JP2008002113A - Construction machinery - Google Patents

Abstract

[PROBLEMS] To provide a construction machine capable of ensuring a sufficient front view of an operator, improving work efficiency, having a good weight balance and excellent work efficiency.
In a construction machine 1, a cab 4 and a work machine 5 are arranged side by side in a vehicle width direction. The work machine 5 includes a first boom 51 pivoted on a swing body 3 so as to be swingable in a vertical direction, and a first boom 51. A second boom 52 pivoted to the left and right of the first boom 51; a bracket pivotally pivotable to the second boom 52 in a horizontal direction; an arm pivoted on the bracket; A bracket, and a link member 52D that constitutes a link mechanism together with the second boom 52, and the pivot position of the second boom 52 in the first boom 51 is offset from the axis of the first boom 51 to the cab 4 side. The pivot position of the link member 52 </ b> D in 51 is closer to the arm than the pivot position of the second boom 52 in the first boom 51.
[Selection] Figure 2

Description

  The present invention relates to a construction machine, and more specifically to a construction machine having an offset boom.

Conventionally, construction machines such as a hydraulic excavator having an offset boom are known. This hydraulic excavator is configured to include a revolving body that is turnable on the traveling device, a cab that is provided on the revolving body, and a working machine that is provided beside the cab on the revolving body.
The work machine further includes a first boom, a second boom that is an offset boom, a bracket, an arm, and a bucket, and the first boom is pivotally pivoted on the swinging body in the vertical direction. A second boom is pivotally pivoted in the horizontal direction at the tip of the first boom axis, and a bracket is pivoted pivotally in the horizontal direction at the tip of the second boom.
Here, the bracket and the first boom tip are connected to each other by a link rod and constitute a four-bar parallel link mechanism together with the second boom. The bracket is pivoted so that the arm can swing up and down, and the bucket is pivoted around the horizontal axis at the tip of the arm.

In such a hydraulic excavator, the proximal end side and the distal end side bracket of the second boom constituting the four-joint parallel link mechanism are connected by an offset cylinder, and the second boom is connected to the first boom by expansion and contraction of the offset cylinder. The bracket position can be offset with respect to the axis of the first boom.
As a result, the position of the arm connected to the bracket and the position of the bucket connected to the arm can be freely offset in the vehicle width direction with respect to the axis of the first boom. Even so, excavation work can be easily performed by offsetting the bucket.

Incidentally, as shown in FIG. 9, in the conventional excavator 100 having such an offset boom, when the second boom is swung to the left and the bucket is offset to the cab side, the axis of the first boom is extended. The offset angle, which is the angle formed by the axis of the second boom with respect to the line, is increased. When the offset angle increases, as shown by a one-dot chain line in FIG. 9, the locus of the bucket tip when the first boom and the arm are swung up and down is indicated by a solid line in the figure, and the offset angle is zero. There is a problem that the excavation depth becomes shallower as the trajectory becomes smaller.
Therefore, in order to secure the excavation radius and excavation depth in front of the cab, the excavator in which the tip of the first boom is curved and the pivot position of the second boom in the first boom is offset to the front of the cab. Has been proposed (see, for example, Patent Document 1). In such a hydraulic excavator, since the bucket is positioned in front of the cab with the offset angle being zero, the excavation radius and the excavation depth are maximized in the front of the cab.

Japanese Patent Laid-Open No. 10-317412

  However, in the hydraulic excavator described in Patent Document 1, since the tip portion of the first boom protrudes from the front of the cab, there is a problem that the operator's field of view is blocked, the maneuverability is deteriorated, and the working efficiency is lowered. In addition, since the first boom is heavier by the weight of the curved portion at the tip of the first boom, the weight balance of the hydraulic excavator is deteriorated, and the counterweight has to be heavier, and the work efficiency is lowered. is there. Furthermore, since the pivot position of the second boom in the first boom is offset from the axis of the first boom to the front of the cab, the reach of the bucket is narrowed in front of the right side of the cab, and the work efficiency in front of the right side of the cab is reduced. There is also a problem that it falls.

  An object of the present invention is to provide a construction machine that can ensure a sufficient forward view of an operator, improve work efficiency, and is excellent in weight balance and excellent in work efficiency.

  A construction machine according to a first aspect of the present invention is a construction machine including a revolving body that is turnably provided on a traveling device, and a cab and a work machine that are provided on the revolving body, wherein the cab and the work machine include: When the front of the revolving unit is directed in the traveling direction of the traveling device, the working unit is arranged side by side in a vehicle width direction orthogonal to the traveling direction, and the work implement is pivotally pivotable to the revolving unit in the vertical direction. A first boom, a second boom pivoted to the left and right with respect to the first boom, a bracket pivoted horizontally at the tip of the second boom, and the bracket An arm pivotally pivotable in the vertical direction, a link member that forms a four-bar linkage mechanism together with the second boom connecting the first boom and the bracket, and tips of the first boom and the second boom Between An offset cylinder which is provided along the link member and swings the second boom by extending and contracting, and the pivot position of the second boom in the first boom is determined from the axis of the first boom to the cab. The pivot position of the link member in the first boom is closer to the arm than the pivot position of the second boom in the first boom.

A construction machine according to a second aspect of the present invention is a construction machine comprising a revolving body provided on a traveling device so as to be turnable, and a cab and a work machine provided on the revolving body, wherein the cab and the work machine include: When the front of the revolving unit is directed in the traveling direction of the traveling device, the working unit is arranged side by side in a vehicle width direction orthogonal to the traveling direction, and the work implement is pivotally pivotable to the revolving unit in the vertical direction. A first boom, and a second boom pivoted to the left and right with respect to the first boom,
A bracket pivotally pivoted in the horizontal direction at the tip of the second boom, an arm pivoted pivotally in the vertical direction on the bracket, and the second boom connecting the first boom and the bracket. And a link member constituting a four-bar linkage mechanism, and an offset cylinder provided along the link member between the tip ends of the first boom and the second boom and swinging the second boom by extending and contracting. The pivot position of the second boom in the first boom is offset to the cab side from the axis of the first boom, and the pivot position of the offset cylinder in the first boom is the position in the first boom. The second boom is located on the cab side with respect to the pivot position of the second boom.

A construction machine according to a third invention is characterized in that, in the first invention or the second invention, the offset dimension is greater than 0% and less than 20% of the vehicle width dimension.
Here, the vehicle width dimension is the dimension between the outer end portions of the left and right crawler tracks when having a crawler type traveling device, and the dimension between the outer end portions of the left and right tires when having a tire type traveling device. is there.

  In the construction machine according to a fourth aspect of the present invention, in any one of the first to third aspects, the pivot position of the offset cylinder in the first boom is greater than the pivot position of the second boom in the first boom. It is on the arm side.

  A construction machine according to a fifth invention is the construction machine according to any one of the first invention to the fourth invention, wherein a bent portion bent in an offset direction is formed at a tip portion of the first boom, and a side surface of the bent portion. Is characterized in that a pipe insertion hole for inserting a pipe member for supplying pressure oil to the second boom side is formed.

  A construction machine according to a sixth invention is the construction machine according to the fifth invention, comprising a bucket pivotally pivoted on the arm, wherein the second boom is composed of a cylindrical body having a space inside, and the pipe insertion hole Is communicated with the inside of the cylindrical body, and the piping member for supplying pressure oil to the cylinders for the second boom, the arm, and the bucket is inserted into the piping insertion hole. The tubular member is inserted with the piping member for supplying pressure oil to the cylinders for the arm and the bucket.

  According to a seventh aspect of the present invention, there is provided the construction machine according to any one of the first to sixth aspects of the present invention, wherein the rear end portion of the first boom is provided at the front end portion of the first boom when the revolving body is in a very small turning posture. Is characterized in that a chamfered portion is formed so as not to protrude outward from the widthwise end of the traveling device.

According to the first invention, since the pivot position of the second boom in the first boom is offset from the axis of the first boom to the cab side, the offset angle until the bucket is moved to the front of the cab can be small. A sufficient excavation radius and excavation depth can be secured in front of the cab. In addition, since the pivot position of the link member in the first boom is closer to the arm side than the pivot position of the second boom in the first boom, the second boom is swung to the opposite side to the pivot side of the link member. Even if it is made to do, it is difficult for a link member to interfere with the 2nd boom, and it can offset a bucket position largely. From these things, the working range of the cab right and left front can be expanded, and the working efficiency in front of the cab can be improved.
Furthermore, by swinging the second boom greatly, the distance from the revolving body to the tip of the work machine can be shortened when the work machine is accommodated, and the construction machine can be prevented from protruding from the transportation vehicle. it can. Thereby, transportability can be improved, ensuring the safety at the time of transport of a construction machine.

  According to the second invention, the pivot position of the second boom in the first boom is offset to the cab side from the axis of the first boom, and the pivot position of the offset cylinder in the first boom is the position of the second boom in the first boom. Since it is located on the cab side relative to the pivot position, when the second boom is swung to the cab side, the offset angle can be small and the offset cylinder does not interfere with the second boom. For this reason, the second boom can be swung to the cab side to widen the work range on the cab side, and a sufficient excavation radius and excavation depth can be ensured. Thereby, working efficiency can be improved.

According to the third invention, since the offset dimension is larger than 0% and smaller than 20% of the vehicle width dimension, the tip portion of the first boom does not protrude to the front of the cab, and is necessary for work. Visibility can be sufficiently secured.
Further, the pivot position of the second boom in the first boom can be prevented from being close to the end in the width direction of the revolving structure, and the weight balance of the construction machine can be prevented from changing due to the offset of the pivot position. be able to. Thereby, the stability at the time of work is maintained and work can be performed efficiently.
Furthermore, since the offset dimension is small and the left side surface of the first boom and the right side surface of the second boom are substantially flush with each other, an increase in the weight of the work implement can be prevented and the torsional rigidity of the offset boom can be kept high. . As a result, the weight balance and stability of the excavator can be kept good, and work can be performed efficiently without increasing the weight of the counterweight.

  According to the fourth invention, since the pivot position of the offset cylinder in the first boom is on the arm side with respect to the pivot position of the second boom in the first boom, the second boom is swung opposite to the pivot side of the offset cylinder. Even when it is moved, it is difficult for the offset cylinder to interfere with the second boom, and the bucket can be largely offset.

  According to the fifth invention, the pipe insertion hole for inserting the pipe member for supplying the pressure oil to the second boom side is formed on the side surface of the bent portion formed at the distal end portion of the first boom. The piping member can be extended to the second boom side without causing the piping member to go outside the bent portion of the first boom. For this reason, it can prevent that a piping member is damaged by operation | movement of a working machine.

  According to the sixth invention, a pipe member for supplying pressure oil to the cylinders for the second boom, the arm, and the bucket is inserted into the pipe insertion hole, and the cylindrical body constituting the second boom is formed. Since the piping member for supplying pressure oil to each cylinder for arms and buckets is inserted, damage to the piping member due to contact with the outside can be prevented. Thereby, work can be performed without worrying about the piping member coming into contact with the outside, and work efficiency is improved.

  According to the seventh aspect, since the chamfered portion is formed at the front end portion of the first boom, the rear end portion of the first boom protrudes outward from the width direction end portion of the traveling device during the so-called ultra-small turning. Can be effectively suppressed. Thereby, turning in a narrow place can be performed more safely.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
[1] Overall Configuration In FIGS. 1 and 2, a hydraulic excavator 1 (construction machine) includes a traveling device 2, a revolving structure 3, a cab 4, and a work machine 5.
The traveling device 2 is a crawler type, and a track frame (not shown) provided immediately below the revolving structure 3 and a pair of traveling bodies 21 provided at both ends of the track frame in the vehicle width direction perpendicular to the traveling direction. It is configured with. The traveling body 21 includes a drive wheel protruding from the track frame and a crawler belt 22 wound around the idle wheel, and the hydraulic excavator 1 extends along the extending direction of the crawler belt 22 by driving the drive wheel. Move forward and backward.

  On the track frame of the traveling device 2, a revolving structure 3 is provided so as to be able to turn. A cab 4 is provided at a position eccentric from the center of the revolving body 3, and an operator gets on the cab 4 to operate the hydraulic excavator 1. An operator seat 41 is provided in the cab 4, and work machine levers (not shown) are provided on both sides of the operator seat 41. Although not shown, the floor surface 42 of the cab 4 is provided with a travel lever for travel operation and an operation pedal for offset operation. A work machine 5 is provided on the right side of the cab 4. That is, the cab 4 and the work implement 5 are arranged side by side in the vehicle width direction on the revolving structure 3 with the front of the revolving structure 3 facing the traveling direction of the traveling device 2.

[2] Detailed Configuration of Work Machine 5 The work machine 5 includes a first boom 51, a second boom 52, a bracket 53, an arm 54, and a bucket 55, and a boom cylinder 51A and an offset cylinder 52A for operating these elements. Arm cylinder 54A and bucket cylinder 55A. Here, each of the cylinders 51A, 52A, 54A, and 55A is a hydraulic cylinder, and its hydraulic source is a hydraulic pump that is driven by an engine (not shown) provided in the revolving structure 3.

  As for the 1st boom 51, the base end side is pivoted by the revolving structure 3 by the foot pin 51B, and expansion and contraction of the boom cylinder 51A that connects the distal end portion of the first boom 51 and the revolving structure 3 below the first boom 51, It can be swung vertically. The first boom 51 includes a chamfered portion 511 having a chamfered portion bent in the vertical direction of the first boom 51 and a bent portion 512 bent so as to be offset from the axial direction of the first boom 51. In preparation.

  As shown in FIG. 3, the bent portion 512 has a shape in which the distal end side is bent toward the cab 4 while the first boom 51 is supported on the revolving body 3. A pipe insertion hole 513 for inserting a hydraulic pipe for supplying pressure oil to the cylinders 52A, 54A, 55A is formed. And the 2nd boom 52 is pivoted by the pin 51C at the front-end | tip of the 1st boom 51 of such a structure.

  The second boom 52 is composed of a cylindrical body having a space inside, and an opening portion of the cylindrical body of the first boom 51 is connected to the pipe insertion hole 513 of the first boom 51. It faces the pipe insertion hole 513 and is connected to the second boom 52. Specifically, the second boom 52 is pivotally pivotable to the left and right with respect to the first boom at a position offset from the axis of the first boom 51 toward the cab 4 at the tip of the bent portion 512. A potentiometer 52B (see FIG. 3) for detecting an offset angle when the second boom 52 swings is provided at the base end portion of the second boom 52.

Such a front end portion of the second boom 52 and the bent portion 512 of the first boom 51 are connected to each other by the offset cylinder 52A on the left side, that is, the cab 4 side. That is, the tip of the cylinder rod of the offset cylinder 52A is pivoted to the tip of the second boom 52 by the pin 52C, and the cylinder bottom of the offset cylinder 52A is pivoted to the bent portion 512 by the pin 51D.
Further, in the second boom 52, among the hydraulic pipes inserted through the pipe insertion holes 513, the hydraulic pipes for the arm cylinder 54 </ b> A and the bucket cylinder 55 </ b> A are inserted into the second boom 52. A bracket 53 is connected to the tip of the second boom 52.

  The bracket 53 is pivotally pivoted in the horizontal direction at the tip of the second boom 52 by a pin (not shown), and the bracket 53 and the bent portion 512 of the first boom 51 are linked to each other on the link rod ( Link member) 52D. That is, one end of the link rod 52D is pivoted to the bracket 53 by the pin 53A, and the other end is pivoted to the bent portion 512 by the pin 51D.

  Here, the link rod 52D and the offset cylinder 52A are pivoted by a common pin 51D. The position of the pin 51D, that is, the pivot position of the link rod 52D in the first boom 51, and the offset cylinder 52A in the first boom 51 The pivot position is located forward of the pivot position of the second boom 52 in the first boom 51, that is, the position of the pin 51C. The link rod 52D and the offset cylinder 52A may be pivoted by separate pins without providing the respective pivot positions on the same axis.

  The bent portion 512 of the first boom 51, the second boom 52, the bracket 53, and the link rod 52D constitute a four-joint parallel link mechanism, and an offset cylinder 52A that connects the bent portion 512 and the distal end portion of the second boom 52. The bracket 53 swings with respect to the axis of the first boom 51 due to the expansion and contraction of the first boom 51. An arm 54 is connected to the tip of the bracket 53.

The arm 54 is pivoted at the tip of the bracket 53 so as to be swingable in the vertical direction. A cylinder mounting portion 541 for mounting an arm cylinder 54A is provided in the vicinity of the pivot portion of the arm 54, and the cylinder mounting portion 541 detects an arm angle that is a swing angle of the arm 54 with respect to the bracket 53. A potentiometer (not shown) is provided.
Here, in the arm cylinder 54A, the cylinder body portion is pivoted on the bracket 53 and the tip of the cylinder rod is pivoted on the cylinder mounting portion 541 so that the arm cylinder 54A can swing in the vertical direction. The arm 54 swings up and down by the expansion and contraction of the arm cylinder 54A. A bucket 55 is attached to the tip of the arm 54.

  The bucket 55 is a part for actually excavating or loading excavated earth and sand on a dump truck or the like, and is attached to the tip of the arm 54 so as to be swingable around a horizontal axis. The bucket 55 and the cylinder mounting portion 541 of the arm 54 are connected by a bucket cylinder 55A, and the bucket 55 swings by expanding and contracting the bucket cylinder 55A.

On the other hand, as shown in FIG. 2, in such a hydraulic excavator 1, the first boom 51 in the dimension from the axis of the first boom 51 to the pin 51 </ b> C, that is, the pivot position of the second boom 52 in the first boom 51. The offset dimension D from the axis to the cab 4 side is set to be greater than 0% and less than 20% of the vehicle width dimension W of the excavator 1. In such a setting, the front end portion of the first boom 51 does not overhang the front of the cab 4, so that the operator's view is not hindered.
Further, the pivot position of the second boom 52 is set within 10% of the vehicle width dimension W from the turning center of the revolving structure 3. This restricts the pivot position of the second boom 52 in the first boom 51 from being greatly separated from the turning center of the revolving structure 3, thereby preventing the weight balance of the excavator 1 from deteriorating.

[3] Action of Hydraulic Excavator 1 In the hydraulic excavator 1 configured as described above, the first boom is connected to the arm 54 connected to the bracket 53 and the bucket 55 connected to the arm 54 from the movement of the parallel link described above. It can be offset parallel to the left and right with respect to the 51 axis. That is, as shown in FIG. 4, by contracting the offset cylinder 52 </ b> A, the second boom 52 swings to the left, whereby the positions of the arm 54 and the bucket 55 are offset to the left with respect to the axis of the first boom 51. To do. At this time, the offset angle θ2, which is the angle formed by the axis of the second boom 52 with respect to the axis of the first boom 51, is equivalent to the amount of offset of the position of the pin 51C toward the cab 4 within the aforementioned setting range. Smaller than that. Therefore, as shown by the one-dot chain line in FIG. 5, the locus of the tip of the bucket 55 when offset to the front of the cab 4 is compared with the locus when the offset angle θ2 is zero, which is indicated by the solid line in the figure. A sufficient excavation radius can be secured in front of the cab 4 without much difference.

On the other hand, in FIG. 4, by extending the offset cylinder 52 </ b> A, the second boom 52 swings to the right, and thereby the positions of the arm 54 and the bucket 55 are offset to the right with respect to the axis of the first boom 51. At this time, since the pin 51D is located on the front side of the pin 51C, even when the second boom 52 is swung to the right, the link rod 52D and the offset cylinder 52A are unlikely to interfere with the second boom 52. The second boom 52 can also be swung to the right. As a result, the bucket 55 can be largely offset to the right side, and the work area in front of the cab 4 on the right side is enlarged.
Moreover, since the 2nd boom 52 can be rock | fluctuated largely to the right side, the transport efficiency at the time of transport of the hydraulic shovel 1 can be improved. This point will be described below with reference to FIGS.

The hydraulic excavator 1 may be transported while being loaded on a dump truck. At this time, it is necessary to prevent the work machine 5 from protruding from the dump truck to an obstacle to transport. Specifically, as shown in FIGS. 6 and 7, the second boom 52 is swung to the right side in a state of being loaded on a dump vessel 90 (not shown), and the bracket 53 is pivoted from the turning center of the revolving structure 3. Reduce the radial distance to the tip of the. Then, the swivel body 3 is slightly swung counterclockwise, and the bucket 55 is placed on the outer frame of the vessel 90 so that the arm 54, the bucket 55 and the link portion thereof do not protrude greatly forward. The protrusion of 1 is set within a predetermined value.
As described above, since the hydraulic excavator 1 can swing the second boom 52 to the right as well, it is possible to effectively prevent the hydraulic excavator 1 from protruding from the vessel 90 at this time.

  Furthermore, the hydraulic excavator 1 according to the present embodiment is a so-called ultra-small turning type, and as shown in FIG. 8, the work implement 5 does not protrude greatly from the end in the width direction of the traveling device 2 to the outside. It is set so that it can be turned. At this time, the chamfered portion 511 of the first boom 51 effectively suppresses the first boom 51 from protruding from the end portion in the width direction of the traveling device 2.

[4] Modifications of Embodiments The present invention is not limited to the above-described embodiments, and includes other configurations that can achieve the object of the present invention. The following modifications and the like are also included in the present invention. It is.
In the above embodiment, the cab 4 is provided on the left side of the revolving unit 3 and the work implement 5 is provided on the right side in a state where the front of the revolving unit 3 is directed in the traveling direction of the traveling device 2. It is not restricted and each positional relationship may be reverse. In this case, the position of the pin 51C needs to be offset to the right from the axis of the first boom 51.

  In the embodiment, the offset cylinder 52A is connected to the distal end portion of the first boom 51 and the distal end portion of the second boom 52. However, the present invention is not limited to this, and the proximal end portion of the second boom 52 and the bracket 53 are connected. It may be connected. In this case, the relationship between the expansion / contraction direction of the offset cylinder 52 </ b> A and the rotation direction of the second boom 52, that is, the relationship between the expansion / contraction direction of the offset cylinder 52 </ b> A and the offset direction of the bucket 55 with respect to the axis of the first boom 51. This is the opposite of the case of the above embodiment.

  In the embodiment, the hydraulic excavator 1 is used. However, the present invention is not limited to this, and other construction machines may be used as long as they have an offset boom. For example, a tire type traveling device is provided instead of a crawler type traveling device. It may be a construction machine. Further, the cab 4 is recognized not only with the mounted type, but also with a canopy, and the offset direction of the pivot position of the second boom 52 by the arrangement of the control device such as a work implement lever and the operator seat 41. Possible forms are also included in the present invention.

  In the above-described embodiment, the four-joint link mechanism is configured by using the cylindrical second boom 52. However, the present invention is not limited thereto. For example, the second boom 52 and the link rod 52D are each a so-called C having a C-shaped cross section. A four-node link may be configured by forming a channel and the concave portions facing each other. In this case, the space formed by the concave portions facing each other of the second boom 52 and the link rod 52D corresponds to the space inside the second boom 52.

  In addition, although the present invention has been particularly illustrated and described with respect to specific embodiments, the present invention is not limited to the embodiments described above without departing from the scope of the technical idea and object of the present invention. The trader can add various modifications.

  The present invention can be used for a hydraulic excavator and is applicable to any construction machine having an offset boom.

It is a side view which shows the construction machine which concerns on one Embodiment of this invention. It is a top view which shows the construction machine in the said embodiment. It is a perspective view which partially enlarges and shows the connection part of the 1st boom and 2nd boom of the construction machine in the said embodiment. It is a figure which shows the motion of the working machine of the construction machine in the said embodiment. It is a figure which shows the operation | movement locus | trajectory of the bucket tip of the construction machine in the said embodiment. It is a side view which shows the state at the time of transport of the construction machine in the said embodiment. It is a top view which shows the state at the time of transport of the construction machine in the said embodiment. It is a side view which shows the ultra small turning state of the construction machine in the said embodiment. It is a figure which shows the operation | movement locus | trajectory of the bucket tip of the conventional construction machine.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Hydraulic excavator (construction machine), 2 ... Traveling device, 3 ... Revolving body, 4 ... Cab, 5 ... Working machine, 51 ... 1st boom, 52 ... 2nd boom, 52A ... Offset cylinder, 52D ... Link rod ( Link member), 53 ... Bracket, 54 ... Arm, 511 ... Chamfered portion, 512 ... Bent portion, 513 ... Pipe insertion hole, D ... Offset dimension, W ... Vehicle width dimension.

Claims (7)

A construction machine comprising a revolving body provided on a traveling device so as to be able to turn, and a cab and a work machine provided on the revolving body,
The cab and the work implement are juxtaposed in a vehicle width direction orthogonal to the traveling direction when the front of the revolving structure is directed to the traveling direction of the traveling device,
The working machine is
A first boom pivoted on the swivel body in a vertically swingable manner;
A second boom pivoted to the left and right with respect to the first boom;
A bracket pivotally pivoted horizontally at the tip of the second boom;
An arm pivoted on the bracket so as to be swingable in the vertical direction;
A link member constituting a four-bar linkage mechanism together with the second boom connecting the first boom and the bracket;
An offset cylinder provided along the link member between the first boom and the second boom tip, and swinging the second boom by extending and contracting;
The pivot position of the second boom in the first boom is offset from the axis of the first boom to the cab side,
The construction machine characterized in that the pivot position of the link member in the first boom is closer to the arm than the pivot position of the second boom in the first boom. A construction machine comprising a revolving body provided on a traveling device so as to be able to turn, and a cab and a work machine provided on the revolving body,
The cab and the work implement are juxtaposed in a vehicle width direction orthogonal to the traveling direction when the front of the revolving structure is directed to the traveling direction of the traveling device,
The working machine is
A first boom pivoted on the swivel body in a vertically swingable manner;
A second boom pivoted to the left and right with respect to the first boom;
A bracket pivotally pivoted horizontally at the tip of the second boom;
An arm pivoted on the bracket so as to be swingable in the vertical direction;
A link member constituting a four-bar linkage mechanism together with the second boom connecting the first boom and the bracket;
An offset cylinder provided along the link member between the first boom and the second boom tip, and swinging the second boom by extending and contracting;
The pivot position of the second boom in the first boom is offset from the axis of the first boom to the cab side,
The construction machine characterized in that the pivot position of the offset cylinder in the first boom is closer to the cab than the pivot position of the second boom in the first boom. In the construction machine according to claim 1 or 2,
The construction is characterized in that the offset dimension is greater than 0% and less than 20% of the vehicle width dimension. The construction machine according to any one of claims 1 to 3,
Before SL pivot region of the offset cylinder of the first boom, the first than the pivot region of the second boom in the boom, construction machine, characterized in that in said arm. The construction machine according to any one of claims 1 to 4,
A bent portion that is bent in the offset direction is formed at the tip of the first boom,
A construction machine, wherein a pipe insertion hole for inserting a pipe member for supplying pressure oil to the second boom side is formed on a side surface of the bent portion. The construction machine according to claim 5,
The arm is provided with a pivotally pivoted bucket,
The second boom is composed of a cylindrical body having a space inside,
The pipe insertion hole communicates with the inside of the cylindrical body,
The piping member for supplying pressure oil to the cylinders for the second boom, the arm, and the bucket is inserted into the piping insertion hole,
The construction machine, wherein the pipe member for supplying pressure oil to the cylinders for the arm and the bucket is inserted into the cylindrical body. The construction machine according to any one of claims 1 to 6,
A chamfered portion is formed at the front end portion of the first boom so that the rear end portion of the first boom does not protrude outward from the end portion in the width direction of the traveling device when the revolving body is in a very small turning posture. Construction machinery characterized by

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