JP2001271379A - Truck frame of construction machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain damage to the bottom of a truck frame due to collision with rock or the like while traveling or the like on the non-leveled ground. SOLUTION: Two protection plates 28 are attached detachably to the bottom 24B of a center frame 24 forming a truck frame 23, and the bottom plate 24B is covered by the protection plates 28 from the underside, whereby the protection plates 28 can prevent rock or the like from hitting directly against the bottom plate 24B of the center frame 24 during travel in a rock crushing site or the like for example and the life of the truck frame 23 can be lengthened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a truck frame of a construction machine constituting a lower traveling body such as a hydraulic shovel and a hydraulic crane.

[0002]

2. Description of the Related Art In general, a hydraulic excavator used for excavation work such as earth and sand is provided with a crawler-type lower traveling body, and is configured to be able to stably travel on uneven ground such as muddy ground and crushed stone sites. I have.

A conventional hydraulic excavator of this type will be described with reference to FIGS.

In the figure, reference numeral 1 denotes a hydraulic excavator, which comprises a crawler type lower traveling body 2 and a lower traveling body 2.
An upper revolving structure 4 is mounted on the upper revolving structure 4 so as to be revolvable via a revolving wheel 3, and a working device 5 is provided on the front side of the upper revolving structure 4 so as to be able to move up and down.

[0005] Reference numeral 6 denotes a track frame constituting the lower traveling body 2. The track frame 6 is, as shown in FIG. 9 and FIG.
And left and right side frames 8, 8 located on both left and right sides of the center frame 7.

Reference numeral 7 denotes a center frame which constitutes a central portion of the track frame 6. The center frame 7 is formed in a substantially H-shape by a thick steel plate or the like, and has an upper plate 7A and a bottom plate 7B which face upward and downward. A cylindrical tubular plate 7C fixed to a central portion between the upper plate 7A and the bottom plate 7B by welding or the like;
It is fixed by welding or the like between the upper plate 7A and the bottom plate 7B,
Four vertical plates 7D, 7D,... Located before and after the outer periphery of the cylindrical plate 7C, and four other vertical plates 7E, 7E,. It is constituted as a can-made structure consisting of.

A round body 7F for mounting the turning wheel 3 is fixed to the upper surface of the central portion of the upper plate 7A by welding or the like, and the central portion of the upper plate 7A and the bottom plate 7B has a smaller diameter than the cylindrical plate 7C. Circular holes 7G and 7H are formed respectively.

Reference numerals 8 denote left and right side frames provided on the left and right sides of the center frame 7 and extending in the front and rear directions, respectively. Each side frame 8 has a substantially U-shaped cross section. The center frame 7 is fixed to the left and right ends of the center frame 7 by welding or the like.

A driving wheel bracket 9 is fixed to one end of each side frame 8 by welding or the like, and a driving wheel 10 is provided on each driving wheel bracket 9. On the other hand, an idle wheel bracket 11 is fixed to the other end side of each side frame 8 by welding or the like, and an idle wheel 12 is rotatably provided on each idle wheel bracket 11.

The driving wheels 10 and the idler wheels 12 provided on the left and right side frames 8 respectively have crawler belts 13.
When the crawler belt 13 is driven by the drive wheels 10, the hydraulic excavator 1 can stably travel on uneven terrain such as a muddy ground or a crushed stone site.

[0011]

In the prior art described above, when the excavator 1 travels on flat ground, the center frame 7 constituting the track frame 6 is not required.
Since the bottom plate 7B is relatively far away from the ground, it is unlikely that the bottom plate 7B collides with the rock G on the ground and is damaged.

However, when the hydraulic excavator 1 travels on rough terrain such as a crushed stone site, for example, as shown in FIG.
In many cases, the bottom plate 7B is damaged by colliding with the bottom plate 7B bottom surface or the like, and there is a problem that the life of the track frame 6 is shortened due to the damage of the bottom plate 7B.

When the bottom plate 7B of the center frame 7 is damaged, it is necessary to repair the damaged portion promptly. However, since the center frame 7 is a can-made structure, the bottom plate 7B and the ground are not connected. However, there is a problem that the damaged bottom plate 7B cannot be easily repaired because the working space for performing the repair work is narrow.

In order to solve the above-mentioned problems, it is conceivable to take measures such as increasing the thickness of the bottom plate 7B of the center frame 7 or welding a thick plate to the bottom surface of the bottom plate 7B.
When the plate thickness of the entire B is increased, the weight of the excavator 1 becomes unnecessarily large, and when a plate material is welded to the bottom surface of the bottom plate 7B, this welding operation is complicated. is there.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems of the prior art, and is directed to a truck frame for a construction machine in which the bottom of a center frame can be prevented from being damaged by collision of rocks or the like and the life thereof can be extended. It is intended to provide.

[0016]

In order to solve the above-mentioned problems, the present invention provides a center frame and left and right side frames provided on both left and right sides of the center frame and extending forward and backward. Applied to truck frames of construction machinery.

A feature of the structure adopted by the first aspect of the present invention is that a protective plate which is located between the side frames and covers a bottom surface of the center frame is detachably attached to the center frame. .

[0018] With this configuration, the bottom surface of the center frame is protected by the protective plate. For example, when a construction machine travels on rough terrain such as a crushed stone site, rocks and the like are removed from the bottom surface of the center frame. And the center frame can be prevented from being damaged. Further, since the protection plate is detachably attached to the center frame, even if the protection plate is damaged by collision of rocks or the like, the damaged protection plate can be removed from the center frame and repaired or replaced.

According to a second aspect of the present invention, the protection plate is constituted by combining a plurality of protection plates which are separately attached and detached.

With this configuration, only the damaged protection plate among the plurality of protection plates can be removed from the center frame and repaired, so that the repair work can be easily performed.

According to a third aspect of the present invention, the protection plate includes a flat plate portion that covers a bottom surface of the center frame, and a temporary plate that is provided on the flat plate portion and engages with the center frame to temporarily fix the flat plate portion to the center frame. And the joint part.

With this configuration, the flat plate portion can be temporarily fixed to the center frame by engaging the engagement portion of the protection plate with the center frame, thereby facilitating the work of attaching the heavy protection plate. Can be done.

According to a fourth aspect of the present invention, the protection plate is provided with a bolt insertion hole through which a bolt for attaching the protection plate to the bottom surface of the center frame is inserted, and the bolt insertion hole accommodates a head of the bolt. The configuration is such that a head accommodation hole is provided.

[0024] With this configuration, the head of the bolt for attaching the protection plate to the bottom surface of the center frame can be prevented from protruding from the protection plate toward the ground, and rocks and the like can be formed on the head of the bolt. Damage of the bolt due to collision can be suppressed.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a truck frame of a construction machine according to the present invention will be described in detail below with reference to FIGS. In the present embodiment, the same components as those in the above-described related art are denoted by the same reference numerals, and description thereof will be omitted.

In the figure, reference numeral 21 denotes a hydraulic excavator. The hydraulic excavator 21 includes a lower traveling body 22 of a crawler type and an upper revolving body 4 rotatably mounted on the lower traveling body 22 via a revolving wheel 3. And a working device 5 provided on the front side of the upper swing body 4 so as to be able to move up and down.

Reference numeral 23 denotes a track frame constituting the lower traveling body 22. The track frame 23 is applied to this embodiment in place of the conventional track frame 6, and is substantially the same as the conventional track frame 6. The center frame 24 and the left and right side frames 8 described later. However, the track frame 23 according to the present embodiment is different from that according to the prior art in that protective plates 28, 28 described below are attached to the bottom of the center frame 24.

Reference numeral 24 denotes a center frame which forms the center of the track frame 23. As shown in FIGS. 2 to 4, the center frame 24 is substantially made of a thick steel plate or the like.
An upper plate 24A and a bottom plate 24B formed in a mold shape and facing in the upper and lower directions; a cylindrical tubular plate 24C fixed to a central portion between the upper plate 24A and the bottom plate 24B by welding or the like;
Are fixed between the base plate 24C and the bottom plate 24B by welding or the like, and are positioned before and after the outer periphery of the tube plate 24C, respectively, and at the left and right sides of the outer periphery of the tube plate 24C. Are formed as a can-making structure composed of four other vertical plates 24E, 24E,.

On the upper surface of the central portion of the upper plate 24A, a round body 24F for mounting the turning wheel 3 is fixed by welding or the like. In addition, circular holes 24G, 24 having a smaller diameter than the cylindrical plate 24C are formed at the center of the upper plate 24A and the bottom plate 24B.
H is formed respectively.

Are four bolt insertion holes provided at the front and rear positions of the bottom plate 24B. As shown in FIG. 3, these bolt insertion holes 25 are circular holes 24H of the bottom plate 24B. Two holes are formed in the vicinity of the front edge 24B1 located on the front side and near the rear edge 24B2 located behind the circular hole 24H.

Are four bolt insertion holes provided at the left and right positions of the bottom plate 24B. Each of the bolt insertion holes 26 is a left edge located on the left side of the circular hole 24H in the bottom plate 24B. 2 in the vicinity of the portion 24B3 and in the vicinity of the right edge 24B4 located on the right side of the circular hole 24H.
They are drilled individually.

Are four nuts provided on the upper surface side of the bottom plate 24B. These nuts 27 are concentric with the bolt insertion holes 26 formed at the left and right positions of the bottom plate 24B. At a predetermined position by welding or the like.

Reference numerals 28 denote bottom plates 2 of the center frame 24.
4B that is detachably attached to the front and rear directions individually
The protection plates 28 are formed of a single plate. The protection plates 28 cover the bottom surface of the center frame 24 from below by abutting each other from the front and the rear.

Each protective plate 28 is formed of, for example, a steel plate thicker than the bottom plate 24B of the center frame 24, and has a substantially rectangular flat plate portion 2 covering the bottom surface of the bottom plate 24B.
8A and the engaging plate portion 2 formed integrally with the flat plate portion 28A by bending the counter abutting portion side of the flat plate portion 28A into an L shape.
8B. The engagement plate portion 28B of the protection plate 28 located on the front side is connected to the front edge portion 24B of the bottom plate 24B.
Engage with 1. The engagement plate portion 28B of the protection plate 28 located on the rear side engages with the rear edge 24B2 of the bottom plate 24B.

Here, the flat plate portion 28A has front and rear dimensions of the front and rear edges 24B1 and 24B of the bottom plate 24B.
2, and the left and right dimensions are slightly smaller than the distance between the left and right edges 24B3 and 24B4 of the bottom plate 24B. On the other hand, the engagement plate 2
8B faces the flat plate portion 28A by bending the anti-abutting portion side of the flat plate portion 28A into an L shape, and the upper and lower intervals between the flat plate portion 28A and the engaging plate portion 28B are the thickness of the bottom plate 24B. It is set slightly larger than.

Reference numerals 29, 29 denote two bolt insertion holes formed in the left and right corners of the flat plate portion 28A of the protection plate 28 on the abutting portion side, and each of the bolt insertion holes 29 is a bottom plate. The bolt 32 is provided at a position corresponding to each of the bolt insertion holes 26 formed in the hole 24B, and a later-described bolt 32 is inserted therethrough. Also,
The bolt insertion hole 29 is provided with a bolt head accommodation hole 29A on the bottom surface side of the flat plate portion 28A of the protection plate 28 so as to be concentric with the bolt insertion hole 29. The bolt head accommodation hole 29A is Is formed as a bottomed hole having a large hole diameter. The bolt head accommodation hole 29A accommodates the head 32A of the bolt 32 to prevent the head 32A from projecting from the bottom surface of the flat plate portion 28A.

Reference numerals 30 and 30 denote two bolt insertion holes formed in the center of the flat plate portion 28A of the protection plate 28 on the side of the anti-abutting portion. Each of the bolt insertion holes 30 is formed in the bottom plate 24B. The bolt 33 is provided at a position corresponding to each of the bolt insertion holes 25, and a later-described bolt 33 is inserted. In addition, the bolt insertion hole 30 is formed on the bottom surface side of the flat plate portion 28A of the protection plate 28 so as to be concentric with the bolt insertion hole 30.
A is provided, and the bolt head receiving hole 30 </ b> A is formed as a bottomed hole having a larger hole diameter than the bolt insertion hole 30. The bolt head receiving hole 30A is
By accommodating the head 33A, the protrusion of the head 33A from the bottom surface of the flat plate portion 28A is suppressed.

Reference numerals 31 and 31 denote engagement plate portions 28B of the protection plate 28.
As shown in FIG. 4, each of the bolt insertion holes 31 is concentric with each of the bolt insertion holes 30 formed on the counter-abutting portion side of the flat plate portion 28A. And a bolt 33 is inserted through the position.

Numerals 32, 32 are two bolts for detachably attaching the protection plate 28 to the bottom plate 24B of the center frame 24. Each of the bolts 32 is a bolt insertion hole 2 of the flat plate portion 28A.
9. Bottom plate 24B through bolt insertion hole 26 of bottom plate 24B
Is screwed to a nut 27 fixed to the upper surface of the nut. At this time, the head 32A of the bolt 32 is accommodated in a bolt head accommodation hole 29A formed concentrically with the bolt insertion hole 29.

Reference numerals 33 and 33 denote two bolts for detachably attaching the protection plate 28 to the bottom plate 24B of the center frame 24 together with the above-mentioned bolts 32. The bolts 33 are the bolt insertion holes 30 of the flat plate portion 28A and the bottom plate. 24B, and is inserted into the bolt insertion hole 31 of the engagement plate portion 28B and protrudes to the upper surface side of the engagement plate portion 28B.
Is screwed to the nut 34 on the upper surface side. At this time, the head 33A of the bolt 33 is accommodated in the bolt head accommodation hole 30A formed concentrically with the bolt insertion hole 30.

The track frame 23 according to the present embodiment
Has the above-described configuration. Next, an operation procedure for attaching the front and rear protection plates 28 to the bottom plate 24B of the center frame 24 will be described.

First, as shown in FIG.
8 is slid backward and the rear protective plate 28 is slid forward, so that the abutting portion of each protective plate 28 abuts at the center of the bottom plate 24B of the center frame 24.

At this time, the engaging plate 2 of the front protection plate 28
8B is engaged with the front edge 24B1 of the bottom plate 24B, and the engagement plate 28B of the rear protection plate 28 is engaged with the rear edge 24B2 of the bottom plate 24B. Thus, the protection plate 28, which is a heavy object, can be temporarily fixed to the bottom plate 24B, and the bolt insertion holes 29,
30, the bolt insertion holes 26, 25 provided in the bottom plate 24B.
Can be positioned with respect to

In this state, the bolt 32 is fixed to the flat plate 28A.
After being inserted through the bolt insertion hole 29 of the bottom plate 24B and the bolt insertion hole 26 of the bottom plate 24B, the bolt 33 is screwed to the nut 27 fixed to the upper surface of the bottom plate 24B, and the bolt 33 is connected to the bolt insertion hole 30 of the flat plate portion 28A and the bolt of the bottom plate 24B. After passing through the insertion hole 25 and the bolt insertion hole 31 of the engagement plate portion 28B, the engagement plate portion 28
B is screwed to the nut 34 on the upper surface side.

In this manner, the front protection plate 28 is fastened to the bottom plate 24B by using the bolts 32 and 33 while the engagement plate portion 28B is engaged with the front end edge 24B1 of the bottom plate 24B, and the rear protection plate 28 is The protection plate 28 is configured such that the engagement plate portion 28B
B while being engaged with the rear edge 24B2 of each of the bolts 32,
33 to the bottom plate 24B. Thus, the two protection plates 28 are detachably attached to the bottom plate 24B in a state of closing the circular hole 24H, and cover the bottom surface of the bottom plate 24B from below, so that rocks and the like can be moved when traveling at a crushed stone site or the like. 24B is prevented from directly colliding.

Thus, in the present embodiment, the bottom plate 24B of the center frame 24 constituting the track frame 23
Is covered from below by the two protective plates 28. Therefore, even if the rock G or the like is deposited in a convex shape on the ground on which the hydraulic excavator 21 runs, for example, at a crushed stone site, the rock G Is the bottom plate 24B of the center frame 24
Can be reliably prevented by the protective plate 28 from directly colliding.

Therefore, the bottom plate 24 of the center frame 24
By suppressing damage to B and increasing the strength of the center frame 24, the life of the track frame 23 can be extended. Also, the bottom plate 24 of the center frame 24
Since the circular holes 24H formed in B can be closed by the respective protection plates 28, the rock G or the like is prevented from jumping into the center frame 24 through the circular holes 24H, and the center joint disposed in the center frame 24 is prevented. , Hydraulic piping (both not shown) and the like can be protected, and the reliability of the hydraulic excavator 21 can be improved.

In addition, the protection plate 28 includes bolts 32, 33
Since the protective plate 28 is detachably attached to the bottom plate 24B of the center frame 24 by using, even if the protective plate 28 is damaged by the collision of the rock G or the like, the fastening state by the bolts 32 and 33 is released to move the protective plate 28 to the center. By removing the protective plate 28 from the frame 24, repair and replacement of the damaged protective plate 28 can be performed quickly and easily.

For this reason, the bottom plate 24 of the center frame 24
B can be covered at all times by a protective plate 28 having no damage and having sufficient strength.
3 can be further extended.

Further, since the bottom plate 24B of the center frame 24 is covered by the two protection plates 28, only the damaged protection plate 28 of each protection plate 28 can be removed from the center frame 24. Damaged protection plate 2
8 can be more easily repaired and replaced.

In this embodiment, a bolt head receiving hole 29A concentric with the bolt insertion hole 29 and a bolt head receiving hole concentric with the bolt insertion hole 30 are provided on the bottom surface of the flat plate portion 28A constituting the protection plate 28. A hole 30A is provided, and a head 32A of a bolt 32 for fastening the protection plate 28 to the center frame 24 is received in a bolt head receiving hole 29A, and a head 33A of the bolt 33 is provided.
Is accommodated in the bolt head accommodation hole 30A.

Therefore, the heads 32 of the bolts 32, 33
A, 33A can be prevented from colliding with rocks,
It is possible to prevent the protection plate 28 from falling off the center frame 24 due to the breakage of the bolts 32, 33, and to prevent the heads 32A, 33A of the bolts 32, 33 from being deformed so that a tool such as a spanner cannot be used. it can.

Further, in the present embodiment, the protection plate 28
A flat plate portion 28A that covers the bottom plate 24B of the center frame 24 from below, and the bottom plate 2 that is provided integrally with the flat plate portion 28A.
4B, an engaging plate portion 28B that engages with one of the front and rear edge portions 24B1 and 24B2.

For this reason, the bottom plate 24 of the center frame 24
When the protection plate 28 is mounted on the bottom plate B, the engagement plate 28B of the protection plate 28 is moved to the front and rear edge portions 24B1, 24B of the bottom plate 24B.
By engaging with one of B2, the protection plate 28, which is a heavy object, can be temporarily fixed to the bottom plate 24B, and the bolt insertion holes 29, 30 provided in the flat plate portion 28A can be provided.
Can be positioned with respect to the bolt insertion holes 26 and 25 provided in the bottom plate 24B. Thereby, the bolt 3
The work of fastening the protection plate 28 to the bottom plate 24B using the two and 33 can be performed safely and easily.

In the above-described embodiment, the case where the bottom plate 24B of the center frame 24 is covered with the two protective plates 28 has been described as an example. However, the present invention is not limited to this. The bottom plate 24B of the center frame 24 may be covered with a plate or three or more protective plates.

In this case, for example, as shown in a modified example shown in FIG.
8 ′, 28 ′,...
4B may be covered. Each of these protective plates 28 'is composed of a flat plate portion 28A' and an engaging plate portion 28B ', similarly to the above-described protective plate 28, and the flat plate portion 28A' has bolt insertion holes 29 ', 30' and a bolt head. Housing hole 29
A 'and 30A' are provided one by one,
B 'is provided with one bolt insertion hole (not shown) at a position concentric with the bolt insertion hole 30'.

In the case where the bottom plate 24B of the center frame 24 is covered with the four protection plates 28 ', only the damaged protection plate 28' is repaired and replaced among the protection plates 28 '. Workability can be further improved.

In the above-described embodiment, the case where the present invention is applied to the track frame 23 constituting the lower traveling body 22 of the hydraulic excavator 21 has been described as an example. However, the present invention is not limited to this, and the present invention is not limited to this. The present invention can also be applied to a truck frame of another construction machine.

[0059]

As described in detail above, according to the first aspect of the present invention, the protection plate for covering the bottom surface of the center frame is detachably attached to the center frame. When the vehicle travels on rough terrain, it is possible to prevent rocks or the like deposited in a convex shape from directly colliding with the bottom surface of the center frame, thereby suppressing damage to the center frame. Therefore, the life of the truck frame can be extended, and the reliability of the construction machine can be improved.

Further, since the protective plate is detachably attached to the center frame, even if the protective plate is damaged by a collision with a rock or the like, the damaged protective plate can be removed from the center frame and repaired or replaced. Repair and replacement of the protection plate can be performed quickly and easily.

According to the second aspect of the present invention, since the protection plate is constituted by combining a plurality of protection plates which can be individually attached and detached, only the damaged protection plate among the plurality of protection plates is used. Can be removed from the center frame, and repair and replacement of the damaged protective plate can be performed more easily.

According to the third aspect of the present invention, the protection plate is provided on the flat plate portion covering the bottom surface of the center frame, and the flat plate portion is temporarily attached to the center frame by engaging with the center frame provided on the flat plate portion. The flat portion can be temporarily fixed to the center frame by engaging the engaging portion with the center frame, since
The operation of attaching the heavy protection plate to the center frame can be performed safely and easily.

According to the fourth aspect of the present invention, the protection plate is provided with a bolt insertion hole through which a bolt for attaching the protection plate to the bottom surface of the center frame is inserted, and the bolt insertion hole receives the bolt head. Since the head receiving hole is provided, it is possible to prevent the head of the bolt for attaching the protection plate to the bottom surface of the center frame from protruding from the protection plate toward the ground. For this reason, it is possible to prevent rocks and the like from colliding with the head of the bolt, such that the protection plate falls off the center frame due to the breakage of the bolt, or the head of the bolt is deformed and tools such as wrench cannot be used. Defects can be suppressed.

[Brief description of the drawings]

FIG. 1 is a rear view of a hydraulic shovel provided with a track frame according to an embodiment of the present invention as viewed from the rear side.

FIG. 2 shows a center frame, a protection plate and the like as indicated by arrows II- in FIG.
It is a bottom view seen from II direction.

FIG. 3 is a bottom view of the same position as FIG. 2 showing a state where a protection plate is removed from a center frame.

FIG. 4 is an exploded perspective view showing the track frame and the protection plate according to the present embodiment with the protection plate removed.

FIG. 5 is a cross-sectional view of the mounting state of the center frame and the protection plate viewed from the direction indicated by arrows VV in FIG. 1;

FIG. 6 is a bottom view showing a modification of the protection plate at the same position as in FIG. 3;

FIG. 7 is a left side view of a hydraulic shovel provided with a track frame according to the related art as viewed from the left side.

FIG. 8 is a rear view of a hydraulic shovel including a track frame according to the related art as viewed from the rear side.

FIG. 9 is a bottom view of the center frame and the like as viewed from the direction indicated by arrows IX-IX in FIG. 8;

FIG. 10 is a perspective view showing a track frame according to the related art.

[Explanation of symbols]

 8 side frame 23 track frame 24 center frame 24B bottom plate (bottom surface) 28, 28 'protection plate 28A, 28A' flat plate portion 28B, 28B 'engagement plate portion (engagement portion) 29, 29', 30, 30 'bolt insertion hole 29A, 29A ', 30A, 30A' bolt head receiving holes 32, 33 bolts 32A, 33A bolt heads

Claims (4)

[Claims] 1. A truck frame for a construction machine comprising a center frame and left and right side frames provided on both left and right sides of the center frame and extending forward and rearward, wherein the center frame includes A truck frame for a construction machine, wherein a protection plate for covering a bottom surface of the center frame is detachably mounted between side frames. 2. The track frame of a construction machine according to claim 1, wherein the protection plate is configured by combining a plurality of protection plates that are separately attached and detached. 3. The protection plate includes a flat plate portion that covers a bottom surface of the center frame, and an engaging portion provided on the flat plate portion and temporarily fixing the flat plate portion to the center frame by engaging with the center frame. Claim 1 or 2 constituted.
A truck frame for a construction machine according to claim 1. 4. The protection plate has a bolt insertion hole through which a bolt for attaching the protection plate to the bottom surface of the center frame is inserted, and the bolt insertion hole has a bolt head accommodation hole for accommodating a head of the bolt. Claims 1 and 2 that are provided.
Or a truck frame for a construction machine according to item 3.