JP4066675B2

JP4066675B2 - Joist structure of vehicle bed

Info

Publication number: JP4066675B2
Application number: JP2002054940A
Authority: JP
Inventors: 清孝渕川
Original assignee: Mitsubishi Fuso Truck and Bus Corp
Current assignee: Mitsubishi Fuso Truck and Bus Corp
Priority date: 2002-01-24
Filing date: 2002-01-24
Publication date: 2008-03-26
Anticipated expiration: 2022-01-24
Also published as: JP2003212146A

Description

【０００１】
【発明の属する技術分野】
本発明は、車両特にトラックの荷台を車台フレームに支持する根太の構造に関するものである。
【０００２】
【従来の技術】
従来のトラックにおける荷台及び根太構造の一例を、便宜的に本発明に係る根太構造を適用した図１の概略斜視図を援用して説明する。図中符号１０はトラックの荷台を総括的に示し、同荷台１０は、図示を省略されている車台フレームの車両前後方向に延在する左右一対のサイドレール上に夫々装着された縦根太１２と、同縦根太１２上に夫々車幅方向に延在して多数配設された横根太１４とからなる格子状の根太構造を備えている。上記縦根太１２及び横根太１４には、従来はアトピン材等の南洋木材が広く使用され、縦根太１２と横根太１４とは、両者の交差部分を上下方向に貫通する締付ボルトによって締結され、横根太１４上に荷台の載貨床面を形成する床材１６が釘打ちにより固着されていた。（なお、図１では、図面の過度の混雑を避けるため床板１６が一枚の板として示されているが、実際には、複数の幅が狭い帯板状床材を列設して形成されたものが多い。）
【０００３】
また、図１において、１８は荷台１０の左右の側壁を限界する側方あおり、２０は荷台１０の後壁を限界する後方あおり、２２は荷台１０の前壁を限界すると共に、車両の急停止等に際し荷台１０に積載された貨物等が慣性により前方に移動して荷台前方に配置されているキャブ（図示せず）に衝突することを防止する防護柵を備えた前端架構、２４は車両の後輪の上方部分を覆う後輪タイヤハウス、２６は荷台１０の両側部下方に配設されたセフティガードである。
【０００４】
上記縦根太１２は、長さが数メートル以上もある長大な部材であるため、アトピン材等南洋木材の資源減少と共に、価格が高くなる傾向があり、しかも重量が大きい等の観点から、縦根太１２を鋼材で作ることにより、車両重量を低減し、かつコスト低減を図ることが検討されている。なお、この場合にも、横根太１４は、床板１６を釘打ちにより横根太１４に簡単に固着することができる等荷台取付時の作業性が良いこと、走行中頻繁に作用する上下方向の衝撃から積載貨物を保護するクッション性が良く、同時に、上記衝撃によって発生する騒音を効果的に低減することができる等の種々の利点があるので、従来通りアトピン等の木製とすることが有利であると考えられる。
【０００５】
上記事情から、図５及び図６に示すような根太構造を製作し試験を行った。この構造は、図示しない車台フレームのサイドレール上に装着される縦根太１２を、断面形状が長方形の中空管状の鋼材で作り、アトピン等の木材で作られた断面形状が長方形の横根太１４を上記縦根太１２上に横置して、断面形状がＬ字状をなす鋼材製の根太結合用ブラケット２８により結合したものである。
【０００６】
上記根太結合用ブラケット２８は、その下方部分の一方のフランジ２８ａを溶接によって縦根太１２の一側壁に固着されて上方に延在し、縦根太１２の上面より上方に延びた他方のフランジ２８ｂには、横根太１４が車両前後方向に延在する締付ボルト３０及び協働するナット３２によって一体的に締結される。上記締付ボルト３０を挿通させるために、上記他方のフランジ２８ｂ及び横根太１４には、夫々円形のボルト孔が同軸的に穿設されている。
また、横根太１４の縦根太１２に当接する交差部下端部分には、車両の走行中、極めて頻繁に作用する上下方向に衝撃荷重によって木部が損耗することを防止するために、薄鋼板製の溝形の保護板３４が介装され、上記根太結合用ブラケット２８のフランジ２８ｂには、保護板３４の上方に立上った側辺の一端部を受容するため板厚に相応した僅かな段差又はせぎり２８ｃが形成されている。
【０００７】
上記図５及び図６に示した根太構造について荷台１０上に所定重量の貨物を搭載し、或いは積荷状態を模した負荷試験を行なったところ、図７に示されているように、薄鋼板製の保護板３４が先ず摩損して早期に消失し、次に縦根太１２の上面に当接する横根太１４の下端部分が損耗して、締付ボルト３０が横根太１４側に下傾し、根太結合用ブラケット２８の上方部分が、図示のように大きく変形することが判明した。このような横根太１４の損耗に起因する根太結合用ブラケット２８の変形は、車台フレームの後輪サスペンション用の重ね板ばね装置の前後両端を支持するスプリングブラケットに近接する部分の根太結合部において特に著しく、変形が大きい場合、根太結合用ブラケット２８のフランジ２８ａの下方部分が縦根太１２に溶接して固着されているので、修理に多大の手間を要し整備コストが著しく高価となる不具合がある。
【０００８】
【発明が解決しようとする課題】
本発明は、南洋木材資源の保存、根太構造の軽量化及びコスト低減を図るため、縦根太を鋼材で作り、横根太を木材製とした上記根太構造の問題点、即ち横根太の摩耗に起因して生起する根太結合用ブラケットの変形を効果的に防止して、長期間の使用により不可避的に生起する木材製横根太の摩耗にも拘わらず根太結合用ブラケットの変形を効果的に防止し、保守維持に要するコストの低減を図ることを、主たる目的とするものである。
【０００９】
【課題を解決するための手段】
上記目的を解決するため、本発明は、車両前後方向に延在して配設された左右一対の鋼材製縦根太と、上記縦根太上に車幅方向に延在して配設された木材製の横根太と、一方のフランジの下方部分が上記縦根太の側壁に固着され上記フランジの上方で他方のフランジの上方部分に穿設されて上下方向に延びる長孔状ボルト孔を有し上記他方のフランジが上記横根太の側面に当接するＬ型断面の根太結合用ブラケットと、上記長孔状ボルト孔の上端部分を挿通すると共に上記上端部分の円弧中心と略一致する位置で上記横根太の車体前後方向に延在する円形断面のボルト孔を挿通し上記横根太と上記他方のフランジを締結する締付ボルトとを備えたことを特徴とする車両荷台の根太構造を提案するものである。
【００１０】
【発明の実施の形態】
以下本発明の好ましい実施形態を図１乃至図４について具体的に説明する。（なお、図１を援用し、かつ図４乃至図７を参照して説明した根太構造の構成部材及び部分と実質的に同一又は対応する構成部材及び部分には、同一の符号を用いる。）
本発明に係る根太構造は、車台フレームのサイドレール（図示せず）上に装着されて車両前後方向に延在する左右一対の縦根太１２と、夫々車幅方向に延在して上記縦根太１２上に並設された多数横根太１４とを備えている。
【００１１】
上記縦根太１２は、上述したアトピン等南洋木材の資源保護、重量軽減、コスト低減等の観点から、鋼材によって作られた断面形状が長方形をなす中空管状部材によって形成される。また、横根太１４は、荷台床板１６を釘打ちにより横根太に取付けることができるので、荷台架装の作業性が良いこと、車両の稼働中、床板１６が破損したような場合、補修が容易であって、保守整備性が良いこと、木材固有のクッション性のため積載貨物の損傷が少なく、走行中の貨物の動揺による騒音の発生が少なく、また縦根太１２と較べて著しく短尺の安い材料で足る等種々の事情からアトピン等の木材で作られ、図示のように高さが幅より大きい縦長長方形の断面形状を有する。
【００１２】
縦根太１２と横根太１４とは、両者の交差部分に配設されたＬ形断面の鋼製根太結合用ブラケット２８によって締結される。根太結合用ブラケット２８は、その一方のフランジ２８ａの下方部分を溶接によって上記縦根太１２の一側壁に固着されて上方に延在し、他方のフランジ２８ｂの縦根太１２の上面より上方に延びた部分に、図４の斜視図に良く示されているような上下方向に長軸を有する長孔からなるボルト孔３６が穿設されている。
【００１３】
一方、横根太１４には、上記ボルト孔３６に対向する部分に車体前後方向に延在する円形断面のボルト孔３８が穿設され、同ボルト孔３８の中心線は、上記長円孔状ボルト孔３６の上方円弧部分の中心と略一致するように設けられ、またボルト孔３８は横根太１４の上下方向における略中央部分に配設される。また、横根太１４の縦根太１２に対向する下端部には、薄鋼板製の溝形をなす保護板３４が釘４０により固着され、一方、根太結合用ブラケット２８のフランジ２８ｂには、保護板３４の側辺の一端部を受容するために、保護板の板厚に相応した段差又はせぎり２８ｃが設けられている。
【００１４】
縦根太１２と横根太１４とは、上記ボルト孔３６の上端部分と、ボルト孔３８とを一線をなすように整合させて締付ボルト３０を挿通し、ナット３２を締付けることにより強固に締結される。車体前後方向に延在する締付ボルト３０及び協働するナット３２によって横根太１４を縦根太１２に締結し固着する構成であるため、横根太１４の強度上の弱点部を形成するボルト孔３８の穿設部分における強度は、従来の根太構造、即ち縦根太１２及び横根太１４を何れもアトピン等木質材料で作り、両者の交差部分を、上下方向に延在する締付ボルトによって締結したものと較べると、通常横根太１４として車両前後方向の幅より上下方向の高さが大きい角材が使用されるので、ボルト孔３８の穿設による断面積の減少が従来構造より相対的に小さくなり、相応して横根太１４の強度が向上する。また、縦根太１２を鋼製の中空管状部材とすることにより、従来のアトピン等木材製縦根太と比較し、同等以上の強度を確保しながら軽量化を図り、かつコストを低減することができる。
【００１５】
上記根太構造を備えた車両の稼働時に、走行中極めて頻繁に作用する主として上下方向の衝撃的負荷によって、縦根太１２と横根太１４との交差結合部において、横根太１４の下端部分に装着された薄鋼板製の保護板３４が次第に摩耗して、やがて欠落し、次に横根太１４の下方部分が摩損することとなるが、この場合、摩損した分だけ、締付ボルト３０が長孔状のボルト孔３６に沿って下降することができるので、横根太１４が平らな姿勢で下方に変位し、図７について上述したような根太結合用ブラケット２８の変形を生起することがなく、修理に多大の費用を必要とする不具合がなく、保守整備のコストを低減することができる。
【００１６】
本発明は、上記実施形態に限定されるものではなく、特許請求の範囲内で種々の変更、修正を加え実施することができる。例えば鋼材製の縦根太１２をコ字状断面又は□形断面の鋼材成形部材とすることができる。
【００１７】
【発明の効果】
叙上のように、本発明に係る車両荷台の根太構造は、車両前後方向に延在して配設された左右一対の鋼材製縦根太と、上記縦根太上に車幅方向に延在して配設された木材製の横根太と、一方のフランジの下方部分が上記縦根太の側壁に固着され上記フランジの上方で他方のフランジの上方部分に穿設されて上下方向に延びる長孔状ボルト孔を有し上記他方のフランジが上記横根太の側面に当接するＬ型断面の根太結合用ブラケットと、上記長孔状ボルト孔の上端部分を挿通すると共に上記上端部分の円弧中心と略一致する位置で上記横根太の車体前後方向に延在する円形断面のボルト孔を挿通し上記横根太と上記他方のフランジを締結する締付ボルトとを備えたことを特徴とし、従来縦根太に広く採用されていたアトピン等南洋木材の資源確保に寄与すると共に、根太構造の軽量化及び製造コスト、整備コストの低減を達成することができるので、産業上有益である。
【図面の簡単な説明】
【図１】本発明が適用されるトラック用荷台の概念的斜視図である。
【図２】図１における縦根太１２と横根太１４との締結部分を示す側面図である。
【図３】図２のＩＩＩ−ＩＩＩ線に沿い矢印方向に視た断面図である。
【図４】図２の根太結合用ブラケットを抽出して示した斜視図である。
【図５】縦根太に鋼製の中空管状部材を採用した根太構造の一例を示す斜視図である。
【図６】図５に示した根太構造の側面図である。
【図７】図６に示した根太構造において横根太が摩耗した状態を示す側面図である。
【符号の説明】
１０…荷台、１２…縦根太、１４…横根太、２８…根太結合用ブラケット、３０…締付ブラケット、３２…ナット。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a joist structure for supporting a vehicle, particularly a truck bed, on a chassis frame.
[0002]
[Prior art]
An example of a loading platform and a joist structure in a conventional truck will be described with reference to the schematic perspective view of FIG. 1 to which the joist structure according to the present invention is applied for convenience. In the figure, reference numeral 10 generally indicates a truck bed, and the truck bed 10 includes vertical joists 12 mounted on a pair of left and right side rails extending in the vehicle front-rear direction of a chassis frame (not shown). In addition, a grid-like joist structure is provided which includes a plurality of horizontal joists 14 extending in the vehicle width direction on the vertical joists 12. The vertical joists 12 and the horizontal joists 14 have conventionally been widely used southern wood such as atopin materials, and the vertical joists 12 and the horizontal joists 14 are fastened by fastening bolts that penetrate the intersecting portions of the two in the vertical direction. The floor material 16 forming the loading floor surface of the loading platform was fixed on the side joists 14 by nailing. (Note that in FIG. 1, the floor plate 16 is shown as a single plate in order to avoid excessive congestion in the drawing, but in practice, a plurality of narrow strip strips are arranged in a row. There are many things.)
[0003]
In FIG. 1, 18 is a lateral side that limits the left and right side walls of the loading platform 10, 20 is a rear side that limits the rear wall of the loading platform 10, and 22 limits the front wall of the loading platform 10, and the vehicle suddenly stops. For example, a front end frame 24 having a protective fence for preventing cargo loaded on the loading platform 10 from moving forward due to inertia and colliding with a cab (not shown) disposed in front of the loading platform, A rear wheel tire house 26 that covers the upper part of the rear wheel, 26 is a safety guard disposed below both sides of the loading platform 10.
[0004]
Since the vertical joist 12 is a long member having a length of several meters or more, it has a tendency to increase in price due to a decrease in resources of southern sea wood such as atopin material, and from the viewpoint of high weight, etc. It has been studied to reduce the vehicle weight and reduce the cost by making the steel 12 from steel. In this case as well, the horizontal joist 14 is easy to fix the floor board 16 to the horizontal joist 14 by nailing, has good workability at the time of mounting an equal cargo bed, and has a vertical impact that frequently acts during traveling. Since there are various advantages such as good cushioning properties to protect the cargo from the load and, at the same time, the noise generated by the impact can be effectively reduced, it is advantageous to use wood such as an atopin as usual. it is conceivable that.
[0005]
From the above circumstances, a joist structure as shown in FIGS. 5 and 6 was manufactured and tested. In this structure, a vertical joist 12 mounted on a side rail of a chassis frame (not shown) is made of a hollow tubular steel material having a rectangular cross-sectional shape, and a horizontal joist 14 having a rectangular cross-sectional shape made of wood such as an atopin is formed. The steel plate is placed on the vertical joist 12 and joined by a joist joint bracket 28 made of steel having an L-shaped cross section.
[0006]
The joist coupling bracket 28 has one flange 28a at a lower portion thereof fixed to one side wall of the vertical joist 12 by welding and extending upward, and is attached to the other flange 28b extending upward from the upper surface of the vertical joist 12. The side joists 14 are fastened together by a fastening bolt 30 extending in the longitudinal direction of the vehicle and a cooperating nut 32. In order to allow the tightening bolts 30 to be inserted, circular bolt holes are coaxially formed in the other flange 28b and the lateral joists 14.
In addition, the lower end portion of the crossing portion that abuts the vertical joist 12 of the horizontal joists 14 is made of a thin steel plate in order to prevent the timber from being worn by an impact load in the vertical direction that acts extremely frequently during traveling of the vehicle. A groove-shaped protection plate 34 is interposed, and the flange 28b of the joist coupling bracket 28 receives a first end portion of the side rising above the protection plate 34, and has a slight thickness corresponding to the plate thickness. A step or margin 28c is formed.
[0007]
A load test simulating a loaded state was carried out on the loading platform 10 for the joist structure shown in FIG. 5 and FIG. 6, and as shown in FIG. First, the protective plate 34 is worn out and disappears early, then the lower end portion of the horizontal joist 14 that contacts the upper surface of the vertical joist 12 is worn out, and the tightening bolt 30 is inclined downward to the side joist 14 side. It has been found that the upper portion of the coupling bracket 28 is greatly deformed as shown. Such deformation of the joist coupling bracket 28 due to the wear of the horizontal joists 14 is particularly caused in the joist coupling portion in the vicinity of the spring bracket that supports the front and rear ends of the overlap spring device for the rear wheel suspension of the chassis frame. When the deformation is remarkably large, the lower portion of the flange 28a of the joist coupling bracket 28 is welded and fixed to the vertical joist 12, so that there is a problem that a great deal of labor is required for repair and the maintenance cost becomes extremely expensive. .
[0008]
[Problems to be solved by the invention]
The present invention is due to the problem of the joist structure described above, in which the vertical joist is made of steel and the joist is made of wood in order to preserve the southern sea wood resources, lighten the joist structure, and reduce the cost. This effectively prevents the deformation of the joisting brackets that occur in the long run, and effectively prevents the joisting brackets from deforming despite the wear of the wooden joists that are inevitably caused by long-term use. The main purpose is to reduce the cost required for maintenance.
[0009]
[Means for Solving the Problems]
In order to solve the above-described object, the present invention provides a pair of left and right steel joists extending in the vehicle longitudinal direction and wood arranged in the vehicle width direction on the vertical joists. the a and horizontal joists manufacturing, one of the lower portion of the flange extends vertically is formed in the upper portion of the other flange above the flange is fixed to the side wall of the vertical joists elongated hole bolt hole The horizontal flange is inserted at the position where the other flange passes through the upper end portion of the long bolt bolt hole and substantially coincides with the arc center of the upper end portion. proposes a vehicle cargo bed joists structure characterized in that a inserted through the bolt holes of circular cross-section fastening bolts that enter into the transverse joists and the other flange extending in the longitudinal direction of the vehicle body is there.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to FIGS. (In addition, the same code | symbol is used for the structural member and part which are substantially the same as or correspond to the structural member and part of the joist structure which referred FIG. 1 and demonstrated with reference to FIG. 4 thru | or FIG. 7.)
The joist structure according to the present invention includes a pair of left and right vertical joists 12 mounted on a side rail (not shown) of a chassis frame and extending in the vehicle front-rear direction, and each of the vertical joists extending in the vehicle width direction. 12 and a large number of horizontal joists 14 arranged side by side.
[0011]
The vertical joists 12 are formed of a hollow tubular member having a rectangular cross-sectional shape made of steel from the viewpoints of resource protection, weight reduction, cost reduction, and the like of the above-described southern sea wood such as atopin. Also, the side joist 14 can be mounted on the side joist plate 16 by nailing, so that the work of the load carrier mounting is good and the repair is easy when the floor plank 16 is damaged during operation of the vehicle. In addition, because of good maintenance and maintenance, and because of the inherent cushioning properties of wood, there is little damage to the loaded cargo, less noise is generated by the movement of the running cargo, and a material that is significantly shorter than the vertical joist 12 It is made of wood such as atopin for various reasons such as being sufficient, and has a vertically-long rectangular cross-sectional shape whose height is larger than the width as shown in the figure.
[0012]
The vertical joist 12 and the horizontal joist 14 are fastened by a steel joist coupling bracket 28 having an L-shaped cross section disposed at the intersecting portion thereof. The joist coupling bracket 28 has a lower portion of one flange 28a fixed to one side wall of the vertical joist 12 by welding and extends upward, and extends upward from an upper surface of the vertical joist 12 of the other flange 28b. A bolt hole 36 made of a long hole having a long axis in the vertical direction as well shown in the perspective view of FIG. 4 is formed in the portion.
[0013]
On the other hand, the side joist 14 is formed with a bolt hole 38 having a circular cross section extending in the longitudinal direction of the vehicle body at a portion facing the bolt hole 36, and the center line of the bolt hole 38 is the oblong hole bolt. The bolt hole 38 is provided substantially at the center of the horizontal joist 14 in the vertical direction. Further, a protective plate 34 having a groove shape made of a thin steel plate is fixed to a lower end portion of the horizontal joist 14 facing the vertical joist 12 by a nail 40, while a protective plate is attached to the flange 28b of the joist coupling bracket 28. In order to receive one end portion of the side edge of 34, a step or margin 28c corresponding to the thickness of the protective plate is provided.
[0014]
The vertical joist 12 and the horizontal joist 14 are firmly fastened by aligning the upper end portion of the bolt hole 36 and the bolt hole 38 so as to form a line and inserting the tightening bolt 30 and tightening the nut 32. The Since the horizontal joists 14 are fastened and fixed to the vertical joists 12 by the fastening bolts 30 extending in the longitudinal direction of the vehicle body and the cooperating nuts 32, the bolt holes 38 that form weak points on the strength of the horizontal joists 14. The strength at the perforated part is the conventional joist structure, that is, the vertical joist 12 and the horizontal joist 14 are both made of a wood material such as atopin, and the crossing part of both is fastened by a fastening bolt extending in the vertical direction. In comparison, since a square member having a height in the vertical direction larger than the width in the vehicle longitudinal direction is normally used as the horizontal joist 14, the reduction in the cross-sectional area due to the drilling of the bolt hole 38 is relatively smaller than that in the conventional structure. Correspondingly, the strength of the lateral joists 14 is improved. Moreover, by making the vertical joist 12 into a steel hollow tubular member, it is possible to reduce the weight and to reduce the cost while ensuring the same or higher strength as compared with the conventional vertical joist made of wood such as atopin. .
[0015]
When the vehicle having the joist structure is in operation, it is attached to the lower end portion of the joist 14 at the cross-joint portion of the joist 12 and the joist 14 mainly due to an impact load in the vertical direction that acts very frequently during traveling. The protective plate 34 made of thin steel plate gradually wears out and eventually disappears, and the lower portion of the lateral joist 14 is then worn away. In this case, the tightening bolt 30 is shaped like a long hole. Therefore, the horizontal joist 14 is displaced downward in a flat posture, and the deformation of the joist coupling bracket 28 as described above with reference to FIG. There is no problem requiring a large amount of expenses, and the maintenance cost can be reduced.
[0016]
The present invention is not limited to the above embodiment, and can be implemented with various changes and modifications within the scope of the claims. For example, the vertical joists 12 made of steel can be formed into a steel material forming member having a U-shaped cross section or a □ -shaped cross section.
[0017]
【The invention's effect】
As described above, the joist structure of the vehicle loading platform according to the present invention includes a pair of left and right steel vertical joists extending in the vehicle front-rear direction, and extends in the vehicle width direction on the vertical joists. and horizontal joists made of wood disposed Te, one of the lower portion of the flange extending vertically are formed in the upper portion of the other flange above the flange is fixed to the side wall of the vertical joists elongated hole An L-shaped joist coupling bracket having a bolt hole and the other flange abutting the side face of the horizontal joist, and the upper end portion of the elongated bolt hole is inserted and substantially coincides with the arc center of the upper end portion position is characterized in that a said transverse joists body longitudinal inserted through bolt holes of circular cross section extending in a direction above horizontal joists and the other fastening bolts that enter into a flange, the conventional vertical joists Reliable resource of southern timber such as atopin which has been widely adopted Together contributes to weight reduction and manufacturing cost of the joists structure, it is possible to achieve a reduction in maintenance costs, it is beneficial industrially.
[Brief description of the drawings]
FIG. 1 is a conceptual perspective view of a truck bed to which the present invention is applied.
2 is a side view showing a fastening portion between a vertical joist 12 and a horizontal joist 14 in FIG. 1; FIG.
3 is a cross-sectional view taken along the line III-III in FIG.
4 is a perspective view showing the joist coupling bracket of FIG. 2 in an extracted manner. FIG.
FIG. 5 is a perspective view showing an example of a joist structure in which a hollow tubular member made of steel is adopted as a vertical joist.
6 is a side view of the joist structure shown in FIG. 5. FIG.
7 is a side view showing a state in which a horizontal joist is worn in the joist structure shown in FIG. 6. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Loading platform, 12 ... Vertical joist, 14 ... Horizontal joist, 28 ... Bracket for joist combination, 30 ... Fastening bracket, 32 ... Nuts.

Claims

A pair of left and right vertical steel joists extending in the longitudinal direction of the vehicle, a wooden joist extending in the vehicle width direction on the vertical joists, and below one flange The portion is fixed to the side wall of the vertical joist and is provided in the upper portion of the other flange above the flange and has a long hole-shaped bolt hole extending in the vertical direction. The other flange is in contact with the side surface of the horizontal joist. A circular cross section extending in the front-rear direction of the lateral joist at the position where it substantially passes the center of the arc of the upper end portion and the bracket for connecting the joist having an L-shaped cross section in contact with the upper end portion of the elongated hole-shaped bolt hole. vehicle cargo bed of joists structure inserted through the bolt hole, characterized in that a fastening bolt that enter into the transverse joists and the other flange.