JP2011246931A - Work machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a work machine which enables stable support without a cradle of a working attachment in assemble/disassemble and transportation with being folded, keeps an overall height of the folded attachment low, and avoids damage to a working device and a link mechanism.SOLUTION: In a working machine, such as a demolition machine including a super long attachment which is triple-folded at an inter-boom 26 so that a boom 25 is in an upper side and an arm 27 is in a lower side with both an inter-boom and an arm cylinders 30, 31 being in the shortest state when in assemble/disassemble and transportation of a working attachment 24, a flat part 27a is formed at a bottom surface of the arm 27 over substantially its full length so as to be horizontal to be grounded in a folded state of the working attachment 24, and a working device cylinder 32 and a link mechanism 33 are provided to an upper surface of the arm in the folded state so as to be positioned in an installation space S defined between a leading end of the arm and the boom for cylinders and the like.

Description

  The present invention relates to a work machine such as a dismantling machine configured by attaching a work attachment to a base machine.

  The background art will be described by taking as an example a dismantling machine with an ultra-long attachment used for dismantling high-rise buildings.

  As shown in FIG. 5, the demolition machine includes a front portion of a base machine 3 which includes a crawler type lower traveling body 1 and an upper revolving body 2 which is mounted on the lower traveling body 1 so as to be rotatable about a vertical axis. And the work attachment 4 is mounted.

  The work attachment 4 includes a boom 5 that can be raised and lowered to the base machine 3 (upper swing body 2), and a short length that is attached to the tip of the boom 5 so as to be rotatable about a horizontal axis for the purpose of expanding the work range. An inter-boom 6, an arm 7 attached to the tip of the inter-boom 6 so as to be rotatable about a horizontal axis, and a working device attached to the tip of the arm 7 (open / closed type called nibler in the example) The crushing apparatus of FIG. 1 is provided, but a bucket for excavation or a breaker for crushing may be attached).

  The boom 5 is formed by detachably connecting an upper front boom 5b to a lower main boom 5a, and is disassembled into a set of a base machine 3 and a main boom 5a, and a set of work attachments 4 excluding the main boom 5a. And then transported (see FIG. 6) and assembled after transport.

  Note that the front boom 5b is normally configured by detachably connecting a plurality of stages of boom bodies, but here, it is shown as a single unit for the sake of simplification of the drawing.

  Further, as cylinders (hydraulic cylinders) for operating the work attachment 4, a boom cylinder 9 for raising and lowering the boom 5 (entire attachment), an inter boom cylinder 10 for operating the inter boom 6, and an arm cylinder 11 for rotating the arm 7. In addition, a working device cylinder 12 for rotating the working device 8 is provided. A link mechanism 13 converts the thrust of the working device cylinder 12 to the working device 8 by converting it into turning power.

  The inter boom and arm cylinders 10 and 11 are provided between the boom 5 (front boom 5b) and the inter boom 6 and between the inter boom 6 and the arm 7, respectively, on the front side of the attachment.

  Further, the work device cylinder 12 is provided between the arm 7 and the work device 8 on the attachment rear side.

  The above configuration is shown in Patent Documents 1 and 2.

  Further, Patent Document 3 discloses that the working device cylinder 12 and the link mechanism 13 are arranged on the opposite side (arm front side) to the known technique shown in FIGS.

JP-A-11-193543 Japanese Utility Model Publication No. 5-67652 JP-A-8-226236

  Conventionally, in such a dismantling machine with an ultra-long attachment, at the time of disassembly / assembly, as shown in the solid line of FIG. 5 and FIG. The boom 5 is on the upper side and the arm 7 is on the lower side with the inter boom 6 as a boundary, and is folded and placed on the ground.

  6 and 7, when transported, the base machine 3 and the main boom 5a are separated into a set of the base machine 3 and the main boom 5a and a set of the work attachment 4 excluding the main boom 5a, and placed on a transport vehicle 14 such as a trailer. Transport. At this time, the working device 8 is removed.

  The assembly work after transportation and the work of reassembling the work attachment 4 according to the application are performed in the same manner.

  5 to 7, reference numeral 15 denotes a grounding bracket provided on the lower surface side of the arm in the folded state.

  However, in the known techniques shown in FIGS. 5 to 7 and Patent Documents 1 and 2, when disassembling / assembling and transporting the work attachment 4, the work attachment 4 is folded as shown by the solid line in FIG. Since the arm 7 positioned on the lower side is grounded only at a small part (actually, the grounding bracket 15) as shown in the drawing, the work is performed in a state separated from the main boom 5a. The support state of the attachment 4 becomes unstable.

  Therefore, conventionally, the work attachment 4 is supported by a table 16 indicated by a two-dot chain line in FIG. 6 during disassembly / assembly and transportation.

  In other words, in the known technique, the arm shape and the folding posture are determined on the assumption that the work attachment 4 is supported by the pedestal 16 in the folded state.

  However, although this pedestal 16 is shown in a simplified manner in FIG. 6, in actuality, it is necessary to have a full-scale thing sufficient to stably support the entire attachment, and the structure is complicated, large and heavy, and the cost is low. It was disadvantageous in terms of handling.

  Further, since the entire attachment is raised by the cradle 16, the total height H1 of the attachment during disassembly / assembly and transportation (see FIG. 5) becomes large, and the disassembly and assembly work becomes a work at a high place, thereby improving workability and safety. In addition to being disadvantageous in terms of transportation, it had become a barrier to transportation, such as having to use low-floor trailer transportation.

  Furthermore, since the working device cylinder 12 and the link mechanism 13 (hereinafter, the working device cylinder mechanism may be collectively referred to as “working device cylinder mechanism”) are positioned on the lower surface side (grounding surface side) in the folded state, the working device cylinder mechanism is The attachment height H1 has become larger and larger because there is a possibility that the arm tip may be damaged due to contact with the loading platform and the arm tip side needs to be folded in order to avoid this.

  According to the known technique described in Patent Document 3, since the working device cylinder mechanism is located on the arm upper surface side in the attachment folded state, there is no fear of contact between the mechanism and the ground and the loading platform, but the attachment supporting state However, the problem that the cradle is unstable, the cradle is necessary, and the total height of the attachment is increased by the cradle cannot be solved.

  Therefore, the present invention can stably support a work attachment in a folded state without disassembly in a disassembly / assembly or transportation, or even with a simple and small cradle, while keeping the overall height low, and the working device cylinder and the link mechanism. A work machine capable of preventing breakage is provided.

  According to the first aspect of the present invention, a work attachment is attached to the base machine, and the work attachment is attached to the base machine so that it can be raised and lowered, and is attached to the tip of the boom so as to be rotatable around a horizontal axis. An inter-boom, an arm pivotably attached to the tip of the inter-boom about a horizontal axis, a work cylinder attached to the tip of the arm, a boom cylinder for raising and lowering the boom, and an attachment An inter boom cylinder for rotating an inter boom provided between the boom and the inter boom on the front side, and an arm cylinder for rotating the arm provided between the inter boom and the arm on an attachment front side; A work device cylinder for rotating the work device via a link mechanism. In disassembling / assembling and transporting, the inter boom and the arm both cylinders are in the most contracted state, and the boom is folded into a three-fold state with the boom at the upper side and the arm at the lower side with the inter boom as a boundary. On the lower surface side of the arm with the work attachment folded, a flat portion is formed which is grounded over a length range sufficient to support the entire attachment in a state in which the attachment is folded. The apparatus cylinder and the link mechanism are provided on the upper surface side of the arm in the folded state so as to be positioned in the arm tip side space formed between the arm tip side part and the boom.

  According to a second aspect of the present invention, in the configuration of the first aspect, the flat portion is formed on the lower surface side of the arm in the folded state over substantially the entire length of the arm.

  According to a third aspect of the present invention, in the configuration of the first or second aspect, the upper surface of the arm in the folded state is formed as an inclined surface that descends toward the tip of the arm.

  According to a fourth aspect of the present invention, in the configuration of the third aspect, the cross-sectional area of the arm is maximized at an intermediate point in the arm length direction, and the tip side portion of the upper surface of the arm in the folded state is at the tip side of the arm tip. On the other hand, the base end portion of the intermediate point is formed on the inclined surface that descends toward the base end of the arm, so that the entire upper surface of the arm has an upward convex shape. It is formed.

  According to a fifth aspect of the present invention, in the configuration of any one of the first to fourth aspects, the attachment points A of the inter boom and the arm cylinders with respect to the inter boom are A and B, and the attachment point A is lowered in the folded state of the attachment. Side, mounting point B is located on the upper side, and both the mounting points A and B are displaced in the width direction of the inter boom. It is attached.

  According to the present invention, a flat portion that is grounded over a length range sufficient to support the entire attachment in the attachment folded state is formed on the lower surface side of the arm in the attachment folded state. The entire work attachment can be supported sufficiently stably by this grounding portion during assembly and transportation.

  As a result, the cradle can be omitted or replaced with a complementary, simple and compact one, which is advantageous in terms of cost and handling. The workability and safety of work, and the transportability can be improved.

  In addition, since the work device cylinder mechanism is disposed on the arm upper surface side (arm tip side space formed between the arm tip side part and the boom) in the attachment folded state, the mechanism is damaged by contact with the ground. There is no fear, and the arm tip side portion can be brought closer to the ground, that is, the entire arm can be brought closer to the horizontal.

For this reason,
(1) forming a flat part over a long range;
(2) The arm tip side space can be made large enough to install the work device cylinder mechanism.

  In this case, according to the second aspect of the present invention, since the flat portion is formed substantially over the entire length of the arm, the effects of folding the work attachment, improving the stability in the ground contact state, and reducing the total height of the attachment are enhanced.

  According to the invention of claim 3, since the arm upper surface side is inclined downward toward the arm tip, the arm tip side space is further expanded. For this reason, installation of the working device cylinder mechanism is facilitated.

  By the way, if the entire upper surface of the arm is inclined downward in this case, the cross-sectional area of the arm may be insufficient and the strength may be reduced.

  In this regard, according to the invention of claim 4, the cross-sectional area of the arm is maximized at the intermediate point in the arm length direction, and the tip side portion of the arm upper surface in the folded state is lowered downward toward the arm tip. On the other hand, by forming the base end side part from the middle point on the inclined surface that is descending toward the arm base end, the entire upper surface of the arm is formed in an upwardly convex shape. The area can be secured and the strength can be maintained.

  Moreover, since the space (arm base end side space) formed between the arm base end side portion and the boom can be widened, the inter-boom and arm both cylinders can be installed without difficulty.

  According to the fifth aspect of the present invention, the attachment points of the inter boom and arm cylinders with respect to the inter boom are A and B (see FIG. 2), and the attachment point A is located on the lower side and the attachment point B is located on the upper side. Since both cylinders are mounted in a state that satisfies the two conditions that the mounting points A and B are displaced in the width direction of the inter boom, both cylinders are in the same phase (from the top in the attachment folding posture). Compared with the known technique arranged at the same position in the attachment width direction as viewed), the occupied space in the height direction of both cylinders can be reduced while securing an equivalent moment length.

  This makes it possible to reduce the boom-arm distance (necessary length of the inter-boom) when the attachment is folded, further lowering the overall height of the attachment and further improving the safety, workability, and transportability of disassembly / assembly work. be able to.

  In this case, by combining with the configuration of the fourth aspect, the arm base end side space can be secured and the inter boom and arm both cylinders can be easily installed while keeping the total height of the attachment low.

It is a schematic side view of the folding state of the dismantling machine with a super-long attachment concerning the embodiment of the present invention. It is the figure which expanded a part of FIG. It is a schematic side view of the state which isolate | separates and transports a work attachment from a base machine and a main boom. FIG. 4 is a view corresponding to FIG. 3 in a state in which the working device cylinder is contracted from the state shown in FIG. It is a schematic side view which shows the conventional demolition machine. It is a schematic side view at the time of attachment transportation of the conventional demolition machine. It is a partially enlarged view at the time of disassembly / assembly and transportation of a conventional dismantling machine.

  An embodiment of the present invention will be described with reference to FIGS.

  In the following embodiments, the dismantling machine with an ultra-long attachment is applied to the background technology.

In an embodiment,
(i) A base machine 23 is constituted by a crawler-type lower traveling body 21 and an upper revolving body 22 mounted on the lower traveling body 21 so as to be rotatable about a vertical axis. The dismantling machine is constructed by attaching the work attachment 24,
(ii) The work attachment 24 includes a boom 25 (consisting of a main boom 25a and a front boom 25b) attached to the base machine 23 (upper turning body 22) so as to be raised and lowered, and a tip of the boom 25 around a horizontal axis. A short inter boom 26 that is rotatably attached, an arm 27 that is rotatably attached to the tip of the inter boom 26 around a horizontal axis, and a work device 28 that is attached to the tip of the arm 27. The point to have,
(iii) As cylinders for operating the work attachment 24, a boom cylinder 29 for raising and lowering the boom 25 (entire attachment), an inter boom cylinder 30 for rotating the inter boom 26, an arm cylinder 31 for rotating the arm 27, and A work device cylinder 32 for rotating the work device 28 via the link mechanism 33 is provided;
(iv) The inter boom and arm cylinders 30, 31 are provided between the boom 25 (front boom 25b) and the inter boom 26 and between the inter boom 26 and the arm 27 on the front side of the attachment,
(v) When disassembling and transporting, both the inter-boom and arm cylinders 30 and 31 are in the most contracted state, and the work attachment 24 is folded into a three-fold state with the boom 25 on the upper side and the arm 27 on the lower side. 3 and 4 and separated into a set of base machine 23 and main boom 25a and a set of work attachments 24 excluding main boom 25a, and transported by transport vehicle 34. After transport, the same state The assembling point is the same as the known technique shown in FIGS.

  Differences from the known technique are as follows.

  First, a flat portion 27a that is horizontal (parallel to the ground) in the folded state is formed on the lower surface side of the arm when the work attachment 24 is folded.

  The flat portion 27a is substantially the entire arm length including the portion of the lower surface of the arm other than the distal end portion and the proximal end portion (the hatched portion in FIG. 2), that is, the portion directly below the center of gravity of the attachment when the attachment is folded. When the flat portion 27a is grounded in the attachment folded state, the entire attachment 24 is supported on the ground or the loading platform in the folded state.

  Basically, with this configuration, the work attachment 24 can be made independent during disassembly / assembly and transportation, and can be supported sufficiently stably.

  As a result, the cradle can be omitted or replaced with a complementary simple and small one, which is advantageous in cost and handling and is free from raising by the cradle, and has an overall height H2 (excluding the main boom 25a). The overall height of the attachment (see FIG. 1) can be reduced, and the workability and safety of disassembly / assembly work and the transportability can be improved.

  Secondly, the working device cylinder 32 and the link mechanism 33 (working device cylinder mechanism) include an arm tip side space S1 (referenced only in FIG. 2) formed between the arm tip side portion and the boom 25 (front boom 25b). Is provided on the upper surface side of the arm 27 in a folded state.

  Thereby, there is no possibility that the working device cylinder mechanism is damaged due to contact with the ground or the loading platform.

  Further, by disposing the working device cylinder mechanism on the upper surface side of the arm, the arm tip side portion can be brought close to the ground, that is, the entire arm can be made almost horizontal.

  Therefore, as described above, the flat portion 27a can be formed over a long range substantially over the entire length of the arm, and the arm tip side space S1 can be made large enough to install the working device cylinder mechanism. Become.

  Furthermore, the following effect is acquired by arrange | positioning a working device cylinder mechanism in the arm upper surface side in an attachment folding state.

  (i) Compared with the case where it is arranged on the lower surface side of the arm, the movement of the working device 28 due to the expansion / contraction of the working device cylinder 32 is reversed, so that the excavating force when the bucket is used as the working device 28 is reduced. However, the holding force (force to push the crushing device upward) when using the crushing device of the example is improved.

  The ultra-long dismantling machine is advantageous in this respect because the work using this holding force is overwhelmingly large.

  (ii) The working device cylinder mechanism and the hydraulic piping for the working device cylinder 32 can be protected from dismantling.

  (iii) Since the working device cylinder mechanism is easy to see from the operator who has boarded the base machine during work, it is easy to avoid contact between the working device cylinder mechanism and the dismantling object and stroke end work of the working device cylinder 32.

  Note that hydraulic piping (not shown) for the working device cylinder 32 is routed on the arm upper surface side (or a side surface) in the attachment folded state in accordance with the working device cylinder mechanism.

  FIG. 3 shows a case where the working device cylinder 32 is transported in a state slightly longer than the most contracted state, and FIG. 4 shows a case where the working device cylinder 32 is transported in the most contracted state.

  In the state of FIG. 3, the front boom 25b needs to be inclined slightly upward toward the boom base end side in order to avoid interference between the work device cylinder mechanism and the front boom 25b, so that the total height of the attachment slightly increases. On the other hand, in the state of FIG. 4, the front boom 25 b can be made substantially horizontal, so that the effect of reducing the overall height of the attachment is enhanced.

  In addition, this dismantling machine has the following configurations (I) and (II).

  (I) The cross-sectional area of the arm 27 is maximized at the intermediate point in the arm length direction, the portion 27b on the distal end side of the intermediate point on the upper surface of the arm in the folded state is directed toward the distal end of the arm and the proximal end relative to the intermediate point The side portion 27c is formed in an inclined surface that is firstly lowered toward the base end of the arm, so that the entire upper surface of the arm is formed in an upwardly convex shape.

  With this configuration, while ensuring the necessary arm strength, the arm distal end side space S1 and the arm proximal end side space S2 formed between the arm 27 and the front boom 25b on the arm proximal end side (referenced only in FIG. 2). Therefore, it is easy to install the working device cylinder mechanism in the former and the inter boom and arm cylinders 30 and 31 in the latter.

  (II) In the known technique shown in FIGS. 5 to 7, the inter boom and arm cylinders 10 and 11 are arranged in the same phase (the same position in the attachment width direction when viewed from the top in the attachment folding posture). It is necessary to maintain an interval between the cylinders 10 and 11 so that they do not interfere with each other.

  For this reason, the occupied space of the height direction of both cylinders 10 and 11 becomes large.

  On the other hand, as shown in FIG. 7, the attachment points of the boom 5 and the arm 7 with respect to the inter boom 6 are X1 and X2, and the attachment points of both the cylinders 10 and 11 with respect to the inter boom 6 (acting points of cylinder thrust) are Y1 and Y2. Then, the force that operates the inter boom 6 and the arm 7 is proportional to the distance between the X1 and Y1 and the distance between the X2 and Y2 (hereinafter referred to as the moment length) α1 and α2. A certain size is required for the lengths α1 and α2.

  As a result, the distance between the boom 5 and the arm 7 in the folded posture (required length of the inter boom 6) is increased, which is one of the causes for the increase in the overall height H1 of the attachment.

Therefore, in this dismantling machine, the attachment points of the inter boom and arm cylinders 30 and 31 with respect to the inter boom 26 are designated as A and B (see FIG. 2).
B. When the attachment is folded, the attachment point A is located on the lower side and the attachment point B is located on the upper side.
B. Both the inter-boom and arm cylinders 30 and 31 are mounted in a state satisfying the two conditions that both mounting points A and B are displaced in the width direction of the inter-boom 26.

    More specifically, one inter boom cylinder 30 has a boom 25 (front boom 25b) and an intermediate portion (attachment point A) in the height direction of the inter boom 26 at the center in the width direction of the boom 25 and the inter boom 26. ) Is installed between.

  Then, two arm cylinders (only one is shown) 31 are arranged on both sides in the width direction of the inter boom 26 and the arm 27 with the inter boom cylinder 30 sandwiched from the left and right, and one end (rod end) on the arm 27. The other end (tube end) is attached to the inter boom 26 via brackets 35 and 36 at a position higher than the inter boom cylinder attachment point A, respectively.

  The bracket 35 is provided on the side surface portion of the inter boom 26 near the middle upper portion in the height direction so as to protrude rearward and obliquely upward in the attachment fold position.

  Thereby, both the cylinders 30 and 31 are provided in the state which mutually shifted the phase and cross | intersected X shape by side view.

  According to this configuration, as shown in FIGS. 5 to 7, the required moment lengths β1 and β2 (moment lengths of the known technology) are compared with the known technology in which both cylinders 10 and 11 are provided in the same phase and separated vertically. The occupied space in the height direction of both cylinders 30 and 31 can be reduced while securing (equal to or more than α1 and α2).

  Thereby, since the distance between the boom 25 and the arm 27 (required length of the inter boom 26) in the attachment folding posture can be reduced, the total height H1 of the attachment is further reduced, and the safety and workability of the disassembly / assembly work are further improved. Can be made.

  In addition, since the overall height during attachment transportation can be reduced, truck transportation that was not possible with the known technology can be achieved if the weight limit is cleared, and costs can be reduced, and the center of gravity of the attachment can be lowered for stable transportation. Can be improved.

  In this case, as a synergistic effect of forming the upper surface of the arm in the folded state of the attachment in a convex shape, the arm base end side space S2 is secured while the overall height of the attachment is kept low, and the inter-boom and arm cylinders 30, 31 are It can be installed easily.

  As another aspect related to the above (II), the inter-boom attachment point B of the arm cylinder 31 may be set at the same position as the connection point of the boom 25 with respect to the inter-boom 26.

  In addition, each of the interboom and arm cylinders 30 and 31 is linked to a pair of left and right cylinders in a state of being displaced in the width direction of the interboom 26 and intersecting the X shape when viewed from the side. The ends of both links may be attached to the inter boom 26 as attachment points A and B.

Other embodiments
(1) The flat portion 27a on the lower surface side of the arm in the folded state of the attachment is preferably formed over the entire length of the arm as in the above embodiment in view of the stability of the attachment support, but the folded state of the work attachment 24 If the length range sufficient to support the entire work attachment 24 including the portion directly below the center of gravity in the above can be secured, it may be formed in a shorter range than the above embodiment.

  (2) A grounding bracket may be provided at a plurality of locations in the arm length direction on the lower surface side of the arm when the attachment is folded. In this way, the arm 7 can be stably supported even if there is some unevenness on the grounding surface, and damage and peeling of the paint due to direct grounding of the lower surface of the arm can be prevented.

  (3) In the said embodiment, although the structure of Claim 5 was employ | adopted about the inter boom and arm both cylinders 30 and 31 as an advantageous structure at the point which makes the attachment total height in a folded state low, FIG. Similarly to the known technique shown, a configuration may be adopted in which both cylinders 30 and 31 are arranged separately in the vertical direction.

  Even in this case, the entire attachment can be stably supported by the simple or small stand in the folded state, and the overall height of the attachment can be lowered by omitting or simplifying the stand and bringing the entire arm close to the horizontal. The basic effect is ensured.

  (4) The present invention can be applied not only to a dismantling machine but also to an excavator with a bucket attached to the tip of an attachment or a crusher with a breaker attached as a working device.

DESCRIPTION OF SYMBOLS 21 Lower traveling body 22 Upper revolving body 23 Base machine 24 Work attachment 25 Boom 25a Main boom 25b Front boom 26 Inter boom 27 Arm 27a The flat part 27b of the arm lower surface in the attachment folded state Proximal end portion 28 Working device 29 Boom cylinder 30 Inter boom cylinder 31 Arm cylinder 32 Working device cylinder 33 Link mechanism S1 Arm tip side space S2 Arm base side space

Claims (5)

  A work attachment is attached to the base machine, and the work attachment includes a boom attached to the base machine so that it can be raised and lowered, an inter boom attached to the tip of the boom so as to be rotatable about a horizontal axis, and the inter boom. And a work cylinder attached to the tip of the arm, a boom cylinder for raising and lowering the boom, and the boom and the interface on the front side of the attachment. An inter boom cylinder that rotates an inter boom provided between the boom and an boom, an arm cylinder that is provided between the inter boom and the arm on the front side of the attachment, and rotates the arm; Disassembly / assembly, transportation In addition, the work attachment is folded in a working machine that is folded into a three-fold state in which the inter-boom and arm cylinders are in the most contracted state, and the boom is on the upper side and the arm is on the lower side. A flat portion is formed on the lower surface side of the arm in a slender state, which is horizontal in the folded state of the attachment and is grounded over a length range sufficient to support the entire attachment, and the working device cylinder and the link mechanism. Is provided on the upper surface side of the arm in the folded state so as to be located in the arm tip side space formed between the arm tip side part and the boom.   2. The work machine according to claim 1, wherein the flat portion is formed on the lower surface side of the arm in the folded state over substantially the entire length of the arm.   The work machine according to claim 1 or 2, wherein the upper surface of the arm in the folded state is formed as an inclined surface that descends toward the tip of the arm.   While the cross-sectional area of the arm is maximized at an intermediate point in the arm length direction, the tip side portion of the upper surface of the arm in the folded state is formed on an inclined surface that descends toward the tip of the arm, 4. The work according to claim 3, wherein the base end side portion with respect to the intermediate point is formed in an inclined surface that is inclined downward toward the arm base end, so that the entire upper surface of the arm is formed in an upward convex shape. machine.   The attachment points of the inter boom and arm cylinders with respect to the inter boom are A and B, and the attachment point A is located on the lower side, the attachment point B is located on the upper side in the attachment folded state, and both the attachment points A, The inter-boom and arm cylinders are mounted in a state that satisfies the two conditions that B is displaced in the width direction of the inter-boom. The working machine described.

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