Patent Publication Number: US-2019185063-A1

Title: Work vehicle

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a U.S. National stage application of International Application No. PCT/JP2017/029079, filed on Aug. 10, 2017. This U.S. National stage application claims priority under 35 U.S.C. § 119(a) to Japanese Patent Application No. 2016-157884, filed in Japan on Aug. 10, 2016, the entire contents of which are hereby incorporated herein by reference. 
    
    
     BACKGROUND 
     Field of the Invention 
     The present invention relates to a work vehicle. 
     Background Information 
     Conventionally, a restrictor is provided to prevent the cab from coming loose from the body frame when a work vehicle such as a hydraulic excavator topples and is subjected to a pressing force on the side of the cab (see JP-A 2004-189089, for example). 
     On the other hand, with the work vehicle in JP-A 2004-189089, the cab rear frame is made of a heavy-gauge material so that it will be stiff enough that the cab rear frame will not be deformed by an impact force from the side face of the cab in the event that the vehicle overturns, etc. Also, by disposing a restrictor near the stiffened cab rear frame allows any impact produced by the restriction caused by the restrictor during overturning can also be borne by the cab rear frame. 
     SUMMARY 
     However, with the above-mentioned conventional work vehicle, the cab ended up being heavier. 
     It is an object of the present invention to provide a work vehicle with which the necessary strength can be ensured and the cab can be made lighter. 
     The work vehicle pertaining to the first aspect comprises a cab, a body frame, and a restrictor. The body frame has a base component, and a support frame that is provided on the upper side of the base component and supports the cab. The restrictor has a retaining member and an impact absorber. The retaining member is disposed on the lower side of the support frame. The impact absorber is disposed on the cab side of the retaining member. 
     Providing the impact absorber to the restrictor allows at least some of the impact generated in the cab due to restriction during overturning of the work vehicle to be absorbed through plastic deformation. Accordingly, the impact generated in the cab can be alleviated, and the frame of the cab need not be made of a heavy-gauge material, and so can be made thinner. 
     Therefore, it is possible to further reduce the weight of the cab. 
     The work vehicle pertaining to the second aspect is the work vehicle pertaining to the first aspect, further comprising a damper. The damper is provided to the body frame, supports the cab, and damps vibrations in the cab. 
     It is possible to alleviate vibrations and impacts occurring in the cab during normal use such as when the work vehicle is travelling or working. 
     Also, if the work vehicle topples or collides with a rock or the like, the restrictor can keep the cab from separating from the body frame. 
     The work vehicle pertaining to the third aspect is the work vehicle pertaining to the first aspect, further comprising a work implement that is disposed on the body frame. The restrictor is provided on the opposite side from the work implement. 
     Since there is a high probability that an impact will be exerted on the side of the cab where the work implement is not provided, providing the restrictor on the opposite side from the work implement is an effective way to keep the cab from separating from the body frame. 
     The work vehicle pertaining to the fourth aspect is the work vehicle pertaining to the first aspect, wherein the cab has a first cab frame and a second cab frame. The first cab frame is formed in the up and down direction on the opposite side of the cab from the side on which the work implement is disposed. The second cab frame is formed in the up and down direction on the opposite side of the cab from the side on which the work implement is disposed, and is lower in stiffness than the first cab frame. The restrictor is provided in a vicinity below the first cab frame and in a vicinity below the second cab frame. The coefficient of elasticity of the impact absorber of the restrictor provided in the vicinity below the second cab frame is lower than the coefficient of elasticity of the impact absorber of the restrictor provided in the vicinity below the first cab frame. 
     Because of this difference in the coefficient of elasticity, an impact exerted on the first cab frame will be greater than that on the second cab frame when an impact is exerted on the cab, but since the first cab frame is stiffer than the second cab frame, the impact can be stopped. 
     For example, when driving the work vehicle, the driver can focus on what is in front of the cab, so it is unlikely that there will be an impact caused by collision or the like on the front side of the cab, but since the driver cannot focus his attention to the rear, an impact is more likely on the rear side. The weight of the cab can be minimized by making the cab frame on the front side, which is less likely to be subjected to impact, from a lighter gauge material than the cab frame on the rear side, which is more likely to receive an impact. Also, even if an impact is exerted on the cab frame on the thinned front side, since the coefficient of elasticity is set lower, the impact can be absorbed. 
     The work vehicle pertaining to the fifth aspect is the work vehicle pertaining to the first aspect, wherein the impact absorber is fixed directly or indirectly to the floor frame of the cab. 
     When an impact causes the cab to move away from the vehicle body frame, the retaining member hits the support frame of the vehicle body frame from the below, and the movement of the cab is restricted. At the time of this contact, the impact absorber is pulled, which moderates the impact through plastic deformation of the impact absorber. 
     The work vehicle pertaining to the sixth aspect is the work vehicle pertaining to the fifth aspect, wherein the impact absorber has a first cylindrical section, a second cylindrical section, and a connecting portion. The first cylindrical section is fixed to the retaining member. The second cylindrical section is fixed to the floor frame of the cab, and its lower end is positioned lower than the upper end of the first cylindrical section. 
     An elastic force is generated by the bending of the connecting portion of the impact absorber, which lessens the collision of the retaining member against the support frame. 
     The work vehicle pertaining to the seventh aspect is the work vehicle pertaining to the fifth aspect, wherein the impact absorber is a spring member. The upper end of the impact absorber is fixed to the floor frame of the cab, and its lower end is fixed to the retaining member. 
     When a spring member is provided, the collision of the retaining member against the support frame can be lessened by the elastic force of the spring member. 
     The work vehicle pertaining to the eighth aspect is the work vehicle pertaining to the fifth aspect, wherein the impact absorber is a rubber member. The impact absorber is fixed to the floor frame of the cab via a first metal member that is bonded to the impact absorber and is fixed to the floor frame of the cab, and is fixed to the retaining member via a second metal member that is bonded to the impact absorber and is fixed to the retaining member. 
     When a rubber member is provided, the collision of the retaining member against the support frame can be lessened by the elastic force of the rubber member. 
     The work vehicle pertaining to the ninth aspect is the work vehicle pertaining to the fifth aspect, wherein the upper face of the retaining member is curved so that its position becomes lower moving toward the outer peripheral side. 
     The portion of the retaining member that collides with the supporting frame of the body frame is formed in a curved shape. This makes it less likely that there will be one-sided contact of the retaining member against the support frame when the cab is tilted with respect to the body frame. 
     The work vehicle pertaining to the tenth aspect is the work vehicle pertaining to the first aspect, wherein the restrictor further has a linking member that links the floor frame and the retaining member. The impact absorber is fixed to the retaining member and is disposed lower than the support frame. 
     When an impact causes the cab to move away from the body frame, the impact absorber hits the supporting frame of the body frame from below, and the movement of the cab is restricted. At the time of this contact, the impact absorber is compressed, and the impact can be lessened by the energy generated by deformation (either elastic deformation or plastic deformation) of the impact absorber. 
     The work vehicle pertaining to the eleventh aspect is the work vehicle pertaining to the tenth aspect, wherein the impact absorber has a first cylindrical section, a second cylindrical section, and a connecting portion. The first cylindrical section is fixed to the retaining member. The lower end of the second cylindrical section is positioned lower than the upper end of the first cylindrical section. The connecting portion connects the upper end of the first cylindrical section and the lower end of the second cylindrical section. 
     An elastic force is generated by the bending of the connecting portion of the impact absorber, which lessens the collision of the impact absorber against the support frame. 
     The work vehicle pertaining to the twelfth aspect is the work vehicle pertaining to the tenth aspect, wherein the impact absorber is a spring member or a rubber member. 
     When a spring member or a rubber member is provided, collision of the impact absorber against the supporting frame can be lessened by the elastic force of the spring member or rubber member. 
     The work vehicle pertaining to the thirteenth aspect is the work vehicle pertaining to the third aspect, wherein the retaining member is a plate-shaped member disposed such that a main face thereof is opposite the supporting frame. The restrictor is disposed such that the end of the main face on the work implement side is higher than the end on the opposite side from the work implement. 
     Disposing the restrictor at an angle makes it less likely that there will be one-sided contact of the restrictor with the body frame when the cab tilts toward the work implement side with respect to the body frame. 
     The work vehicle pertaining to the fourteenth aspect is the work vehicle pertaining to the first aspect, wherein the impact absorber has an insertion component and a protruding portion. The insertion component is inserted into a through-hole formed in the floor frame of the cab. The protruding portion is provided above the floor frame and is formed so as to protrude from the insertion component to further outside than the through-hole. The protruding portion is curved so that its position becomes higher moving toward the outer peripheral side, and has a lower face that comes into contact around the periphery of the through-hole. 
     Since the protruding portion of the impact absorber has a lower face that is curved toward the through-hole side, it is less likely that there will be one-sided contact of the impact absorber around the periphery of the through-hole when the cab is tilted with respect to the body frame. 
     The work vehicle pertaining to the fifteenth aspect is the work vehicle pertaining to the fourteenth aspect, wherein the insertion component has a first cylindrical section, a second cylindrical section, and a connecting portion. The first cylindrical section is fixed to the retaining member. The second cylindrical section is inserted into the through-hole, and its lower end is located lower than the upper end of the first cylindrical section. The connecting portion connects the upper end of the first cylindrical section and the lower end of the second cylindrical section. 
     An elastic force is generated by the bending of the connecting portion of the impact absorber, which lessens the collision of the impact absorber against the support frame. 
     The present invention provides a work vehicle with which the necessary strength can be ensured and the weight of the cab can be reduced. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is an oblique view of a hydraulic excavator in Embodiment of the present invention; 
         FIG. 2  is an oblique view of the body frame and the cab of the hydraulic excavator in  FIG. 1 ; 
         FIG. 3  is an exploded oblique view showing a state in which the cab has been removed from the body frame in  FIG. 2 ; 
         FIG. 4  is an oblique view illustrating the positional relation between the body frame and the cab in  FIG. 2 ; 
         FIG. 5  is a cross section along the arrow G-G′ in  FIG. 2 ; 
         FIG. 6  is a diagram showing the area near the left end as viewed along the arrow H in  FIG. 5 ; 
         FIG. 7  is a cross section along the I-I′ line in  FIG. 6 ; 
         FIG. 8  is a cross section of the configuration of the restrictor in Embodiment 2 of the present invention; 
         FIG. 9  is a cross section of the configuration of the restrictor in Embodiment 3 of the present invention; 
         FIG. 10  is cross section of the configuration of the restrictor in Embodiment 4 of the present invention; 
         FIG. 11  is cross section of the configuration of the restrictor in Embodiment 5 of the present invention; 
         FIG. 12  is cross section of the configuration of the restrictor in Embodiment 6 of the present invention; 
         FIG. 13  is cross section of the configuration of the restrictor in Embodiment 7 of the present invention; 
         FIG. 14  is cross section of the configuration of the restrictor in Embodiment 8 of the present invention; and 
         FIG. 15  is cross section of the configuration of the restrictor in Embodiment 9 of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENT(S) 
     A hydraulic excavator will be described as an example of the work vehicle of the present invention through reference to the drawings. 
     Embodiment 1 
     The hydraulic excavator in Embodiment 1 of the present invention will now be described. 
     Configuration 
     Overall Configuration of Hydraulic Excavator  100   
       FIG. 1  is a diagram of a hydraulic excavator  100  according to an embodiment of the present invention. The hydraulic excavator  100  comprises a vehicle body  1  and a work implement  4 . 
     The vehicle body  1  has a traveling unit  2  and a rotating unit  3 . The traveling unit  2  has a pair of traveling devices  2   a  and  2   b . The traveling devices  2   a  and  2   b  have crawler belts  2   d  and  2   e , respectively. 
     The rotating unit  3  is mounted on the traveling unit  2 . The rotating unit  3  is provided so as to be able to rotate with respect to the traveling unit  2 . The rotating unit  3  has a cab  5 , a body frame  6 , a damper  7  (see  FIG. 6  (discussed below)), and a restrictor  8  (see  FIG. 6  (discussed below)). 
     The body frame  6  is disposed on the upper side of the traveling unit  2 . The cab  5  is disposed at the front-left position of the body frame  6 . As shown in  FIG. 3  (discussed below), a plurality of dampers  7  are provided to the body frame  6  and support the cab  5 . As shown in  FIG. 6  (discussed below), the restrictor  8  restricts the cab  5  from being separated from the body frame  6  in the event of overturning or collision. 
     In the description of the overall structure, the longitudinal direction means the longitudinal direction of the cab  5 . Also, the longitudinal direction of the vehicle body  1  is assumed to coincide with the longitudinal direction of the cab  5 , that is, the rotating unit  3 . Also, the left and right direction, or to the side, refers to the vehicle width direction of the vehicle body  1 . In  FIG. 1 , the forward direction is indicated by the arrow F, and the backward direction is indicated by the arrow B. Also, the right direction is indicated by the arrow R, and the left direction is indicated by the arrow L. 
     The rotating unit  3  further has a fuel tank  12 , a hydraulic fluid tank  13 , an engine compartment  14 , a counterweight  15 , and so forth. The fuel tank  12 , the hydraulic fluid tank  13 , the engine compartment  14 , the counterweight  15 , and so on are disposed on the body frame  6 , to the rear of the cab  5 . 
     As shown in  FIG. 1 , the work implement  4  is attached to the front central position of the rotating unit  3 , and has a boom  9 , an arm  10 , and an excavation bucket  11 . The proximal end of the boom  9  is rotatably supported by the body frame  6 . The distal end of the boom  9  is rotatably linked to the proximal end of the arm  10 , and the distal end of the arm  10  is rotatably linked to the excavation bucket  11 . 
     The cab  5  is disposed on the left L side of the work implement  4 . 
     Cab  5   
       FIG. 2  is an oblique view of the body frame  6  and the cab  5 . 
     The cab  5  has a floor frame  51 , a ceiling frame  52 , a right-front support  53   a  and a right-rear support  53   b  on the right face side, a left-front support  54   a , a left-rear support  54   b , and a left-middle support  54   c  on the left face side. 
     The right-front support  53   a , the right-rear support  53   b , the left-front support  54   a,  the left-rear support  54   b , and the left-middle support  54   c  are formed facing upward from the floor frame  51 , and are each connected to the ceiling frame  52 . 
     The right-front support  53   a  is provided at the end on the right R side of the front face of the cab  5 , and the right-rear support  53   b  is provided at the end on the right R side of the rear face of the cab  5 . 
     The left-front support  54   a  is provided at the end on the left L side of the front face of the cab  5 , and the left-rear support  54   b  is provided at the end on the left L side of the rear face of the cab  5 . The left-middle support  54   c  is provided on the left side face of the cab  5 , in between the left-front support  54   a  and the left-rear support  54   b . The right-front support  53   a  and the left-front support  54   a  are disposed opposite each other in the left and right direction, and the right-rear support  53   b  and the left-rear support  54   b  are disposed opposite each other in the left and right direction. The support opposite the left-middle support  54   c  is not formed on the right side face, but a panel  58   a  connecting the support  53   a  and the support  53   b  is provided to the lower part of the right side face. 
     The right-rear support  53   b  and the left-rear support  54   b  on the rear face side are formed thicker than the right-front support  53   a  and the left-front support  54   a  on the front face side, and are therefore stiffer. 
     Body Frame  6   
       FIG. 3  is an oblique view showing a state in which the cab  5  and the body frame  6  are separated. The body frame  6  has a substantially planar base component  60 , a work implement support  61  that supports the work implement  4 , and a cab platform  62  on which the cab  5  is disposed. 
     The work implement support  61  is formed at the front-center position of the base component  60  of the body frame  6 . As shown in  FIG. 3 , the work implement support  61  has a pair of opposing vertical plates  611  and  612  formed along the longitudinal direction. The proximal end of the boom  9  is rotatably disposed between the vertical plates  611  and  612 . The cab  5  is disposed on the left side of the vertical plate  611 , which is disposed on the left side. 
     The cab platform  62  is formed just to the left of the work implement support  61 , at the front-left position of the base component  60 . The cab platform  62  has a front support frame  621  disposed in the left and right direction on the base component  60 , a rear support frame  622  disposed in the left and right direction on the base component  60 , and a left support frame  623  that connects the left end of the rear support frame  622  and the front support frame  621 . A middle support frame  624  is provided in the left and right direction between the front support frame  621  and the rear support frame  622 . 
     Dampers  7   
     The dampers  7  damp vibrations occurring in the cab  5  during normal running and working. 
     As shown in  FIG. 3 , holes are formed at the left and right ends of the upper face of the front support frame  621 , and the dampers  7  is disposed in these holes. Also, holes are formed at the left and right ends of the upper face  622   a  (see  FIG. 5 ) of the rear support frame  622 , and the dampers  7  are disposed in these holes. 
     The cab  5  is disposed on the upper side of these four dampers  7 . The cab  5  is supported on the body frame  6  by the dampers  7 . 
       FIG. 4  is a diagram showing the positional relation between the body frame  6  and the cab  5 . In  FIG. 4 , the cab  5  is indicated by a two-dot chain line. As shown in  FIG. 4 , the dampers  7  are disposed in the lower vicinity of the supports  53   a ,  53   b ,  54   a , and  54   b.    
       FIG. 5  is a cross section along the G-G′ line in  FIG. 2 . The dampers  7  each have a case  71  in the interior of which a coil spring or the like is provided, and a stud  72  protruding upward from the case  71 . The case  71  is fixed to the upper face  622   a  of the rear support frame  622 , and the upper end of the stud  72  is fixed to the floor frame  51  of the cab  5 . 
     Restrictor  8   
     The restrictor  8  restricts the cab  5  from being separated from the body frame  6  in the event of overturning, collision, or the like.  FIG. 6  is a view as seen in the direction of the arrow H in  FIG. 5 . 
     As shown in  FIG. 6 , the restrictor  8  is disposed in the vicinity of the right side of the damper  7  disposed on the side of the rear support frame  622  with the left face side (the arrow L side) of the cab  5 . The restrictor  8  is fixed to the floor frame  51  of the cab  5  and is disposed to pass through a through-hole  622   s  formed in the upper face  622   a  of the rear support frame  622 . 
     The restrictor  8  has a retaining member  81  and an impact absorber  82 . 
     The retaining member  81  is disk shaped, and is formed metal, for example. The retaining member  81  is disposed lower than the upper face  622   a  of the rear support frame  622  so that the upper face  81   s , which is the main face thereof, is opposite the through-hole  622   s . The retaining member  81  is formed larger in diameter than the through-hole  622   s.    
     The impact absorber  82  is provided on the cab  5  side of the retaining member  81 . The impact absorber  82  has a substantially cylindrical shape in which two steel pipes having different diameters appear to be overlapping one over the other, and the center axis  82   a  of the cylinder is disposed in the vertical direction. The impact absorber  82  has elasticity and is inserted into the through-hole  622   s.    
       FIG. 7  is a cross section along the I-I′ line in  FIG. 6 . As shown in  FIG. 7 , the impact absorber  82  is formed by a steel pipe, and has a first cylindrical section  821 , a second cylindrical section  822 , a connecting portion  823 , and a lid  824 . 
     The first cylindrical section  821  is inserted through the through-hole  622   s , and a slight gap is provided between the first cylindrical section  821  and the edge of the through-hole  622   s.    
     The lid  824  is connected to the lower end of the first cylindrical section  821 , and the lid  824  is disposed so as to block off the opening at the lower end of the first cylindrical section  821 . The retaining member  81  has a through-hole  81   a  formed in the vertical direction, and a through-hole is also formed in the lid  824 . 
     A bolt  83  is inserted into the through-hole  81   a  of the retaining member  81  and the through-hole of the lid  824  from below. A nut  84  is disposed on the upper side of the lid  824 , and the nut  84  and the bolt  83  are threaded together. The lid  824  and the first cylindrical section  821  are fixed to the retaining member  81  by the bolt  83  and the nut  84 . 
     The second cylindrical section  822  is formed larger in diameter than the first cylindrical section  821 . The second cylindrical section  822  is disposed coaxially with the first cylindrical section  821  (on the central axis  82   a  shown in  FIG. 6 ). The upper end  822   a  of the second cylindrical section  822  is fixed to the edge of the through-hole  51   a  formed in the floor frame  51  of the cab  5 , by welding or the like. The lower end  822   b  of the second cylindrical section  822  is normally positioned lower than the upper end  821   a  of the first cylindrical section  821 . 
     The connecting portion  823  connects the upper end  821   a  of the first cylindrical section  821  and the lower end  822   b  of the second cylindrical section  822 . The connecting portion  823  has a cylindrical shape at the center in the vertical direction, and its upper end curves inward and is connected to the upper end  821   a  of the first cylindrical section  821 , and its lower end curves outward and is connected to the lower end  822   b  of the second cylindrical section  822 . Since the connecting portion  823  is curved and connected to the first cylindrical section  821  and the second cylindrical section  822 , the impact absorber  82  has elasticity. 
     For example, if the hydraulic excavator  100  in this embodiment topples, or if an object strikes the hydraulic excavator  100 , and the cab  5  is subjected to an impact, the cab  5  is restricted from separating from the body frame  6  because the retaining member  81  hits the upper face  622   a  (the edge  622   e  of the through-hole  622   s ) of the rear support frame  622 , and the impact in this restriction is moderated by the elastic force of the impact absorber  82 . 
     In a state in which the hydraulic excavator  100  is stopped, a gap S is formed between the retaining member  81  and the upper face  622   a . This gap S is formed so that the retaining member  81  does not tough the upper face  622   a  within the vertical vibration range of the cab  5  during normal use of the hydraulic excavator  100 . This is because when the retaining member  81  comes into contact with the upper face  622   a  during normal use, it affects the damping function of the dampers  7  with respect to vibration of the cab  5 . 
     Embodiment 2 
     A restrictor  108  used in the hydraulic excavator in Embodiment 2 of the present invention will now be described. 
     The hydraulic excavator  100  in Embodiment 2 differs from Embodiment 1 in the configuration of the restrictor. Therefore, in Embodiment 2 the description will focus on the configuration of the restrictor. In Embodiment 2, those components that are the same as in other embodiments will be numbered the same and will not be described again. This also applies to the embodiments given below. 
       FIG. 8  is a cross section of the configuration of the restrictor  108  in Embodiment 2. 
     The restrictor  108  in Embodiment 2 has a retaining member  181 , an impact absorber  182 , and a cylindrical member  183 . The retaining member  181  is disk shaped, and is disposed so that its upper face  181   s  (a main face) is opposite the through-hole  622   s . The retaining member  181  is disposed lower than the upper face  622   a  of the rear support frame  622 , and is formed to have a larger diameter than the through-hole  622   s.    
     The impact absorber  182  is a coiled spring member, and is disposed closer to the cab  5  side than the retaining member  181 . The impact absorber  182  is disposed through the through-hole  622   s  so that its central axis extends in the up and down direction. The upper end  182   a  of the impact absorber  182  is fixed to the floor frame  51 . A through-hole  51   a  is formed in the floor frame  51 , and a protrusion  51   b  is formed from the edge of the through-hole  51   a  toward the inside of the through-hole  51   a . The upper end  182   a  of the impact absorber  182  is latched to the protrusion  51   b.    
     On the other hand, the lower end  182   b  of the impact absorber  182  is fixed to the retaining member  181 . A through-hole  181   a  is formed in the retaining member  181  in the up and down direction. A protrusion  181   b  is formed from the edge of the through-hole  181   a  toward the inside of the through-hole  181   a . The lower end  182   b  of the impact absorber  182  is latched to the protrusion  181   b.    
     The cylindrical member  183  is disposed on the outside of the impact absorber  182 . The upper end  183   a  of the cylindrical member  183  is joined to the floor frame  51  by welding or the like. The cylindrical member  183  is inserted into the through-hole  622   s  of the rear support frame  622 . The lower end  183   b  of the cylindrical member  183  is in contact with the retaining member  181 . A gap S between the retaining member  81  and the upper face  622   a  of the rear support frame  622  is ensured by the cylindrical member  183 . 
     With the above configuration, when an impact is exerted on the cab  5 , the separation of the cab  5  from the body frame  6  is restricted when the retaining member  181  hits the upper face  622   a  (around the through-hole  622   s ), but the impact of this restriction is moderated by the elastic force of the impact absorber  182 , which is a spring member. 
     Embodiment 3 
     A restrictor  208  used in the hydraulic excavator of Embodiment 3 of the present invention will now be described. 
       FIG. 9  is a cross section of the configuration of the restrictor  208  in Embodiment 3. The restrictor  208  in Embodiment 3 has the retaining member  81  and an impact absorber  282 . 
     As in Embodiment 1, the retaining member  81  is disk shaped, is disposed lower than the upper face  622   a  of the rear support frame  622 , and is formed larger in diameter than the through-hole  622   s . A gap S is formed between the retaining member  81  and the upper face  622   a.    
     The impact absorber  282  is a rubber member formed in a cylindrical shape. The impact absorber  282  is disposed through the through-hole  622   s  so that its axis extends in the up and down direction. The impact absorber  282  is disposed between the floor frame  51  and the retaining member  81 . 
     The impact absorber  282  is fixed to the floor frame  51  via a first metal member  284 . A concave portion is formed in the center of the upper end face of the impact absorber  282 . The first metal member  284  is disposed in the concave portion and is bonded to the impact absorber  282 . A threaded hole  284   a  is formed in the first metal member  284  in the up and down direction. A bolt  286  inserted from above the floor frame  51  through the through-hole  51   a  is threaded into the hole  284   a  to fix the impact absorber  282  to the floor frame  51 . 
     Also, the impact absorber  282  is fixed to the retaining member  81  via a second metal member  285 . A concave portion is formed in the center of the lower end face of the impact absorber  282 . The second metal member  285  is disposed in the concave portion and is bonded to the impact absorber  282 . A threaded hole  285   a  is formed in the second metal member  285  in the up and down direction. A bolt  83  inserted from below the retaining member  81  through the through-hole  81   a  is threaded into the hole  285   a  to fix the impact absorber  282  to the retaining member  81 . 
     With the above configuration, when the cab  5  is subjected to an impact, the cab  5  is restricted from separating from the body frame  6  because the retaining member  81  hits the upper face  622   a  (the periphery of the through-hole  622   s ), but the impact of this restriction is moderated by the elastic force of the impact absorber  282 , which is a rubber member. 
     Embodiment 4 
     Next, a restrictor  308  used in the hydraulic excavator in Embodiment 4 of the present invention will be described. 
       FIG. 10  is a cross section of the configuration of the restrictor  308  in Embodiment 4. The restrictor  308  in Embodiment 4 has a retaining member  381  and the impact absorber  82 . 
     The retaining member  381  of the restrictor  308  in Embodiment 4 differs from the restrictor  8  in Embodiment 1 in the shape of the retaining member  381 . 
     A curved surface  381   a  is formed on the cab  5  side (the side opposite the through-hole  622   s ) of the retaining member  381 . The curved surface  381   a  is formed such that its position gradually becomes lower moving from the center toward the outer periphery. 
     Forming the curved surface  381   a  prevents the retaining member  381  from coming into one-sided contact around the periphery of the through-hole  622   s  when the cab  5  is tilted in the left and right direction (for example, in the direction of the arrow J) with respect to the body frame  6  due to an impact exerted on the hydraulic excavator  100 . 
     The retaining member  381  on which the curved surface  381   a  is formed as in Embodiment 4 may be used in place of the retaining members  81  and  181  described in Embodiments 1 to 3. 
     Embodiment 5 
     A restrictor  408  used in the hydraulic excavator of Embodiment 5 of the present invention will now be described. 
       FIG. 11  is a cross section of the configuration of the restrictor  408  in Embodiment 5. The restrictor  408  in Embodiment 5 has the retaining member  81 , an impact absorber  482 , and a cylindrical member  483 . 
     The retaining member  81  is similar to that of the first embodiment in that it is disk shaped, and is formed from a metal, for example. The retaining member  81  is disposed lower than the upper face  622   a  of the rear support frame  622 , and is formed to have a diameter larger than that of the through-hole  622   s.    
     The impact absorber  482  is provided on the cab  5  side of the retaining member  81  and lower than the upper face  622   a  (the through-hole  622   s ). 
     As in Embodiment 1, the impact absorber  482  has a substantially cylindrical shape in which two steel pipes of different diameters appear to be overlapping, and the central axes of the cylinders are disposed in the up and down direction. 
     As shown in  FIG. 11 , the impact absorber  482  is formed from steel pipe and has a first cylindrical section  484 , a second cylindrical section  485 , and a connecting portion  486 . 
     The lower end  484   b  of the first cylindrical section  484  is fixed to the retaining member  81  by welding or the like. 
     The second cylindrical section  485  is formed in a larger diameter than the first cylindrical section  484 . The second cylindrical section  485  is disposed coaxially with the first cylindrical section  484 . The lower end  485   b  of the second cylindrical section  485  is located lower than the upper end  484   a  of the first cylindrical section  484 . 
     The diameter of the second cylindrical section  485  is larger than the through-hole  622   s , and a gap S is formed between the upper end  485   a  of the second cylindrical section  485  and the upper face  622   a.    
     The connecting portion  486  connects the upper end  484   a  of the first cylindrical section  484  and the lower end  485   b  of the second cylindrical section  485 . The connecting portion  486  is cylindrical in its middle in the up and down direction, and its upper end curves inward and connects to the upper end  484   a  of the first cylindrical section  484 , while the lower end of the connecting portion  486  curves outward and connects to the lower end  485   b  of the second cylindrical section  485 . Since the connecting portion  486  is curved and connects the first cylindrical section  484  and the second cylindrical section  485 , the impact absorber  482  has elasticity. 
     The cylindrical member  483  is inserted into the through-hole  622   s  and is disposed between the floor frame  51  and the retaining member  81 . A threaded hole  483   a  that goes through in the up and down direction is formed in the central portion of the cylindrical member  483 . 
     The cylindrical member  483  is fixed to the lower side of the floor frame  51  by threading the bolt  489 , which is inserted into the through-hole  51   a  from above the floor frame  51 , into the threads at the upper part of the screw hole  483   a . When the bolt  83  inserted into the through-hole  81   a  from under the retaining member  81  is threaded into the threads formed at the lower part of the screw hole  483   a , this fixes the retaining member  81  to the lower side of the cylindrical member  483 . 
     With the above configuration, when an impact is exerted on the cab  5 , the cab  5  is restricted from separating from the body frame  6  because the impact absorber  482  hits the upper face  622   a , and the impact in this restriction is lessened by elastic force. 
     Embodiment 6 
     Next, a restrictor  508  used in the hydraulic excavator in Embodiment 6 of the present invention will be described. The restrictor  508  in Embodiment 6 differs from the restrictor  408  in Embodiment 5 in the configuration of the impact absorber. 
       FIG. 12  is a cross section of the configuration of the restrictor  508  in Embodiment 6. The restrictor  508  in Embodiment 6 has the retaining member  81 , an impact absorber  582 , and the cylindrical member  483 . 
     The retaining member  81  is the same as in Embodiment 5. Also, as in Embodiment 5, the cylindrical member  483  is fixed to the floor frame  51  with the bolt  489 , and is fixed to the retaining member  81  by the bolt  83 . 
     The impact absorber  582  is a coiled spring member, and is disposed on the outside of the cylindrical member  483  so as to surround the cylindrical member  483 . The diameter of the impact absorber  582  is larger than the diameter of the through-hole  622   s . The lower end  582   b  of the impact absorber  582 , which is a spring member, is fixed to the retaining member  81 . In a state in which the hydraulic excavator  100  is stopped, a gap S is formed between the upper end  582   a  of the impact absorber  582  and the upper face  622   a.    
     With the above configuration, when an impact is exerted on the cab  5 , the cab  5  is restricted from separating from the body frame  6  because the impact absorber  582  hits the upper face  622   a , and the impact in this restriction is lessened by elastic force. 
     Embodiment 7 
     Next, a restrictor  608  used in the hydraulic excavator in Embodiment 7 of the present invention will be described. The restrictor  608  in Embodiment 7 differs from the restrictor  508  in Embodiment 6 in the configuration of the impact absorber. 
       FIG. 13  is a cross sectional configuration diagram of the restrictor  608  in Embodiment 7 of the present invention. 
     The restrictor  608  in Embodiment 7 has the retaining member  81 , an impact absorber  682 , and the cylindrical member  483 . 
     The impact absorber  682  of the restrictor  608  in Embodiment 7 is a rubber member, unlike the impact absorber  582  in Embodiment 6. 
     The impact absorber  682 , which is a rubber member, is cylindrical and is disposed around the outer periphery of the cylindrical member  483 . The diameter of the impact absorber  682  is larger than the diameter of the through-hole  622   s . The impact absorber  682  is disposed lower than the upper face  622   a . The lower end  682   b  of the impact absorber  682  is in contact with the upper face  81   s  of the retaining member  81 . A gap S is formed between the upper end  682   a  of the impact absorber  682  and the upper face  622   a.    
     With the above configuration, when an impact is exerted on the cab  5 , the cab  5  is restricted from separating from the body frame  6  because the impact absorber  682  hits the upper face  622   a , and the impact in this restriction is lessened by elastic force. 
     Embodiment 8 
     Next, a restrictor  708  used in the hydraulic excavator in Embodiment 8 of the present invention will be described. 
       FIG. 14  is a cross sectional configuration diagram of the restrictor  708  in Embodiment 7 of the present invention. The restrictor  708  shown in  FIG. 14  is the product of attaching the restrictor  8  in Embodiment 1 to the floor frame  51  in an inclined state. 
     As shown in  FIG. 14 , the restrictor  708  is disposed so that its center axis  708   a  is inclined in the left direction L as it goes upward. 
     The retaining member  81  is inclined so that the end  81 R on the right direction R side of the upper face  81   s  is positioned higher than the end  81 L on the left direction L side. In a state in which the hydraulic excavator  100  is stopped, the impact absorber  82  is inclined so as to hold the retaining member  81  in an inclined state. The center axis of the first cylindrical section  821  and the second cylindrical section  822  of the impact absorber  82  coincides with the central axis  708   a.    
     The restrictor  708  in this embodiment can exhibit the following effect by being inclined with respect to the vertical direction. 
     If the hydraulic excavator  100  has tipped to the left direction L side, the cab  5  comes into contact with the ground, etc., and the cab  5  inclines with respect to the body frame  6  in the direction of the arrow J and tries to separate from the body frame  6 . If the cab  5  is inclined with respect to the body frame  6 , the restrictor  708  is also inclined, so that when the retaining member  81  hits the upper face  622   a  of the body frame  6 , the retaining member  81  is parallel to the upper face  622   a.    
     Therefore, the retaining member  81  can be prevented from coming into one-sided contact with the upper face  622   a.    
     The restrictors  108 ,  208 ,  308 ,  408 ,  508 , and  608  in Embodiments 2 to 7 above may be disposed so that their central axis is inclined as in Embodiment 8. 
     Embodiment 9 
     Next, a restrictor  808  used in the hydraulic excavator in Embodiment 9 of the present invention will be described. 
       FIG. 15  is a cross sectional configuration diagram of the restrictor  808  in Embodiment 9. As shown in  FIG. 15 , the restrictor  808  in Embodiment 9 has the retaining member  81  and an impact absorber  882 . The impact absorber  882  has an insertion component  883  that is inserted into the through-hole  622   s , and a protruding portion  884 . The insertion component  883  has a first cylindrical section  821 , a second cylindrical section  822 , and a connecting portion  823 , and has the same configuration as the impact absorber  82  in Embodiment 1. 
     In Embodiment 9, unlike Embodiment 1, the upper end  822   a  of the second cylindrical section  822  is not fixed to the floor frame  51 , and the protruding portion  884  is provided to the upper end  822   a.    
     The protruding portion  884  is formed so as to extend outward from the whole periphery of the upper end  822   a  beyond the through-hole  51   a.    
     The lower face  884   a  of the protruding portion  884  is curved so that its position becomes higher moving toward the outer peripheral side. The lower face  884   a  hits the edge of the through-hole  51   a.    
     The restrictor  808  in Embodiment 9 has a configuration in which the protruding portion  884  is provided to hold the second cylindrical section  822  on the floor frame  51 . 
     With the above configuration, when an impact is exerted on the cab  5 , the cab  5  is restricted from separating from the body frame  6  because the retaining member  81  hits the upper face  622   a  (the periphery of the through-hole  622   s ), but the impact in this restriction is lessened by the elastic force of the impact absorber  882 . 
     Forming the lower face  884   a  so as to be curved prevents the protruding portion  884  from coming into one-sided contact with the periphery of the through-hole  51   a  when the cab  5  is inclined in the left and right direction (such as in the direction of the arrow J) with respect to the body frame  6  due to an impact applied to the hydraulic excavator  100 . 
     Features, Etc, 
     (1) 
     As shown in  FIGS. 7 to 15 , the hydraulic excavator  100  (an example of a work vehicle) in Embodiments 1 to 9 comprises the cab  5 , the body frame  6 , and the restrictor  8 ,  108 ,  208 ,  308 ,  408 ,  508 ,  608 ,  708 , or  808 . The body frame  6  has the base component  60  and the rear support frame  622  (an example of a support frame) that is provided on the upper side of the base component  60  and supports the cab  5 . The restrictor  8 ,  108 ,  208 ,  308 ,  408 ,  508 ,  608 ,  708 , or  808  is provided to the floor frame  51  of the cab  5  and is disposed between the base component  60  and the floor frame  51 . The restrictor  8 ,  108 ,  208 ,  308 ,  408 ,  508 ,  608 ,  708 , or  808  has the retaining member  81 ,  181 , or  381  and the impact absorber  82 ,  182 ,  282 ,  482 ,  582 ,  682 , or  882 . The retaining member  81 ,  181 , or  381  is disposed on the lower side of the rear support frame  622 . The impact absorber  82 ,  182 ,  282 ,  482 ,  582 ,  682 , or  882  is disposed on the cab  5  side of the retaining member  81 ,  181  or  381 . 
     At least some of the impact generated in the cab  5  by restriction in the event that the hydraulic excavator  100  topples can be absorbed by providing an impact absorber to the restrictor  8 ,  108 ,  208 ,  308 ,  408 ,  508 ,  608 ,  708 , or  808 . Therefore, the impact generated in the cab  5  can be lessened, and the frame of the cab  5  need not be made of a thick material, so the thickness of the frame can be reduced. 
     Therefore, it is possible to further reduce the weight of the cab  5 . 
     (2) 
     The hydraulic excavator  100  (an example of a work vehicle) in Embodiments 1 to 9 further comprises the dampers  7 . As shown in  FIG. 6 , the dampers  7  are provided to the body frame  6  and support the cab  5 , and also damp any vibrations generated in the cab  5 . 
     Vibration and impact occurring in the cab  5  can be lessened during normal use of the hydraulic excavator  100 , such as traveling and working. 
     Also, if the hydraulic excavator  100  should topple or collide with a rock or the like, the restrictor  8 ,  108 ,  208 ,  308 ,  408 ,  508 ,  608 ,  708 , or  808  can restrict the cab  5  from separating from the body frame  6 . 
     (3) 
     As shown in  FIGS. 2, 5 and 6 , the hydraulic excavator  100  (an example of a work vehicle) in Embodiments 1 to 9 further comprises the work implement  4  disposed on the body frame  6 . The restrictor  8 ,  108 ,  208 ,  308 ,  408 ,  508 ,  608 ,  708 , or  808  is provided on the opposite side from the work implement  4 . 
     The side of the cab  5  on which the work implement  4  is not provided is more likely to be subjected to an impact, so the restrictor  8 ,  108 ,  208 ,  308 ,  408 ,  508 ,  608 ,  708 , or  808  is provided on the opposite side from the work implement  4 , which allows separation of the cab  5  from the body frame  6  to be effectively restricted. 
     (4) 
     As shown in  FIGS. 7 to 10 and 14 , in the hydraulic excavator  100  (an example of a work vehicle) in Embodiments 1 to 4 and 8, the impact absorber  82 ,  182 , or  282  of the restrictor  8 ,  108 ,  208 ,  308 ,  708  is fixed directly or indirectly to the floor frame  51  of the cab  5 . 
     When the cab  5  moves away from the body frame  6  due to an impact, the retaining member  81 ,  181 , or  381  hits the rear support frame  622  (the periphery of the through-hole  622   s ) of the body frame  6  from below, and movement of the cab  5  is restricted. This contact causes the impact absorber  82 ,  182 , or  282  to be pulled, and the impact can be lessened by the elastic force of the impact absorber  82 ,  182 , or  282 . 
     (5) 
     As shown in  FIG. 7 , with the hydraulic excavator  100  (an example of a work vehicle) in Embodiment 1, the impact absorber  82  has the first cylindrical section  821 , the second cylindrical section  822 , and the connecting portion  823 . The first cylindrical section  821  is fixed to the retaining member  81 . The second cylindrical section  822  is fixed to the floor frame  51  of the cab  5 , and its lower end  822   b  is located lower than the upper end  821   a  of the first cylindrical section  821 . 
     An elastic force is generated by the bending of the connecting portion  823  of the impact absorber  82 , which softens the collision of the retaining member  81  against the rear support frame  622 . 
     (6) 
     With the hydraulic excavator  100  (an example of a work vehicle) in Embodiment 2, as shown in  FIG. 8 , the impact absorber  182  is a spring member. The upper end  182   a  of the impact absorber  182  is fixed to the floor frame  51  of the cab  5 , and the lower end  182   b  is fixed to the retaining member  181 . 
     Providing the impact absorber  182 , which is a spring member, means that the collision of the retaining member  181  against the rear support frame  622  can be softened by the elastic force of the spring member. 
     (7) 
     With the hydraulic excavator  100  (an example of a work vehicle) in Embodiment 3, as shown in  FIG. 9 , the impact absorber  282  is a rubber member. The impact absorber  282  is fixed to the floor frame  51  of the cab  5  via the first metal member  284  that is bonded to the impact absorber  282  and fixed to the floor frame  51  of the cab  5 , and is also fixed to the retaining member  81  via the second metal member  285  that is bonded to the impact absorber  282  and fixed to the retaining member  81 . 
     Providing the impact absorber  282 , which is a rubber member, means that the collision of the retaining member  181  against the rear support frame  622  can be softened by the elastic force of the rubber member. 
     (8) 
     With the hydraulic excavator  100  (an example of a work vehicle) in Embodiment 4, as shown in  FIG. 10 , the curved surface  381   a  (an example of an upper face) of the retaining member  381  is curved so that its position becomes lower moving toward the outer peripheral side. 
     The portion of the retaining member  381  that collides with the rear support frame  622  (around the through-hole  622   s ) of the body frame  6  is curved. This makes it less likely that the retaining member  381  will come into one-way contact with the rear support frame  622  when the cab  5  is inclined with respect to the body frame  6 . 
     (9) 
     As shown in  FIGS. 11 to 13 , with the hydraulic excavator  100  (an example of a work vehicle) in Embodiments 5, 6, and 7, the restrictor  408 ,  508 , or  608  further has the cylindrical member  483  (an example of a linking member) that links the floor frame  51  and the retaining member  81 . The impact absorber  482 ,  582 , or  682  is fixed to the retaining member  81  and is disposed lower than the rear support frame  622  (an example of a support frame). 
     When the cab  5  moves away from the body frame  6  due to an impact, the impact absorber  482 ,  582 , or  682  hits the rear support frame  622  of the body frame  6  from below, and movement of the cab  5  is restricted. In this contact, the impact absorber  482 ,  582 , or  682  is compressed, and the impact can be lessened by the elastic force of the impact absorber  482 ,  582 , or  682 . 
     (10) 
     As shown in  FIG. 11 , with the hydraulic excavator  100  (an example of a work vehicle) in Embodiment 5, the impact absorber  482  has the first cylindrical section  484 , the second cylindrical section  485 , and the connecting portion  486 . The first cylindrical section  484  is fixed to the retaining member  81 . The lower end  485   b  of the second cylindrical section  485  is positioned lower than the upper end  484   a  of the first cylindrical section  484 . The connecting portion  486  connects the upper end  484   a  of the first cylindrical section  484  and the lower end  485   b  of the second cylindrical section  485 . 
     An elastic force is generated by the bending of the connecting portion  486  of the impact absorber  482 , which softens the collision of the impact absorber  482  against the rear support frame  622 . 
     (11) 
     With the hydraulic excavator  100  (an example of a work vehicle) in Embodiments 6 and 7, as shown in  FIGS. 12 and 13 , the impact absorber  582  or  682  is a spring member or a rubber member. 
     Providing a spring member or a rubber member means that the collision of the impact absorber  582  or  682  against the rear support frame  622  can be softened by the elastic force of the spring member or the rubber member. 
     (12) 
     With the hydraulic excavator  100  (an example of a work vehicle) in Embodiment 8, as shown in  FIG. 14 , the retaining member  81  is disk shaped (an example of a plate shape), and the upper face  81   s  (an example of a main face) is disposed opposite the rear support frame  622  (an example of a support frame). The restrictor  708  is disposed such that the end  81 R of the upper face  81   s  on the work implement  4  side is higher than the end  81 L on the opposite side from the work implement. 
     Disposing the restrictor  708  so that it is inclined makes it less likely that the retaining member  81  will come into one-sided contact with the body frame  6  when the cab  5  is inclined toward the work implement  4  side with respect to the body frame  6 . 
     (13) 
     With the hydraulic excavator  100  (an example of a work vehicle) in Embodiment 9, as shown in  FIG. 15 , the impact absorber  882  has the insertion component  883  and the protruding portion  884 . The insertion component  883  is inserted into the through-hole  51   a  (an example of a through-hole) formed in the floor frame  51  of the cab  5 . The protruding portion  884  is provided higher than the floor frame  51  and protrudes from the insertion component  883  so as to extend outward from the through-hole  51   a . The protruding portion  884  is curved so as to have a higher position moving toward the outer peripheral side, and has a lower face  884   a  that makes contact around the through-hole  51   a.    
     Since the protrusion  884  of the impact absorber  882  has the lower face  884   a  that curves toward the through-hole  51   a , it is less likely that the impact absorber  882  will come into one-sided contact around the through-hole  51   a  when the cab  5  is inclined with respect to the body frame  6 . 
     (14) 
     With the hydraulic excavator  100  (an example of a work vehicle) in Embodiment 9, as shown in  FIG. 15 , the insertion component  883  has the first cylindrical section  821 , the second cylindrical section  822 , and the connecting portion  823 . The first cylindrical section  821  is fixed to the retaining member  81 . The second cylindrical section  822  is inserted into the through-hole  51   a , and its lower end  822   b  is located lower than the upper end  821   a  of the first cylindrical section  821 . The connecting portion  823  connects the upper end  821   a  of the first cylindrical section  821  and the lower end  822   b  of the second cylindrical section  822 . 
     An elastic force is generated by the bending of the connecting portion  823  of the impact absorber  882 , and the collision of the impact absorber  882  against the rear supporting frame  622  can be softened. 
     Other Embodiments 
     Embodiments of the present invention were described above, but the present invention is not limited to or by the above embodiments, and various modifications are possible without departing from the gist of the invention. 
     (A) 
     In Embodiments 1 to 9, one restrictor  8 ,  108 ,  208 ,  308 ,  408 ,  508 ,  608 ,  708 , or  808  is provided, but two or more restrictors may be provided. For example, as shown in  FIG. 6 , the restrictor  8  of Embodiment 1 is disposed near the support  54   b  on the left face side of the rear support frame  622 , but may also be disposed near the support  54   a  on the left face side of the front support frame  621 . 
     The restrictor  8  may be provided in the vicinity below the support  54   b  (an example of a first cab frame) and the support  54   a  (an example of a second cab frame). 
     In this case, as described in Embodiment 1, since the support  54   b  is stiffer than the support  54   a , the coefficient of elasticity of the impact absorber  82  of the restrictor  8  provided in the vicinity below the support  54   b  is set to be higher than the coefficient of elasticity of the impact absorber of the restrictor  8  provided in the vicinity below the support  54   a.    
     Due to the difference in the coefficient of elasticity, when an impact is exerted on the cab  5 , the impact exerted on the support  54   b  is greater than that on the support  54   a , but since the support  54   b  is stiffer than the support  54   a , the support  54   b  can stop the impact. For example, when driving the hydraulic excavator  100 , the driver can focus on what is in front of the cab, so it is unlikely that there will be an impact caused by collision or the like on the front side of the cab, but since the driver cannot focus his attention to the rear, an impact is more likely on that side. In view of this, the weight of the cab  5  can be reduced as much as possible by making the front side support  54   a , which is less likely to be subjected to impact, thinner than the back side support  54   b , which is more likely to be subjected to impact. If an impact should be exerted on the thinner front support  54   a , it can absorb this impact because its coefficient of elasticity is set lower. 
     In Embodiments 2 to 9, the restrictor  108 ,  208 ,  308 ,  408 ,  508 ,  608 ,  708 , or  808  may be provided to the front support frame  621  as in the above description. 
     (B) 
     In the above embodiments and in (A) of the above-mentioned other embodiments, the restrictor  8 ,  108 ,  208 ,  308 ,  408 ,  508 ,  608 ,  708 , or  808  was said to be provided to the rear support frame  622  and the front support frame  621 , but the restrictor  8 ,  108 ,  208 ,  308 ,  408 ,  508 ,  608 ,  708 , or  808  may be provided near the left end of the middle support frame  624 . 
     In the above embodiments, as shown in  FIG. 4 , the middle support frame  624  is disposed between the support  54   a  and the support  54   c  in the longitudinal direction, but the middle support frame  624  may be disposed below the support  54   c , and the restrictor  8 ,  108 ,  208 ,  308 ,  408 ,  508 ,  608 ,  708 , or  808  may be disposed near the support  54   c.    
     (C) 
     In the above embodiments and in (A) of the above-mentioned other embodiments, the restrictor  8 ,  108 ,  208 ,  308 ,  408 ,  508 ,  608 ,  708 , or  808  is provided on the opposite side from the work implement  4 , but may also be provided on the work implement  4  side. 
     (D) 
     In Embodiments 1 to 9, the hydraulic excavator  100  is used as an example of a work vehicle, but this is not the only option, and it may instead be a wheel loader, a bulldozer, a motor grader, or the like. 
     INDUSTRIAL APPLICABILITY 
     The work vehicle of the present invention has the effect of ensuring the required strength and reducing the weight of the cab, and can be widely applied, for example, to hydraulic excavators, wheel loaders, bulldozers, motor graders, and the like.