JP2013036295A - Installation method and installation device for precast block - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an installation method and an installation device for precast block, allowing a clearance (work space) for installing a precast block to be made as small as possible.SOLUTION: A precast block 1 is transported by transportation means. Installation devices 10... are mounted and fixed on locations where grout holes 2a... in a lower floor slab 2 of the precast block 1 are necessary from the upper face side of the lower floor slab 2. Jacks 30... of the installation devices 10... are extended to lift up the precast block 1 and then the transportation means below the precast block 1 is removed. The jacks 30... of the installation devices 10... are contracted and the precast lock 1 is installed on an installation position. And then, the installation devices 10... are detached from the grout holes 2a... to the upper face side of the lower floor slab 2 and removed. Thus, a clearance around the precast block can be made as small as possible.

Description

  The present invention relates to a method and apparatus for installing a precast block.

For example, when a precast block such as a box culvert is installed at a predetermined installation point, it is often lifted by a large crane or a portal crane. However, it is difficult to lift and install large precast blocks by placing cranes near the installation point in places where buildings are densely populated or where traffic is heavy, such as in urban areas.
For this reason, the precast blocks that have been transported by transport vehicles are unloaded at a location away from the actual installation point, placed on the carriage when transported to the installation point, and laid from the unloading point to the installation point. Generally, it is transported along a trajectory.
In addition, the precast block thus transferred to the installation point by the carriage is lifted by the jack, and after the carriage is removed, the jack is shortened to be installed at the installation point (see, for example, Patent Document 1).

JP-A-8-144360

By the way, as described in Patent Document 1, when a precast block is lifted by a jack at an installation point, between the precast block and the existing precast block during the installation work, or between the precast block and the excavation groove during the installation work It is necessary to secure a sufficient working space, i.e., a gap, for operating the jack and attaching / detaching the jack between the side walls of the door.
However, if a sufficient work space is secured between the precast block being installed and the existing precast block, it may take time to move the precast block to the existing precast block after removing the jack. is there.
In addition, in order to secure a sufficient working space between the precast block during installation and the side wall of the excavation groove, the excavation groove must be excavated with an excessively wide width. When there is a restriction on the size of the land to be constructed as described above, it may be difficult to excavate the excavation groove while securing the work space.

  An object of the present invention is to provide a precast block installation method and an installation apparatus capable of reducing a gap for installing a precast block as much as possible.

In order to solve the above problems, the invention according to claim 1 transfers the precast block to the installation point by the transfer means,
The upper surface of the lower floor slab is provided with a plurality of pre-formed blocks in the lower floor slab in advance and provided with jacks that extend in the vertical direction at necessary locations of the grout holes that penetrate the lower floor slab in the thickness direction. Fixed from the side,
Lift the precast block by extending the jack of the installation device, then remove the transfer means below the precast block,
After the precast block is installed at the installation point by shortening the jack of the installation apparatus, the installation apparatus is removed from the grout hole to the upper surface side of the lower floor slab and removed.

Here, the necessary part is one of the plurality of grout holes, which does not interfere with the transfer device when the installation device is attached and lifts the precast block, and can lift the precast block in a balanced manner. Pointing to the grout hall.
In order to lift the precast block in a well-balanced manner, at least three grout holes are arranged in a balanced manner on the lower floor slab, and at least three installation devices are arranged in at least three grout holes arranged in a well-balanced manner. It is necessary to fix it. In general, grout holes are formed at the four corners of the lower floor slab, and the installation device is mounted and fixed to each of the grout holes at the four corners.

According to a second aspect of the present invention, in the precast block installation method according to the first aspect, an anchor plate with which a lower end portion of the installation device abuts via a slide means is installed in advance at the installation point. ,
When the precast block is transferred to the installation point by the transfer means, the precast block before the installation and the existing precast block are transferred so as to form a gap that does not contact the precast blocks. And
After removing the transfer means below the precast block, the precast block is moved to the existing precast block side by sliding the lower end portion of the installation device with respect to the anchor plate by the slide means. And

  The invention according to claim 3 is the precast block installation method according to claim 1 or 2, wherein after the installation device is removed from the grout hole, a grout material is injected from the grout hole as necessary. It is characterized by doing.

Invention of Claim 4 is an installation apparatus used for the installation method of the precast block as described in any one of Claims 1-3,
A cylindrical metal fitting fixed to a grout hole formed in the lower floor slab, having a hole portion coaxial with the grout hole, and having an internal thread formed on the inner peripheral surface of the hole portion,
By forming a male screw on the outer peripheral surface, the bushing is screwed into the cylindrical bracket from the upper surface side of the lower floor slab, and has a hole portion coaxial with the grout hole,
The bushing is provided with the jack mounted and fixed from the upper surface side of the lower floor slab,
The jack is inserted into the hole of the bushing so as to be slidable along the axial direction of the hole; and
The cylinder has a jack body fixed to the bushing while moving the cylinder up and down in the vertical direction along the axial direction of the hole of the bushing.

According to the present invention, since the installation device can be mounted or removed on the upper surface side of the lower floor slab, between the precast block during the installation work and the existing precast block, or between the precast block during the installation work and the side wall of the excavation groove The precast block can be installed at the installation point without securing a work space between the two, and the gap around the precast block can be minimized.
As a result, the precast block transferred to the installation point can be installed on the existing precast block side without securing a sufficient gap, so that the work of bringing the precast block to the existing precast block side can be reduced. .
In addition, since the excavation groove where the precast block is installed can be excavated without securing a sufficient working space between the precast block and the side wall of the excavation groove, the excavation groove is excavated with an extra wide width. There is no need to do so, and the labor involved in excavation of the excavation groove can be reduced.
Furthermore, even if there is a limit to the size of land to be constructed as in an urban area, the precast block installation work can be performed reliably. Moreover, after transferring the precast block, the construction can be performed without using a large machine such as a crane.

It is a perspective view which shows a precast block and a grout hole. It is a fragmentary sectional view which shows the state which attached the installation apparatus of this invention to the grout hole. It is a top view which shows the state which slides a precast block to the existing precast block side among the installation methods of this invention. It is sectional drawing which shows the positional relationship etc. of the precast block in a digging groove. It is sectional drawing which shows another structure with a cylindrical metal fitting. It is a perspective view which shows the connection method of a bushing and a jack.

Embodiments of the present invention will be described below with reference to the drawings.
1 to 6, reference numeral 1 denotes a precast block. The precast block 1 of the present embodiment is a box culvert, and includes a lower floor slab 2, an upper floor slab 3, and side walls 4 and 4 provided between both ends of the lower floor slab 2 and the upper floor slab 3. It is formed in a rectangular tube shape.
In the lower floor slab 2, grout holes 2 a... Penetrating the lower floor slab 2 in the thickness direction are formed at the four corners of the lower floor slab 2. These grout holes 2a ... are used for filling the grout material between the lower surface of the lower floor slab 2 and the installation point as necessary after the precast block 1 is grounded.
Although the precast block 1 of the present embodiment is a box culvert, the present invention is not limited to this, and any suitable one can be used as long as it has a bottom surface like the lower floor slab 2.

The precast block 1 is carried in by a transport vehicle or the like, and is unloaded at a location away from the actual installation point. From this unloading point to the installation point, the excavation groove 5 in which the precast block 1 is embedded is excavated.
The width of the excavation groove 5 is set slightly longer than the width of the precast block 1 (the length between the side walls 4 and 4). Therefore, it is set so that only a slight gap is formed between the side wall 6 of the excavation groove 5 and the side wall 4 of the precast block 1.
Here, the slight gap between the side wall 6 of the excavation groove 5 and the side wall 4 of the precast block 1 is a gap that allows the precast block 1 to bend the curve of the excavation groove 5. ing.
In addition, the foundation concrete 7 is flattened on the bottom surface of the excavation groove 5 with as little unevenness as possible. Furthermore, a track 8 is laid and fixed on the upper surface of the foundation concrete 7 from the unloading point to the installation point, and the carriage 9 on which the precast block 1 is placed can be moved along the track 8. (See FIGS. 2 to 4).
The carriage 9 can be removed from the track 8 simply by lifting it, and the track 8 can also be removed by removing it from the upper surface of the foundation concrete 7.
The track 8 is formed by connecting a plurality of metal rail members along the extending direction of the excavation groove 5. Furthermore, although not shown, this track 8 is fixed to the foundation concrete 7 via a laid iron plate.

In each of the grout holes 2a formed in the four corners of the lower floor slab 2 of the precast block 1, as shown in FIG. 2, an installation device 10 for installing the precast block 1 at an installation point is provided on the lower floor. The plate 2 is mounted and fixed from the upper surface side.
The installation apparatus 10 includes a cylindrical metal member 20, a bushing 23, and a jack 30.

The cylindrical metal fitting 20 has a hole 21 coaxial with the grout hole 2a. A female screw is formed on the inner peripheral surface of the hole 21.
Further, as shown in FIGS. 2 and 5, a plurality of flange-shaped convex portions 22 and groove portions 29 are provided on the outer peripheral surface in order to improve adhesion performance. The plurality of convex portions 22 and the groove portions 29 are arranged at intervals in the axial direction of the cylindrical metal fitting 20.
The cylindrical metal fitting 20 is embedded when the precast block 1 is formed. At the same time when the grout hole 2a is formed in the lower floor slab 2, the cylindrical metal fitting 20 is engaged with the hole wall of the grout hole 2a. . That is, the cylindrical metal fitting 20 is integrated with the lower floor slab 2.

The bushing 23 includes a cylindrical main body 24, a hole 25 formed in the cylindrical main body 24 and coaxial with the grout hole 2 a, and flange portions 26 and 26 provided at the upper end of the cylindrical main body 24. .
The inner peripheral surface of the hole 25 is a smooth surface, and a male screw is formed on the outer peripheral surface of the cylindrical body 24.
The flange portions 26 and 26 are provided at equal intervals at two locations in the circumferential direction of the upper end portion of the cylindrical main body 24. These two flange portions 26, 26 are arranged at an appropriate interval. Here, the appropriate intervals may be equal intervals or unequal intervals, and are arranged at equal intervals in the present embodiment.
The bushing 23 is screwed into the cylindrical metal fitting 20 from the upper surface side of the lower floor slab 2. That is, the bushing 23 can be fixed to the cylindrical fitting 20 by screwing the male screw on the outer peripheral surface of the bushing 23 and the female screw of the hole 21 of the cylindrical fitting 20.

The jack 30 is mounted and fixed from the upper surface side of the lower floor slab 2 and includes a cylinder 31 and a jack body 35.
The jack 30 is a long stroke jack that is hydraulic and has a long cylinder 31.

The cylinder 31 is inserted into the hole 25 of the bushing 23 so as to be slidable along the axial direction of the hole 25.
The cylinder 31 is formed in a long shape so as to form a sufficient space in which the track 8 and the carriage 9 can be removed when the precast block 1 is lifted upward.
The cylinder 31 is set so as to protrude below the lower floor slab 2 when extended, and not to protrude below the lower floor slab 2 when contracted.

An anchor plate 33 is disposed below the lower end portion of the cylinder 31 in order to prevent the foundation concrete 7 from being damaged by direct contact of the lower end portion of the cylinder 31. The upper surface of the anchor plate 33 is a smooth surface.
The lower end portion of the cylinder 31 is coated with a low friction material 32 such as a fluororesin, so that the cylinder 31 can be slid on the upper surface of the anchor plate 33. That is, the low friction material 32 attached to the lower end portion of the cylinder 31 is a sliding means.
Since the installation devices 10 are respectively fixed to the grout holes 2a at the four corners of the lower floor slab 2, the four installation devices 10 are used. For this reason, four anchor plates 33 are also used.

  The jack body 35 is fixed to the bushing 23, and is configured so that the cylinder 31 can be advanced and retracted in the vertical direction along the axial direction of the hole 25 of the bushing 23. In order to expand and contract the cylinder 31 by the jack body 35, it can be expanded and contracted by increasing or loosening the hydraulic pressure in the jack body 35. The hydraulic pressure is controlled by a hydraulic control device (not shown).

At the lower end portion of the jack body 35, flange portions 36 are provided at two locations in the circumferential direction of the lower end portion of the jack body 35. These two flange portions 36, 36 are arranged at an appropriate interval. Here, the appropriate intervals may be equal intervals or unequal intervals, and are arranged at equal intervals in the present embodiment.
The flange portions 36 and 36 of the jack body 35 and the flange portions 26 and 26 of the bushing 23 are connected by a joint fitting 40 as shown in FIGS.
The joint fitting 40 includes an annular main body 41 and a plurality of hooking ribs 42 formed integrally with the inner peripheral surface of the annular main body 41.
The diameter of the inner peripheral surface of the annular body 41 is slightly larger than the diameter of the upper end portion of the bushing 23 including the flange portions 26 and 26 and the diameter of the lower end portion of the jack body 35 including the flange portions 36 and 36. It is set to be large.
The hook ribs 42 are formed in an arc shape along the inner peripheral surface of the annular main body 41, and are arranged at equal intervals two at each of the upper end portion and the lower end portion of the inner peripheral surface of the annular main body 41. ing. The distance between the two hooking ribs 42, 42 at the upper end and the distance between the two hooking ribs 42, 42 at the lower end are determined by the flanges 26, 26 of the bushing 23 and the flange of the jack body 35. The dimensions are set such that the portions 36 and 36 can be inserted. And each flange part 26 and 36 inserted from this space | interval part will be fitted between the upper and lower hooking ribs 42 and 42 by rotating the joint metal fitting 40 itself or the jack 30 to the circumferential direction. As a result, the flange portions 36 and 36 of the jack body 35 and the flange portions 26 and 26 of the bushing 23 are connected.

Next, a method for installing the precast block 1 will be described.
The precast block 1 of the present embodiment is a precast block that is installed second or later among a plurality of precast blocks that are installed in the excavation groove 5. Therefore, there is a precast block that has been constructed prior to this precast block 1, and in the present embodiment, for convenience, it will be referred to as an existing precast block 1a.

First, the precast block 1 that has been carried in by a transport vehicle or the like and unloaded at a location distant from the actual installation point is placed on the upper surface of a carriage 9 arranged on the track 8.
And the trolley | bogie 9 is transferred to an installation point with transfer vehicles, such as a battery locomotive (not shown), for example.

Note that the anchor plate 33 is disposed in advance on the foundation concrete 7 at the installation point at a position located below the cylinder 31.
Further, when the precast block 1 is transferred to the installation point by the carriage 9, as shown in FIGS. 3 and 4, the precast block 1 is interposed between the precast block 1 and the existing precast block 1a. , 1a is transferred so as to form a gap that does not contact each other.
Further, a plurality of installation blocks 34 on which the precast block 1 is actually installed are arranged in advance around the anchor plate 33 at a distance from the anchor plate 33.
The installation block 34 is set so that its height is higher than the height (thickness) of the anchor plate 33.

Subsequently, the installation apparatus 10 is mounted and fixed from the upper surface side of the lower floor slab 2 to each of the grout holes 2a formed at the four corners of the lower floor slab 2.
That is, first, the bushing 23 is screwed and fixed from the upper surface side of the lower floor slab 2 to the cylindrical metal fitting 20 provided in advance in the grout hole 2a. At this time, a gap is formed between the flange portions 26 and 26 and the upper surface of the cylindrical metal fitting 20 so that the hooking ribs 42 and 42 at the lower end of the joint metal fitting 40 can be inserted.
Next, the joint fitting 40 is attached to the bushing 23 from above so that the interval between the hook ribs 42 and 42 at the lower end of the joint fitting 40 passes through the flange portions 26 and 26. Then, the joint fitting 40 is rotated in the circumferential direction, and the hooking ribs 42 and 42 at the lower end portion are inserted between the flange portions 26 and 26 of the bushing 23 and the upper surface of the tubular fitting 20 and pulled. Multiply.
Next, the jack 30 is mounted and fixed from the upper surface side of the lower floor slab 2. That is, while the cylinder 31 is inserted into the hole 25 of the bushing 23, the flange portions 36 and 36 of the jack body 35 are inserted from the interval between the hook ribs 42 and 42 at the upper end of the joint fitting 40. Then, the jack main body 35 is rotated in the circumferential direction, and the flange portions 36, 36 of the jack main body 35 are connected to the upper surfaces of the flange portions 26, 26 of the bushing 23 and the hooking ribs 42, 42 of the upper end portion. Insert between and hook.

Subsequently, after the precast block 1 is lifted by extending the jacks 30 of the installation devices 10..., The track 8 and the carriage 9 below the precast block 1 are removed.
That is, the cylinder 31 is extended by adjusting so as to increase the hydraulic pressure of the jack body 35. Since the anchor plate 33 is disposed below the cylinder 31, the cylinder 31 is extended until the lower end portion comes into contact with the upper surface of the anchor plate 33. When the lower end portion of the cylinder 31 comes into contact with the anchor plate 33 without deviation, the cylinder 31 is further extended to lift the precast block 1.
The four jacks 30 are linked via a hydraulic control device, and can lift the precast block 1 without tilting.
When the precast block 1 is lifted in this way, first, the cart 9 is removed, and then the track 8 is removed.

Subsequently, the precast block 1 lifted by the installation device 10 is lowered to a position just before the bottom surface of the lower floor slab 2 comes into contact with the installation block 34 and then moved to the existing precast block 1a side.
That is, since the low friction material 32 is coated on the lower end portion of the cylinder 31 as a sliding means, the lower friction portion of the low friction material 32 is used to connect the lower end portion of the cylinder 31 to the anchor plate. 33, the precast block 1 is moved to the existing precast block 1a side. This prevents the precast block 1 and the existing precast block 1a from coming into strong contact before bringing the precast block 1 to the existing precast block 1a side. The precast block 1a can be prevented from being damaged, and can be installed without a gap between the two.
The distance by which the precast block 1 is moved to the existing precast block 1a side is set to such a distance that the cylinder 31 does not fall from the anchor plate 33. Therefore, when the precast block 1 is transferred to the installation point by the carriage 9, the cylinder 31 does not fall from the anchor plate 33 due to a gap formed between the precast block 1 and the existing precast block 1a. It is a gap of a degree.

Subsequently, by shortening the cylinder 31, the precast block 1 is gradually lowered and installed at the installation point. That is, the precast block 1 is placed on the installation block 34. At this time, a gap through which the grout to be injected passes can be formed between the lower floor slab 2 and the anchor plate 33. As described above, since the four jacks 30 are interlocked, the precast block 1 can be lowered without inclination.
Thereafter, the installation devices 10 are removed from the grout holes 2a to the upper surface side of the lower floor slab 2 and removed.
That is, first, the jack body 35 is rotated in the circumferential direction, and the flange portions 36 and 36 are removed from between the upper surfaces of the flange portions 26 and 26 of the bushing 23 and the hooking ribs 42 and 42 of the upper end portion, Further, the upper end of the joint fitting 40 is extracted upward from the interval between the hooking ribs 42, 42. At this time, the cylinder 31 is also extracted from the hole 25 of the bushing 23, whereby the jack 30 can be lifted upward and removed.
Next, the joint fitting 40 is rotated in the circumferential direction, and the hooking ribs 42 and 42 at the lower end are removed from between the flange portions 26 and 26 of the bushing 23 and the upper surface of the tubular fitting 20. The joint fitting 40 is pulled upward so that the gap between the hooking ribs 42, 42 at the lower end passes through the flanges 26, 26. Thereby, the joint fitting 40 can be removed.
Next, the bushing 23 is removed in the upward direction by rotating in the direction of releasing the screwed state between the screws.
The anchor plates 33 and the installation blocks 34 are left below the precast block 1 even after the installation apparatus 10 is removed.

After the installation devices 10 are removed from the grout hole 2a, for example, an inlet (not shown), which is a device with a check valve, is attached to the grout hole 2a, and the grout material is injected from the inlet. .
The injected grout material is filled in a gap (gap) between the lower floor slab 2 of the precast block 1 and the foundation concrete 7. Since the lower floor slab 2 and the foundation concrete 7 can be brought into close contact with each other by solidifying the grout material, the installation stability of the precast block 1 can be improved.
As described above, the precast block 1 can be installed at a predetermined installation point of the excavation groove 5.

In the present embodiment, the attaching / detaching work of the bushing 23, the joint fitting 40, and the jack 30 can be performed manually.
If the installation apparatus 10 can be attached and removed above the lower floor slab 2 and a space for a worker can be secured, the construction can be performed regardless of the shape of the precast block. Therefore, although the precast block 1 of the present embodiment is a box culvert, it is not limited to this and can be changed as appropriate.
In the present embodiment, the grout material is injected from the grout hole 2a. However, the present invention is not limited to this when dry mortar is previously provided in the gap at the installation point.

In the present embodiment, four grout holes 2a are formed on the four corners of the lower floor slab 2, that is, on the lower floor slab 2. However, the present invention is not limited to this. It is sufficient that at least three are formed on the floor slab 2.
However, the grout hole 2a to which the installation device 10 is mounted interferes with the transfer device when the precast block 1 is lifted regardless of the number of grout holes 2a formed in the lower floor slab 2. What is formed in a place where the precast block 1 can be lifted with good balance without being matched is selected.
In the case of a precast block having a particularly large size, a number of grout holes in consideration of the filling properties of the grout are formed in the lower floor slab, and a number of installation devices 10 corresponding to the weight of the precast block may be mounted.

According to the present embodiment, the installation device 10 can be mounted or removed on the upper surface side of the lower floor slab 2, so that the space between the precast block 1 and the existing precast block 1 a, or between the precast block 1 and the excavation groove 5. Without securing a working space between the side walls 6 and 6, the precast block 1 can be installed at the installation point, and the gap around the precast block 1 can be minimized.
As a result, the precast block 1 transferred to the installation point can be installed on the existing precast block 1a side without securing a sufficient gap, so that the precast block 1 is moved to the existing precast block 1a side. Can save time and effort.
In addition, the excavation groove 5 in which the precast block 1 is installed can be excavated without securing a sufficient work space between the precast block 1 and the side walls 6 and 6 of the excavation groove 5, so that the extra width is increased. It is not necessary to excavate the excavation groove 5 in a wide state, and the labor involved in excavation of the excavation groove 5 can be reduced.
Furthermore, even if there is a restriction on the size of land to be constructed as in an urban area, the installation work of the precast block 1 as described above can be performed reliably. Moreover, after the precast block 1 is transferred, the construction can be performed without using a large machine such as a crane.

DESCRIPTION OF SYMBOLS 1 Precast block 1a Existing precast block 2 Lower floor slab 2a Grout hole 3 Upper floor slab 4 Side wall 5 Excavation groove 6 Side wall 7 Foundation concrete 8 Track 9 Bogie 10 Installation device 20 Cylindrical metal fitting 21 Hole 22 Protrusion 23 Bushing 24 Cylindrical Body 25 Hole portion 26 Flange portion 29 Groove portion 30 Jack 31 Cylinder 32 Low friction material 33 Anchor plate 34 Installation block 35 Jack body 36 Flange portion 40 Joint metal fitting 41 Annular body 42 Hooking rib

Claims (4)

Transfer the precast block to the installation point by transfer means,
The upper surface of the lower floor slab is provided with a plurality of pre-formed blocks in the lower floor slab in advance and provided with jacks that extend in the vertical direction at necessary locations of the grout holes that penetrate the lower floor slab in the thickness direction. Fixed from the side,
Lift the precast block by extending the jack of the installation device, then remove the transfer means below the precast block,
Installation of the precast block characterized in that after the precast block is installed at the installation point by shortening the jack of the installation device, the installation device is removed from the grout hole to the upper surface side of the lower floor slab and removed. Method. At the installation point in advance, a lower end portion of the installation device is installed with an anchor plate that comes into contact with the slide means,
When the precast block is transferred to the installation point by the transfer means, the precast block before the installation and the existing precast block are transferred so as to form a gap that does not contact the precast blocks. And
After removing the transfer means below the precast block, the precast block is moved to the existing precast block side by sliding the lower end portion of the installation device with respect to the anchor plate by the slide means. The precast block installation method according to claim 1.   The method for installing a precast block according to claim 1 or 2, wherein after the installation device is removed from the grout hole, a grout material is injected from the grout hole as necessary. An installation device used in the precast block installation method according to any one of claims 1 to 3,
A cylindrical metal fitting fixed to a grout hole formed in the lower floor slab, having a hole portion coaxial with the grout hole, and having an internal thread formed on the inner peripheral surface of the hole portion,
By forming a male screw on the outer peripheral surface, the bushing is screwed into the cylindrical bracket from the upper surface side of the lower floor slab, and has a hole portion coaxial with the grout hole,
The bushing is provided with the jack mounted and fixed from the upper surface side of the lower floor slab,
The jack is inserted into the hole of the bushing so as to be slidable along the axial direction of the hole; and
An apparatus for installing a precast block, comprising: a jack body fixed to the bushing while the cylinder is advanced and retreated in the vertical direction along the axial direction of the hole of the bushing.

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