Patent Publication Number: US-2022220699-A1

Title: Cab and work vehicle

Description:
TECHNICAL FIELD 
     The present disclosure relates to a cab and a work vehicle. 
     BACKGROUND ART 
     For example, Japanese Patent Laying-Open No. 2011-105032 (PTL 1) discloses a cab for a hydraulic excavator, including a pair of left and right pillars, a beam member arranged between the pair of left and right pillars, and a gusset plate placed at a corner portion where the pillars and the beam member are connected to each other. 
     CITATION LIST 
     Patent Literature 
     
         
         PTL 1: Japanese Patent Laying-Open No. 2011-105032 
       
    
     SUMMARY OF INVENTION 
     Technical Problem 
     In the cab disclosed in PTL 1 above, the gusset plate is placed at the corner portion where the pillars and the beam member are connected to each other, in order to increase the strength of the cab. However, the gusset plate has a substantially triangular shape in a plan view, and is provided such that two sides of the substantially triangular shape orthogonal to each other are joined to inner surfaces of the pillars and the beam member. Therefore, it is concerned that a space in the cab surrounded by the pillars and the beam member may be invaded greatly by the gusset plate. 
     Accordingly, an object of the present disclosure is to provide a highly-rigid cab in which a wide space can be secured, and a work vehicle including the cab. 
     Solution to Problem 
     A cab according to the present disclosure includes: a pillar member; a beam member; and a rib member. The pillar member extends in an up-down direction. The beam member extends in a left-right direction. The beam member is connected to an upper end of the pillar member. The rib member is provided at a corner portion where the pillar member and the beam member intersect with each other. The rib member is connected to the pillar member and the beam member. The rib member is embedded in at least one of the pillar member and the beam member. 
     “The rib member is embedded in at least one of the pillar member and the beam member” means that at least a part of the rib member is arranged in a recessed portion provided in at least one of the pillar member and the beam member. 
     A work vehicle according to the present disclosure includes the above-described cab. 
     Advantageous Effects of Invention 
     According to the present disclosure, there can be provided a highly-rigid cab in which a wide space can be secured, and a work vehicle including the cab. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view showing a hydraulic excavator. 
         FIG. 2  is a perspective view showing a frame structure of a cab in  FIG. 1 . 
         FIG. 3  is another perspective view showing the frame structure of the cab in  FIG. 1 . 
         FIG. 4  is a perspective view showing a rail member for guiding a front transparent member in  FIG. 2 . 
         FIG. 5  is a side view showing an operation for opening and closing the front transparent member in  FIG. 2 . 
         FIG. 6  is a cross-sectional view showing the cab at a corner portion of an upper surface and a right surface. 
         FIG. 7  is a perspective view showing the cab in a range surrounded by a two-dot chain line VII in  FIG. 3  in an enlarged manner. 
         FIG. 8  is a perspective view showing the cab in a range surrounded by a two-dot chain line VIII in  FIG. 2  in an enlarged manner. 
         FIG. 9  is a perspective view showing a state in which a ceiling member and girder members have been removed from the cab shown in  FIG. 7 . 
         FIG. 10  is a perspective view showing a state in which the ceiling member and the girder members have been removed from the cab shown in  FIG. 8 . 
         FIG. 11  is an exploded view of the cab shown in  FIG. 9 . 
         FIG. 12  is an exploded view of the cab shown in  FIG. 10 . 
         FIG. 13  is a perspective view showing a rib member in  FIGS. 7 to 12 . 
         FIG. 14  is a cross-sectional view showing the cab when seen in a direction indicated by an arrow line XIV-XIV in  FIG. 10 . 
         FIG. 15  is a cross-sectional view showing the cab when seen in a direction indicated by an arrow line XV-XV in  FIG. 10 . 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     An embodiment of the present disclosure will be described with reference to the drawings. In the drawings referenced below, the same or corresponding components are denoted by the same reference numerals. 
       FIG. 1  is a perspective view showing a hydraulic excavator. First, an overall structure of the hydraulic excavator including a cab according to the present embodiment will be described. 
     As shown in  FIG. 1 , a hydraulic excavator  100  includes a vehicular body  11  and a work implement  12 . Vehicular body  11  includes a revolving unit  13  and a traveling unit  15 . 
     Traveling unit  15  includes a pair of crawler belts  15 Cr and a travel motor  15 M. Hydraulic excavator  100  can travel by rotation of crawler belts  15 Cr. Travel motor  15 M is provided as a drive source of traveling unit  15 . Traveling unit  15  may include a wheel (tire). 
     Revolving unit  13  is provided on traveling unit  15 . Revolving unit  13  can swing about the center of swing  26  with respect to traveling unit  15 . The center of swing  26  corresponds to an axis extending in the up-down direction. Revolving unit  13  includes a cab (operator&#39;s cab)  30 . A living space  120  for an operator is formed in cab  30 . An operator&#39;s seat  31  is provided in living space  120  for the operator. The operator rides in living space  120  and is seated on operator&#39;s seat  31  to operate hydraulic excavator  100 . 
     Revolving unit  13  includes an engine compartment  19  and a counter weight that is provided in a rear portion of revolving unit  13 . Engine compartment  19  accommodates an engine, a hydraulic oil tank, an air cleaner, a hydraulic pump, and the like. 
     Work implement  12  is attached to vehicular body  11 . Work implement  12  is attached to revolving unit  13 . Work implement  12  performs operations such as excavation of soil. Work implement  12  includes a boom  16 , an arm  17 , and a bucket  18 . 
     Boom  16  is pivotably coupled to vehicular body  11  (revolving unit  13 ) through a boom pin  23 . Arm  17  is pivotably coupled to boom  16  through an arm pin  24 . Bucket  18  is pivotably coupled to arm  17  through a bucket pin  25 . 
     Work implement  12  further includes boom cylinders  20 A and  20 B, an arm cylinder  21 , and a bucket cylinder  22 . 
     Boom cylinders  20 A and  20 B, arm cylinder  21 , and bucket cylinder  22  each are a hydraulic cylinder driven by hydraulic oil. Boom cylinders  20 A and  20 B, which are provided as one pair, each are provided on a corresponding one of both sides of boom  16 , and operate boom  16  to pivot. Arm cylinder  21  operates arm  17  to pivot. Bucket cylinder  22  operates bucket  18  to pivot. 
     Herein, the front-rear direction refers to a front direction and a rear direction of the operator seated on operator&#39;s seat  31 . The direction facing the operator seated on operator&#39;s seat  31  is defined as the front direction, and the direction backward the operator seated on operator&#39;s seat  31  is defined as the rear direction. The left-right (lateral) direction refers to a left direction and a right direction of the operator seated on operator&#39;s seat  31 . When the operator seated on operator&#39;s seat  31  faces the front, the right side of the operator is defined as the right direction. When the operator seated on operator&#39;s seat  31  faces the front, the left side of the operator is defined as the left direction. The up-down direction refers to a direction orthogonal to a plane including the front-rear direction and the left-right direction. The side downward the ground is defined as a lower side, and the side upward the sky is defined as an upper side. 
       FIGS. 2 and 3  are perspective views showing a frame structure of the cab in  FIG. 1 . Next, the structure of cab  30  will be described. 
     As shown in  FIGS. 1 to 3 , cab  30  is formed of a box having a rectangular parallelepiped shape and including a front surface  30 A, a rear surface  30 B, a right surface  30 C, a left surface  30 D, a top surface  30 E, and a bottom surface  30 F. 
     Front surface  30 A is provided to face the front side. Rear surface  30 B is provided to face the rear side. Right surface  30 C is provided to face the right side. Right surface  30 C faces work implement  12  in the left-right direction. Left surface  30 D is provided to face the left side. Top surface  30 E is provided to face the upper side. Bottom surface  30 F is provided to face the lower side. Bottom surface  30 F faces a frame of revolving unit  13  in the up-down direction. 
     As shown in  FIGS. 2 and 3 , cab  30  includes a floor member  40 , a pair of left and right pillar members  42  ( 42 L and  42 R), a pair of left and right pillar members  43  ( 43 L and  43 R), a pair of left and right pillar members  44  ( 44 L and  44 R), beam members  51 ,  52  and  53 , a pair of left and right girder members  54  ( 54 L and  54 R), and a pair of left and right girder members  55  ( 55 L and  55 R). 
     Floor member  40 , pillar members  42 , pillar members  43 , pillar members  44 , beam members  51 ,  52  and  53 , girder members  54 , and girder members  55  are integrally formed with each other by welding, to thereby form a cab frame. 
     Floor member  40  is provided on bottom surface  30 F. Floor member  40  is formed of a plate member (e.g., a steel plate). 
     Each of pillar members  42 , pillar members  43 , pillar members  44 , beam members  51 ,  52  and  53 , girder members  54 , and girder members  55  is formed of a frame member extending in one direction in an elongated manner. Pillar members  42 , pillar members  43 , pillar members  44 , beam members  51 ,  52  and  53 , girder members  54 , and girder members  55  are provided around living space  120  for the operator. Living space  120  for the operator is provided at a position surrounded by pillar members  42 , pillar members  43 , pillar members  44 , beam members  51 ,  52  and  53 , girder members  54 , and girder members  55 . 
     Pillar members  42 , pillar members  43  and pillar members  44  are erected on floor member  40 . Pillar members  42 , pillar members  43  and pillar members  44  are connected to floor member  40 . Pillar members  42 , pillar members  43  and pillar members  44  extend in the up-down direction between top surface  30 E and bottom surface  30 F. 
     Pillar member  42 L and pillar member  42 R are arranged to be spaced apart from each other in the left-right direction. Pillar member  42 L and pillar member  42 R are located to face each other in the left-right direction. Pillar member  42 L is provided at a corner portion where front surface  30 A and left surface  30 D intersect with each other. Pillar member  42 R is provided at a corner portion where front surface  30 A and right surface  30 C intersect with each other. Pillar member  42 L is provided at a front end of left surface  30 D. Pillar member  42 R is provided at a front end of right surface  30 C. Pillar member  42 L and pillar member  42 R are provided on the front side of operator&#39;s seat  31  shown in  FIG. 1 . 
     Pillar member  43 L and pillar member  43 R are arranged to be spaced apart from each other in the left-right direction. Pillar member  43 L and pillar member  43 R are located to face each other in the left-right direction. Pillar member  43 L and pillar member  43 R are provided on the lateral sides of operator&#39;s seat  31  shown in  FIG. 1 . Pillar member  43 L is provided on left surface  30 D. Pillar member  43 R is provided on right surface  30 C. Pillar member  43 L and pillar member  43 R are provided on the rear side of pillar member  42 L and pillar member  42 R. 
     Pillar member  44 L and pillar member  44 R are arranged to be spaced apart from each other in the left-right direction. Pillar member  44 L and pillar member  44 R are located to face each other in the left-right direction. Pillar member  44 L is provided at a corner portion where left surface  30 D and rear surface  30 B intersect with each other. Pillar member  44 L is provided at a rear end of left surface  30 D. Pillar member  44 R is provided at a corner portion where right surface  30 C and rear surface  30 B intersect with each other. Pillar member  44 R is provided at a rear end of right surface  30 C. 
     Pillar member  44 L and pillar member  44 R are provided on the rear side of pillar member  43 L and pillar member  43 R. Pillar member  44 L and pillar member  44 R are provided on the rear side of operator&#39;s seat  31  shown in  FIG. 1 . 
     Beam members  51 ,  52  and  53 , girder members  54  and girder members  55  are provided on top surface  30 E. Beam member  51 , beam member  52  and beam member  53  extend in the left-right direction. Girder members  54  and girder members  55  extend in the front-rear direction. 
     Beam member  51  is provided at a corner portion where front surface  30 A and top surface  30 E intersect with each other. A left end of beam member  51  is connected to a connection portion that connects pillar member  42 L and below-described girder member  54 L. A right end of beam member  51  is connected to a connection portion that connects pillar member  42 R and below-described girder member  54 R. 
     Beam member  52  is provided on the rear side of beam member  51 . A right end of beam member  52  is connected to an upper end of pillar member  43 R. A left end of beam member  52  is connected to an upper end of pillar member  43 L. 
     Beam member  53  is provided at a corner portion where top surface  30 E and rear surface  30 B intersect with each other. Beam member  53  is provided on the rear side of beam member  52 . A right end of beam member  53  is connected to an upper end of pillar member  44 R. A left end of beam member  53  is connected to an upper end of pillar member  44 L. 
     Girder member  54 L and girder member  54 R are arranged to be spaced apart from each other in the left-right direction. Girder member  54 L and girder member  54 R are located to face each other in the left-right direction. 
     Girder member  54 L is provided at a corner portion where left surface  30 D and top surface  30 E intersect with each other. A front end of girder member  54 L is connected to an upper end of pillar member  42 L. Girder member  54 L and pillar member  42 L are formed of an integrated frame member. A rear end of girder member  54 L is connected to an upper end of pillar member  43 L. Girder member  54 R is provided at a corner portion where right surface  30 C and top surface  30 E intersect with each other. A front end of girder member  54 R is connected to an upper end of pillar member  42 R. Girder member  54 R and pillar member  42 R are formed of an integrated frame member. A rear end of girder member  54 R is connected to an upper end of pillar member  43 R. 
     Girder member  55 L and girder member  55 R are arranged to be spaced apart from each other in the left-right direction. Girder member  55 L and girder member  55 R are located to face each other in the left-right direction. 
     Girder member  55 L is provided at a corner portion where left surface  30 D and top surface  30 E intersect with each other. A front end of girder member  55 L is connected to an upper end of pillar member  43 L. A rear end of girder member  55 L is connected to an upper end of pillar member  44 L. Girder member  55 R is provided at a corner portion where right surface  30 C and top surface  30 E intersect with each other. A front end of girder member  55 R is connected to an upper end of pillar member  43 R. A rear end of girder member  55 L is connected to an upper end of pillar member  44 R. 
     As shown in  FIGS. 1 and 2 , cab  30  further includes a ceiling member  45  and a door member  32 . Ceiling member  45  is provided on top surface  30 E. Ceiling member  45  is formed of a plate member (e.g., a steel plate). Ceiling member  45  is provided on beam members  51 ,  52  and  53 , girder members  54 , and girder members  55 . 
     Door member  32  is provided on left surface  30 D so as to be openable and closable. Door member  32  is opened and closed when the operator enters and leaves living space  120 . 
     As shown in  FIG. 2 , cab  30  further includes a front transparent member  46 , a lower transparent member  47  and a lateral transparent member  48 . Each of front transparent member  46 , lower transparent member  47  and lateral transparent member  48  is formed of a transparent member that allows light to transmit therethrough. Each of front transparent member  46 , lower transparent member  47  and lateral transparent member  48  is formed of, for example, glass or acryl. 
     Front transparent member  46  and lower transparent member  47  are provided on front surface  30 A. Front transparent member  46  and lower transparent member  47  are provided between pillar member  42 L and pillar member  42 R in the left-right direction. Front transparent member  46  and lower transparent member  47  are provided on the front side of pillar members  43 . Front transparent member  46  and lower transparent member  47  are provided on the front side of operator&#39;s seat  31 . Front transparent member  46  is provided on the upper side of lower transparent member  47 . 
     Lateral transparent member  48  is provided on right surface  30 C. Lateral transparent member  48  is provided across pillar member  42 R, pillar member  43 R and pillar member  44 R in the front-rear direction. Lateral transparent member  48  may be provided only across pillar member  42 R and pillar member  43 R in the front-rear direction. 
       FIG. 4  is a perspective view showing a rail member for guiding the front transparent member in  FIG. 2 .  FIG. 5  is a side view showing an operation for opening and closing the front transparent member in  FIG. 2 . 
     As shown in  FIGS. 2, 4 and 5 , lower transparent member  47  and lateral transparent member  48  are of fixed type, whereas front transparent member  46  is of movable type that allows front transparent member  46  to be opened and closed. Front transparent member  46  is opened and closed between a position where front surface  30 A enters an open state and a position where front surface  30 A enters a closed state. 
     A frame  91  is attached to front transparent member  46 . Frame  91  has a frame shape that extends along a perimeter edge of front transparent member  46 . Frame  91  has a rectangular frame shape. A plurality of rollers  92  are attached to frame  91 . Each roller  92  is rotatable about an axis extending in the left-right direction. The plurality of rollers  92  are provided at four corners of frame  91  having a rectangular frame shape. 
     Cab  30  further includes a pair of left and right rail members  56  ( 56 L and  56 R). Rail members  56  can guide front transparent member  46  that is opened and closed. 
     Rail member  56 L is provided across the corner portion where front surface  30 A and left surface  30 D intersect with each other and the corner portion where top surface  30 E and left surface  30 D intersect with each other. Rail member  56 L extends in the up-down direction at the corner portion where front surface  30 A and left surface  30 D intersect with each other. Rail member  56 L is attached to pillar member  42 L at the corner portion where front surface  30 A and left surface  30 D intersect with each other. Rail member  56 L extends in the front-rear direction at the corner portion where top surface  30 E and left surface  30 D intersect with each other. Rail member  56 L is attached to girder member  54 L, pillar member  43 L and girder member  55 L at the corner portion where top surface  30 E and left surface  30 D intersect with each other. Rail member  56 L extends from pillar member  42 L to pillar member  43 L and further extends from pillar member  43 L toward pillar member  44 L in the front-rear direction. 
     Rail member  56 R is provided across the corner portion where front surface  30 A and right surface  30 C intersect with each other and the corner portion where top surface  30 E and right surface  30 C intersect with each other. Rail member  56 R extends in the up-down direction at the corner portion where front surface  30 A and right surface  30 C intersect with each other. Rail member  56 R is attached to pillar member  42 R at the corner portion where front surface  30 A and right surface  30 C intersect with each other. Rail member  56 R extends in the front-rear direction at the corner portion where top surface  30 E and right surface  30 C intersect with each other. Rail member  56 R is attached to girder member  54 R, pillar member  43 R and girder member  55 R at the corner portion where top surface  30 E and right surface  30 C intersect with each other. Rail member  56 R extends from pillar member  42 R to pillar member  43 R and further extends from pillar member  43 R toward pillar member  44 R in the front-rear direction. 
     Each of rail members  56  has a recessed shape that can receive rollers  92 . Rollers  92  attached to the left and right sides of frame  91  are fitted into rail member  56 L and rail member  56 R, respectively. Rollers  92  are guided by rail members  56 , and thereby, front transparent member  46  is opened and closed between a position where front surface  30 A enters an open state and a position where front surface  30 A enters a closed state. When front transparent member  46  is operated to the position where front surface  30 A enters the open state, front transparent member  46  moves to top surface  30 E. 
     Next, a connection structure for pillar members  43 , beam member  52 , girder members  54 , and girder members  55  will be described. Although a connection structure for pillar member  43 R, beam member  52 , girder member  54 R, and girder member  55 R will be representatively described below, a connection structure for pillar member  43 L, beam member  52 , girder member  54 L, and girder member  55 L is also similar. 
       FIG. 6  is a cross-sectional view showing the cab at the corner portion of the top surface and the right surface. A cross-sectional position shown in  FIG. 6  corresponds to a cross-sectional position when seen in a direction indicated by an arrow line VI-VI in  FIG. 2 . 
       FIG. 6  shows front transparent member  46  when front transparent member  46  moves to the position where front surface  30 A enters the open state, and an operator protection space  130 . The ISO standard defines a space to be secured around the operator in order to prevent the operator from being crushed by cab  30  that becomes deformed when hydraulic excavator  100  falls down. Operator protection space  130  corresponds to this space. 
     As shown in  FIG. 6 , the right end of beam member  52  is connected to the upper end of pillar member  43 R. Beam member  52  and pillar member  43 R together form a corner portion that makes an angle of 90°. Living space  120  for the operator is formed on the lateral side of pillar member  43 R and on the lower side of beam member  52 . 
     Rail member  56 R is provided in living space  120  for the operator. Rail member  56 R is provided to pass through the corner portion formed by beam member  52  and pillar member  43 R, while extending in the front-rear direction. Rail member  56 R is attached to pillar member  43 R at a position distant from and below beam member  52 . 
     Cab  30  further includes a duct member  96 . Duct member  96  is a duct for an air conditioner through which cold air flows. Duct member  96  is provided in living space  120  for the operator. Duct member  96  is provided below ceiling member  45 . Duct member  96  extends in the front-rear direction. Duct member  96  has a flat cross section that is short in the up-down direction and long in the left-right direction, when cut along a plane that is orthogonal to the front-rear direction. 
     Duct member  96  is provided to pass through the corner portion formed by beam member  52  and pillar member  43 R. Duct member  96  is attached to beam member  52  at a position distant from and on the lateral side of pillar member  43 R. Duct member  96  is provided, in the up-down direction, between beam member  52  and front transparent member  46  when front transparent member  46  moves to the position where front surface  30 A enters the open state. 
       FIG. 7  is a perspective view showing the cab in a range surrounded by a two-dot chain line VII in  FIG. 3  in an enlarged manner.  FIG. 8  is a perspective view showing the cab in a range surrounded by a two-dot chain line VIII in  FIG. 2  in an enlarged manner.  FIGS. 9 and 10  are perspective views showing a state in which the ceiling member and the girder members have been removed from the cab shown in  FIGS. 7 and 8 , respectively.  FIGS. 11 and 12  are exploded views of the cab shown in  FIGS. 9 and 10 , respectively. 
     As shown in  FIGS. 7 to 12 , cab  30  further includes a rib member  61 . Rib member  61  is provided at the corner portion where pillar member  43 R and beam member  52  intersect with each other. Rib member  61  is connected to pillar member  43 R and beam member  52 . 
     Rib member  61  is provided at the corner portion where the right end of beam member  52  and the upper end of pillar member  43 R intersect with each other. Rib member  61  is formed of a plate member (e.g., a steel plate). Rib member  61  is provided such that the front-rear direction corresponds to a thickness direction. Rib member  61  is connected to pillar member  43 R and beam member  52  by welding. 
     Rib member  61  is embedded in at least one of pillar member  43 R and beam member  52 . Rib member  61  is embedded in pillar member  43 R and beam member  52 . Rib member  61  is provided such that at least a part of rib member  61  is arranged in a slit  85  and a slit  86  as recessed portions provided in pillar member  43 R and beam member  52 . Rib member  61  is provided such that at least a part of rib member  61  overlaps with pillar member  43 R and beam member  52  when seen in the front-rear direction. 
       FIG. 13  is a perspective view showing the rib member in  FIGS. 7 to 12 . As shown in  FIG. 13 , rib member  61  includes a vertical rib portion  62  and a horizontal rib portion  63 . 
     Vertical rib portion  62  extends in the up-down direction. Horizontal rib portion  63  extends in the left-right direction. Horizontal rib portion  63  (a right end of horizontal rib portion  63 ) is continuous to an upper end of vertical rib portion  62 . Rib member  61  as a whole has an L shape including a corner portion  70  at a position where vertical rib portion  62  and horizontal rib portion  63  intersect with each other, when seen in the front-rear direction. 
       FIG. 14  is a cross-sectional view showing the cab when seen in a direction indicated by an arrow line XIV-XIV in  FIG. 10 . As shown in  FIGS. 7 to 12 and 14 , vertical rib portion  62  is embedded in pillar member  43 R. 
     Pillar member  43 R is formed of a hollow pipe member. Pillar member  43 R has a rectangular cross-sectional shape when cut along a horizontal plane. 
     Pillar member  43 R includes an inner plate portion  74  and an outer plate portion  73 . Inner plate portion  74  is formed of a plate member in which the left-right direction corresponds to a thickness direction. Outer plate portion  73  is formed of a plate member  71  in which the left-right direction corresponds to a thickness direction. Inner plate portion  74  and outer plate portion  73  are arranged to be spaced apart from each other in the left-right direction. Inner plate portion  74  is provided in pillar member  43 R and inside living space  120  for the operator. Outer plate portion  73  is provided in pillar member  43 R and outside living space  120  for the operator. 
     Pillar member  43 R is provided with slit  85 . Slit  85  has an opening shape that can receive vertical rib portion  62 . Slit  85  extends in the up-down direction. Slit  85  reaches a tip of the upper end of pillar member  43 R in the up-down direction. Slit  85  has a slit shape in which the front-rear direction corresponds to a width direction and the up-down direction corresponds to a longitudinal direction. Slit  85  passes through pillar member  43 R in the left-right direction. Slit  85  is open to inner plate portion  74  and outer plate portion  73 . 
     Vertical rib portion  62  is arranged in slit  85 . Vertical rib portion  62  is provided so as not to protrude from inner plate portion  74  toward the inside of living space  120  for the operator at a position other than corner portion  70 . Vertical rib portion  62  is provided to protrude from outer plate portion  73  toward the outside of living space  120  for the operator. Inner plate portion  74  and outer plate portion  73  sandwich vertical rib portion  62  arranged in slit  85  in the front-rear direction. Vertical rib portion  62  is inserted through pillar member  43 R in the left-right direction. 
     Vertical rib portion  62  is connected to pillar member  43 R by welding. Vertical rib portion  62  and pillar member  43 R are, for example, welded along an opening edge of slit  85  in inner plate portion  74  and outer plate portion  73 . 
     The material of pillar member  43 R is not limited to the above-described pipe member, and pillar member  43 R may be formed of a solid member. Pillar member  43 R may be provided with a groove portion having a bottom that can receive vertical rib portion  62 . 
       FIG. 15  is a cross-sectional view showing the cab when seen in a direction indicated by an arrow line XV-XV in  FIG. 10 . As shown in  FIGS. 7 to 12 and 15 , horizontal rib portion  63  is embedded in beam member  52 . 
     Beam member  52  is formed of a hollow pipe member. Beam member  52  has a rectangular cross-sectional shape when cut along a plane that is orthogonal to the left-right direction. 
     Beam member  52  includes an upper plate portion  76  and a lower plate portion  77 . Each of upper plate portion  76  and lower plate portion  77  is formed of a plate member in which the up-down direction corresponds to a thickness direction. Upper plate portion  76  and lower plate portion  77  are arranged to be spaced apart from each other in the up-down direction. Upper plate portion  76  is provided in beam member  52  and outside living space  120  for the operator. Lower plate portion  77  is provided in beam member  52  and inside living space  120  for the operator. 
     Beam member  52  is provided with slit  86  and an opening  87 . Slit  86  and opening  87  extend in the left-right direction. Slit  86  and opening  87  have a slit shape in which the front-rear direction corresponds to a width direction and the left-right direction corresponds to a longitudinal direction. Slit  86  passes through lower plate portion  77 . Slit  86  reaches a tip of a right end of lower plate portion  77  in the left-right direction. Opening  87  passes through upper plate portion  76 . 
     Horizontal rib portion  63  is arranged in slit  86 . Horizontal rib portion  63  is provided so as not to protrude from beam member  52  toward the inside of living space  120  for the operator at a position other than corner portion  70 . Horizontal rib portion  63  is provided so as not to protrude from beam member  52  toward the outside of living space  120  for the operator. Horizontal rib portion  63  is inserted into beam member  52  through slit  86 . Lower plate portion  77  sandwiches horizontal rib portion  63  arranged in slit  86  in the front-rear direction. Horizontal rib portion  63  abuts against upper plate portion  76  inside beam member  52 . Horizontal rib portion  63  is exposed to the outside of beam member  52  through opening  87 . 
     Horizontal rib portion  63  is connected to beam member  52  by welding. Horizontal rib portion  63  and beam member  52  are, for example, welded along an opening edge of slit  86  in lower plate portion  77  and an opening edge of opening  87  in upper plate portion  76 . 
     The material of beam member  52  is not limited to the above-described pipe member, and beam member  52  may be formed of a solid member. Beam member  52  may be provided with a groove portion having a bottom that can receive horizontal rib portion  63 . In addition, the configuration in which horizontal rib portion  63  is embedded in beam member  52  may be replaced with the configuration in which vertical rib portion  62  is embedded in pillar member  43 R, or the configuration in which vertical rib portion  62  is embedded in pillar member  43 R may be replaced with the configuration in which horizontal rib portion  63  is embedded in beam member  52 . 
     When seen in the front-rear direction, an area of vertical rib portion  62  that overlaps with pillar member  43 R is equal to or larger than an area of vertical rib portion  62  that does not overlap with pillar member  43 R (that protrudes from pillar member  43 R toward the inside and/or the outside of living space  120  for the operator). When seen in the front-rear direction, the area of vertical rib portion  62  that overlaps with pillar member  43 R may be smaller than the area of vertical rib portion  62  that does not overlap with pillar member  43 R. 
     When seen in the front-rear direction, an area of horizontal rib portion  63  that overlaps with beam member  52  is equal to or larger than an area of horizontal rib portion  63  that does not overlap with beam member  52  (that protrudes from beam member  52  toward the inside and/or the outside of living space  120  for the operator). When seen in the front-rear direction, the area of horizontal rib portion  63  that overlaps with beam member  52  may be smaller than the area of horizontal rib portion  63  that does not overlap with beam member  52 . 
     Vertical rib portion  62  may be provided so as not to protrude from pillar member  43 R toward the inside and/or the outside of living space  120  for the operator. Horizontal rib portion  63  may be provided so as not to protrude from beam member  52  toward the inside and/or the outside of living space  120  for the operator. 
     As shown in  FIG. 1 , hydraulic excavator  100  may perform operations on a rough terrain or an inclined terrain, depending on an operation purpose or an operation environment, and thus, hydraulic excavator  100  may fall down in such an operation place. When hydraulic excavator  100  falls down, excessive external force (particularly, horizontal force to left surface  30 D) is applied to cab  30 . In such a case, it is required to effectively suppress deformation of cab  30  in order to appropriately protect the operator in cab  30 . 
     In order to deal with this, as shown in  FIGS. 6 to 12 , in hydraulic excavator  100 , rib member  61  is provided at the corner portion where pillar member  43  ( 43 L,  43 R) and beam member  52  intersect with each other. Such a configuration can achieve an increase in strength of the connection portion that connects pillar member  43  and beam member  52 . Thus, it is possible to suppress the occurrence of buckling at the connection portion that connects pillar member  43  and beam member  52  when hydraulic excavator  100  falls down, which causes large deformation of cab  30 . 
     In addition, in hydraulic excavator  100 , a highly rigid rollover protective structure (ROPS) is implemented by above-described pillar member  43  and beam member  52  that form a gate shape around living space  120  for the operator. Thus, it is possible to effectively suppress the deformation of cab  30 . 
     Rib member  61  is embedded in pillar member  43  and beam member  52 . According to such a configuration, it is possible to suppress protrusion of rib member  61  from pillar member  43  and beam member  52  toward living space  120  for the operator. Thus, wide living space  120  for the operator can be secured at the corner portion where pillar member  43  and beam member  52  intersect with each other. 
     If the rib member is provided so as not to be embedded in pillar member  43 , it is necessary to provide rail member  56  at a position distant from pillar member  43  in the left-right direction, in order to avoid interference between rail member  56  and the rib member. In this case, it is concerned that living space  120  for the operator may be invaded greatly in the left-right direction by rail member  56 , or the width of front transparent member  46  in the left-right direction may decrease, which may cause poor visibility from the operator. If the rib member is provided so as not to be embedded in beam member  52 , it is necessary to provide duct member  96  at a position distant from and on the lower side of beam member  52 , in order to avoid interference between duct member  96  and the rib member. In this case, it is concerned that living space  120  for the operator may be invaded greatly in the up-down direction by duct member  96 . 
     In hydraulic excavator  100 , rib member  61  is provided such that vertical rib portion  62  is embedded in pillar member  43  and horizontal rib portion  63  is embedded in beam member  52 , and thus, the above-described concerns can be resolved. In addition, wide living space  120  for the operator is secured, and thus, operator protection space  130  for protecting the operator when hydraulic excavator  100  falls down can be easily set in cab  30 . 
     In addition, pillar member  43  is provided with slit  85  that passes through pillar member  43  in the left-right direction, and vertical rib portion  62  is arranged in slit  85 . With such a configuration, the integrity of pillar member  43  and vertical rib portion  62  is increased, and thus, rib member  61  can more effectively contribute to an increase in connection strength between pillar member  43  and beam member  52 . 
     As shown in  FIGS. 6, 9 and 11 , pillar member  43 R includes an upper pillar portion  81  and a lower pillar portion  82 . Lower pillar portion  82  is located below upper pillar portion  81 . A lower end of lower pillar portion  82  is connected to floor member  40  shown in  FIG. 2 . An upper end of upper pillar portion  81  is connected to beam member  52 . 
     Lower pillar portion  82  has a width B 2  in the left-right direction. Upper pillar portion  81  has a width B 1  smaller than width B 2  in the left-right direction (B 1 &lt;B 2 ). A cross-sectional area of upper pillar portion  81  when cut along a horizontal plane is smaller than a cross-sectional area of lower pillar portion  82  when cut along a horizontal plane. 
     Between beam member  52  and lower pillar portion  82  in the up-down direction, upper pillar portion  81  has a recessed shape that is recessed from the inside toward the outside of cab  30  in the left-right direction. The inside of cab  30  corresponds to the inside of living space  120  for the operator, and the outside of cab  30  corresponds to the outside of living space  120  for the operator. A distance in the left-right direction between upper pillar portion  81  of pillar member  43 R and upper pillar portion  81  of pillar member  43 L is longer than a distance in the left-right direction between lower pillar portion  82  of pillar member  43 R and lower pillar portion  82  of pillar member  43 L. 
     Slit  85  is provided over the whole of upper pillar portion  81  in the up-down direction. Slit  85  is provided to extend from upper pillar portion  81  to an upper end of lower pillar portion  82  in the up-down direction. 
     According to such a configuration, upper pillar portion  81  has a recessed shape that is recessed from the inside toward the outside of cab  30  in the left-right direction, and thus, wider living space  120  for the operator can be secured at the corner portion where pillar member  43  ( 43 L,  43 R) and beam member  52  intersect with each other. In addition, width B 2  of lower pillar portion  82  in the left-right direction is greater than width B 1  of upper pillar portion  81  in the left-right direction. Therefore, the rigidity of pillar member  43  can be increased on the base side connected to floor member  40 . 
     Upper pillar portion  81  includes a pillar inner surface  84 . Pillar inner surface  84  is provided to face the inside of cab  30 . Pillar inner surface  84  is formed of a plane. Pillar inner surface  84  is formed of a plane that is orthogonal to the left-right direction. Rail member  56 R is provided along pillar inner surface  84 . Rail member  56 R is attached to pillar inner surface  84 . 
     According to such a configuration, rail member  56  ( 56 L,  56 R) is provided along pillar inner surface  84  formed of a plane, and thus, rail member  56  can be provided in a stable attitude. In addition, a space is formed on the lateral side of pillar inner surface  84  due to the recessed shape of upper pillar portion  81 , and thus, it is possible to more effectively suppress great invasion of living space  120  for the operator by rail member  56 . 
     As shown in  FIG. 6 , a length (height) H 1  of rail member  56 R from pillar inner surface  84  in the left-right direction is equal to or less than a length (height) H 2  of a height difference between upper pillar portion  81  and lower pillar portion  82  in the left-right direction (H 1 ≤H 2 ). Length (height) H 1  of rail member  56 R from pillar inner surface  84  in the left-right direction may be equal to length (height) H 2  of the height difference between upper pillar portion  81  and lower pillar portion  82  in the left-right direction (H 1 =H 2 ). 
     With such a configuration, rail member  56  ( 56 L,  56 R) does not protrude from lower pillar portion  82  in the left-right direction, and thus, it is possible to more effectively suppress great invasion of living space  120  for the operator by rail member  56 . 
     Length (height) H 1  of rail member  56 R from pillar inner surface  84  in the left-right direction may be equivalent to length (height) H 2  of the height difference between upper pillar portion  81  and lower pillar portion  82  in the left-right direction. In this case, an absolute value of a difference between length H 1  and length H 2  (|H 1 −H 2 |) is equal to or smaller than a value of 1/10 of H 2  (|H 1 −H 2 |≤H 2 × 1/10). 
     According to such a configuration, the length of rail member  56  ( 56 L,  56 R) that protrudes from lower pillar portion  82  in the left-right direction does not increase significantly, and thus, it is possible to suppress great invasion of living space  120  for the operator by rail member  56  similarly to the foregoing. 
     As shown in  FIGS. 9, 11 and 13 , vertical rib portion  62  includes a wide portion  65  and a narrow portion  64 . 
     Wide portion  65  is located below narrow portion  64 . Wide portion  65  is embedded in lower pillar portion  82 . Wide portion  65  is arranged in slit  85  provided at the upper end of lower pillar portion  82 . Narrow portion  64  is embedded in upper pillar portion  81 . Narrow portion  64  is arranged in slit  85  provided in upper pillar portion  81 . 
     Wide portion  65  has a width B 4  in the left-right direction. Narrow portion  64  has a width B 3  smaller than width B 4  in the left-right direction (B 3 &lt;B 4 ). A width of vertical rib portion  62  in the left-right direction decreases from wide portion  65  toward narrow portion  64 . The width of vertical rib portion  62  in the left-right direction has a minimum value at narrow portion  64  and increases from narrow portion  64  toward the upper side. The width of vertical rib portion  62  in the left-right direction has a maximum value at wide portion  65  and decreases from wide portion  65  toward the lower side. 
     Between beam member  52  and lower pillar portion  82  in the up-down direction, upper pillar portion  81  has a recessed shape that is recessed from the inside toward the outside of cab  30  in the left-right direction. Therefore, the height difference in the left-right direction is provided in a boundary portion between upper pillar portion  81  and lower pillar portion  82 . In contrast, vertical rib portion  62  has such a shape that the width of vertical rib portion  62  in the left-right direction decreases from wide portion  65  toward narrow portion  64 . Therefore, the width of vertical rib portion  62  in the left-right direction can be changed in accordance with the shape of the height difference between upper pillar portion  81  and lower pillar portion  82  in the left-right direction. Thus, it is possible to more effectively suppress protrusion of vertical rib portion  62  from pillar member  43  toward living space  120  for the operator. 
     As shown in  FIG. 13 , vertical rib portion  62  includes a vertical rib inner surface  68 . Vertical rib inner surface  68  is provided to face the inside of cab  30 . Vertical rib inner surface  68  is provided to face the left side. In narrow portion  64 , vertical rib inner surface  68  has a valley shape that is recessed toward the outside of cab  30 . In wide portion  65 , vertical rib inner surface  68  has a peak shape that protrudes toward the inside of cab  30 . 
     Horizontal rib portion  63  includes a horizontal rib inner surface  67 . Horizontal rib inner surface  67  is provided to face the inside of cab  30 . Horizontal rib inner surface  67  is provided to face the lower side. 
     Vertical rib inner surface  68  and horizontal rib inner surface  67  are continuous to each other with a curved surface  69  interposed therebetween. Curved surface  69  is provided at corner portion  70  of rib member  61 . Curved surface  69  has an arc shape having a constant curvature. The center of the arc shape of curved surface  69  is located in living space  120  for the operator. 
     According to such a configuration, vertical rib inner surface  68  and horizontal rib inner surface  67  are continuous to each other with curved surface  69  interposed therebetween. Therefore, even when excessive external force is applied to the connection portion that connects pillar member  43  and beam member  52 , the occurrence of stress concentration on corner portion  70  of rib member  61  can be suppressed. Thus, it is possible to more effectively suppress deformation of cab  30 . 
     As shown in  FIGS. 7 to 12 , girder member  54 R and girder member  55 R are butted against the upper end of pillar member  43 R (upper pillar portion  81 ) in the front-rear direction. Girder member  54 R and girder member  55 R are connected, by welding, to pillar member  43 R at the position where girder member  54 R and girder member  55 R are butted. 
     Pillar member  43 R further includes connection portions  72  ( 72 P and  72 Q). 
     Each of connection portions  72  is formed of a plate member in which the left-right direction corresponds to a thickness direction. Connection portions  72  are formed of plate member  71  together with outer plate portion  73 . Connection portions  72  extend to protrude in the front-rear direction. Connection portions  72  have an arm shape extending to protrude in the front-rear direction from outer plate portion  73 . 
     Connection portion  72 P and connection portion  72 Q are provided to be paired in the front-rear direction. Connection portion  72 P extends to protrude from outer plate portion  73  toward the front side. Connection portion  72 P is provided along a lower end of girder member  54 R. Girder member  54 R is connected to connection portion  72 P by welding. Connection portion  72 Q extends to protrude from outer plate portion  73  toward the rear side. Connection portion  72 Q is provided along a lower end of girder member  55 R. Girder member  55 R is connected to connection portion  72 Q by welding. 
     According to such a configuration, girder member  54 R is connected to connection portion  72 P along the front-rear direction, in addition to the upper end of pillar member  43 R, and girder member  55 R is connected to connection portion  72 Q along the front-rear direction, in addition to the upper end of pillar member  43 R. Therefore, the connection strength between pillar member  43 R and girder members  54 R and  55 R can be increased. 
     Although description has been given of the case in which connection portions  72  ( 72 P and  72 Q) and outer plate portion  73  are formed of integrated plate member  71 , the present disclosure is not limited thereto. The plate member including connection portions  72  ( 72 P and  72 Q) may be joined to the plate member that forms outer plate portion  73  from outside living space  120  for the operator. 
     The configuration and effect of cab  30  and hydraulic excavator  100  according to the present embodiment described above will be summarized. 
     Cab  30  includes: pillar member  43 ; beam member  52 ; and rib member  61 . Pillar member  43  extends in an up-down direction. Beam member  52  extends in a left-right direction. Beam member  52  is connected to an upper end of pillar member  43 . Rib member  61  is provided at a corner portion where pillar member  43  and beam member  52  intersect with each other. Rib member  61  is connected to pillar member  43  and beam member  52 . Rib member  61  is embedded in pillar member  43  and beam member  52  as at least one of pillar member  43  and beam member  52 . 
     According to such a configuration, rib member  61  is provided at the corner portion where pillar member  43  and beam member  52  intersect with each other, and thus, the connection strength between pillar member  43  and beam member  52  can be increased. Therefore, it is possible to achieve highly-rigid cab  30  that is less likely to become deformed even when excessive external force is applied. Since rib member  61  is embedded in pillar member  43  and beam member  52 , it is possible to suppress protrusion of rib member  61  from pillar member  43  and beam member  52  toward living space  120  for the operator, which is a space in cab  30 . Thus, wide living space  120  for the operator can be secured at the corner portion where pillar member  43  and beam member  52  intersect with each other. 
     Rib member  61  is embedded in pillar member  43 . Pillar member  43  includes upper pillar portion  81  and lower pillar portion  82 . Upper pillar portion  81  is connected to beam member  52 . Lower pillar portion  82  is located below upper pillar portion  81 . Upper pillar portion  81  has a width smaller than that of lower pillar portion  82  in the left-right direction. Between beam member  52  and lower pillar portion  82  in the up-down direction, upper pillar portion  81  has a recessed shape that is recessed from an inside toward an outside of cab  30  in the left-right direction. 
     According to such a configuration, rib member  61  is embedded in pillar member  43  and upper pillar portion  81  has a recessed shape that is recessed from the inside toward the outside of cab  30  in the left-right direction. Therefore, wider living space  120  for the operator can be secured at the corner portion where pillar member  43  and beam member  52  intersect with each other. In addition, since lower pillar portion  82  has a width greater than that of upper pillar portion  81  in the left-right direction, the rigidity of pillar member  43  can be increased in lower pillar portion  82 . 
     Upper pillar portion  81  includes pillar inner surface  84 . Pillar inner surface  84  is provided to face the inside of cab  30 . Pillar inner surface  84  is formed of a plane. Cab  30  further includes rail member  56 . Rail member  56  extends in a front-rear direction and is provided along pillar inner surface  84 . 
     According to such a configuration, rail member  56  is provided along pillar inner surface  84  formed of a plane, and thus, rail member  56  can be provided in a stable attitude. In addition, since a space is formed on the lateral side of pillar inner surface  84  due to the recessed shape of upper pillar portion  81 , it is possible to suppress great invasion of living space  120  for the operator by rail member  56 . 
     A length of rail member  56  from pillar inner surface  84  in the left-right direction is equal to or shorter than a length of a height difference between upper pillar portion  81  and lower pillar portion  82  in the left-right direction. A length of rail member  56  from pillar inner surface  84  in the left-right direction may be equivalent to a length of a height difference between upper pillar portion  81  and lower pillar portion  82  in the left-right direction. 
     According to such a configuration, it is possible to more effectively suppress great invasion of living space  120  for the operator by rail member  56 . 
     Rib member  61  includes vertical rib portion  62 . Vertical rib portion  62  is embedded in pillar member  43 . Vertical rib portion  62  includes wide portion  65  and narrow portion  64 . Wide portion  65  is embedded in lower pillar portion  82 . Narrow portion  64  is embedded in upper pillar portion  81 . Narrow portion  64  has a width smaller than that of wide portion  65  in the left-right direction. A width of vertical rib portion  62  in the left-right direction decreases from wide portion  65  toward narrow portion  64 . 
     According to such a configuration, the width of vertical rib portion  62  in the left-right direction can be changed in accordance with the shape of the height difference between upper pillar portion  81  and lower pillar portion  82  in the left-right direction. Thus, it is possible to more effectively suppress protrusion of vertical rib portion  62  from pillar member  43  toward living space  120  for the operator. 
     Rib member  61  includes vertical rib portion  62 . Vertical rib portion  62  is embedded in pillar member  43 . Pillar member  43  is provided with slit  85 . Slit  85  passes through pillar member  43  in the left-right direction. Slit  85  extends in the up-down direction. Vertical rib portion  62  is arranged in slit  85 . 
     According to such a configuration, the integrity of pillar member  43  and vertical rib portion  62  is increased, and thus, rib member  61  can more effectively contribute to an increase in connection strength between pillar member  43  and beam member  52 . 
     Pillar member  43  includes plate member  71 . Plate member  71  is provided such that the left-right direction corresponds to a thickness direction. In plate member  71 , slit  85  is open. Plate member  71  includes connection portion  72  ( 72 P,  72 Q). Connection portion  72  ( 72 P,  72 Q) extends in a front-rear direction. Cab  30  further includes girder member  54  and girder member  55 . Girder member  54  and girder member  55  extend in the front-rear direction. Girder member  54  and girder member  55  are connected to the upper end of pillar member  43  and connection portion  72  ( 72 P,  72 Q). 
     According to such a configuration, girder member  54  is connected to connection portion  72 P along the front-rear direction, and girder member  55  is connected to connection portion  72 Q along the front-rear direction. Therefore, the connection strength between pillar member  43  and girder members  54  and  55  can be increased. 
     Rib member  61  is embedded in beam member  52 . Cab  30  further includes duct member  96 . Duct member  96  is provided below beam member  52 . 
     According to such a configuration, rib member  61  is embedded in beam member  52 , and thus, duct member  96  can be provided directly below beam member  52 . Thus, it is possible to suppress great invasion of living space  120  for the operator by duct member  96 . 
     The rib member includes vertical rib portion  62  and horizontal rib portion  63 . Vertical rib portion  62  is embedded in pillar member  43 . Horizontal rib portion  63  is continuous to an upper end of vertical rib portion  62 . Horizontal rib portion  63  is embedded in beam member  52 . Vertical rib portion  62  includes vertical rib inner surface  68 . Vertical rib inner surface  68  is provided to face an inside of cab  30 . Horizontal rib portion  63  includes horizontal rib inner surface  67 . Horizontal rib inner surface  67  is provided to face the inside of cab  30 . Horizontal rib inner surface  67  is continuous to vertical rib inner surface  68  with curved surface  69  interposed therebetween. 
     According to such a configuration, horizontal rib inner surface  67  is continuous to vertical rib inner surface  68  with curved surface  69  interposed therebetween, and thus, the occurrence of stress concentration on corner portion  70  of rib member  61  where vertical rib portion  62  and horizontal rib portion  63  intersect with each other can be suppressed. 
     Cab  30  further includes, as pillar member  43 , pillar member  43 R as a first pillar member and pillar member  43 L as a second pillar member. Pillar member  43 R and pillar member  43 L are arranged to be spaced apart from each other in the left-right direction. One end of beam member  52  in the left-right direction is connected to an upper end of pillar member  43 R. The other end of beam member  52  in the left-right direction is connected to an upper end of pillar member  43 L. 
     According to such a configuration, the connection strength between beam member  52  and pillar members  43 R and  43 L is increased by rib member  61 . Therefore, a highly rigid rollover protective structure (ROPS) can be implemented by pillar member  43 R, beam member  52  and pillar member  43 L. 
     Hydraulic excavator  100  as a work vehicle includes cab  30 . According to such a configuration, deformation of cab  30  when hydraulic excavator  100  falls down can be effectively suppressed. In addition, operator protection space  130  for protecting the operator can be easily set in cab  30 . 
     Although the configuration in which rib member  61  is embedded in both of pillar member  43  and beam member  52  has been described in the present embodiment, rib member  61  may be embedded in one of pillar member  43  and beam member  52 . 
     In addition, the cab in the present disclosure is applicable not only to the hydraulic excavator but also to work vehicles such as, for example, a crane, a wheel loader and a motor grader. 
     It should be understood that the embodiment disclosed herein is illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims. 
     REFERENCE SIGNS LIST 
       11  vehicular body;  12  work implement;  13  revolving unit;  15  traveling unit;  15 Cr crawler belt;  15 M traveling motor;  16  boom;  17  arm;  18  bucket;  19  engine compartment;  20 A,  20 B boom cylinder;  21  arm cylinder;  22  bucket cylinder;  23  boom pin;  24  arm pin;  25  bucket pin;  26  center of swing;  30  cab;  30 A front surface;  30 B rear surface;  30 C right surface;  30 D left surface;  30 E top surface;  30 F bottom surface;  31  operator&#39;s seat;  32  door member;  40  floor member;  42 ,  42 L,  42 R,  43 ,  43 L,  43 R,  44 ,  44 L,  44 R pillar member;  45  ceiling member;  46  front transparent member;  47  lower transparent member;  48  lateral transparent member;  51 ,  52 ,  53  beam member;  54 ,  54 L,  54 R,  55 ,  55 L,  55 R girder member;  56 ,  56 L,  56 R rail member;  61  rib member;  62  vertical rib portion;  63  horizontal rib portion;  64  narrow portion;  65  wide portion;  67  horizontal rib inner surface;  68  vertical rib inner surface;  69  curved surface;  70  corner portion;  71  plate member;  72 ,  72 P,  72 Q connection portion;  73  outer plate portion;  74  inner plate portion;  76  upper plate portion;  77  lower plate portion;  81  upper pillar portion;  82  lower pillar portion;  84  pillar inner surface;  85 ,  86  slit;  87  opening; 91 frame;  92  roller;  96  duct member;  100  hydraulic excavator;  120  living space;  130  operator protection space.