 6, the rear support column 41 can be erected at an angle of approximately 90 ° with respect to the axial direction of the boom 2. . Further, before extending the second telescopic cylinder 7, as shown in FIG. 5, a tension member 8 is provided between the front strut 42 and the rear strut 41 raised by the first telescopic cylinder 6.
If the second support cylinder 41 is extended and the rear support column 41 is pressed, the front support column 42 can also be rotated forward simultaneously as shown in FIG. Become so. Then, in the state shown in FIG. 6, the tension member 48 having a constant length can be provided between the tip portion 42b of the front support column 42 and the proper position of the jib.

Each tip 4 of the rear strut 41 and the front strut 42
Sheaves 51 and 52 are attached to 1b and 42b, respectively. The sheaves 51 and 52 are mounted by commonly using the shafts 51a and 52a that pivotally support the outer ends of the front and rear link pieces 43a and 43b of the spacing member 43, respectively. Further, on the outer peripheral portions of the sheaves 51 and 52, disengagement prevention guides 54 and 55 that prevent the rope 14 from the loading winch 13 via the sheaves from coming off the sheaves are arranged. Each of the slip-off prevention guides 54, 55 uses a roller, and each of the rollers 54, 55 is attached as shown in FIG. That is, the roller 54 for the rear strut side sheave 51 is attached to the support piece 54a provided near the outer end of the rear link piece 43b of the spacing member 43, and the rear link piece 43b is attached to the rear side. When the roller 54 swings with respect to the support column 41, the roller 54 also moves on the outer peripheral portion of the sheave 51. Further, the roller 54 for the rear strut side sheave 51 has a structure in which both the columns 41 and 42 are stored on the boom 2 side as shown in FIG. The jib support device 4 shown in FIG. 2 is located on the front surface side (upper side in FIG. 4) of the column 41.
In the used state (the state where both columns are open and the spacing member 43 is in tension), the roller 54 is located outside in the extension direction of the rear column 41. On the other hand, the roller 55 for the front strut side sheave 52 is attached to a support piece 48c provided on a connecting member 48b that connects the base end portions of the base end ropes 48a of the tension members 48. This connecting member 4
8b is rotatably attached to the shaft 52a of the front strut tip portion 42b. Then, as shown in FIG. 4, when the base end side rope 48a is stored in the vertically long internal space of the front support column 42, the roller 55 is located on the front side of the front support column 42 (upper side in FIG. 4). However, when the jib support device 4 shown in FIG. 2 is in use, the roller 55 is located outside in the extension direction of the front support column 42.

Prior to the assembling of the jib support device 4, the ropes 14 from the winch 13 for loading are routed through the sheaves 51, 52 provided at the distal ends of the columns 41, 42, respectively, prior to the assembly of the jib support device 4. To be done. At that time, the tip end side of the rope 14 is pulled out forward through the space between the sheaves (51, 52) and the slip-off prevention guides (rollers 54, 55). Rollers 54, 5 when pulling forward
5, when the roller comes into contact with the roller,
When the rope is pulled out, the frictional force is reduced and the rope 14
You will be able to pull out lightly. The rope 14 is passed through while the columns 41 and 42 are stored on the boom side. At that time, the rollers 54 and 55 are inserted.
Is located on the upper side (front side) of each of the column front ends 41b, 42b as shown in FIG. 4, the rope can be easily threaded, and the rollers 54,
Even if 55 is located on the front side of the front end of the column, when the jib support device 4 is in use, it automatically comes to the outside in the column extension direction as shown in FIG. It will be routed to each sheave 51, 52 without any trouble.

A loading winch 13 is mounted on the swivel base 11. The tip end side of the rope 14 extended from the loading winch 13 passes through the respective sheaves 51, 52 provided on the respective tip end portions 41b, 42b of the rear strut 41 and the front strut 42, and further, the jib tip end portion. 3b
After passing through the sheave 53, it hangs downward. A hook 15 is attached to the tip of the rope 14.

A stopper device 16 is provided between the jib base end portion 3a and the boom tip end portion 2b to prevent the jib 3 from being turned over backward beyond the allowable elevation limit angle. The stopper device 16 includes an abutting member 17 provided on an upper portion of the jib 3 on the proximal end side and a receiving portion 63 (see FIG. 3) provided on a proximal end portion of the support 61 of the first telescopic cylinder 6. is doing. As the abutting member 17, the same one as the known example shown in FIG. 11 is used. As shown in FIG. 3, the receiving portion 63 provided at the base end portion of the support 61 allows the jib 3 to have an allowable elevation limit as shown by reference numeral 3'when the first telescopic cylinder 6 is in the most extended state. It is located at a position where it can receive the abutting member 17 on the jib side when trying to reverse backward beyond an angle, and when the first telescopic cylinder 6 is contracted as indicated by reference numeral 6 ', the receiving portion 63 has the reference numeral. At the position 63 ', even if the jib 3 is turned upside down to the position 3', the abutting member 17
It is located in a position where it cannot be received.

As described above, in the crane with a jib according to this embodiment, the receiving portion 63 can be received or not received by the abutting member 17 on the jib 3 side by expanding and contracting the first telescopic cylinder 6. Since it is possible to displace the stopper device 16 between the use state and the non-use state, the operation of changing the stopper device 16 between the use state and the non-use state can be performed only by the extension / contraction operation of the first extension / contraction cylinder 6.

In the crane with a jib of the first embodiment, the jib supporting device 4 is assembled in the following manner. First, as shown in FIG. 4, the rope 14 from the winch 13 for loading is provided on both columns 41 and 42 in a state in which the boom 2 is laid down to a substantially horizontal posture and both columns 41 and 42 are stored on the boom 2 side. Guide it forward through each sheave 51, 52. Next, the rope 45 from the jib undulating winch 44 is wound around the sheave 46 at the tip of the rope 47 connected to the tip portion 41b of the rear support 41, and then the tip of the rope 45 is fixed on the swivel base 11. To do. Then, in a state where the links 8a and 8b of the strut member 8 are freely expanded and contracted, the first expansion cylinder 6 is expanded to support 61.
As shown in FIG. 5, the front supporting column 42 stored on the boom 2 side is raised by the pressing portion 61a until the spacing member 43 is tensioned. At this time, the rear support column 41 is still lying down to the boom 2 side due to its own weight, and only the front support column 42 is raised, so that the front and rear link pieces 43a and 43b of the spacing member 43 are bent as shown in FIG. It automatically releases from the state and tensions in a straight line. Further, both links 8a and 8b of the strut member 8 are automatically extended.

Next, in this state, the strut members 8 are stretched between the support columns 41 and 42. In that case, the extending links 8a and 8b only need to be connected by the pins 8c. And then, the second telescopic cylinder 7 is extended,
The pressing portion 72 presses the rear strut 41 stored on the side of the boom 2, and the front strut 42 together with the rear strut 41 is indirectly pressed and rotated toward the jib 3 side, so that both strut 41, 4 are supported.
2 up to the position shown in FIG. At this time, the proximal end rope 48a of the tension member stored in the vertically long space of the front support column 42 automatically hangs downward, and the length of the jib 3 is extended to the tip end of the proximal end rope 48a. Correspondingly, a suitable number of ropes are connected to form a tension member 48 having a predetermined length. Then, when the tip end portion 42b of the front support column 42 and the proper position (tip portion 3b) of the jib 3 are connected by the tension member 48, the assembling work of the jib supporting device 4 is completed.

After the jib support device 4 is assembled in this way, the boom 2 is extended and the boom 2 is lifted by the hoisting cylinder 21 while feeding out the rope 45 from the jib hoisting winch 44 as shown in FIG. Then, the jib 3 is suspended vertically. At this time, the front end portion 41 of the rear support column 41
The rope 47 connected to b is the first telescopic cylinder 6
It is placed on the roller 62 provided on the support 61. Then, by winding up the jib hoisting winch 44 in the state of FIG. 8, the jib 3 can be raised up to a predetermined angle via the front centering on the proximal end pivotal support portion.

As described above, in the crane with a jib according to the first embodiment, the columns 42 and 41 can be individually raised by the first and second telescopic cylinders 6 and 7, respectively, and both columns are supported. Since it is possible to assemble the jib support device 4 in a state in which the gap holding member 43 is automatically tensioned, the jib support device 4 can be assembled by raising the columns 42 and 41. It is not necessary to use another crane for connecting the spacing members 43. Further, both ends of the spacing member 43 are preliminarily set on the columns 42, 41.
Since the two columns 42 and 41 are connected to each other, the work of connecting the space holding members 43 after opening both the columns 42 and 41 by a predetermined distance becomes unnecessary, and accordingly, the worker does not have to climb to a high place. When the front support column 42 is raised by the first telescopic cylinder 6 by the first step, it is necessary for an operator to set the tension member 8 between the two columns.
Since the support members are set close to the base end portion (at a low position), the work of setting the supporting member 8 can be performed at a relatively low position. In order to disassemble the assembled jib support device 4, the assembly work of the jib support device may be performed in the reverse order.

Since the support 61 is provided on the movable side of the first telescopic cylinder 6 and the roller 62 through which the jib hoisting rope 47 is passed is provided on the support 61, the first telescopic cylinder 6 can be extended. The roller 62 can be placed in the use position by the use of the roller 62, and when the roller 62 is not used, the roller 62 can be placed in the lower unobtrusive position by contracting the first telescopic cylinder 6.

Further, a part of the stopper device 16 which prevents the support 61 provided on the movable side of the first telescopic cylinder 6 from reversing the jib 3 with respect to the boom 2 beyond the allowable elevation limit angle ( Receiver 6 for receiving the abutting member 17 on the jib side
3), and the support 61 can be displaced between the position where the abutting member 17 of the jib can be received and the position where it cannot be received by expanding and contracting the first expandable cylinder 6. The operation of changing the stopper device 16 to the use state and the non-use state can be performed only by the extension / contraction operation of the first extension / contraction cylinder 6.

In the crane with a jib of the second embodiment shown in FIGS. 9 to 10, the front and rear columns 42 and 41 are stored on the boom side shown in FIG. 9 from a desired standing position (tension) shown in FIG. To stand up to the position where the member can be installed),
Only one telescopic cylinder 9 is used. That is, in the crane with a jib of the second embodiment, between the front end portions 42b and 41b of the front support column 42 and the rear support column 41,
A bendable spacing member 43 similar to that in the first embodiment is provided. Further, a telescopic cylinder 9 having a large telescopic stroke is provided in the vicinity of the boom tip portion 2b, and by extending the telescopic cylinder 9, the front support column 42 in the retracted posture can be immediately raised to a desired position. ing. That is, when the telescopic cylinder 9 is extended from the state where both the columns 41 and 42 are stored on the boom side, the pressing portion 9a at the tip of the movable side (which is circularly rotated by the swinging link 91) causes the engaging portion of the front column 42 to engage. By pressing 66, the front support column 42 is rotated forward to open the interval holding member 43, and after the spacing support member 43 is tensioned, the rear support column 41 is pulled and the rear support column 41 is also raised. Become so. In addition, the telescopic cylinder 9 includes a front support column 42 and a front end portion 42 thereof.
A stroke is required to stand up to a position where a tension member 48 having a predetermined length can be interposed between the b and the jib 3 at a proper position. Further, in the second embodiment, the strut members 8 of the first embodiment are not necessary to raise both the columns, but the strut members 8 may be provided in the second embodiment.
The rest of the configuration of the second embodiment is similar to that of the first embodiment.

In the crane with jib of the second embodiment,
Compared to the crane with a jib of the first embodiment, one telescopic cylinder 9 can raise the front support column 42 of the support columns 41, 42 stored on the boom side at a stretch to a desired large angle, and As a result, the rear support column 41 can also be raised up to a desired angle, so a telescopic cylinder 9 with a large stroke is required, but one extension cylinder is sufficient to raise both support columns. Moreover, both columns can be raised by one operation. Both columns 41, 4
2 is erected to the state shown in FIG. 10, and then a tension member is interposed as in the case of the first embodiment, the jib supporting device 4
Is completed.

[Brief description of drawings]

FIG. 1 is an overall side view showing a usage state of a crane with a jib according to a first embodiment of the present application.

FIG. 2 is a partially enlarged view of FIG.

FIG. 3 is a partially enlarged vertical sectional view of FIG.

FIG. 4 is a first process chart showing the method of assembling the jib supporting device in the crane with jib of FIG. 1.

5 is a state change diagram of FIG. 4. FIG.

FIG. 6 is a state change diagram of FIG.

FIG. 7 is an enlarged plan view of both columns and a spacing member portion of FIG.

FIG. 8 is an explanatory view of a method for swinging up a jib of the crane with a jib of FIG. 1.

FIG. 9 is a view corresponding to FIG. 4 of the crane with a jib according to the second embodiment of the present application.

FIG. 10 is a state change diagram of FIG. 9;

FIG. 11 is a side view of a known crane with a jib.

FIG. 12 is an explanatory view of an assembling method of the jib supporting device in the crane with jib of FIG. 11.

FIG. 13 is a side view of another known crane with a jib.

[Explanation of symbols]

2 is a boom, 2b is a boom tip, 3 is a jib, 4 is a jib supporting device, 6 is a first telescopic cylinder, 7 is a second telescopic cylinder, 8 is a tension member, 9 is an telescopic cylinder, and 16 is a stopper device. , 17 is an abutting member, 41 is a rear support, 4
1a is a base end part, 41b is a front end part, 42 is a front support column, 42
a is a base end part, 42b is a front end part, 43 is a spacing member, 4
4 is a winch for raising and lowering a jib, 45 is a rope, 48 is a tension member, 61 is a support, 62 is a roller, and 63 is a receiving part.

Claims (4)

[Claims] 1. A jib support device (4) for mounting a jib (3) mounted on a tip (2b) of a boom (2) so as to be capable of undulating.
The jib support device (4) and the jib (3) can be separated from the boom tip portion (2b) while the support by the jib support device (4) is released.
Is a front and rear two columns, each of which has a base end portion (42a, 41a) pivotally attached to a boom tip end portion (2b) and which is mounted on the back side of the boom (2) so as to be swingable within a jib undulation surface. (42, 41) and a gap holding member (43) for holding the gap between the front strut (42) and the rear strut (41) thereof.
And a tension member (48) for connecting the front end portion (42b) of the front strut (42) and an appropriate place of the jib (3),
A winch (44) for hoisting a jib provided on the base end side of the boom (2) and a direct or indirect connection to the tip end (41b) of the rear strut (41) extending from the winch (44). A crane with a jib provided with a fixed rope (45), wherein the spacing member (43) is allowed to move toward a side where the front strut (42) and the rear strut (41) are close to each other. On the other hand, when the front strut (42) and the rear strut (41) are separated from each other by a predetermined distance, the front strut (42) is tensioned to prevent further separating operation of the both strut, and the rear strut (41) The front column (42) and the front column (42) are connected to the boom (2) while the base ends (41a, 42a) of both columns are pivotally attached to the boom tip (2b) in a state where the tension member (48) is disconnected. ) Can be collapsed to the storage position close to the rear side of the base end, Rear pillar (41) and the front strut (42) between said spacing member (43) rear pillar in a state of tension (41)
A bracing member (8) is provided to prevent close movement between the front strut (42) and the front strut (42), and is extended in the vicinity of the boom tip (2b) to the front strut (42) that is in the retracted posture and is not fixed. By pressing the front support column (42), the spacing member (43)
First telescopic cylinder (6) that stands up to the extent that
And the rear strut (41) in the retracted position is unfixed by the extension between the front strut (42) and the rear strut (41) in the state where the strut member (8) cannot perform the proximity operation. And push the rear strut (41) up to a position where the front strut (42) can interpose the tension member (48) between the front end (42b) and the jib (2) at a proper position. And a second telescopic cylinder (7) to be obtained, respectively. 2. The first telescopic cylinder (6) according to claim 1, wherein the first telescopic cylinder (6) extends toward the movable side of the first telescopic cylinder (6) to project outward from the rear surface side of the boom tip (2b). A crane with a jib, characterized in that a support (61) is provided, and a roller (62) through which the jib hoisting rope (47) is passed is provided in the support (61). 3. The jib (3) between the upper part of the jib (3) on the proximal end side and the boom tip (2b) is turned backward with respect to the boom (2) beyond an allowable elevation limit angle. There is provided a stopper device (16) for preventing the contact, and the stopper device (16) is provided with an abutting member (17) provided on an upper portion of the jib (3) at the proximal end side and a first telescopic cylinder (6). A support (61) provided on the movable side, and a position where the support (61) can receive the abutting member (17) and a position where the support (61) cannot receive it due to expansion and contraction of the first telescopic cylinder (6). A crane with a jib characterized by being displaced between the two. 4. A jib supporting device (4) is provided with a jib (3) mounted on the tip (2b) of the boom (2) so as to be able to move up and down.
The jib support device (4) and the jib (3) can be separated from the boom tip portion (2b) while the support by the jib support device (4) is released.
Is a front and rear two columns, each of which has a base end portion (42a, 41a) pivotally attached to a boom tip end portion (2b) and which is mounted on the back side of the boom (2) so as to be swingable within a jib undulation surface. (42, 41) and a gap holding member (43) for holding the gap between the front strut (42) and the rear strut (41) thereof.
And a tension member (48) for connecting the front end portion (42b) of the front strut (42) and an appropriate place of the jib (3),
A winch (44) for hoisting a jib provided on the base end side of the boom (2) and a direct or indirect connection to the tip end (41b) of the rear strut (41) extending from the winch (44). A crane with a jib provided with a fixed rope (45), wherein the spacing member (43) is allowed to move toward a side where the front strut (42) and the rear strut (41) are close to each other. On the other hand, when the front strut (42) and the rear strut (41) are separated from each other by a predetermined distance, the front strut (42) is tensioned to prevent further separating operation of the both strut, and the rear strut (41) The front column (42) and the front column (42) are connected to the boom (2) while the base ends (41a, 42a) of both columns are pivotally attached to the boom tip (2b) in a state where the tension member (48) is disconnected. ) Can be collapsed to the retracted position close to the rear side of the base end side. Arm tip near (2b), the tip portion of the pressing to said front pillar (42) in a non-fixed state said front strut with respect to the front pillar (42) in the retracted position by extending (4
2b) and the jib (3) in place, the tension member (4
8) A crane with a jib, characterized in that it is provided with a telescopic cylinder (9) that can stand up to a position where it can be interposed.