JP7167077B2 - working machine - Google Patents

Description

The present invention relates to a work machine equipped with a detachable counterweight.

Generally, in working machines such as hydraulic excavators and hydraulic cranes, a front working machine such as an excavator or crane is provided on the front side of the vehicle body, and a detachable counterweight is provided on the rear side of the vehicle body to balance the front working machine. . There is also known a work machine provided with an attaching/detaching device for attaching/detaching the counterweight to/from the back plate of the vehicle body (for example, see Patent Documents 1, 2, and 3).

The attachment/detachment device has, for example, a support shaft attached to the upper end of the counterweight and extending in the left-right direction, one end of which is rotatably connected to the support shaft, and the other end of which is rotatably connected to a bracket of the vehicle body. and a link mechanism.

JP 2016-44512 A JP-A-08-319637 JP 2007-162454 A

In the attachment/detachment device having the above configuration, the back plate and the counterweight are misaligned in the left-right direction due to the play of the link mechanism or the like during attachment work. Also, since the counterweight is very heavy, alignment in the left-right direction is very difficult.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described actual situation, and its object is to provide a work machine equipped with an attaching/detaching device for attaching/detaching a counterweight to/from a back plate, and to improve the horizontal position of the back plate and the counterweight. A technology that facilitates alignment will be provided.

To achieve the above object, the present invention provides a lower traveling body, an upper revolving body rotatably supported by the lower traveling body, a front work machine supported by the upper revolving body and extending forward, and A working machine comprising a counterweight detachably attached to a back plate provided at the rear of an upper revolving body, and an attachment/detachment device supported by the upper revolving body for attaching/detaching the counterweight to/from the back plate. The attachment/detachment device includes a bracket attached to the lower portion of the back plate, a first support shaft extending in the left-right direction, a second support shaft extending in the left-right direction and rotatably connected to the counterweight, and a connector having a connecting member rotatably connected to each of the first support shaft and the second support shaft, and a state in which the counterweight is attached to the back plate, one end of which is connected to the first support shaft and the other end is rotatably connected to the bracket forward of the first support shaft, and the hydraulic cylinder expands and contracts by supplying and discharging hydraulic oil, and the counterweight is attached to the back plate. a rotating arm whose one end is rotatably connected to the first support shaft and whose other end is rotatably supported by the bracket in front of the first support shaft; The back plate has a guide groove whose lateral width gradually narrows downward from the upper surface, and the back plate extends rearward from the back surface facing the counterweight, and the counterweight is attached to the back plate. It is characterized by having a pin that abuts against and is guided by the guide groove in the process of pulling.

Advantageous Effects of Invention According to the present invention, it is possible to easily align the back plate and the counter weight in the left-right direction in a work machine provided with an attaching/detaching device for attaching/detaching the counter weight to/from the back plate. Problems, configurations, and effects other than those described above will be clarified by the following description of the embodiments.

1 is a side view of a hydraulic excavator that is a typical example of a working machine according to the present invention; FIG. It is a back view of a backboard and an attaching/detaching device. It is a side view of a back plate and an attaching/detaching device. It is a perspective view of a counterweight. FIG. 4 is a diagram showing the positional relationship between pins and guide grooves and the positional relationship between guide holes and bosses in the process of attaching the counterweight to the back plate;

An embodiment of a working machine according to the present invention will be described with reference to the drawings. FIG. 1 is a side view of a hydraulic excavator 1, which is a representative example of a working machine according to the present invention. A specific example of the working machine is not limited to the hydraulic excavator 1, but may be any machine (for example, a crane, a demolition machine, an earth drill, etc.) equipped with a lower running body, an upper revolving body, a front working machine, and a counterweight. may Further, front, rear, left, and right in this specification are based on the viewpoint of an operator who operates the hydraulic excavator 1 on board, unless otherwise specified.

A hydraulic excavator 1 includes a lower traveling body 2 and an upper revolving body 3 supported by the lower traveling body 2 . The lower traveling body 2 has a pair of left and right crawlers 8 . When the rotation of a travel motor (not shown) is transmitted to rotate the pair of left and right crawlers 8, the hydraulic excavator 1 travels. However, the undercarriage 2 may be of a wheeled type instead of the crawler 8 .

The upper revolving body 3 is supported by the lower traveling body 2 so as to be able to revolve. The upper revolving body 3 includes a revolving frame 5 serving as a base, a front working machine 4 attached to the center of the front end of the revolving frame 5 so as to be capable of rotating in the vertical direction, and a cab (operating machine) disposed on the front left side of the revolving frame 5 . seat) 7, a back plate 10 (see FIGS. 2 and 3) arranged at the rear of the revolving frame 5, a counterweight 20 detachably attached to the back plate 10, and a counterweight 20 with respect to the back plate 10. and an attaching/detaching device 30 (see FIGS. 2 and 3) for attaching/detaching the .

The front working machine 4 includes a boom 4a supported by the upper revolving body 3 so as to be able to rise and fall, an arm 4b supported swingably at the tip of the boom 4a, and a bucket supported swingably at the tip of the arm 4b. 4c, and hydraulic cylinders 4d, 4e, 4f that drive boom 4a, arm 4b, and bucket 4c.

The cab 7 has an internal space where an operator who operates the hydraulic excavator 1 rides. Inside the cab 7 are arranged a seat (not shown) on which an operator sits, and operating devices (a steering wheel, pedals, levers, switches, etc.) operated by the operator seated on the seat. When an operator riding in the cab 7 operates the operation device, the lower traveling body 2 travels, the upper revolving body 3 revolves, and the front working machine 4 operates.

Next, configurations of the back plate 10, the counterweight 20, and the attachment/detachment device 30 will be described with reference to FIGS. 2 to 4. FIG. FIG. 2 is a rear view of the back plate 10 and the attachment/detachment device 30. FIG. FIG. 3 is a side view of the back plate 10 and the attaching/detaching device 30. FIG. 4 is a perspective view of the counterweight 20. FIG.

As shown in FIGS. 2 and 3 , the back plate 10 is a plate-like member extending vertically and horizontally at the rear portion of the upper rotating body 3 . Hereinafter, of the surfaces of the back plate 10, the rear facing surface (the surface facing the mounted counterweight 20) is referred to as "back surface 11". The back plate 10 has a pair of pins 12a, 12b, a pair of guide holes 13a, 13b, and a pair of bolt holes 14a, 14b. Further, the back plate 10 supports the attachment/detachment device 30 at the central portion of the back surface 11 in the left-right direction.

A pair of pins 12a and 12b, a pair of guide holes 13a and 13b, and a pair of bolt holes 14a and 14b are formed to be spaced apart in the left-right direction. In other words, the pair of pins 12a and 12b, the pair of guide holes 13a and 13b, and the pair of bolt holes 14a and 14b are formed on opposite sides of the attaching/detaching device 30. As shown in FIG.

The pair of pins 12a, 12b presents a cylindrical outer shape. The pins 12a and 12b protrude rearward from the rear surface 11 at the upper portion of the rear plate 10. As shown in FIG. A pair of guide holes 13 a and 13 b extend forward from the rear surface 11 in the lower portion of the rear plate 10 . The guide holes 13a and 13b do not need to penetrate the back plate 10 as long as they are open on the back surface 11 side of the back plate 10. - 特許庁A pair of bolt holes 14a and 14b pass through the back plate 10 in the thickness direction between the pins 12a and 12b and the guide holes 13a and 13b in the vertical direction.

The counterweight 20 is a heavy object for balancing the weight with the front working machine 4 . Hereinafter, of the surfaces of the counterweight 20, the surface facing upward is referred to as "upper surface 21", and the surface facing forward (the surface facing the back plate 10 when mounted) is referred to as "abdominal surface 22". As shown in FIG. 4, the counterweight 20 includes a recess 23, a pair of mounting brackets 24a and 24b, a pair of guide grooves 25a and 25b, a pair of bosses 26a and 26b, and a pair of bolt holes 27a and 27b. have

The concave portion 23 is a concave portion extending rearward from the abdominal surface 22 in the center portion of the counterweight 20 in the left-right direction. The recessed portion 23 is a space in which the attaching/detaching device 30 is accommodated when the counterweight 20 is attached to the back plate 10 . The pair of guide grooves 25a, 25b, the pair of bosses 26a, 26b, and the pair of bolt holes 27a, 27b are arranged on opposite sides of the recess 23 in the left-right direction.

A pair of mounting brackets 24 a and 24 b are provided inside the recess 23 . The mounting brackets 24a and 24b are formed with through holes 28a and 28b (the reference number "28a" is omitted from the drawing) penetrating in the left-right direction. The counterweight 20 is rotatably connected to the attachment/detachment device 30 via support shafts 42a and 42b (see FIG. 2) inserted through the through holes 28a and 28b.

The pair of guide grooves 25a and 25b are recessed downward from the upper surface of the counterweight 20 and extend in the front-rear direction. The width of the guide grooves 25a and 25b in the left-right direction (hereinafter referred to as "opening width") gradually narrows downward. In other words, the gap between the pair of side walls defining the left and right sides of the guide grooves 25a and 25b gradually narrows downward.

The opening widths of the upper ends of the guide grooves 25a and 25b are larger than the diameters of the pins 12a and 12b. The opening width of the lower ends of the guide grooves 25a, 25b is slightly larger than the diameter of the pins 12a, 12b. Furthermore, the vertical length (groove depth) of the guide grooves 25a and 25b is longer than the diameter of the pins 12a and 12b.

A pair of bosses 26 a and 26 b protrude forward from the abdominal surface 22 of the counterweight 20 . The bosses 26a, 26b have a smaller diameter at the distal end than at the proximal end. That is, the bosses 26a and 26b are tapered. The bosses 26 a and 26 b enter the guide holes 13 a and 13 b of the back plate 10 during the process of mounting the counterweight 20 on the back plate 10 . The bosses 26a and 26b abut on the bottom walls of the guide holes 13a and 13b when the counterweight 20 is attached to the back plate 10. As shown in FIG.

A pair of bolt holes 27a and 27b penetrate the counterweight 20 in the front-rear direction. The bolt holes 27a and 27b are formed at positions communicating with the bolt holes 14a and 14b of the back plate 10 when the counterweight 20 is attached to the back plate 10. As shown in FIG. Bolts (not shown) for fixing the counterweight 20 to the back plate 10 are screwed into the communicating bolt holes 14a, 27a and the bolt holes 14b, 27b.

The attaching/detaching device 30 is a device for attaching/detaching the counterweight 20 to/from the back plate 10 . The attachment/detachment device 30 is fixed to the back surface 11 at the center of the back plate 10 in the left-right direction. As shown in FIGS. 2 and 3, the attachment/detachment device 30 includes a support bracket (bracket) 31, a coupler 32, a hydraulic cylinder 33, and rotating arms 34a and 34b (hereinafter collectively referred to as a "rotating arm"). It may be described as "moving arm 34".).

The support bracket 31 protrudes rearward from the rear surface 11 of the back plate 10 . The support bracket 31 is arranged at the center of the back plate 10 (more specifically, between the pair of pins 12a and 12b, the pair of guide holes 13a and 13b, and the pair of bolt holes 14a and 14b) in the left-right direction. ing. Support bracket 31 supports hydraulic cylinder 33 and pivot arm 34 .

The support bracket 31 is composed of fixing plates 31a and 31b and support plates 31c, 31d, 31e and 31f. The fixing plates 31a and 31b are fixed to the rear surface 11 of the back plate 10 at vertically spaced positions. The support plates 31c, 31d, 31e, and 31f are fixed to the fixed plates 31a and 31b at positions spaced apart in the left-right direction. The support plates 31c, 31d, 31e, and 31f project rearward from the fixed plates 31a and 31b and extend vertically.

The support plates 31 c and 31 d rotatably support the other end of the hydraulic cylinder 33 via the support shaft 35 . The support plates 31c and 31e rotatably support the other end of the rotating arm 34a via the support shaft 36a. The support plates 31d and 31f rotatably support the other end of the rotating arm 34b via the support shaft 36. As shown in FIG.

The connector 32 connects the counterweight 20 with the hydraulic cylinder 33 and the rotating arm 34 . More specifically, the connecting tool 32 connects the counterweight 20 to the hydraulic cylinder 33 and the rotating arm 34 so as to be rotatable about two orthogonal rotating axes. One of the two orthogonal rotation axes extends in the left-right direction.

The coupler 32 includes a support shaft (first support shaft) 41 and support shafts (second support shafts) 42a and 42b (hereinafter collectively referred to as "support shaft 42"). , connecting members 43a and 43b (hereinafter, they may be collectively referred to as “connecting members 43”).

The support shaft 41 extends in the left-right direction. One end of the hydraulic cylinder 33 and one end of the rotating arms 34 a and 34 b are rotatably connected to the support shaft 41 . Furthermore, connecting members 43a and 43b are rotatably connected to the support shaft 41 at both ends outside the rotating arms 34a and 34b.

The support shaft 42 extends in the left-right direction. The support shafts 42a, 42b are inserted into the through holes 28a, 28b of the mounting brackets 24a, 24b. That is, the support shaft 42 is rotatably connected to the counterweight 20 via the mounting brackets 24a and 24b. Connecting members 43a and 43b are rotatably connected to the support shafts 42a and 42b. In other words, the support shaft 42 rotatably connects the connecting member 43 and the counterweight 20 .

The connecting member 43 is rotatably connected to each of the support shafts 41 and 42 . In other words, the connecting member 43 connects the support shafts 41 and 42 . The connecting member 43a includes a first connecting member 44a, a second connecting member 45a, and a support shaft (third support shaft) 46a. The connecting member 43b has the same configuration as the connecting member 43a, and includes a first connecting member 44b, a second connecting member 45b, and a support shaft (third support shaft) 46b.

The first connecting member 44 a is rotatably connected to the support shaft 41 . The second connecting member 45a is rotatably connected to the support shaft 42. As shown in FIG. The support shaft 46 a extends in a direction orthogonal to the support shafts 41 and 42 . The extending direction of the support shaft 46 a changes depending on the rotation angles of the hydraulic cylinder 33 and the rotation arm 34 . The support shaft 46a rotatably connects the first connecting member 44a and the second connecting member 45a.

The hydraulic cylinder 33 includes a cylinder tube 33a having a bottom chamber and a rod chamber, and a cylinder rod 33b projecting from the cylinder tube 33a. The hydraulic cylinder 33 expands and contracts as hydraulic fluid is supplied and discharged. More specifically, the hydraulic cylinder 33 is extended by supplying hydraulic fluid to the bottom chamber and discharging hydraulic fluid from the rod chamber. Further, the hydraulic cylinder 33 is contracted by supplying the hydraulic oil to the rod chamber and discharging the hydraulic oil from the bottom chamber.

The cylinder rod 33b (one end of the hydraulic cylinder 33) is rotatably connected to the support shaft 41. As shown in FIG. A cylinder tube 33 a (the other end of the hydraulic cylinder 33 ) is connected to the support bracket 31 so as to be rotatable around the support shaft 35 .

The rotating arms 34a and 34b are arranged on opposite sides of the hydraulic cylinder 33 in the left-right direction. One ends of the rotating arms 34 a and 34 b are rotatably connected to the support shaft 41 . The other ends of the rotating arms 34a and 34b are connected to the support bracket 31 so as to be rotatable about the support shafts 36a and 36b.

The support shafts 35 , 36 a and 36 b are positioned forward of the support shaft 41 in a state where the counterweight 20 is attached to the back plate 10 . The support shafts 36 a and 36 b are arranged in front of and above the support shaft 35 . Further, the support shaft 41 is always positioned above the imaginary line L connecting the centers of the support shafts 35 and 36b regardless of the expansion/contraction state of the hydraulic cylinder 33 (in other words, the position of the counterweight 20).

FIG. 5 is a diagram showing the positional relationship between the pins 12a, 12b and the guide grooves 25a, 25b and the positional relationship between the guide holes 13a, 13b and the bosses 26a, 26b in the process of attaching the counterweight 20 to the back plate 10. is.

When the hydraulic cylinder 33 is contracted, the hydraulic cylinder 33 and the rotating arm 34 are rotated rearward about the support shafts 35, 36a, 36b, and the counterweight 20 is removed from the back plate 10. As shown in FIG. When the hydraulic cylinder 33 is contracted to the maximum extent, the counterweight 20 is placed on the ground behind the hydraulic excavator 1 .

On the other hand, when the hydraulic cylinder 33 is extended, the hydraulic cylinder 33 and the rotating arm 34 rotate forward about the support shafts 35, 36a, and 36b. At this time, the counterweight 20 advances toward the back plate 10 while rising. When the hydraulic cylinder 33 is fully extended, the counterweight 20 comes into contact with the rear surface of the back plate 10 .

The locus of movement when the counterweight 20 is attached to the back plate 10 has an arc shape with the support shafts 36a and 36b as the center and the length of the rotating arm 34 as the radius. The counterweight 20 is positioned at the lowest position when the hydraulic cylinder 33 is fully contracted, and is positioned at the highest position when the hydraulic cylinder 33 is fully extended.

Here, play exists between the cylinder tube 33a and the support shaft 35, between the cylinder rod 33b and the support shaft 41, and between the rotating arm 34 and the support shafts 36a, 36b, 41. Further, relative rotation of the first connecting members 44a, 44b and the second connecting members 45a, 45b around the support shafts 46a, 46b changes the relative positions of the back plate 10 and the counterweight 20 in the left-right direction. .

Therefore, the counterweight 20 may be displaced in the left-right direction from the predetermined position in the process of being attached to the back plate 10 . Therefore, as shown in FIG. 5, in this embodiment, the back plate 10 and the counterweight 20 are aligned in the horizontal direction by pins 12a and 12b and guide grooves 25a and 25b.

First, when the counterweight 20 advances while rising, the pins 12a and 12b enter the guide grooves 25a and 25b from above. At this time, as shown in FIG. 6A, the positions of the pins 12a and 12b may be shifted from the center of the guide grooves 25a and 25b in the horizontal direction. Also, the positions of the bosses 26a and 26b may deviate from the centers of the guide holes 13a and 13b in the horizontal direction. Furthermore, bosses 26a and 26b are located below guide holes 13a and 13b.

Also, as the counterweight 20 approaches the back plate 10, the pins 12a and 12b move downward within the guide grooves 25a and 25b. At this time, the pins 12a and 12b approach the center of the guide grooves 25a and 25b in the left-right direction while being guided by the side walls of the guide grooves 25a and 25b whose opening width gradually narrows downward. As a result, the guide holes 13a, 13b and the bosses 26a, 26b are brought closer together in the vertical and horizontal directions.

When the hydraulic cylinder 33 is fully extended, the pins 12a and 12b come into contact with the bottom walls of the guide grooves 25a and 25b as shown in FIG. 6(B). As a result, the back plate 10 and the counterweight 20 are aligned in the left-right direction. Further, the lower ends of the guide holes 13a and 13b and the lower ends of the bosses 26a and 26b have the same height position.

At this time, the back plate 10 and the counterweight 20 are separated from each other by a predetermined distance in the front-rear direction. However, the bolt holes 14a and 27a are aligned and the bolt holes 14b and 27b are aligned vertically and horizontally. That is, the bolt holes 14a and 27a communicate with each other, and the bolt holes 14b and 27b communicate with each other.

Next, when bolts are screwed into the communicating bolt holes 14a and 27a and the bolt holes 14b and 27b, the counterweight 20 moves in parallel toward the back plate 10. As shown in FIG. As a result, the bosses 26a and 26b enter the guide holes 13a and 13b. Bosses 26a and 26b abut bottom walls of guide holes 13a and 13b.

Then, the counterweight 20 is attached to the back plate 10 by screwing the bolts until the back plate 10 and the counterweight 20 come into contact with each other. Further, when the bottom chamber and rod chamber of the hydraulic cylinder 33 are communicated with the hydraulic oil tank, the weight of the counterweight 20 is supported by the bottom walls of the guide holes 13a and 13b.

According to the above embodiment, for example, the following operational effects are obtained.

According to the above embodiment, by arranging the hydraulic cylinder 33 and the other end of the rotating arm 34 (that is, the support shafts 35, 36a, 36b) in front of the support shaft 41, the counterweight 20 is lifted while the back is lifted. Move forward toward the plate 10 .

As the counterweight 20 ascends and advances, the pins 12a and 12b enter the guide grooves 25a and 25b from above and move downward along the guide grooves 25a and 25b. Here, if the counterweight 20 is displaced in the left-right direction, the pins 12a and 12b abut against the side walls of the guide grooves 25a and 25b and move downward while being guided.

Since the opening widths of the guide grooves 25a and 25b are narrowed downward, the back plate 10 and the counterweight 20 are automatically aligned in the horizontal direction in the process of moving the pins 12a and 12b downward. be done. Further, the back plate 10 and the counterweight 20 are automatically vertically aligned by the contact of the pins 12a and 12b with the bottom walls of the guide grooves 25a and 25b.

Further, according to the above embodiment, the support shaft 41 is always positioned above the imaginary line L. As shown in FIG. As a result, the attachment/detachment device 30 can remove the counterweight 20 from the back plate 10 only by contracting the hydraulic cylinder 33 , and attach the counterweight 20 to the back plate 10 only by extending the hydraulic cylinder 33 . In other words, there is no need to combine extension and retraction of the hydraulic cylinder 33 in the process of removing (or attaching) the counterweight 20 from the back plate 10 . As a result, the configuration of the attaching/detaching device 30 can be simplified.

Further, according to the above embodiment, the weight of the counterweight 20 is screwed into the bolt holes 14a, 14b, 27a, 27b by bringing the bosses 26a, 26b into contact with the bottom walls of the guide holes 13a, 13b. It can be supported by the bolts and the bosses 26a, 26b abutting on the bottom walls of the guide holes 13a, 13b. This allows thinner bolts to be used to support the same weight of counterweight 20 . Also, the counterweight 20 having a larger weight can be supported with bolts having the same diameter.

In the above embodiment, the guide holes 13a and 13b are formed in the back plate 10, and the bosses 26a and 26b are formed in the counterweight 20. However, the arrangement of the guide holes and bosses is limited to the above example. not. That is, it is sufficient that one of the boss and the guide hole is formed on the rear surface 11 of the back plate 10 and the other of the boss and the guide hole is formed on the abdominal surface 22 of the counterweight 20 .

The above-described embodiments are illustrative examples of the present invention and are not intended to limit the scope of the present invention only to those embodiments. Those skilled in the art can implement the invention in various other forms without departing from the spirit of the invention.

REFERENCE SIGNS LIST 1 hydraulic excavator 2 lower running body 3 upper swing body 4 front work machine 4a boom 4b arm 4c bucket 4d, 4e, 4f, 33 hydraulic cylinder 5 swing frame 7 cab (driver's seat)
8 Crawler 10 Back plate 11 Rear surface 12a, 12b Pins 13a, 13b Guide holes 14a, 14b, 27a, 27b Bolt holes 20 Counterweight 21 Upper surface 22 Abdominal surface 23 Concave portions 24a, 24b Mounting brackets 25a, 25b Guide grooves 26a, 26b Bosses 28a, 28b through-hole 30 attachment/detachment device 31 support bracket (bracket)
31a, 31b fixed plate 31c, 31d, 31e, 31f support plate 32 connector 34a, 34b rotating arm 35, 36a, 36b support shaft 41 support shaft (first support shaft)
42a, 42b support shaft (second support shaft)
43a, 43b connecting member 44a, 44b first connecting member 45a, 45b second connecting member 46a, 46b support shaft (third support shaft)

Claims (5)

a lower running body;
an upper rotating body rotatably supported by the lower traveling body;
a front working machine supported by the upper revolving body and extending forward;
a counterweight detachably attached to a back plate provided at the rear of the upper rotating body;
A working machine comprising an attachment/detachment device supported by the upper revolving body for attaching and detaching the counterweight to and from the back plate,
The attachment/detachment device
a bracket attached to the bottom of the back plate;
A first support shaft extending in the left-right direction, a second support shaft extending in the left-right direction and rotatably connected to the counterweight, and rotatably connected to each of the first support shaft and the second support shaft. a connector having a connecting member;
With the counterweight attached to the back plate, one end is connected to the first support shaft and the other end is rotatably connected to the bracket in front of the first support shaft to supply hydraulic oil. a hydraulic cylinder that expands and contracts by supplying and discharging;
With the counterweight attached to the back plate, one end is rotatably connected to the first support shaft, and the other end is rotatably supported by the bracket forward of the first support shaft. a rotating arm;
The counterweight has a guide groove whose lateral width gradually narrows downward from the upper surface,
The back plate has a pin that extends rearward from the back surface facing the counterweight and is guided by contacting the guide groove while the counterweight is attached to the back plate. working machine. The work machine according to claim 1,
The connecting member is
a first connecting member rotatably connected to the first support shaft;
a second connecting member rotatably connected to the second support shaft;
and a third support shaft extending in a direction orthogonal to the first support shaft and the second support shaft and rotatably connected to the first connection member and the second connection member, respectively. working machine. The work machine according to claim 1,
one of a boss and a guide hole into which the boss enters during the process of attaching the counterweight to the back plate is formed on the back surface of the back plate;
The other of the boss and the guide hole is formed on the abdominal surface of the counterweight facing the back plate,
A working machine according to claim 1, wherein a lower end of the boss and a lower end of the guide hole have the same height position when the pin comes into contact with the bottom wall of the guide groove. In the working machine according to claim 3,
A working machine, wherein the boss has a tapered shape. The work machine according to claim 1,
A working machine, wherein the other end of the rotating arm is rotatably supported by the bracket in front of and above the other end of the hydraulic cylinder.

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