Abstract:
Production of a working vehicle frame consumes high costs because it requires high rigidity. A simple construction improves the rigidity of the frame and reduces costs required for the production. In a structure of a frame ( 9 ) for a working vehicle ( 1 ), side sections of the frame ( 9 ) are constructed in a boat form, and, in a front view, the width of a lower section of the frame ( 9 ) is set smaller than that of the central section in the vertical direction of the frame ( 9 ). Further, a mast plate ( 63 ) for supporting a front loader ( 2 ) and a front axle installation plate section ( 75 ) are integrated, and side frames ( 62 ) constructing the side section of the frame ( 9 ) and the mast plate ( 63 ) are jointed in a lateral T shape in a side view.

Description:
BACKGROUND OF THE INVENTION 
   1. Technical Field 
   The present invention relates to a frame structure for a working vehicle. More particularly, the present invention relates to a simple and low-cost frame structure that is lightweight and has high rigidity. 
   2. Background Art 
   A combination of angle pipes and steel I-beams is known for a frame structure for a working vehicle (for example, see the Japanese Patent Laid Open Gazette No. 2004-1769). 
   BRIEF SUMMARY OF THE INVENTION 
   Problem to Be Solved by the Invention 
   Generally, it is difficult to work with a frame that consists of the combination of angle pipes and steel I-beams. Further, the assembly of such frames is labor intensive. An object of the present invention is to improve the rigidity of the frame and to reduce costs required for production by a simple construction. 
   Solution 
   The present invention provides a frame structure for a working vehicle, comprising: a side frame having a boat form in a side view; and a front frame attached to the side frame. In the frame structure, a mast plate member, serving as a part of a mast for supporting a front loader, and a front axle support member for supporting a front axle are integrally constructed in the front frame. 
   Preferably, the mast plate member is disposed to overlap the side frame, and is fixed to the side frame. 
   Preferably, a mast is constructed by means of fixing the mast plate member to a mast member for supporting a front loader, the mast member is provided at a back face thereof with a partition plate, and a piping for a working machine is passed through an opening of the partition plate into the mast. 
   Preferably, left and right sets of the side frame and the front frame attached to the side frame are provided in parallel, and a front plate is provided between front edges of the front frames so that the front plate and the left and right sets of side and front frames are constructed in U-shaped in a top view, a front axle installation plate is fixed to the front axle support member and two plates extended in the longitudinal direction from the upper portion of the front axle installation plate are attached to the front plate, and a box-shaped arrangement is constructed by the two plates and the front axle installation plate. 
   Preferably, left and right sets of the side frame and the front frame attached to the side frame are provided in parallel, and the distance between a lower edge of the left set of side and front frames and a lower edge of the right set of side and front frames is narrower than that between a vertical central portion of the left set of side and front frames and a vertical central portion of the right set of side and front frames. 
   A method of connecting the mast plate and the side frames in the present invention is plug-welding by providing a hole at the overlapping section of the mast plate and the side frames. Thus, piping in a chassis can be passed without a decrease of strength. 
   In the frame structure, a plate for connecting the frame at a bottom face of a mast section projects outside the frame, and a tank installed in the working vehicle is hung therefrom, so that the tank capacity can be enlarged. 
   Said two plates also work as a stopper against oscillating of the front axle. In the frame, a hole for tie-down is provided at a front plate connecting front edges of the frames, so that the number of parts can be reduced and the working vehicle is fixed strongly at a low cost. 
   EFFECTS OF THE INVENTION 
   According to the present invention, the number of parts constructing the frame of the vehicle can be reduced, and a contact area of the side frame and the mast plate member attached to the front frame can be enlarged, whereby the rigidity of the joint section of the side frame and the mast plate member can be improved. 
   According to the present invention, required parts can be reinforced effectively. 
   According to the present invention, by a simple construction, space saving and protection of the piping can be achieved. 
   According to the present invention, the rigidity of a front section of the chassis can be improved, and load given to a loader connected to the mast etc. can be smoothly transmitted. 
   According to the present invention, the rigidity of the working vehicle can be secured, and at the same time, the interference with steering wheels can be prevented. 

   
     BRIEF DESCRIPTION OF DRAWINGS 
       FIG. 1  is a side view of a working vehicle. 
       FIG. 2  is a top view of a frame structure of a working vehicle. 
       FIG. 3  is a side view of the frame structure of the working vehicle. 
       FIG. 4  is a front view of the frame structure of the working vehicle. 
       FIG. 5  is a perspective view of the frame structure of the working vehicle seen from the upper front. 
       FIG. 6  is a perspective view of the frame structure of the working vehicle seen from the lower back. 
       FIG. 7  is a side view partly in section of a connection structure of a front frame and a side frame. 
       FIG. 8  is a perspective view partly in section of a structure of a front part of the working vehicle. 
       FIG. 9  is a perspective view of a structure of a left front part of the frame. 
       FIG. 10  is a perspective view of a structure of front lower part of the frame. 
       FIG. 11  is a bottom view of the structure of front lower part of the frame. 
       FIG. 12  is a side view of the side frame. 
       FIG. 13  is a sectional view taken on line B-B in  FIG. 12 . 
       FIG. 14  is a perspective view of rear structure of the frame. 
       FIG. 15  is a schematic view of an attachment structure for attaching a transmission to the frame. 
       FIG. 16  is a schematic view of an attachment structure of a rear axle. 
       FIG. 17  is a side view partly in section of an inner structure of a mast member. 
       FIG. 18  is a view of a reinforcement structure of a boss. 
       FIG. 19  is a perspective view of an attachment structure of a tank. 
       FIG. 20  is a side view of the attachment structure of the tank. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The present invention provides a frame structure for a working vehicle by means of combining bent plates. 
   First Embodiment 
   A working vehicle as a mode for carrying out the invention will be described below. 
     FIG. 1  is a side view of a working vehicle. 
   A working vehicle  1  shown in  FIG. 1  is a tractor loader backhoe, equipped with a loader  2  and a digger apparatus  3 . An operation part  4  is provided at a center portion of the vehicle  1 , and the loader  2  is provided in front of the operation part  4 , and the digger apparatus  3  is provided in a rear of the operation part  4 . Front wheels  7  and rear wheels  8  are equipped with the vehicle  1 , so as to enable driving of the vehicle  1  with the loader  2  and the digger apparatus  3 . 
   A steering wheel  5  and a seat  6  are provided in the operation part  4 , and an operation apparatus for driving direction and an operation apparatus for the loader  2  are provided at the side of the seat  6 . Thus, a driving direction of the vehicle  1  and the loader  2  can be operated at the operation part  4 . The loader  2  that is one of the loading devices is connected beside the vehicle  1  and extended forward, and a bucket is provided at a head of the loader. An engine is provided at a front portion of a frame  9  that is a chassis of the vehicle  1 , and the engine is covered in a bonnet  30  provided on the frame  9 . The loader  2  is provided outside of the bonnet  30 . 
   The digger apparatus  3  is detachably attached to a rear portion of the vehicle  1 , and the digger apparatus  3  is operated by an operation apparatus provided in a rear of the seat  6 . 
   A hydraulic oil tank  90  is provided beside the operation part  4 , which works as steps for getting on and off the operation part  4 . The step formed on a fuel tank is provided at the opposite side to the operation part  4 . 
   Next, a frame structure of the working vehicle will be described below. 
     FIG. 2  is a top view of a frame structure of the working vehicle. 
     FIG. 3  is a side view of the frame structure of the working vehicle. 
     FIG. 4  is a front view of the frame structure of the working vehicle. 
     FIG. 5  is a perspective view of the frame structure of the working vehicle seen from the upper front. 
     FIG. 6  is a perspective view of the frame structure of the working vehicle seen from the lower back. 
   The frame  9  for the working vehicle mainly comprises two side frames  62  which are extended in the longitudinal direction and provided parallel to each other, two front frames  63  which are respectively connected to front portions of the side frames  62 , and a front plate  61  which connects front portions of the front frames  63  to each other. A mast member  64  is constructed on an outer face of each of the front frames  63 , and a rib  65  connects between the front frames  63 . 
   A partition  74  working as a connection member is provided between the side frames  62 , thereby providing the frame  9  as a rudder structure. The partition  74  is a cross member provided at a substantially center portion of the frame  9  so as to divide a space between the side frames  62  into an engine arrangement part and a transmission arrangement part. 
   In the side frame  62 , a beam  62   b  is extended outward. The beam  62   b  is extended in the transversal direction, so that the beam  62   b  is substantially right-angled to the side frame  62 . The section form of the beam  62   b  is a C-shaped form, thereby supporting a base member of the operation part  4 . 
   The front frame  63  is extended backwardly upward slantwise from the front lower portion of the frame  9 . The front frame  63  is extended upward from the connection section thereof connected to the side frame  62 , and the mast member  64  is attached to the part of the front frame  63  extended upward. The engine and the bonnet  30  are provided between the front frames  63 . Lift units of the loader  2  are connected to the mast member  64 , which support the loader  2 . 
   A lower mast portion  64   b , which is a lower portion of the mast member  64 , is configured as a member projected to the side. The lower mast portion  64   b  is configured as a member whose side form is L-like characters pushed down horizontally, thereby receiving the vertical force applied to the mast member  64 . With respect to the frame  9 , which is a chassis of the working vehicle, the lower mast portion  64   b  is extended outward, thereby connecting a base of the mast and a side face of the frame. Namely, the lower mast portion  64   b  is connected to the base of the mast member  64  and to the outer face of the front frame  63 . 
   In the working vehicle  1 , a fuel tank and a hydraulic oil tank  90  are hung on the lower mast portion  64   b  and the beam  62   b . The fuel tank and the hydraulic oil tank  90  are respectively connected and supported onto the sides of the lower mast portion  64   b  and the beam  62   b  that are provided at the same side in the working vehicle. Thus, the support structure of the fuel tank and the hydraulic oil tank  90  can be simple and the number of parts can be decreased. Another tank having a different capacity can be easily attached there only if the tank has a similar upper portion to be connected. Furthermore, the frame with high rigidity can be used to support the tanks. The tanks are attached to the base of the lower mast portion  64   b  which constructs the base of the mast connected to the lift units of the loader  2 , so that the space below the projection of the mast can be used effectively and the working vehicle can be constituted compactly. 
   The front plate  61  connects the front portion of the front frames  63  and constructs a front face of the frame  9  which is a chassis of the working vehicle. Two holes  61   b  for tie-down are provided at lower portions of the front plates  61 . A rope for fixation or the like is attached to the hole  61   b  in carrying the working vehicle  1 . The front plate  61  whose left and right sides are provided with the holes  61   b  is durable enough against the tie-down of the vehicle  1  using the holes  61   b . The holes  61   b  are extended in the longitudinal direction, so that the rope passed through the hole  61   b  rarely twists. It is unnecessary for making the tie-down holes to have an additional member welded to the front plate  61 , so that no projection is constructed on the front plate  61  and a front appearance of the working vehicle is improved. 
   A notch is provided at the central upper part of the front plate  61 , whereby a hold mechanism of the bonnet  30  can be easily attached to the notch. 
   The front plate  61  is formed at side portions thereof along the side form of the front frame  63 , and formed so that as it goes downward, the front plate  61  becomes narrow in the lateral width. 
   A frame structure will be described below in detail. 
     FIG. 7  is a side view partly in section of a connection structure of a front frame and a side frame. 
     FIG. 8  is a perspective view partly in section of a structure of a front part of the working vehicle. 
     FIG. 9  is a perspective view of a structure of a left front part of the frame. 
     FIG. 10  is a perspective view of a structure of front lower part of the frame. 
     FIG. 11  is a bottom view of the structure of front lower part of the frame. 
   The frame  9 , which is a chassis of the working vehicle  1 , is mainly constructed as a joint of a flat plate and a bent plate. The frame  9  is reinforced at several parts, so that the frame of the working vehicle can be produced easily and at low cost. The bent plate can be easily constructed by bending, so that the working vehicle can be processed easily and produced at low cost in comparison with the case where the I-steels are used. 
   The lower portion of the frame  9  is formed to be boat-shaped so that when seen from the front, the narrower the frame  9  becomes when viewing the frame  9  from top to bottom along a vertical plane. Namely, each of both sides of the lower portion of the frame  9  inclines inward. The frame  9  is constructed as above mentioned, so that the space around the front wheels  8  can be sufficiency taken and the steerable angle of the front wheels  8  can be widely taken. 
   With respect to the frame  9 , the lower portion of the side frame  62  is bent inside, and the upper and lower ends are horizontally bent inside. As the side frame  62  is bent inside, the effective area of the side frame  62  can be increased in section when viewed in the longitudinal direction, whereby the rigidity of the side frame  62  can be improved. Thus, improving the rigidity of the frame and, at the same time, preventing interference of the frame with the steerable wheels can be achieved. 
   The lower portion of the front frame  63  is also bent inside, similar to the side frame  62 . The inner side of the front frame  63  is jointed to the outer side of the side frame  62 , which constructs the front part of the frame  9 . The front frame  63  is connected at a rear upper portion thereof to the mast member  64 , and connected at a front lower portion thereof to attachment plates  75  and  76  (see  FIGS. 10 and 11 ) provided laterally on a front axle. The upper surface of the attachment plate  75  is connected with two plates  77 , which are extended longitudinally in parallel. The upper surfaces of the plates  77  are connected with the respective side frames  62 , the lower surfaces of the plates  77  are connected with the attachment plate  75 , and the front surfaces of the plates  77  are connected with the front plate  61 . The plates  77  are provided between the front frames  63 . 
   The attachment plate  75  is connected with the plates  77  and the front frames  63 , and the plate  76  is connected with the front plate  61  and the front frames  63 , thereby improving the rigidity of the front lower part of the frame  9  to which the front axle can be attached. In the front lower portion of the frame  9 , the plates  77 , and the attachment plates  75  and  76  are assembled into a form like a curb, which is connected with the front plate  61 , the front frames  63 , and the side frames  62 . As mentioned above, a box structure is constructed, so that the rigidity of the front portion of the frame is improved by the simple construction. 
   The attachment plates  75  and  76  to which the front axle is attached also serve as an oscillation stopper (lateral rolling stopper) of the front axle, which restricts the rolling amount of the front axle by touching the front axle. Accordingly, the number of members in the vicinity of the front axle is reduced. 
   The upper portion of the front frame  63  works as a part of the mast supporting the loader  2 . The lower portion of the front frame  63  works as a support member for the front axle. Thus, the front frame  63  works as a mast support member and a front axle support member, so that the stress is dispersed and the load capacity performance is improved. 
   The mast member  64  and the front axle are connected by the front frame  63 , so that the load given to the mast member  64  can be directly transmitted to the front axle, and the frame of the working vehicle can be rarely strained. 
   As shown in  FIG. 7 , the front frame  63  and the side frame  62  are cross-jointed. The front frame  63  and the side frame  62  are jointed in a lateral T shape or the like, and the side frame  62  is connected to the inner side of the front frame  63 . At a substantially center part of one of the frames  62  and  63  (in this embodiment, a portion the side frame  62  overlapping the front frame  63 ), holes  62   c  and  62   d  are provided, and the side frame  62  is welded at the inner margins of the holes  62   c  and  62   d  with the front frame  63 . Namely, the front frame  63  and the side frame  62  overlapping each other are plug-welded. Thus, the front frame  63  and the side frame  62  are easily connected and the increase of the width caused by the connection can be prevented. 
   The front frame  63  and the side frame  62  are joined by the plug welding, so that the hole used for the welding can be used as a piping. As shown in  FIG. 8 , the front frame  63  has a hole  63   c  through which an exhaust pipe  12   b  connected to a silencer  12  is extended outside of the frame. As shown in  FIG. 9 , the hole  62   c  of the side frame  62  coincides to the hole  63   c  of the front frame  63 , so that a hole communicating inside and outside of the frame is provided. At the front portion of the working vehicle  1 , the bonnet  30  is provided on the frame  9 . The bonnet  30  is hollow and made of resin. The bonnet  30  covers the engine provided on the frame  9 . In the bonnet  30 , the engine and the engine accessories such as a radiator, the silencer  12 , an air cleaner  34  and so on are provided. The bonnet  30  is constructed to enable opening and closing with respect to the frame  9 , whereby the bonnet is opened by rotating the front portion of the bonnet  30  upward. Seals  32  and  33  fitted on the rib  65  are provided between the bonnet  30  and the frame  9 . At the front portion of the working vehicle  1 , a cover  36  is provided, thereby covering the notch of the front plate  61 . 
   The hole  63   c  is provided in the front frame  63  disposed at the left side of the vehicle. The position of the hole  63   c  coincides to the hole  62   c  of the side frame  62 . The margins edges of the holes  62   c  and  63   c  are welded by plug welding, whereby the side frame  62  and the front frame  63  are jointed. Through the hole  63   c , the exhaust pipe  12   b  connected to the silencer  12  is extended, whereby the exhaust gas can be exhausted outside the bonnet  30 . Therefore, a space for piping without interference with the frame  9  is ensured in the plug-welded portion of the frame  9 . 
   Reinforcement structure of the frame at the center part of the vehicle will be described below. 
     FIG. 12  is a side view of the side frame. 
     FIG. 13  is a sectional view taken on line B-B in  FIG. 12 . 
     FIG. 14  is a perspective view of rear structure of the frame. 
   The side frame  62  is formed in narrow C shape seen from front. The side frames  62  are provided thereon with reinforcement members, including pipes  66 , rear reinforcement members  68  and triangle reinforcement members  67 , respectively. Each of the side frame  62  is provided on an upper portion thereof with the pipe  66 , at a rear portion thereof with the rear reinforcement member  68 , and at a rear lower portion thereof with the triangle reinforcement member  67 . On the lower face of center part of the side frame  62 , a lower reinforcement member  69  is attached and extended in the extended direction of the side frame  62 . 
   Onto the upper portion of the side frame  62 , the pipe  66  is attached. The pipe  66  has a square shape in sectional view, and it is extended from the engine arrangement part to the transmission attachment part. The pipe  66  is attached to the inner face of the return part in the upper part of the side frame  62 , and is extended on the side frame  62  from the front end of the upper portion of the side frame  62  to the rear reinforcement member  68 . The pipe  66  penetrates the partition  74  provided at the center part of the side frame  62 . Thus, the part of the chassis frame of the working vehicle receiving a lot of stress can be effectively reinforced, which is reinforced by the angle pipes, so that the long-range attachment can be easily achieved. 
   On the rear portion of the side frame  62 , the rear reinforcement member  68  is provided, and the rear axle is fixed below the rear reinforcement member  68 . The side frame  62  has an opening at the portion thereof onto which the rear reinforcement member  68  is provided, whereby the rear axle is attachable through the opening from the outside of the side frame  62 . 
   The triangle reinforcement member  67  is provided between the rear reinforcement member  68  and the partition  74 , and the triangle reinforcement member  67  is connected with the rear reinforcement member  68  and the partition  74 . The triangle reinforcement member  67  is formed in the inverse L shape in the sectional view. The triangle reinforcement member  67  is connected with the lower bent part and the inner face of the side frame  62 , and the opening side of the member  67  is turned to the side frame  62 . 
   The part of the side frame  62  attached to the triangle reinforcement  67  is formed in a square shape in the sectional view. Thus, the reaction of the side frame  62  against the driving force or the rigidity of the part loaded by the hitch is improved. The part to which a lot of stresses are given in the chassis frame of the working vehicle can be effectively reinforced. 
   The lower reinforcement member  69  is formed in the inverse L shape in the front view, and has a lower extended part into the inside of the vehicle (the opening side of the side frame  62 ). The lower reinforcement member  69  is extended in the working vehicle from the engine arrangement part to the transmission attachment part. The lower reinforcement member  69  is attached to the lower face of the side frame  62 , whereby the part to which a lot of stresses are given can be effectively reinforced, and the frame that is easily assembled and has high rigidity is achieved. 
   The attachment structure for attaching a transmission to the frame  9  will be described below. 
     FIG. 15  is a schematic view of an attachment structure for attaching a transmission to the frame. 
     FIG. 16  is a schematic view of an attachment structure of a rear axle. 
   A transmission  10  is attached through a stay  73  of a rear extended part  72  fixed at the rear portion of the side frame  62 . The transmission  10  is fixed at a lower or side face, thereof not only by the rear axle, but also by the stay  73  extended from the side frame  62  and foamed in the L shape in the front view. In the embodiment shown in  FIG. 15 , the lower end of stay  73  is connected to the lower face of the transmission  10 . As mentioned above, the transmission  10  is fixed to the side frame  62  through the stay  73 , so that the variation of transmissions attachable to the frame is expanded and the frame can be standardized. The stay  73  can receive a part of the force given by the transmission  10  by the deformation or the like. When the transmission  10  gives the excess load, the stay  73  is deformed plastically so as to protect the side frame  62 . 
   The transmission  10  and each of the rear axle cases, constituting a transfer path of the driving force, are arranged in a gate shape in the top view, as shown in  FIG. 16 . In the transfer path, a driving case  10   b  extended in the lateral direction is connected at an outer side end thereof to the front portion of the rear axle case  11  connected with the shaft of the rear wheel  7 , and is connected at an inner side end thereof to the transmission  10 , so as to constitute the gate-shaped arrangement in the top view. The gate-shaped arrangements are laterally symmetrically provided in the vehicle  1 . The rear axle case  11  is a terminal of the change gear mechanism, and the rear axle case  11  is connected to the side frame  62  through a stay  71 . The stay  71  is fixed at an upper end thereof to the outside of the side frame  62 , and is fixed at a lower end thereof to the rear portion of the rear axle case  11 . The rear axle case  11  is supported as mentioned above, so that the stay  71  can absorb a part of the force generated from the rear axle case  11  by the deformation or the like. When the rear axle case  11  gives excessive load, the stay  71  is deformed plastically so as to protect the side frame  62 . The supporting rigidity of the rear axle case  11  is changeable by the characteristic of material of the stay  71 . 
   The structure of the mast  64  will be described below. 
     FIG. 17  is a side view partly in section of an inner structure of the mast member  64 . 
   The mast member  64  is formed in the L shape in the top view and is connected to the outside of the front frame  63  and the upper face of the lower portion  64   b . A partition  64   f  is provided between the mast member  64  and the front frame  63 . The partition  64   f  constructs a space inward from the mast member  64 , whereby the rigidity of the mast member  64  is improved. A piping  79  is provided in the space. 
   Bosses  80  are provided on the inside of the mast member  64 , and bosses  80  are provided on the outside of the front frame  63  so as to correspond to the respective bosses  80 , whereby the lift units of the loader  2  are twin-supported. The partition  64   f  is attached along the bosses  80 , thereby improving the rigidity of the bosses  80 . At the upper portion of the partition  64   f , an opening  64   g  is provided at an upper portion of the partition  64   f , and an opening  64   h  is provided at an upper face of the lower mast portion  64   b . The piping through the space between the partition  64   f  and the mast member  64  is extended outward from the opening  64   g  and the opening  64   h . The partition  64   f  is provided between the twin-supporting mast structures, the piping  79  is inserted from the lower face into the backside of the partition  64   f , and is passed out through the opening  64   g  provided at the front face of the partition  64   f . As a result, the piping  79  is protected by effectively use of the space around the mast member  64 , and the working vehicle can be miniaturized. 
   The reinforcement structure of the boss  80  will be described below. 
     FIG. 18  is a view of a reinforcement structure of the boss.  FIG. 18(   a ) is a perspective view of a reinforcement structure of the boss.  FIG. 18(   b ) is a front view of a reinforcement structure of the boss. 
   The bosses  80  are gently convex, and are connected at their base portions to a reinforcement member  81 . The reinforcement member  81  connecting the base parts of the bosses  80  is formed in the U shape in the front view. The bosses  80  and the reinforcement member  81  are connected by welding, so that the bosses  80  and the reinforcement member  81  are constructed integrally. It can be also available that the bosses  80  and the reinforcement member  81  are formed integrally in advance. 
   The reinforcement member  81  is attached to the front face of the partition  64   f  in the mast member  64  and is connected to the left and right bosses  80 . The reinforcement member  81  can be attached to other bosses  80  above and below the bosses  80  provided at the vertical center part. 
   The bosses  80  are connected with the reinforcement member as mentioned above, so that the bosses  80  and the mast member  64  are easily reinforced. 
   A tank structure provided in a working vehicle will be described below. 
     FIG. 19  is a perspective view of an attachment structure of tanks. 
     FIG. 20  is a side view of the attachment structure of the tanks. 
   At the sides of the operation part  4  in the working vehicle  1 , the hydraulic oil tank  90  and the fuel tank  91  are provided respectively. Some projection members are extended sideward from the frame  9  so as to hang the hydraulic oil tank  90  and the fuel tank  91 . In this embodiment, the lower mast portions  64   b  and the beams  62   b  serve as the projection members. The hydraulic oil tank  90  and the fuel tank  91  are provided below them. 
   Both the lower mast portion  64   b  and the beam  62   b  are extended sideward from each of the side frames  62  as components of the frame  9 . The lower mast portion  64   b  is connected with the side frame  62  and the mast member  64 , thereby contributing for the improvement of the rigidity of the mast member  64 . 
   On an upper face of each of the hydraulic oil tank  90  and the fuel tank  91 , two connection members  96  each of which has a tapped hole are provided. A bolt is screwed into the connection section of each of the tanks through the bottom faces of the lower portion  64   b  and of the beam  62   b . Thus, each of the tanks is fastened on the bottom faces of the lower portion  64   b  and of the beam  62   b . The connection members  96  are extended in the lateral direction on the upper faces of each of the hydraulic oil tank  90  and the fuel tank  91 . Each of the connection members is provided with plural bolts to be screwed. As mentioned above, the connection members  96  are extended in the lateral direction on the upper face of each of the tanks, so that high rigidity and the durability against getting on and off of an operator are ensured even if each of the tanks is loaded on the outside thereof. 
   In this embodiment, the hydraulic tank  90  is provided at the right side of the frame  9 , and the fuel tank  91  is provided at the left side of the frame  9 . Each of the hydraulic tank  90  and the fuel tank  91  is formed in the step shape (L shape) in the front view, so as to have the lower part thereof more extended sideward (to the outside of the vehicle) than the vertical extension of the upper part thereof. Thus, even if the height of the tank is small, the tank has enough capacity, and the hydraulic tank  90  and the fuel tank  91  are miniaturized around the operation part  4 . 
   Furthermore, the step-shaped face can be used as the steps to get on and off the operation part  4 . At each of the corners of the hydraulic tank  90  and the fuel tank  91 , an anti-slip member  94  is provided, whereby the safety when getting on and off is secured. 
   At the fuel tank  91 , an upwardly inclined inlet  93  is protruded toward outside. The inlet  93  is provided between the upper part  91   a  and the lower part  92   b  of the fuel tank  91  and at an angled corner part formed at the outside of the fuel tank  91 . A battery  98  is provided at the upper face of the fuel tank  91 . The battery  98  is provided between the lower mast portion  64   b  and the beam  62   b.    
   The hydraulic tank  90  and the fuel tank  91  are provided as mentioned above, so that they can be used as steps for getting on and off the operation part  4 . When getting on and off, either the hydraulic tank  90  or the fuel tank  91  is stepped on and causes a sound, so that the change of an amount of the hydraulic oil or the fuel are known by means of hearing the sound. The battery  98  can be provided in the clearance of the frame  9 , whereby the space around the frame  9  can be effectively used. 
   Additionally, the battery  98  provided on the fuel tank  91  is covered by the cover installed in the working vehicle  1 , and is protected from rainwater or earth and sand. 
   INDUSTRIAL APPLICABILITY 
   The present invention is applicable to a frame structure for working vehicle. Especially, it is applicable to a frame structure for a working vehicle that needs light weight and high rigidity.