JP2012001321A - Telescopic boom - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a telescopic boom capable of easily adjusting a projection amount of sliding pads provided in an upper part of a rear end of an inner boom material.SOLUTION: The telescopic boom includes: the inner boom material inserted and fitted in an outer boom material relatively axially movably to the tubular outer boom material, and formed with recessed parts opening upward and rearward in the upper part of the rear end; the upper sliding pads 6a, 6b fitted in the recessed parts, and disposed so that the upper sliding pads 6a, 6b can abut on the inner face of an upper part of the outer boom material; spacers interposed between the upper sliding pads 6a, 6b and corresponding bottom faces in the recessed parts; and pressing members 14a, 14b detachably installed at the rear end face of the inner boom material so that the pressing members cover rear faces of the spacers and the upper sliding pads fitted in the recessed parts.

Description

  The present invention relates to a telescopic boom.

  Conventionally, as an example of a boom provided in a crane, an extendable boom configured to be extendable in the axial direction is known, and Patent Document 1 below discloses an example of such an extendable boom.

  The telescopic boom disclosed in Patent Document 1 includes a plurality of tubular boom members having different diameters, and these boom members are inserted by inserting a small-diameter boom member inside a large-diameter boom member. They are combined. The inner boom material can move relative to the outer boom material in the axial direction, and the telescopic boom expands and contracts by the relative movement. Each boom member has a cross-sectional shape having a substantially rectangular upper part and a semicircular lower part.

  An inner sliding pad is provided on the outer surface of the corners on both sides in the width direction located at the upper part of the rear end part of the inner boom material and on the outer surface of the lower part of the rear end part of the inner boom material on the both sides in the width direction. Are provided. Further, outer sliding pads are respectively provided on the inner surfaces of the corners on both sides in the width direction located at the upper part of the distal end portion of the outer boom member and the inner surface of the lower portion of the distal end portion of the outer boom member. The inner sliding pad is in sliding contact with the inner surface of the outer boom member when the inner boom member moves relative to the outer boom member in the axial direction, and the outer sliding pad is moved axially with respect to the outer boom member. When making relative movement, it slides on the outer surface of the inner boom member. The sliding pads provided at the upper corners of the rear end portion of the inner boom material among the inner sliding pads are separated from the plate-shaped rear collar welded to the rear end surface of the inner boom material and the front of the rear collar. It is fixed to the inner boom member by being sandwiched between a plate-like front collar welded to the upper surface of the inner boom member at a position.

Japanese Patent No. 28287979

  By the way, when a suspension load is applied to the telescopic boom, in order to transmit the load from the upper part of the rear end part of the inner boom member to the outer boom member through the sliding pad provided on the upper part, It is necessary to adjust the protruding amount of the sliding pad from the outer surface of the upper part of the inner boom member in accordance with the size of the gap between the outer surface of the upper part of the member and the inner surface of the upper part of the outer boom member.

  However, the telescopic boom described in Patent Document 1 has a problem that the adjustment work of the sliding pad protrusion amount from the upper surface of the rear end portion of the inner boom member becomes complicated.

  Specifically, in the telescopic boom described above, when adjusting the amount of sliding pad protrusion from the upper surface of the rear end portion of the inner boom member, the surface of the sliding pad is removed after the inner boom member is extracted from the outer boom member. Adjust the thickness of the sliding pad, and then insert the inner boom material back into the outer boom material.The amount of protrusion of the sliding pad will be different between the outer surface of the inner boom material and the upper part of the outer boom material. It is necessary to repeat until an appropriate amount of protrusion according to the gap between the inner surface and the operation is complicated.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a telescopic boom capable of easily adjusting the protruding amount of the sliding pad provided at the upper portion of the rear end portion of the inner boom member. It is to be.

  In order to achieve the above object, an extendable boom according to the present invention is an extendable boom that is provided on a crane so as to be able to be raised and lowered, and is configured to be extendable and contracted, and is formed into a cylindrical shape with an outer boom material formed in a cylindrical shape. An inner boom member that is inserted into the outer boom member so as to be axially movable relative to the outer boom member and that has at least upper and rear recesses provided at the upper portion of the rear end portion. A sliding pad that is fitted in the recess and is arranged so as to be able to contact the inner surface of the upper portion of the outer boom member, a surface on the back side of the sliding pad that contacts the inner surface of the outer boom member, and A spacer interposed between the bottom surface of the recess, a fixing member for fixing the sliding pad fitted in the recess to the rear end of the inner boom member, and a fit in the recess Is the sliding pad and detachably attached to a rear end face of the inner boom member so as to cover the rear surface of the spacer has, and a pressing member supporting the sliding pad from the rear side.

  In this telescopic boom, a recess provided in the upper part of the rear end portion of the inner boom material, in which a sliding pad is fitted into the upper and rear sides, covers the rear surface of the sliding pad and the spacer fitted in the concave portion. Since the member can be attached to and detached from the rear end surface of the inner boom member, the protruding amount of the sliding pad from the upper surface of the rear end portion of the inner boom member can be easily adjusted by the spacer.

  Specifically, in this telescopic boom, since the recess provided in the upper part of the rear end portion of the inner boom material opens to the rear side, the inner boom material remains immersed in the outer boom material, The presser plate can be removed from the rear end face of the inner boom member through the opening of the outer boom member from the rear of the cylindrical outer boom member, and the spacer can be replaced. That is, in this telescopic boom, the protruding amount of the sliding pad from the upper surface of the rear end portion of the inner boom member can be adjusted by replacing the spacer while the inner boom member is inserted into the outer boom member. Therefore, the protruding amount of the sliding pad from the upper surface of the rear end portion of the inner boom material is adjusted without repeating the cumbersome and large-scale work of extracting the inner boom material from the outer boom material and inserting it again as in the prior art. be able to. Further, in this telescopic boom, a spacer on the back side of the surface of the sliding pad that contacts the inner surface of the outer boom member with a thickness corresponding to the size of the gap between the outer surface of the inner boom member and the inner surface of the outer boom member. The amount of the sliding pad protruding from the upper surface of the rear end of the inner boom material is interposed between the outer surface of the inner boom material and the inner surface of the outer boom material. The amount of protrusion can be adjusted according to That is, with this telescopic boom, the amount of protrusion of the sliding pad can be adjusted without performing the complicated work of cutting the surface of the sliding pad as in the prior art. From the above, in this telescopic boom, the protruding amount of the sliding pad provided at the upper part of the rear end portion of the inner boom member can be easily adjusted as compared with the conventional one.

  In the telescopic boom, the outer boom member extends in the width direction, and is disposed on one side of the outer top plate portion constituting the upper surface of the outer boom member and the width direction of the outer top plate portion, and vertically. A first outer side plate portion extending on the other side in the width direction of the outer top plate portion and extending in the vertical direction, and extending in the vertical direction. A second outer side plate portion that constitutes the other side surface of the direction, the inner boom member is disposed substantially parallel to the outer top plate portion, and an inner upper plate portion that constitutes the upper surface of the inner boom member; A first inner side plate portion disposed on the first outer side plate portion side with respect to the inner top plate portion and extending substantially parallel to the first outer side plate portion; and the second outer side with respect to the inner top plate portion. A second inner side disposed on the side plate portion side and extending substantially parallel to the second outer side plate portion A first recess is provided on one side of the upper part of the rear end of the inner boom member, and a second recess is provided on the other side. The first recess and the second recess open in the width direction outer side of the inner boom member in addition to the upper side and the rear side, respectively, and the sliding pad is fitted into the first recess and the outer ceiling of the outer boom member is inserted. A first sliding pad disposed so as to be able to contact the lower surface of the plate portion and the inner surface of the first outer side plate portion; the lower surface of the top plate portion of the outer boom member fitted into the second recess portion; It is preferable that the 2nd sliding pad arrange | positioned so that contact | abutting with respect to the inner surface of a 2nd outer side board part is included.

  According to this configuration, the sliding pad can contact the lower surface of the outer top plate portion and the inner surfaces of the both side plate portions of the outer boom material, so that when the inner boom material moves relative to the outer boom material in the axial direction, It is possible to prevent rattling in both the direction and the lateral direction. Further, according to this configuration, when a suspension load and a lateral load are applied to the telescopic boom, both an upward load and a lateral load are effectively applied from the inner boom material to the outer boom material via the sliding pad. Can be communicated to.

  In this case, the inner top plate portion has an upper surface disposed substantially parallel to the lower surface of the outer top plate portion, and the first inner side plate portion is substantially parallel to the inner surface of the first outer side plate portion. The second inner side plate portion has an outer surface disposed substantially parallel to the inner surface of the second outer side plate portion, and the bottom surface of the first recess is the first inner side plate portion. A first lateral surface extending inward in the width direction of the inner boom member substantially parallel to an upper surface of the inner top plate portion from an outer surface of the inner top plate portion, and an outer surface of the first inner side plate portion from the upper surface of the inner top plate portion. A bottom surface of the second recess is substantially parallel to the top surface of the inner top plate portion from the outer surface of the second inner side plate portion. A second horizontal surface extending inward in the width direction and a substantially flat surface from the upper surface of the inner top plate portion to the outer surface of the second inner side plate portion. A first vertical spacer, the first spacer being interposed between the first horizontal surface and a corresponding surface of the first sliding pad, and A first vertical surface spacer interposed between a first vertical surface and a corresponding surface of the first sliding pad, wherein the second spacer includes the second horizontal surface and the second sliding pad. A second horizontal surface spacer interposed between the corresponding surfaces, and a second vertical surface spacer interposed between the second vertical surface and the corresponding surface of the second sliding pad. It is preferable to include.

  According to this configuration, the first horizontal spacer having the thickness corresponding to the size of the gap between the upper surface of the inner top plate portion and the lower surface of the outer top plate portion is set to the first horizontal surface of the first recess and the first. The amount of protrusion of the first sliding pad in the vertical direction can be adjusted by being interposed between the corresponding surfaces of the sliding pad. Further, the first vertical surface spacer having a thickness corresponding to the size of the gap between the outer surface of the first inner side plate portion and the inner surface of the first outer side plate portion is used as the first vertical surface of the first recess and the first sliding pad. It is possible to adjust the protruding amount of the first sliding pad in the width direction of the inner boom member by interposing it between the corresponding surfaces of the inner boom member. In addition, the second horizontal surface spacer having a thickness corresponding to the size of the gap between the upper surface of the inner top plate portion and the lower surface of the outer top plate portion corresponds to the second horizontal surface of the second recess and the second sliding pad. The amount of protrusion of the second sliding pad in the vertical direction can be adjusted by interposing it with the surface to be performed. Further, the second vertical surface spacer having a thickness corresponding to the size of the gap between the outer surface of the second inner side plate portion and the inner surface of the second outer side plate portion is used as the second vertical surface of the second recess and the second sliding pad. It is possible to adjust the protruding amount of the second sliding pad in the width direction of the inner boom member by interposing it with the corresponding surface.

  In this case, the concave portion is provided on one side and the other side with respect to the center in the width direction of the upper portion of the rear end portion of the inner boom member, and among the upper portion of the rear end portion of the inner boom member. The inner surface of the first recess, which is the recess provided on one side with respect to the center in the width direction, is from the first outer surface, which is the outer surface on the one side of the inner boom member, to the upper surface of the inner boom member. A first lateral surface extending inward in the width direction of the inner boom member and a first vertical surface extending downward in parallel to the first outer surface from the upper surface of the inner boom member, the inner boom An inner surface of the second concave portion, which is the concave portion provided on the other side with respect to the center in the width direction in the upper portion of the rear end portion of the material, is a second outer surface that is the outer surface on the other side of the inner boom material. The inner boom material parallel to the upper surface of the inner boom material A second lateral surface extending inward in the width direction; and a second vertical surface extending downward in parallel to the second outer surface from the upper surface of the inner boom member, wherein the sliding pad is fitted into the first recess. A first sliding pad and a second sliding pad fitted in the second recess, and the spacer is interposed between the first lateral surface and a corresponding surface of the first sliding pad. A first horizontal surface spacer, a first vertical surface spacer interposed between the first vertical surface and a corresponding surface of the first sliding pad, a second horizontal surface, and a second sliding pad. A second horizontal surface spacer interposed between the corresponding surfaces, and a second vertical surface spacer interposed between the second vertical surface and the corresponding surface of the second sliding pad. Preferred to include .

  According to this configuration, the first sliding pad and the second sliding pad can contact the inner surface of the outer boom member on both outer sides in the width direction of the rear end portion in addition to the upper side of the rear end portion of the inner boom member. In addition to the load in the vertical direction, the lateral load caused by the horizontal deflection of the telescopic boom can be supported by these sliding pads. Further, in this configuration, the gap between the first sliding pad and the inner surface of the outer boom member in the vertical direction can be adjusted by the first horizontal spacer, and the inner boom member in the width direction can be adjusted by the first vertical spacer. The clearance between the first sliding pad and the inner surface of the outer boom member can be adjusted, and the second lateral spacer can adjust the clearance between the second sliding pad and the inner surface of the outer boom member in the vertical direction. The gap between the second sliding pad and the inner surface of the outer boom member in the width direction of the inner boom member can be adjusted by the two vertical surface spacers. For this reason, the gap between the sliding pads in the vertical direction and the inner surface of the outer boom member and the gap between the sliding pads in the width direction of the inner boom member and the inner surface of the outer boom member are respectively set to the prescribed sizes. By adjusting, it is possible to prevent the inner boom material from being excessively displaced in the vertical direction and the lateral direction with respect to the outer boom material when the vertical boom and the horizontal load are applied to the telescopic boom.

  Furthermore, in this case, in addition to the first lateral surface and the first longitudinal surface, the bottom surface of the first recess includes an end portion located on the inner side in the width direction of the inner boom member, and the first lateral surface, A first inclined surface portion is connected to the lower end portion of the first vertical surface, and is inclined so as to be directed toward the first outer surface as it goes downward. The bottom surface of the second recess includes the second horizontal surface and the first In addition to the two vertical surfaces, the second lateral surface connects the end located on the inner side in the width direction of the inner boom member and the lower end of the second vertical surface, and as it goes downward, the second outer surface side A rearward end portion of the inner boom member that is substantially perpendicular to the first inclined portion from the first inclined portion to a space inside the inner boom member. A first through hole penetrating the second through the second inclined surface portion into a space inside the inner boom member; A second through-hole penetrating substantially perpendicular to the surface portion is provided, and a first bolt hole is provided in a portion of the first sliding pad facing the first slope portion, and the second sliding pad The second bolt hole is provided in a portion facing the second slope portion, and the fixing member is inserted into the first through hole from the inside of the inner boom member and screwed into the first bolt hole. And the first bolt for fastening the first sliding pad and the second through hole inserted from the inside of the inner boom material into the second bolt hole, and the second sliding pad is fastened. Preferably, the second bolt is included.

  According to this configuration, the first sliding pad can be fixed in both the vertical direction and the width direction of the inner boom member with the first bolt extending obliquely with respect to the first horizontal surface and the first vertical surface of the first recess. Therefore, the first sliding pad is fixed as compared with the case where the bolt for fixing the first sliding pad in the vertical direction and the bolt for fixing the first sliding pad in the width direction of the inner boom member are individually provided. Therefore, the number of bolts can be reduced. Similarly, the second bolt can fix the second sliding pad in both the vertical direction and the width direction of the inner boom member, so that the number of bolts for fixing the second sliding pad can be reduced. .

  Furthermore, in this case, the first through hole is a long hole that is long in the inclination direction of the first slope portion, and the second through hole is a long hole that is long in the inclination direction of the second slope portion. preferable.

  According to this configuration, since the thickness of the first horizontal spacer and the thickness of the first vertical spacer are different, the position of the first sliding pad is different from the position of the first sliding pad when both spacers have the same thickness. Even if the first vertical surface is displaced in the direction perpendicular to the first horizontal surface or the first vertical surface, the first bolt is moved in the inclination direction of the first slope portion in the first through hole following the positional displacement of the first sliding pad. By shifting the position along the first sliding pad, the first sliding pad can be effectively fastened. Similarly, when the thickness of the second horizontal surface spacer is different from the thickness of the second vertical surface spacer, the second bolt is moved in the second through hole following the displacement of the second sliding pad. The second sliding pad can be effectively fastened by shifting the position along the inclination direction of the second slope portion.

  As described above, according to the present invention, it is possible to provide a telescopic boom capable of easily adjusting the protruding amount of the sliding pad provided at the upper portion of the rear end portion of the inner boom member.

1 is a schematic side view of a crane to which a telescopic boom according to an embodiment of the present invention is applied. The side surface in the vicinity of the rear end part of both the boom materials schematically showing the relative arrangement of the inner boom material and the outer boom material when adjusting the protruding amount of the upper sliding pad in the telescopic boom according to the embodiment of the present invention. FIG. It is a figure which shows roughly the cross section perpendicular | vertical to the axial direction of an expansion-contraction boom in the state in which the inner side boom material was immersed in the inside of an outer side boom material. It is a perspective view of the rear end part of the inner side boom material of the telescopic boom by one Embodiment of this invention. It is a perspective view which shows the state which removed the pressing member and the upper sliding pad from the rear-end part of the inner side boom material shown in FIG. It is the figure which looked at the upper part of the rear-end part of the state which removed the pressing member from the rear-end part of the inner side boom material shown in FIG. 4 from back. FIG. 5 is a cross-sectional view of an upper part and an upper sliding pad of a rear end portion of the inner boom member in a direction perpendicular to the axial direction of the inner boom member illustrated in FIG. 4.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  First, with reference to FIG.1 and FIG.2, the structure of the telescopic boom by one Embodiment of this invention is demonstrated.

  The telescopic boom 2 according to the present embodiment is provided on an upper swing body 102 of a crane as shown in FIG. A suspended load is suspended from the distal end of the telescopic boom 2 via a wire rope (not shown).

  The telescopic boom 2 of this embodiment includes a plurality of boom members 3, an upper sliding pad 6 (see FIG. 4), a lower sliding pad (not shown), a spacer 10 (see FIG. 6), and a fixing member 12. (See FIG. 7), a presser member 14 (see FIG. 4), and a presser bolt 16 are provided.

  Each boom material 3 is formed in a cylindrical shape having different diameters, and the boom material 3 is combined by inserting the small-diameter boom material 3 inside the large-diameter boom material 3. . Hereinafter, the boom material 3 that receives the small-diameter boom material 3 inside the large-diameter boom material 3 is referred to as an outer boom material 4, and the boom material 3 that is inserted into the outer boom material 4 is the inner boom material 5. That's it. The inner boom member 5 can move relative to the outer boom member 4 in the axial direction, and the telescopic boom 2 expands and contracts by the relative movement.

  As shown in FIG. 3, the outer boom member 4 includes an outer top plate portion 4a, a first outer side plate portion 4b, a first outer bent portion 4c, a second outer side plate portion 4d, a second outer bent portion 4e, and an outer bottom plate portion. 4f.

  The outer top plate portion 4 a is a flat portion that extends in the width direction of the outer boom member 4 and constitutes the upper surface of the outer boom member 4.

  The first outer side plate portion 4 b is a flat plate-like portion constituting the side surface on one side in the width direction of the outer boom member 4. The first outer side plate portion 4b is disposed on one side in the width direction of the outer top plate portion 4a and extends in the vertical direction.

  The first outer bent portion 4c connects the upper end of the first outer side plate portion 4b and the end portion on the first outer side plate portion 4b side in the width direction of the outer top plate portion 4a. It is formed in a shape that is bent stepwise between the outer side plate portion 4b.

  The second outer side plate portion 4 d is a flat plate-like portion constituting the other side surface in the width direction of the outer boom member 4. The second outer side plate portion 4d is disposed on the other side in the width direction of the outer top plate portion 4a and extends in the vertical direction.

  The second outer bent portion 4e connects the upper end of the second outer side plate portion 4d and the end portion on the second outer side plate portion 4d side in the width direction of the outer top plate portion 4a. It is formed in a shape that is bent stepwise between the outer side plate portion 4d.

  The outer bottom plate portion 4f is a portion constituting the bottom surface of the outer boom member 4 and connects the lower end portion of the first outer side plate portion 4b and the lower end portion of the second outer side plate portion 4d.

  The inner boom member 5 includes an inner top plate portion 5a, a first inner side plate portion 5b, a first inner bent portion 5c, a second inner side plate portion 5d, a second inner bent portion 5e, an inner bottom plate portion 5f, and a collar 5g (FIG. 4). See).

  The inner top plate portion 5 a is a flat plate-like portion that constitutes the upper surface 5 h of the inner boom member 5, and extends in the width direction and the longitudinal direction of the inner boom member 5. The inner top plate portion 5a is disposed substantially parallel to the outer top plate portion 4a.

  The first inner side plate portion 5b is a flat plate-like portion constituting the first outer surface 5i that is one outer surface in the width direction of the inner boom member 5. The first inner side plate portion 5 b is disposed on the first outer side plate portion 4 b side with respect to the inner top plate portion 5 a and extends in the vertical direction and the longitudinal direction of the inner boom member 5. In addition, the said up-down direction means the up-down direction in the state in which the expansion-contraction boom 2 was laid down, and it is the same also in the following description. The first inner side plate portion 5b extends substantially parallel to the first outer side plate portion 4b, and is disposed perpendicular to the inner top plate portion 5a.

  The first inner bent portion 5c connects the upper end of the first inner side plate portion 5b and the end portion on the first inner side plate portion 5b side in the width direction of the inner top plate portion 5a. 1 It is formed in a shape that is bent stepwise as it goes toward the inner side plate portion 5b side.

  The second inner side plate portion 5d is a flat plate-like portion constituting the second outer side surface 5j which is the other outer side surface in the width direction of the inner boom member 5. The second inner side plate portion 5d is disposed on the second outer side plate portion 4d side with respect to the inner top plate portion 5a, and extends in the vertical direction and the longitudinal direction of the inner boom member 5. The second inner side plate portion 5d extends substantially parallel to the second outer side plate portion 4d, and is disposed perpendicular to the inner top plate portion 5a.

  The second inner bent portion 5e connects the upper end of the second inner side plate portion 5d and the end portion on the second inner side plate portion 5d side in the width direction of the inner top plate portion 5a. 2. It is formed in a shape that is bent stepwise as it goes toward the inner side plate portion 5d side.

  The inner bottom plate portion 5f is a portion that constitutes the bottom surface of the inner boom member 5, and connects the lower end portion of the first inner side plate portion 5b and the lower end portion of the second inner side plate portion 5d.

  The collar 5g includes an inner top plate portion 5a, a first inner side plate portion 5b, a first inner bent portion 5c, a second inner side plate portion 5d, and a second inner side at a predetermined distance from the rear end of the inner boom member 5. It is a plate-like portion welded to the outer surface of the bent portion 5e and the inner bottom plate portion 5f. The collar 5g is arranged perpendicular to the axial direction of the inner boom member 5.

  As shown in FIG. 5, a first recess 5 k and a second recess 5 m are provided at the upper portion of the rear end portion of the inner boom member 5. The rear end portion of the inner boom member 5 is an end portion located on the rear side of the inner boom member 5 in the longitudinal direction of the crane when the telescopic boom 2 disposed at the front portion of the crane is laid down. It is an end located on the base end side of the telescopic boom 2. The same applies to the following description. In the following description, “rear side” means a rear side in the front-rear direction of the crane in a state where the telescopic boom 2 disposed at the front part of the crane is laid down. The first recessed portion 5k is provided on one side of the upper portion of the rear end portion of the inner boom member 5 with respect to the center in the width direction. Of these, it is provided on the other side with respect to the center in the width direction. Specifically, the first concave portion 5k is provided at a location corresponding to the first inner bent portion 5c in the upper part of the rear end portion of the inner boom member 5, and the second concave portion 5m is formed on the inner boom member 5. It is provided in the location corresponding to the 2nd inner side bending part 5e among the upper parts of a rear-end part.

  The first recess 5k opens to the upper side, the rear side, and the outer side in the width direction of the inner boom member 5. The bottom surface of the first recess 5k includes a first horizontal surface 5n, a first vertical surface 5p, and a first inclined surface portion 5q.

  The first lateral surface 5n extends inward in the width direction of the inner boom member 5 in parallel with the upper surface 5h of the inner boom member 5 from the first outer surface 5i.

  The first vertical surface 5p extends downward from the upper surface 5h of the inner boom member 5 in parallel to the first outer surface 5i.

  The 1st slope part 5q connects the edge part located in the width direction inner side of the inner side boom material 5 among the 1st horizontal surfaces 5n, and the lower end part of the 1st vertical surface 5p, and is 1st outer surface 5i side as it goes below. It is inclined to head toward.

  The second recess 5m opens to the upper side, the rear side, and the outer side in the width direction of the inner boom member 5. The second recess 5m is formed symmetrically with the first recess 5k with respect to the center of the inner boom member 5 in the width direction. The bottom surface of the second recess 5m includes a second horizontal surface 5r, a second vertical surface 5s (see FIG. 6), and a second inclined surface portion 5t.

  The second lateral surface 5r extends inward in the width direction of the inner boom member 5 from the second outer surface 5j of the inner boom member 5 in parallel to the upper surface 5h of the inner boom member 5.

  The second vertical surface 5s (see FIG. 6) extends downward from the upper surface 5h of the inner boom member 5 in parallel to the second outer surface 5j.

  The second inclined surface portion 5t connects the end portion located on the inner side in the width direction of the inner boom member 5 and the lower end portion of the second vertical surface 5s in the second lateral surface 5r, and the second outer surface 5j as it goes downward. Inclined to the side.

  Further, a first through hole 5v and a second through hole 5w (see FIG. 7) are provided at the upper part of the rear end portion of the inner boom member 5.

  The first through hole 5v penetrates a portion where the first slope portion 5q is provided from the first slope portion 5q into the space inside the inner boom member 5 substantially perpendicularly to the first slope portion 5q. . Two first through holes 5v are formed in the first inclined surface portion 5q, and the two first through holes 5v are spaced apart from each other in the front-rear direction. Each of the first through holes 5v is a long hole that is long in the inclination direction of the first inclined surface portion 5q.

  Further, as shown in FIG. 6, a first presser bolt hole 5x and a second presser bolt hole 5y are formed on the rear end surface of the inner boom member 5. A plurality of first presser bolt holes 5x are formed around the first recess 5k in the rear end surface of the inner boom member 5, and the second presser bolt holes 5y are second recesses in the rear end surface of the inner boom member 5. A plurality are formed around 5 m.

  The second through hole 5w penetrates the portion where the second slope portion 5t is provided from the second slope portion 5t to the space inside the inner boom member 5 substantially perpendicularly to the second slope portion 5t. . Two second through holes 5w are formed in the second inclined surface portion 5t, and these two second through holes 5w are arranged apart from each other in the front-rear direction. Each 2nd through-hole 5w consists of a long hole in the inclination direction of the 2nd slope part 5t, respectively.

  The upper sliding pad 6 is fitted in the recesses 5k and 5m provided at the upper part of the rear end portion of the inner boom member 5, and protrudes from the outer surface of the inner boom member 5 in this state. The upper sliding pad 6 is in sliding contact with the inner surface of the upper portion of the outer boom member 4 when the inner boom member 5 moves relative to the outer boom member 4 in the axial direction. Prevents rattling in the vertical and width directions. Further, when a suspension load is applied to the tip of the telescopic boom 2, an upward load is transmitted from the upper part of the rear end part of the inner boom member 5 to the upper part of the outer boom member 4 via the upper sliding pad 6. .

  The upper sliding pad 6 includes a first upper sliding pad 6a fitted into the first recess 5k and a second upper sliding pad 6b fitted into the second recess 5m.

  The first upper sliding pad 6a includes a first pad upper surface portion 6e, a first pad outer surface portion 6f, a first pad lower surface portion 6g (see FIG. 6), a first pad inner surface portion 6h, and a first pad slope portion. 6i.

  The first pad upper surface portion 6e is the upper surface of the first upper sliding pad 6a. The first pad upper surface portion 6e is disposed substantially parallel to the upper surface 5h of the inner boom member 5, and is located above the upper surface 5h. The first pad upper surface portion 6 e is in contact with the lower surface of the outer top plate portion 4 a of the outer boom member 4.

  The first pad outer surface portion 6f is an outer surface located on the outer side in the width direction of the inner boom member 5 in the first upper sliding pad 6a. The first pad outer surface portion 6f is disposed substantially parallel to the first outer surface 5i of the inner boom member 5, and is located on the outer side in the width direction of the inner boom member 5 with respect to the first outer surface 5i. The first pad outer surface portion 6 f contacts the inner surface of the first outer side plate portion 4 b of the outer boom member 4.

  The first pad lower surface portion 6g is the lower surface of the first upper sliding pad 6a. The first pad lower surface portion 6g is disposed substantially parallel to the first lateral surface 5n of the first recess 5k and is opposed to the first lateral surface 5n.

  The first pad inner side surface portion 6h is an inner side surface located on the inner side in the width direction of the inner boom member 5 in the first upper sliding pad 6a. The first pad inner side surface portion 6h is disposed substantially parallel to the first vertical surface 5p of the first recess 5k and is opposed to the first vertical surface 5p.

  The 1st pad slope part 6i has connected the edge part located in the width direction inner side of the inner side boom material 5 among the 1st pad lower surface parts 6g, and the lower end part of the 1st pad inner side surface part 6h, and the 1st recessed part 5k The inclined surface is disposed substantially parallel to the first inclined surface portion 5q and is opposed to the first inclined surface portion 5q.

  Moreover, as shown in FIG. 7, the 1st bolt hole 6j is formed in the 1st pad slope part 6i among the 1st upper side sliding pads 6a. The first bolt hole 6j extends substantially perpendicular to the first pad slope 6i.

  The second upper sliding pad 6b fitted in the second recess 5m has a shape that is symmetrical to the first upper sliding pad 6a with respect to the center in the width direction of the inner boom member 5. Specifically, the second upper sliding pad 6b includes a second pad upper surface portion 6m corresponding to the first pad upper surface portion 6e, a second pad outer surface portion 6n corresponding to the first pad outer surface portion 6f, A second pad lower surface portion 6p corresponding to the first pad lower surface portion 6g, a second pad inner surface portion 6q corresponding to the first pad inner surface portion 6h, and a second pad inclined surface portion corresponding to the first pad inclined surface portion 6i. 6r. In addition, a second bolt hole 6s corresponding to the first bolt hole 6j is formed in the second pad slope portion 6r of the second upper sliding pad 6b.

  A lower sliding pad (not shown) is provided on the inner surface of the lower portion of the front end portion of the outer boom member 4. The lower sliding pad is in sliding contact with the outer surface of the lower portion (inner bottom plate portion 5f) of the inner boom member 5 when the inner boom member 5 moves relative to the outer boom member 4 in the axial direction. Further, when a suspension load is applied to the telescopic boom 2, a downward load is transmitted from the lower portion of the inner boom member 5 to the outer boom member 4 through the lower sliding pad.

  The spacer 10 is used to adjust the protruding amount of the upper sliding pad 6 from the outer surface of the inner boom member 5. The spacer 10 includes a first spacer 20 and a second spacer 22.

  The first spacer 20 is interposed between the back surface of the first upper sliding pad 6a that contacts the inner surface of the outer boom member 4 and the bottom surface of the first recess 5k. The first spacer 20 includes a first lateral spacer 20a interposed between the first lateral surface 5n of the first recess 5k and the first pad lower surface portion 6g of the first upper sliding pad 6a, The first vertical surface spacer 20b is interposed between the first vertical surface 5p of the recess 5k and the first pad inner side surface portion 6h of the first upper sliding pad 6a.

  The first horizontal spacer 20a is a flat member. A plurality of thicknesses are prepared as the first horizontal spacer 20a. The amount of protrusion of the first upper sliding pad 6a from the upper surface 5h of the inner boom member 5 is that of the first lateral surface spacer 20a interposed between the first pad lower surface portion 6g and the first lateral surface 5n. It changes depending on the thickness.

  The first vertical spacer 20b is a flat member. As the first vertical spacer 20b, a plurality of thicknesses are prepared. The protrusion amount of the first upper sliding pad 6a from the first outer surface 5i of the inner boom member 5 is for the first vertical surface interposed between the first pad inner side surface portion 6h and the first vertical surface 5p. It changes according to the thickness of the spacer 20b.

  The second spacer 22 is interposed between the back surface of the second upper sliding pad 6b that contacts the inner surface of the outer boom member 4 and the bottom surface of the second recess 5m. The second spacer 22 includes a second lateral surface spacer 22a interposed between the second lateral surface 5r of the second recess 5m and the second pad lower surface portion 6p of the second upper sliding pad 6b, The second vertical surface spacer 22b is interposed between the second vertical surface 5s of the recess 5m and the second pad inner side surface portion 6q of the second upper sliding pad 6b.

  The second horizontal spacer 22a is a flat member. As the second horizontal spacer 22a, a plurality of thicknesses are prepared. The amount of protrusion of the second upper sliding pad 6b from the upper surface 5h of the inner boom member 5 is that of the second lateral surface spacer 22a interposed between the second pad lower surface portion 6p and the second lateral surface 5r. It changes depending on the thickness.

  The second vertical surface spacer 22b is a flat member. As the second vertical surface spacer 22b, a plurality of thicknesses are prepared. The amount of protrusion of the second upper sliding pad 6b from the second outer surface 5j of the inner boom member 5 is for the second vertical surface interposed between the second pad inner side surface portion 6q and the second vertical surface 5t. It changes according to the thickness of the spacer 22b.

  As shown in FIG. 7, the fixing member 12 is for fixing the upper sliding pad 6 fitted in the recesses 5 k and 5 m to the rear end portion of the inner boom member 5. The fixing member 12 includes a first bolt 12a and a second bolt 12b.

  The first bolt 12 a is for fixing the first upper sliding pad 6 a fitted in the first recess 5 k to the rear end portion of the inner boom member 5. The first bolt 12a is inserted from the inner side of the inner boom member 5 into the first through hole 5v and is screwed into the first bolt hole 6j of the first upper sliding pad 6a. When the first bolt 12a is tightened in this state, the first upper sliding pad 6a sandwiches the first lateral surface spacer 20a between the first pad lower surface portion 6g and the first lateral surface 5n and Fastened to the inner boom member 5 with the first vertical surface spacer 20b sandwiched between the first pad inner side surface portion 6h and the first vertical surface 5p.

  The second bolt 12 b is for fixing the second upper sliding pad 6 b fitted in the second recess 5 m to the rear end portion of the inner boom member 5. The second bolt 12b is inserted into the second through hole 5w from the inside of the inner boom member 5 and screwed into the second bolt hole 6s of the second upper sliding pad 6b. When the second bolt 12b is tightened in this state, the second upper sliding pad 6b sandwiches the second lateral spacer 22a between the second pad lower surface portion 6p and the second lateral surface 5r and Fastened to the inner boom member 5 with the second vertical surface spacer 22b sandwiched between the second pad inner side surface portion 6q and the second vertical surface 5s.

  The pressing member 14 (see FIG. 4) supports the upper sliding pads 6a and 6b fitted in the recesses 5k and 5m from the rear side. The pressing member 14 includes a first pressing member 14a that supports the first upper sliding pad 6a fitted in the first concave portion 5k from the rear side, and a second upper sliding pad 6b fitted in the second concave portion 5m on the rear side. And a second presser member 14b supported from above.

  The first pressing member 14a is made of a flat plate material, and covers the rear surfaces of the first upper sliding pad 6a, the first horizontal spacer 20a, and the first vertical spacer 20b that are fitted into the first recess 5k. A rear end surface of the inner boom member 5 is detachably provided.

  Specifically, the first presser member 14a has a position corresponding to a plurality of first presser bolt holes 5x (see FIG. 6) provided around the first recess 5k in the rear end surface of the inner boom member 5. A plurality of holes (not shown) penetrating in the plate thickness direction of the first pressing member 14a are provided. The presser bolts 16 are inserted into the respective holes, and the presser bolts 16 are screwed into the first presser bolt holes 5x of the inner boom member 5 and tightened, whereby the first presser member 14a is attached to the inner boom member 5. Fastened to the rear end. Then, the first presser member 14a can be removed from the inner boom member 5 by loosening the presser bolt 16 and removing it from the first presser bolt hole 5x. Further, the first pressing member 14a sandwiches the first upper sliding pad 6a fitted in the first recess 5k with the collar 5g. When a suspension load is applied to the telescopic boom 2, a relative positional shift occurs so that the upper portion of the inner boom member 5 is directed forward with respect to the upper portion of the outer boom member 4. A shearing force in the front-rear direction acts on the first upper sliding pad 6a that contacts the lower surface of the top plate portion 4a. The first pressing member 14a prevents deformation of the first upper sliding pad 6a against the shearing force acting on the first upper sliding pad 6a.

  The second pressing member 14b is made of a flat plate material so as to cover the rear surfaces of the second upper sliding pad 6b, the second horizontal surface spacer 22a, and the second vertical surface spacer 22b fitted in the second recess 5m. A rear end surface of the inner boom member 5 is detachably provided. The configuration of the second pressing member 14b is the same as the configuration of the first pressing member 14b.

  Next, in the telescopic boom 2 of the present embodiment, a process for adjusting the protruding amount of the first upper sliding pad 6a and the second upper sliding pad 6b from the outer surface of the inner boom member 5 will be described.

  First, the inner boom member 5 is in the most immersed state in the outer boom member 4. Accordingly, the rear end portion of the inner boom member 5 is disposed in the vicinity of the rear end portion of the outer boom member 4 inside the outer boom member 4 as shown in FIG.

  When adjusting the protruding amount of the first upper sliding pad 6a, the presser bolt 16 (see FIG. 4) is loosened from the rear of the outer boom member 4 through the opening of the outer boom member 4 and removed from the inner boom member 5, and the first The presser member 14 a is removed from the inner boom member 5.

  Next, the first bolt 12a (see FIG. 7) is loosened, and the first lateral surface is used from the rear between the first lateral surface 5n of the first recess 5k and the first pad lower surface portion 6g of the first upper sliding pad 6a. The spacer 20a is inserted. The first lateral surface spacer 20a is selected from a plurality of spacers having different thicknesses so that the amount of protrusion above the first upper sliding pad 6a can be the target protrusion amount. Similarly, the first vertical surface spacer 20b is inserted from the rear between the first vertical surface 5p of the first recess 5k and the first pad inner side surface portion 6h of the first upper sliding pad 6a. In this first vertical surface spacer 20b, the amount of protrusion from the plurality of spacers having different thicknesses to the side of the first upper sliding pad 6a (the outer side in the width direction of the inner boom member 5) is set as the target protrusion amount. Choose a thickness that can.

  Thereafter, the first upper sliding pad 6a, the first horizontal surface spacer 20a, and the first vertical surface spacer 20b are fixed to the inner boom member 5 by tightening the first bolt 12a.

  Finally, the first presser member 14a (see FIG. 4) is arranged so as to cover the rear surface of the first upper sliding pad 6a, and the first presser member 14a is fastened to the rear end surface of the inner boom member 5 with the presser bolt 16. To do.

  The process for adjusting the protruding amount of the second upper sliding pad 6b is the same as the process for adjusting the protruding amount of the first upper sliding pad 6a.

  As described above, in the present embodiment, since the concave portions 5k and 5m provided at the upper part of the rear end portion of the inner boom member 5 are opened to the rear side, the inner boom member 5 is placed inside the outer boom member 4. The presser members 14a and 14b can be removed from the rear end face of the inner boom member 5 through the opening of the outer boom member 4 from the rear side of the tubular outer boom member 4 while being immersed in the spacers 20 and 22. Can be exchanged. That is, in this embodiment, the spacers 20 and 22 are replaced while the inner boom member 5 is inserted into the outer boom member 4, and the upper sliding pad 6a from the upper surface and side surface of the rear end portion of the inner boom member 5 is replaced. , 6b can be adjusted. For this reason, the upper sliding pad 6a from the upper surface and the side surface of the rear end portion of the inner boom member 5 is not repeated without repeating the cumbersome and large-scale operation of extracting the inner boom member from the outer boom member and inserting it again as in the prior art. The protrusion amount of 6b can be adjusted.

  Further, in the present embodiment, the lateral surface spacers 20a and 22a having a thickness corresponding to the size of the gap between the upper surface 5h of the inner boom member 5 and the inner surface of the outer boom member 4 facing the upper surface 5h are replaced with the upper sliding member. By interposing between the lower surfaces 6g, 6p of the pads 6a, 6b and the lateral surfaces 5n, 5r of the recesses 5k, 5m, the amount of protrusion of the upper sliding pads 6a, 6b from the upper surface 5h of the inner boom member 5 can be reduced. The amount of protrusion can be adjusted according to the size of the gap between the upper surface 5h of the inner boom member 5 and the inner surface of the outer boom member 4 facing the upper surface 5h. Further, the vertical spacers 20b and 22b having a thickness corresponding to the size of the gap between the outer surface of the inner boom member 5 and the inner surface of the outer boom member 4 opposed to the outer surface are provided on the upper sliding pads 6a and 6b. By interposing between the inner side surfaces 6h, 6q and the vertical surfaces 5p, 5s of the recesses 5k, 5m, the amount of protrusion of the upper sliding pads 6a, 6b from the outer surfaces 5i, 5j of the inner boom member 5 can be reduced. The amount of protrusion can be adjusted according to the size of the gap between the outer surfaces 5i, 5j of the material 5 and the inner surface of the outer boom material 4 facing the outer surfaces 5i, 5j. That is, in the present embodiment, the amount of protrusion of the upper sliding pads 6a and 6b can be adjusted without performing the complicated work of cutting the surface of the sliding pad as in the prior art.

  From the above, in this embodiment, the protruding amount of the upper sliding pads 6a and 6b provided on the upper part of the rear end portion of the inner boom member 5 can be easily adjusted as compared with the conventional case.

  In the present embodiment, the first upper sliding pad 6a is moved in the vertical direction and the width of the inner boom member 5 by the first bolt 12a extending obliquely with respect to the first horizontal surface 5n and the first vertical surface 5p of the first recess 5k. Since it can be fixed in both directions, a bolt for fixing the first upper sliding pad 6a in the vertical direction and a bolt for fixing the first upper sliding pad 6a in the width direction of the inner boom member 5 are individually provided. The number of bolts for fixing the first upper sliding pad 6a can be reduced compared to the case where the first upper sliding pad 6a is provided. Similarly, the second bolt 12b can fix the second upper sliding pad 6b in both the vertical direction and the width direction of the inner boom member 5, so that a bolt for fixing the second upper sliding pad 6b can be used. The number can be reduced.

  Further, in the present embodiment, when the thickness of the first horizontal surface spacer 20a and the thickness of the first vertical surface spacer 20b are different, the position of the first upper sliding pad 6a is the same as the thickness of both the spacers 20a and 20b. Even if the first upper sliding pad 6a is displaced in the direction perpendicular to the first horizontal surface 5n or the first vertical surface 5p, the first bolt 12a is moved following the positional deviation of the first upper sliding pad 6a. The first upper sliding pad 6a can be effectively fastened by shifting the first through hole 5v along the inclination direction of the first inclined surface portion 5q. Similarly, when the thickness of the second horizontal spacer 22a is different from the thickness of the second vertical spacer 22b, the second bolt 12b is moved to follow the positional shift of the second upper sliding pad 6b. The second upper sliding pad 6b can be effectively fastened by shifting along the inclination direction of the second inclined surface portion 5t in the through hole 5w.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and further includes meanings equivalent to the scope of claims for patent and all modifications within the scope.

  For example, the structure for fixing the upper sliding pad fitted in the recess to the inner boom member is not limited to the fixing structure shown in the above embodiment.

  Further, the first through hole 5v and the second through hole 5w may not be long holes.

2 telescopic boom 4 outer boom material 5 inner boom material 5h upper surface 5i first outer surface 5j second outer surface 5k first recess 5m second recess 5n first horizontal surface 5p first vertical surface 5q first slope 5r second horizontal Surface 5s Second vertical surface 5t Second inclined surface portion 5v First through hole 5w Second through hole 6 Upper sliding pad (sliding pad)
6a First upper sliding pad (first sliding pad)
6b Second upper sliding pad (second sliding pad)
6j First bolt hole 6s Second bolt hole 12 Fixing member 12a First bolt 12b Second bolt 14 First pressing member 16 Second pressing member 20 First spacer 20a First horizontal spacer 20b First vertical spacer 22 Second spacer 22a Second horizontal surface spacer 22b Second vertical surface spacer

Claims (5)

A telescopic boom that can be raised and lowered in a crane and configured to be telescopic,
An outer boom member formed in a tubular shape;
It is formed in a cylindrical shape, is fitted inside the outer boom material so as to be relatively movable in the axial direction with respect to the outer boom material, and is provided with a recess opening at least on the upper side and the rear side at the upper part of the rear end portion. Inner boom material,
A sliding pad that is fitted in the recess and arranged so as to be able to contact the inner surface of the upper portion of the outer boom member;
A spacer interposed between a surface on the back side of the sliding pad that contacts the inner surface of the outer boom member and a bottom surface of the recess;
A fixing member for fixing the sliding pad fitted in the recess to a rear end portion of the inner boom member;
A telescopic boom comprising a pressing member that is detachably attached to a rear end surface of the inner boom material so as to cover a rear surface of the sliding pad and the spacer fitted in the recess, and supports the sliding pad from the rear side. . The outer boom member extends in the width direction, and is disposed on one side in the width direction of the outer top plate portion and the outer top plate portion constituting the upper surface of the outer boom member, and extends in the vertical direction. A first outer side plate portion that constitutes one side surface in the width direction of the material, and is arranged on the other side in the width direction of the outer top plate portion and extends in the vertical direction, on the other side in the width direction of the outer boom material. Including a second outer side plate portion constituting the side surface,
The inner boom member is disposed substantially parallel to the outer top plate portion, and is disposed on the first outer side plate portion side with respect to the inner top plate portion constituting the upper surface of the inner boom member and the inner top plate portion. A first inner side plate portion extending substantially parallel to the first outer side plate portion, and disposed on the second outer side plate portion side with respect to the inner top plate portion, and extending substantially parallel to the second outer side plate portion. A second inner side plate part,
As the recess, a first recess is provided on one side of the upper part of the rear end of the inner boom member, and a second recess is provided on the other side,
The first recess and the second recess open to the outside in the width direction of the inner boom member in addition to the upper side and the rear side, respectively.
The sliding pad is fitted in the first recess and is disposed so as to be able to contact the lower surface of the outer top plate portion of the outer boom member and the inner surface of the first outer side plate portion; 2. A second sliding pad fitted in the second recess and disposed so as to be able to contact the lower surface of the top plate portion and the inner surface of the second outer side plate portion of the outer boom member. The telescopic boom described. The inner top plate portion has an upper surface disposed substantially parallel to the lower surface of the outer top plate portion,
The first inner side plate portion has an outer surface disposed substantially parallel to the inner surface of the first outer side plate portion,
The second inner side plate portion has an outer surface disposed substantially parallel to the inner surface of the second outer side plate portion,
The bottom surface of the first recess includes a first lateral surface extending inward in the width direction of the inner boom member substantially parallel to the upper surface of the inner top plate portion from the outer surface of the first inner side plate portion, and the inner top plate. A first vertical surface extending downwardly from the upper surface of the portion substantially parallel to the outer surface of the first inner side plate portion,
The bottom surface of the second recess includes a second lateral surface extending inward in the width direction of the inner boom member from the outer surface of the second inner side plate portion substantially parallel to the upper surface of the inner top plate portion, and the inner top plate. And a second vertical surface extending downward substantially parallel to the outer surface of the second inner side plate portion from the upper surface of the portion,
The first spacer includes a first horizontal surface spacer interposed between the first horizontal surface and a corresponding surface of the first sliding pad, and a correspondence between the first vertical surface and the first sliding pad. And a first vertical surface spacer interposed between the first surface and the second surface,
The second spacer includes a second horizontal surface spacer interposed between the second horizontal surface and a corresponding surface of the second sliding pad, and a correspondence between the second vertical surface and the second sliding pad. The telescopic boom according to claim 2, further comprising a second vertical surface spacer interposed between the first and second surfaces. In addition to the first horizontal surface and the first vertical surface, the bottom surface of the first recess includes an end portion of the first horizontal surface located on the inner side in the width direction of the inner boom member and the first vertical surface. Connecting the lower end portion, including a first slope portion that slopes toward the first outer surface as it goes downward,
In addition to the second horizontal surface and the second vertical surface, the bottom surface of the second recess includes an end portion of the second horizontal surface located on the inner side in the width direction of the inner boom member and the second vertical surface. A second slope part that connects the lower end part and slopes toward the second outer side as it goes downward;
The rear end portion of the inner boom member includes a first through hole penetrating from the first slope portion to a space inside the inner boom member substantially perpendicularly to the first slope portion, and the second slope portion. A second through hole penetrating substantially perpendicularly to the second slope portion from the inner boom member to the space inside the inner boom member,
A portion of the first sliding pad facing the first slope portion is provided with a first bolt hole,
A portion of the second sliding pad facing the second slope portion is provided with a second bolt hole,
The fixing member is inserted into the first through hole from the inner side of the inner boom member and screwed into the first bolt hole, and the inner side of the inner boom member is fastened to the first sliding pad. The telescopic boom according to claim 3, further comprising: a second bolt that is inserted through the second through hole and is screwed into the second bolt hole to fasten the second sliding pad.   The said 1st through-hole is a long hole long in the inclination direction of a said 1st slope part, and the said 2nd through-hole is a long hole long in the inclination direction of the said 2nd slope part. Telescopic boom.

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