JP2000336692A - Construction machine and bearing device used therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To heighten welding strength between a front and a boss by lengthening a weld line between the tip of the front and the boss in the state of preventing the boss from approaching a working tool. SOLUTION: A bearing device 21 is disposed in such a state that the hole center ○1-○1 of a pinhole 23 formed in a boss part 22A of an arm boss 22 is decentered by a dimension L onto the bucket 11 side from the axial center ○2-○2 of the arm boss 22. A large spaced dimension S1 is thereby ensured between the bucket 11 and boss part 22A by a thin-walled cylinder part 22A1 on the bucket 11 side of the boss part 22A to prevent interference or the like between the arm boss 22 and bucket 11. Moreover, the arm boss 22 can be formed in a large outer diameter dimension D1 by a thick-walled cylinder part 22A2 on the arm 9 side. A weld line 28 between the arm boss 22 and arm 9 can thereby be lengthened to heighten welding strength when welding to the arm 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a construction machine suitable for use in, for example, a hydraulic excavator having a front, and a bearing device used therefor.

[0002]

2. Description of the Related Art In general, a hydraulic excavator, which is a typical construction machine, includes a traveling body including a lower traveling body and an upper rotating body,
It has a front provided on the upper revolving superstructure of the traveling body so as to be able to move up and down, and a working tool such as a bucket provided at a front end of the front via a bearing device. The bearing device includes a cylindrical boss attached to the front end of the front, and a connection pin inserted through a pin hole of the boss and rotatably connecting the work implement (for example,
JP-A-9-151482, JP-A-10-3063
No. 5 publication).

[0003] Here, the boss of the bearing device is fixed by welding in a state fitted to the front end. The bucket is provided with a pair of mounting brackets having pin holes. The bearing device rotatably supports the bucket with respect to the front by inserting the connection pin through the pin hole of the boss and the pin hole of the mounting bracket.

[0004] Grease for smooth rotation of the connecting pin is supplied to the inner peripheral side of the boss. Here, the bearing device disclosed in Japanese Patent Application Laid-Open No. 9-151482 has a configuration in which a greasing passage is provided for supplying grease in the axial direction of the connecting pin inserted into the pin hole of the boss. Further, the bearing device disclosed in Japanese Patent Application Laid-Open No. H10-30635 has a configuration in which a greasing passage for greasing grease is formed in the radial direction of the boss.

[0005]

By the way, the above-mentioned bearing device for a construction machine according to the prior art has a structure in which a boss is fixed to the front end of the front by welding. However, since the boss is formed in a cylindrical shape, the length of the welded portion between the boss and the front is limited to a half of the boss (in a range of approximately 180 degrees). (Hereinafter referred to as a welding line).

Here, in a hydraulic excavator, a large impact force acts on a bucket, a bearing device, and the like when excavating work or the like, so that a welding line between the front and the boss is lengthened to weld the front and the boss. Need to be strengthened.

However, in order to lengthen the welding line between the front and the boss, the outer diameter of the boss must be increased to increase the circumference. In this case, however, the diameter is increased. There is a possibility that the outer peripheral side of the boss approaches the bucket and the two interfere with each other. There is also a problem that a stone or the like is easily bitten between the bucket and the boss.

Further, in the bearing device disclosed in Japanese Patent Application Laid-Open No. 9-151482, since the greasing passage is formed in the axial direction of the connecting pin, the strength of the connecting pin is reduced by the greasing passage. For this reason, it is necessary to increase the outer diameter of the connecting pin in order to maintain the strength of the connecting pin, and there is a problem that the bearing device is unnecessarily enlarged.

On the other hand, in the bearing device disclosed in Japanese Patent Application Laid-Open No. H10-30635, the greasing passage is formed in the radial direction of the boss, so that the grease nipple attached to the outer opening of the greasing passage is not damaged during work. In addition, there is a problem that processing such as embedding the grease nipple in a boss is required.

[0010] The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to simplify a configuration for supplying grease and suppress an increase in the outer dimensions of a connecting pin. And a bearing device used for the construction machine.

Another object of the present invention is to increase the welding line between the front end and the boss in a state where the boss is prevented from approaching the work implement, and to increase the length of the welding line between the front and the boss. An object of the present invention is to provide a construction machine capable of increasing welding strength and a bearing device used therefor.

[0012]

A construction machine according to the present invention comprises a traveling body, a front provided on the traveling body so as to be able to move up and down, and a working tool provided at a front end of the front via a bearing device. The bearing device includes a cylindrical boss attached to the front end of the front, and a connecting pin that is inserted into a pin hole of the boss and rotatably connects the work implement.

[0013] In order to solve the above-mentioned problems,
The feature of the configuration adopted by the invention according to claim 1 is that the center of the pin hole is eccentric to the work tool side with respect to the center of the axis of the boss.

With this configuration, since the pin hole of the boss is eccentric to the work tool, the outer diameter of the boss can be increased without increasing the distance between the work tool and the pin hole. Can be. As a result, the circumference of the boss is lengthened, so that the contact portion between the boss and the front can be increased to increase the welding length and increase the welding strength.

According to the second aspect of the present invention, the boss has a thin-walled cylindrical portion located closer to the working tool than the center of the hole of the pin hole, and has a semi-circular portion located frontward of the center of the hole of the pin hole. The part is formed as a thick cylindrical part.

With this configuration, the thin cylindrical portion of the boss can increase the separation between the work tool and the outer peripheral surface of the boss without increasing the space between the work tool and the pin hole. . In addition, the thick-walled cylinder can increase the outer diameter of the boss and lengthen the welding line between the thick-walled cylinder and the front.

According to the third aspect of the present invention, the boss is provided with a greasing passage that opens at the position of the thick-walled cylindrical portion. Thereby, the greasing passage can be provided by utilizing the thick-walled cylindrical portion formed in the boss portion.

According to a fourth aspect of the present invention, the boss has a structure in which the position of the thick-walled cylindrical portion is welded to the front. As a result, the thick-walled cylinder provided on the boss increases the contact area between the boss and the front, increasing the welding length between the boss and the front, and preventing pin hole deformation due to welding. can do.

According to the fifth aspect of the present invention, the front is constituted by a boom attached to the traveling body so as to be able to move upward and downward, and an arm attached to the tip side of the boom so as to be able to move upward and downward. The bucket is rotatably attached to the tip of the arm.

On the other hand, the invention according to claim 6 comprises a cylindrical boss attached to the front end of the construction machine, and a connecting pin inserted through a pin hole of the boss and rotatably connecting the work implement to the front. In the bearing device for a construction machine having the above configuration, the hole center of the pin hole is bored at a position eccentric to the work tool side with respect to the axis center of the boss, and the boss is positioned from the hole center of the pin hole. Also, the semi-circular portion located on the work tool side is formed as a thin-walled cylindrical portion, and the semi-circular portion located on the front side of the center of the pin hole is formed as a thick-walled cylindrical portion.

With this configuration, the pin hole of the boss portion is eccentric to the work tool side. Therefore, the interval between the work tool and the pin hole is increased by the thin cylinder portion on the work tool side. Instead, only the outer diameter of the boss can be increased. In addition, the boss portion can extend the circumference of the boss by the thick tube portion on the front side, and can increase the welding length by increasing the contact portion between the boss and the front.

In this case, the boss may be provided with a greasing passage that opens at the position of the thick-walled cylindrical portion.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a construction machine according to an embodiment of the present invention will be described in detail with reference to FIGS.

1 is an undercarriage constituting a hydraulic excavator;
Reference numeral 2 denotes an upper revolving structure that is rotatably mounted on the lower traveling structure 1. The lower traveling structure 1 and the upper revolving structure 2 constitute a traveling structure. A building 4, a cab 5, and the like are provided on the revolving frame 3 of the upper revolving superstructure 2.

Reference numeral 6 denotes a front mounted on the front side of the upper revolving unit 2 so as to be able to move up and down. The front 6 is generally constituted by a boom 7, an arm 9, and the like, which will be described later.

Reference numeral 7 denotes a boom which is pin-connected to the center of the front part of the revolving frame 3, and a boom cylinder 8 for raising and lowering the boom 7 is provided between the boom 7 and the revolving frame 3.

Reference numeral 9 denotes an arm which is pin-coupled to the distal end of the boom 7. The arm 9 has an upper surface plate 9A located above and a lower surface plate 9B located below when the front 6 is extended.
And the left and right side plates 9C, 9C are formed in a substantially rectangular tube shape. At the tip of the arm 9, notches 9D, 9D are formed by similarly notching the side plates 9C, and the notches 9D are, as shown in FIG. It is formed in a semicircular shape along the outer peripheral surface of the portion 22A. Further, an arm cylinder 10 is provided between the base end side of the arm 9 and the boom 7 to move the arm 9 up and down with respect to the boom 7.

Numeral 11 denotes a backhoe-type bucket which is a working tool pin-connected to the distal end of the arm 9 via a bearing device 21 which will be described later. The bucket 11 has a substantially U-shape as shown in FIG. Curved bottom plate 12 and side plates 13 and 13 (only one is shown) closing both left and right sides of the bottom plate 12
And a plurality of claws 1 attached to the tip side of the bottom plate 12
(Only one is shown) and left and right mounting brackets 15, 15 located on the base end side of the bottom plate 12 and spaced apart in the left and right directions. I have.

Here, each mounting bracket 15 is provided with a pin hole 15A in which the arm 9 is mounted and a pin hole 15A in which a first link 17 to be described later is mounted, spaced apart in the longitudinal direction. On the inner surfaces corresponding to the holes 15A, 15B, annular reinforcing members 15C, 15C,
... (only two are shown) are welded. Also, the bottom plate 12
A reinforcing plate 16 is mounted on the base end side between the left and right side plates 13 and 13 and the mounting brackets 15 and 15, and the reinforcing plate 16 is provided with each pin hole 1 of the mounting bracket 15.
5A and 15B, and are formed to be bent in a substantially rectangular shape protruding between the bottom plate 12, the side plate 13, and the mounting bracket 15.
Are welded respectively.

Reference numeral 17 denotes a first link, one end of which is pin-connected to a pin hole 15B of each mounting bracket 15, 18, 18;
Is pin-connected at one end to the other end of the first link 17,
The second link (only one link is shown) whose other end is pin-connected to the tip of the arm 9 is shown.

Reference numeral 19 denotes an arm 9 and links 17, 18
And the bucket cylinder 17 is connected to the bucket 11 via links 17 and 18.
Is rotated.

Reference numeral 21 denotes a bearing device provided at the distal end of the arm 9 according to the present embodiment. The bearing device 21 rotatably supports the bucket 11. The bearing device 21 is generally constituted by an arm boss 22, a connecting pin 25, and the like, which will be described later.

Reference numeral 22 denotes a cylindrical arm boss provided on the distal end side of the arm 9. As shown in FIG. 3, the arm boss 22 is a thick cylindrical left and right boss arranged at intervals in the axial direction. The parts 22A, 22A and a thin cylindrical connecting cylinder 22B connecting the boss parts 22A are integrally formed. The arm boss 22 is formed with a nipple accommodating recess 22C for accommodating the grease nipple 27 at an outer end surface of the boss portion 22A and at an end surface of a thick-walled cylindrical portion 22A2 described later.

Reference numeral 23 denotes a pin hole formed on the inner peripheral side of the arm boss 22. The pin hole 23 has a hole center O1-.
O1 is disposed at a position eccentric to the bucket 11 side by a dimension L from the axial center O2-O2 of the arm boss 22. At this time, the boss 22A is positioned at the center O1-O of the pin hole 23.
The semi-circular portion located closer to the bucket 11 than 1 is the thin cylindrical portion 22A1, and the semi-circular portion located closer to the arm 9 than the hole center O1-O1 of the pin hole 23 is the thick cylindrical portion 22A2.
It has become. The thin-walled tube portion 22A1 is
The thickness from the base 3 to the outer peripheral surface of the boss 22A is E1, and the thick cylindrical portion 22A2 is
E2 whose wall thickness up to the outer peripheral surface is larger than wall thickness E1
It has become.

Thus, the arm boss 22 (boss portion 22A) can have a large outer diameter D1 without increasing the distance between the reinforcing plate 16 of the bucket 11 and the hole center O1-O1 of the pin hole 23. it can. At this time, the thickness E1 of the thin cylindrical portion 22A1 can be made substantially equal to the thickness e1 of the boss 32A having a small outer diameter d1 according to a first comparative example shown in FIG.

A cylindrical bush 24 is press-fitted into the pin hole 23, and grease supplied from a greasing passage 26, which will be described later, is interposed between the bush 24 and the connecting pin 25. Leading oil guide holes 24A, 24A are formed in the radial direction.

Numeral 25 denotes a connecting pin formed in a solid cylindrical shape. As shown in FIG.
Is inserted along the hole center O1-O1 across the pin hole 15A of each mounting bracket 15 and the pin hole 23 of the arm boss 22. The connecting pin 25 is slidable with respect to a bush 24 provided in the pin hole 23. Thereby, the connecting pin 25 is connected to the arm boss 2.
2 and the mounting bracket 15 are rotatably connected.

On the other hand, reference numerals 26, 26 denote greasing passages provided in each boss portion 22A of the arm boss 22.
Extends obliquely from the nipple accommodating concave portion 22C provided in the thick cylindrical portion 22A1 of the boss portion 22A to a position corresponding to the oil guide hole 24A of the bush 24. Also, the greasing passage 2
A grease nipple 27 serving as an oil supply port is screwed into an opening in the nipple housing recess 22C of No. 6. The greasing passage 26 supplies grease injected through the grease nipple 27 directly between the bush 24 and the connecting pin 25.

Next, the mounting structure of the arm boss 22 to the arm 9 will be described. First, the boss portion 22A has a thin cylindrical portion 22A1 on the bucket 11 side, and a thickness E thereof.
1 is substantially equal to the wall thickness e1 of the boss 32A having a small outer diameter d1, so that the arm 9 side has a thick wall 22 having a wall thickness E2 larger than the wall thickness E1.
A2. Therefore, the boss portion 22A has a large outer dimension D1 due to the thick cylindrical portion 22A2. The arm boss 22 is formed by the thick cylindrical portion 22 of the boss portion 22A.
Notch 9D formed at the tip of arm 9 with the outer peripheral surface of A2
And in this state, welding is performed between the outer peripheral surface of the thick-walled cylindrical portion 22A2 and the notch 9D.

Therefore, when welding the outer peripheral surface of the boss portion 22A and the notch portion 9D of the arm 9, approximately 180 degrees of the outer periphery of the thick-walled cylindrical portion 22A2 which is half of the boss portion 22A is welded by welding. Line 28 and the thick cylindrical portion 22
A2 can be fixed to the notch 9D of the arm 9 by a long welding line 28, and sufficient welding strength can be obtained.

The bearing device 21 according to the present embodiment has the above-described configuration. Next, the operation of the bearing device 21 will be described.

First, during operation of the hydraulic excavator, when the bucket 11 is rotated on the tip side of the arm 9, the connection pin 2
5 rotates integrally with the mounting bracket 15, and at this time, the connecting pin 25 slides on a bush 24 provided on the arm boss 22.

In the bearing device 21, the pin hole 23 formed in the boss portion 22A of the arm boss 22 is disposed eccentrically to the bucket 11 by a dimension L, and the bucket 11 side of the boss portion 22A is formed as a thin cylindrical portion 22A1. I have. This allows
Hole center O1 of reinforcing plate 16 and pin hole 23 of bucket 11
The arm boss 22 (the boss portion 22A) is made to have a large outer diameter D1 in a state where a sufficient separation dimension S1 is formed between the outer peripheral surface of the boss portion 22A and the reinforcing plate 16 without increasing the interval between the boss portion 22A and the reinforcing plate 16. It can be.

FIG. 5 shows a first comparative example. In this comparative example, the arm boss 32 of the bearing device 31 is formed to have an outer diameter d1 smaller than the outer dimension D1 of the arm boss 22 according to the embodiment. (D1 <D1).
The thickness e1 of the boss portion 32A is
Is set such that the distance from the reinforcing plate 16 is substantially the same as the distance S1 according to the embodiment (s1 ≒ S1). However, the arm boss 32 according to the first comparative example has an outer diameter dimension d smaller than the outer dimension D1 of the arm boss 22 according to the present embodiment.
Since it is 1, the circumference of the boss 32A is short and the length of the welding line 34 with the arm 9 'is also short, so that the welding strength is weak.

FIG. 6 shows a second comparative example. In this comparative example, the arm boss 42 of the bearing device 41 has an outer diameter d2 substantially equal to the outer dimension D1 of the arm boss 22 according to the present embodiment. (D 2 ≒ D 1), and a pin hole 43 is formed coaxially with the arm boss 42. Thereby, the length dimension of the welding line 44 formed between the boss portion 42A and the arm 9 is increased, and the same welding strength as in the embodiment is obtained. However, the thickness e2 of the boss portion 42A is
Since the thickness is larger than the thickness E1 of the thin cylindrical portion 22A1 according to the embodiment (e2> E1), the distance between the boss portion 42A and the reinforcing plate 16 of the bucket 11 is equal to the distance S1 according to the present embodiment. The distance s2 is smaller than (s2 <S1).
The possibility that the 2 and the bucket 11 approach each other and interfere with each other or bite a stone or the like increases.

In this embodiment, as compared with the first and second comparative examples, the pin hole 23 of the arm boss 22 is eccentric toward the bucket 11 by the dimension L, so that the boss portion 22A
The arm 9 has a thin cylinder portion 22A1 on the bucket 11 side.
The side is formed as a thick cylindrical portion 22A2. Thus, the thickness E1 of the thin cylindrical portion 22A1 can be made substantially equal to the thickness e1 of the boss 32A having the small outer diameter d1 according to the first comparative example. Also, the thickness E2 of the thick cylindrical portion 22A2 can make the boss portion 22A a large outer dimension D1.

Therefore, the outer peripheral surface of the arm boss 22 can be arranged in the thin cylindrical portion 22A1 with a large separation S1 from the bucket 11. Moreover, the thick cylindrical portion 22A
2 is a view of a welding line 28 formed between the arm boss 22 and the arm 9 by forming the arm boss 22 to have a large diameter.
And the welding strength can be increased.

On the other hand, by injecting grease from the grease nipple 27 into the greasing passage 26,
6, the bush 24 and the connecting pin 25 through the oil guide hole 24A.
Grease can be supplied between the two.

Thus, according to the present embodiment, since the pin hole 23 of the arm boss 22 is disposed at a position eccentric to the bucket 11 by the dimension L, the separation dimension S 1 between the arm boss 22 and the bucket 11 is set. Secure the bucket 1
1 can be prevented from interfering with the arm boss 22. Moreover, since the diameter of the arm boss 22 can be increased, the welding line 28 between the arm boss 22 and the arm 9 can be formed.
, The welding strength can be increased, the front 6 can be prevented from being damaged, the service life can be extended, and the reliability of the bearing device 21 can be improved.

Further, since the connecting pin 25 can be formed in a solid cylindrical shape, the connecting pin 25 can be set to a small diameter while maintaining the strength of the connecting pin 25, and the bearing device 21
The whole can be compacted. Further, grease can be supplied directly to the sliding portion between the bush 24 and the connecting pin 25, and the sliding portion can be lubricated well.

Further, since the grease supply passage 26 and the grease nipple 27 for supplying grease are provided by utilizing the thick cylindrical portion 22A2 formed on the boss portion 22A, the grease supply passage 26 is easily formed. Operability can be improved.

Further, the thick cylindrical portion 22A2 of the boss portion 22A
Since the side is welded to the arm 9, it is possible to prevent the pin holes 23 and the like from being deformed due to the thermal influence of welding, and it is possible to improve dimensional accuracy, assembly workability, and the like.

In the embodiment, the arm boss 22 of the bearing device 21 has been described as having the boss portions 22A on both sides in the left and right directions. However, the present invention is not limited to this. The arm boss 52 is formed of one cylindrical member as in a bearing device 51 shown in FIG.
A long bush 54 may be press-fitted into the pin hole 53 formed on the inner peripheral side of 2.

In the embodiment, the bearing device 21
Although the case where the backhoe-type bucket 11 is rotatably supported as the working tool has been described as an example, the present invention is not limited to this. For example, a loader-type bucket, a clamshell, a grapple, a hydraulic breaker, or the like may be used. The present invention may be applied to a case where another work tool is rotatably supported.

Further, in the embodiment, the tracked hydraulic excavator has been described as an example of the construction machine. However, the present invention is not limited to this, and may be applied to another construction machine such as a wheel hydraulic excavator. Can be applied.

[0056]

As described in detail above, according to the first aspect of the present invention, a bearing device for rotatably supporting a working tool with respect to the front of a construction machine is provided by using a center of a pin hole as a boss shaft. Since it is configured to be eccentric to the work tool side with respect to the center, the pin hole of the boss can be formed closer to the outer peripheral surface of the boss at a position eccentric to the work tool side. Thus, only the outer diameter of the boss can be increased without increasing the distance between the working tool and the pin hole. As a result, the circumference of the boss is lengthened to increase the contact portion between the boss and the front, and the welding length can be increased. Therefore, the welding strength of the construction machine is increased, and damage between the front and the bearing device is reduced. Thus, the life of the bearing device can be extended, and the reliability of the bearing device can be improved.

According to the second aspect of the present invention, the boss is a thin-walled cylindrical portion located closer to the work implement than the center of the hole of the pin hole, and the boss is located at the front side of the center of the hole of the pin hole. Since the arc portion is formed as a thick-walled cylinder, the distance between the tool and the outer peripheral surface of the boss should be increased without increasing the distance between the tool and the pin hole by the thin-walled cylinder of the boss. Therefore, it is possible to prevent interference between the boss and the work implement. In addition, the outer diameter of the boss can be increased by the thick-walled tube portion, the welding line between the thick-walled tube portion and the front can be lengthened, and the welding strength of the construction machine can be increased.

According to the third aspect of the present invention, since the boss is provided with the greasing passage opening at the position of the thick cylinder portion, the greasing passage is formed by utilizing the thick cylinder portion formed in the boss portion. Can be provided, the greasing passage can be easily formed, and the workability can be improved.

According to the fourth aspect of the present invention, since the boss is configured to weld the position of the thick-walled cylinder to the front, the contact portion between the thick-walled cylinder and the front is increased, and the boss and the front are separated. The welding length between them can be lengthened, and the welding strength can be increased. Further, deformation of the pin hole due to welding can be prevented, and dimensional accuracy, assembling workability, and the like can be improved.

According to the invention of claim 6, in the bearing device, the center of the hole of the pin hole is formed at a position eccentric to the working tool side with respect to the center of the axis of the boss. The semi-circular part located on the work implement side is a thin-walled cylinder part, and the semi-circular part located on the front side from the center of the pin hole is formed as a thick cylinder part. By the thin-walled tubular portion, a sufficient distance between the work tool and the pin hole can be secured without increasing the distance between the work tool and the pin hole, and only the outer diameter of the boss can be increased. In addition, since the boss portion can extend the circumference of the boss by the thick cylinder portion on the front side, the contact length between the boss and the front can be increased and the welding length can be increased. Welding strength can be increased.

In this case, according to the invention of claim 7, the boss can be provided with a greasing passage that opens at the position of the thick-walled cylindrical portion.

[Brief description of the drawings]

FIG. 1 is a front view showing a hydraulic shovel to which a bearing device according to an embodiment of the present invention is applied.

FIG. 2 is an enlarged view of a main part, in which a tip of an arm, a bucket and the like in FIG. 1 are enlarged.

FIG. 3 is a longitudinal sectional view of the bearing device as viewed from a direction indicated by arrows III-III in FIG. 2;

FIG. 4 is a cross-sectional view of the bearing device as viewed from a direction indicated by arrows IV-IV in FIG. 3;

FIG. 5 is a cross-sectional view showing the bearing device according to the first comparative example from the same position as in FIG. 4;

FIG. 6 is a cross-sectional view showing a bearing device according to a second comparative example from the same position as in FIG. 4;

FIG. 7 is a longitudinal sectional view showing a bearing device according to a modification from the same position as in FIG. 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lower traveling body 2 Upper revolving structure 6 Front 7 Boom 9 Arm 11 Bucket (work implement) 15 Mounting bracket 21, 31, 41, 51 Bearing device 22, 32, 42, 52 Arm boss 22A, 32A, 42A Boss part 22A1 Thin cylinder Part 22A2 Thick cylindrical part 23, 33, 43, 53 Pin hole 25 Connecting pin 26 Greasing passage 27 Grease nipple 28, 34, 44 Welding line O1-O1 Center of pin hole O2-O2 Center of arm boss axis L Eccentric dimension D1, d1, d2 Outer diameter of arm boss (boss) E1 Thickness of thin cylinder E2 Thickness of thick cylinder e1, e2 Thickness of arm boss (boss) S1, S1, S2 Separation

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Toshio Hasegawa 650, Kandamachi, Tsuchiura-shi, Ibaraki F-term in the Tsuchiura Plant of Hitachi Construction Machinery Co., Ltd. (Reference) 2D015 AA01 3J011 AA01 AA07 BA02 CA01 DA02 JA02 KA04 MA04 MA27 RA02 3J023 AA03 BA02 EA02 FA02 GA03

Claims (7)

[Claims] 1. A running body, a front provided on the running body so as to be able to move up and down, and a working tool provided at a front end of the front via a bearing device, wherein the bearing device comprises: In a construction machine constituted by a cylindrical boss attached to the tip side of the boss, and a connecting pin inserted through the pin hole of the boss and rotatably connecting the work implement, the center of the hole of the pin hole is A construction machine wherein the boss is eccentric to the work implement side with respect to the axis center of the boss. 2. The boss, wherein a semicircular portion located closer to the work implement than the center of the hole of the pin hole is a thin cylindrical portion, and a semicircular portion located closer to the front side than the center of the hole of the pin hole. The construction machine according to claim 1, wherein the construction machine is formed as a thick tube portion. 3. The construction machine according to claim 2, wherein the boss is provided with a greasing passage that opens at a position of the thick-walled cylindrical portion. 4. The construction machine according to claim 2, wherein the boss is configured to weld the position of the thick wall portion to the front. 5. The front includes a boom mounted on the traveling body so as to be capable of raising and lowering, and an arm mounted on a distal end side of the boom so as to be capable of raising and lowering. 5. The construction machine according to claim 1, wherein the construction machine is a bucket rotatably attached to the construction machine. 6. A construction machine comprising: a cylindrical boss attached to a front end of a construction machine; and a connecting pin inserted into a pin hole of the boss and rotatably connecting a work implement to the front. In the bearing device used, a hole center of the pin hole is formed at a position eccentric to the working tool side with respect to an axis center of the boss, and the boss is closer to the working tool side than a center of the hole of the pin hole. A bearing device for use in a construction machine, wherein a located semicircular arc portion is formed as a thin cylindrical portion, and a semicircular arc portion located on the front side of the center of the pin hole is formed as a thick cylindrical portion. 7. The bearing device according to claim 6, wherein the boss is provided with a greasing passage that opens at the position of the thick-walled tube portion.