Patent Publication Number: US-8973507-B2

Title: Bogie for guide rail type vehicle

Description:
RELATED APPLICATIONS 
     The present application is a National Phase of International Application Number PCT/JP2009/062319, filed Jul. 6, 2009, and claims priority from, Japanese Application Number 2009-064767, filed Mar. 17, 2009. 
     TECHNICAL FIELD 
     The present invention relates to a guide rail type vehicle that runs along a predetermined guideway. More particularly, the present invention relates to a guide rail type vehicle, which is configured so as to be steered by being guided by a guide rail provided on the guideway. 
     BACKGROUND ART 
     There has been conventionally proposed a bogie for a guide rail type vehicle, which runs along a guide rail provided on a guideway by providing a steering mechanism using guide wheels (for example, see Patent Documents 1 and 2). 
       FIG. 11  shows one example of a conventional bogie for a guide rail type vehicle, and is a plan view of a bogie on the front side in the vehicle front and rear direction of a guide rail type vehicle. 
     As shown in  FIG. 11 , a bogie  62  of a guide rail type vehicle  61  runs along a guide rail  63  provided on a guideway, and is connected to a vehicle body (not shown) of the vehicle  61  via a traction link (not shown). 
     The bogie  62  includes a guide frame  64  formed in a rectangular shape in a plan view. A pair of guide wheels  65  is rotatably mounted to a vehicle body end side portion  64   a  of the guide frame  64 . Meanwhile, a pair of guide wheels  66  is rotatably mounted to a vehicle body center side portion  64   b  of the guide frame  64 . The guide wheels  65  and  66  are configured so as to rotate while being in contact with the side surfaces of the guide rail  63 . 
     Also, the bogie  62  includes a pair of right and left running wheels  67 . A steering lever  68  extending toward the vehicle body end side from the running wheel  67 , and a first link lever  69  extending toward the vehicle body center side from the running wheel  67  are provided at the running wheel  67  on the left side relative to the vehicle running direction. An end part  68   a  on the vehicle body center side of the steering lever  68  and an end part  69   a  on the vehicle body end side of the first link lever  69  are connected to the running wheel  67  via a rotation shaft  70 . 
     Meanwhile, a second link lever  71  extending toward the vehicle body center side from the running wheel  67  is provided at the running wheel  67  on the right side relative to the vehicle running direction. An end part  71   a  on the vehicle body end side of the second link lever  71  is connected to the running wheel  67  via a rotation shaft  72 . Also, an end part  69   b  on the vehicle body center side of the first link lever  69  and an end part  71   b  on the vehicle body center side of the second link lever  71  are connected to each other by a tie rod  73  that extends in the vehicle lateral direction. 
     An actuator  74  is provided in the guide frame  64  of the bogie  62 . The actuator  74  is connected to an end part  68   b  on the vehicle body end side of the steering lever  68  via a steering rod  75 . 
     Based on the above-described configuration, in the conventional bogie  62 , a distance L between the center of the guide frame  64  and the connection position of the actuator  74  and the steering rod  75  is changed by the actuator  74 . Accordingly, the pair of right and left running wheels  67  is steered more than the turning angle of the guide frame  64 . 
     PRIOR ART DOCUMENTS 
     Patent Documents 
     
         
         Patent Document 1: U.S. Pat. No. 6,477,963 
         Patent Document 2: Japanese Patent Laid-Open No. 11-321635 
       
    
     SUMMARY OF INVENTION 
     Problems to be Solved by the Invention 
     However, the aforementioned conventional configuration has a problem as described below when the bogie  62  runs along a curved section of the guide rail  63 . 
     For example, when explained by using the running wheel  67  on the left side relative to the running direction as an example, the running wheel  67  on the left side is positioned outside the curved section in the case of a right-hand curve, and the running wheel  67  on the left side is positioned inside the curved section in the case of a left-hand curve even when the curvature radii of the curved sections of the guide rail  63  are equal to each other. Here, if the actuator  74  performs the same control in both the cases of the right-hand curve and the left-hand curve, the running wheel  67  is steered in the same manner in both the case in which the running wheel  67  on the left side is positioned inside the curved section and the case in which the running wheel  67  on the left side is positioned outside the curved section. That is, if the actuator  74  performs the same control in both the cases of the right-hand curve and the left-hand curve, the steering angle of the running wheel  67  positioned inside the curved section, and the steering angle of the running wheel  67  positioned outside the curved section are not equal in the cases of the right-hand curve and the left-hand curve. As a result, the tire and the like of the running wheel  67  may wear unevenly. 
     Moreover, the aforementioned conventional configuration has a problem that when the bogie  62  is displaced in the vehicle lateral direction while running, the vehicle body is also displaced in the vehicle lateral direction along with the bogie  62 , so that the vehicle gives a passenger an uncomfortable ride. In addition, there is also a problem that an impact from the running wheels  67  or the guide wheels  65  and  66  of the bogie  62  is directly transmitted to the vehicle body through a traction link or the like, so that the vehicle gives a passenger a more uncomfortable ride. 
     The present invention has been made in view of the aforementioned circumstances, and it is an object of the invention to provide a bogie for a guide rail type vehicle, which can make the steering angles of running wheels equal in both the cases of right-hand and left-hand curves, and also can suppress the displacement in the vehicle lateral direction during running, and the transmission of an impact from guide wheels to a vehicle body. 
     Means for Solving the Problems 
     To achieve the above object of the related art, according to an embodiment of the present invention, a bogie for a guide rail type vehicle configured so as to be steered by being guided by a guide rail provided on a predetermined guideway when the bogie runs along the guideway, includes: a turn frame arranged below a vehicle body and connected to the vehicle body; an axle having a pair of running wheels and turnably mounted to the turn frame via a bearing; a guide frame mounted to the axle and formed so as to extend in a vehicle front and rear direction; a first pair of guide wheels arranged adjacent to each other in an axle direction so as to contact with the guide rail, and rotatably provided at a vehicle body end side portion in the vehicle front and rear direction of the guide frame; a second pair of guide wheels arranged adjacent to each other in the axle direction so as to contact the guide rail, and rotatably provided at a vehicle body center side portion in the vehicle front and rear direction of the guide frame; a stopper provided so as to project from an upper surface on a vehicle body side of the axle toward the vehicle body; and a pair of stopper receivers arranged facing each other at intervals from the stopper in a vehicle lateral direction, and provided so as to project from the vehicle body toward the axle. 
     Also, according to another embodiment of the present invention, the bogie for the guide rail type vehicle further includes a turn damper arranged so as to connect between the guide frame and the turn frame, to suppress a turning operation of the guide frame, and a restoration rod arranged so as to connect between the guide frame and the turn frame, to restore the guide frame to a straight-running state after the turning operation of the guide frame. 
     Also, according to another embodiment of the present invention, the guide frame is arranged at an offset position relative to a center axis of the axle toward a vehicle body end side in the vehicle front and rear direction such that a distance between the center axis of the axle and the first pair of guide wheels is greater than a distance between the center axis of the axle and the second pair of guide wheels. 
     Also, according to another embodiment of the present invention, the bogie further includes a first pair of guide wheel supports rotatably provided at the vehicle body end side portion of the guide frame so as to be arranged facing each other in the axle direction, each of the first pair of guide wheels being mounted to the vehicle body end side portion of the guide frame via each of the first pair of guide wheel supports, and the first pair of guide wheels being connected to each other by a shock-absorbing rod; and a second pair of guide wheel supports rotatably provided at the vehicle body center side portion of the guide frame so as to be arranged facing each other in the axle direction, each of the second pair of guide wheels being mounted to the vehicle body center side portion of the guide frame via each of the second pair of guide wheel supports, and the second pair of guide wheels being connected to each other by a shock-absorbing rod. 
     Also, according to another embodiment of the present invention, the bogie further includes a first guide wheel supporting member which connects the first pair of guide wheels to each other; a first pair of leaf springs provided at the vehicle body end side portion of the guide frame so as to be arranged facing each other in the axle direction, and the first guide wheel supporting member being mounted to the vehicle body end side portion of the guide frame via the first pair of leaf springs; a second guide wheel supporting member which connects the second pair of guide wheels to each other; and a second pair of leaf springs provided at the vehicle body center side portion of the guide frame so as to be arranged facing each other in the axle direction, and the second guide wheel supporting member being mounted to the vehicle body center side portion of the guide frame via the second pair of leaf springs. 
     Also, according to another embodiment of the present invention, the bogie further includes a first link which connects the first pair of guide wheels to each other, and is arranged tilting relative to the guide rail; a first link support which is provided at the vehicle body end side portion of the guide frame so as to extend toward the vehicle body end side in the vehicle front and rear direction, and the first link being rotatably mounted to the first link support via a first shock-absorbing mechanism having a restoration function; a second link which connects the second pair of guide wheels to each other, and is arranged tilting relative to the guide rail; and a second link support which is provided at the vehicle body center side portion of the guide frame so as to extend toward a vehicle body center side in the vehicle front and rear direction, and the second link being rotatably mounted to the second link support via a second shock-absorbing mechanism having a restoration function. 
     Advantageous Effects of Invention 
     According to the bogie for the guide rail type vehicle in accordance with the present invention, in the bogie for the guide rail type vehicle configured so as to be steered by being guided by the guide rail provided on the predetermined guideway when the bogie runs along the guideway, the bogie includes: the turn frame arranged below the vehicle body and connected to the vehicle body; the axle having the pair of running wheels and turnably mounted to the turn frame via the bearing; the guide frame mounted to the axle and formed so as to extend in the vehicle front and rear direction; the first pair of guide wheels arranged adjacent to each other in an axle direction so as to contact with the guide rail, and rotatably provided at the vehicle body end side portion in the vehicle front and rear direction of the guide frame; the second pair of guide wheels arranged adjacent to each other in the axle direction so as to contact the guide rail, and rotatably provided at the vehicle body center side portion in the vehicle front and rear direction of the guide frame; the stopper provided so as to project from an upper surface on the vehicle body side of the axle toward the vehicle body; and the pair of stopper receivers arranged facing each other at intervals from the stopper in the vehicle lateral direction, and provided so as to project from the vehicle body toward the axle. Thus, when the bogie passes through a curved section of the guide rail, the guide frame is guided by the guide rail, so that the axle and the guide frame are turned together. Accordingly, in both the cases of a right-hand curve and a left-hand curve, the axle and the guide frame are turned in the same manner, and the steering angles of the running wheels become equal. A tire can be thereby prevented from wearing unevenly. 
     Also, even when the bogie is displaced in the vehicle lateral direction when passing through the curved section of the guide rail, the stopper provided on the axle abuts against the stopper receiver on the vehicle body side, and the displacement of the bogie in the vehicle lateral direction can be suppressed. Thus, the displacement of the vehicle body in the vehicle lateral direction is also suppressed, and as a result, the vehicle can give a passenger a more comfortable ride. In addition, since the pair of stopper receivers are arranged at intervals from the stopper in the vehicle lateral direction, an impact from the running wheels or the guide wheels of the bogie is prevented from being transmitted to the vehicle body. As a result, the vehicle can give a passenger a much more comfortable ride. 
     Also, in the bogie for the guide rail type vehicle according to the present invention, the bogie further includes the turn damper arranged so as to connect the guide frame and the turn frame, to suppress the turning operation of the guide frame, and the restoration rod arranged so as to connect the guide frame and the turn frame, to restore the guide frame to the straight-running state after the turning operation of the guide frame. Thus, when the bogie passes through the curved section of the guide rail, the rapid turning of the axle and the guide frame is suppressed by the turn damper. As a result, the bogie can be prevented from vibrating when passing through the curved section of the guide rail. In addition, the guide frame is immediately restored to a straight-running state by the restoration rod after the bogie passes through the curved section of the guide rail. Accordingly, the bogie can stably run along a portion in which the guide rail is changed from a curve line to a straight line. 
     Also, in the bogie for the guide rail type vehicle according to the present invention, the guide frame is arranged at an offset position relative to the center axis of the axle toward the vehicle body end side in the vehicle front and rear direction such that the distance between the center axis of the axle and the first pair of guide wheels is greater than the distance between the center axis of the axle and the second pair of guide wheels. Thus, for example, when the bogie on the front side of the vehicle passes through the curved section of the guide rail, the running wheel is turned by a predetermined angle (a slip angle) toward the inside of the curve relative to the tangential direction of the curve at the position of the running wheel. Accordingly, a cornering force is generated in the tire of the running wheel toward the inside of the curve. That is, when the bogie passes through the curved section of the guide rail, a cornering force is generated in the direction opposite to a centrifugal force acting on the bogie. The load acting on the first and second guide wheels is thereby reduced. As a result, the service life of the first and second guide wheels can be further extended. 
     In addition, for example, in the case of the bogie on the front side, the distance between the center axis of the axle and the first pair of guide wheels is greater than the distance between the center axis of the axle and the second pair of guide wheels. Thus, the load acting on the first guide wheels is reduced based on a lever ratio, and as a result, the service life of the first guide wheels can be further extended. 
     Also, for example, in the case of the bogie on the front side, the guide frame is arranged frontward from the center position of the axle. Thus, the guide frame is guided by the guide rail slightly before the axle, and a trailing effect is generated such that the axle easily follows the guide frame. Accordingly, the running stability of the bogie is further improved. 
     Also, in the bogie for the guide rail type vehicle according to the present invention, the bogie further includes the first pair of guide wheel supports rotatably provided at the vehicle body end side portion of the guide frame so as to be arranged facing each other in the axle direction, each of the first pair of guide wheels being mounted to the vehicle body end side portion of the guide frame via each of the first pair of guide wheel supports, and the first pair of guide wheels being connected to each other by the shock-absorbing rod; and the second pair of guide wheel supports rotatably provided at the vehicle body center side portion of the guide frame so as to be arranged facing each other in the axle direction, each of the second pair of guide wheels being mounted to the vehicle body center side portion of the guide frame via each of the second pair of guide wheel supports, and the second pair of guide wheels being connected to each other by the shock-absorbing rod. Thus, when the bogie runs along the curved section of the guide rail or a joint of the guide rail or the like, an impact on the first and second guide wheels is absorbed by the shock-absorbing rods, and is thus prevented from being transmitted to the guide frame and the bogie. Accordingly, the running stability of the bogie is improved, and the vehicle can give a passenger a more comfortable ride. An impact on the first and second guide wheels themselves is also reduced by the shock-absorbing rods, so that the operating life of the first and second guide wheels can be extended. 
     Also, in the bogie for the guide rail type vehicle according to the present invention, the bogie further includes the first guide wheel supporting member which connects the first pair of guide wheels to each other; the first pair of leaf springs provided at the vehicle body end side portion of the guide frame so as to be arranged facing each other in the axle direction, and the first guide wheel supporting member being mounted to the vehicle body end side portion of the guide frame via the first pair of leaf springs; the second guide wheel supporting member which connects the second pair of guide wheels to each other; and the second pair of leaf springs provided at the vehicle body center side portion of the guide frame so as to be arranged facing each other in the axle direction, and the second guide wheel supporting member being mounted to the vehicle body center side portion of the guide frame via the second pair of leaf springs. Thus, when the bogie runs along the curved section of the guide rail or the joint of the guide rail or the like, an impact on the first and second guide wheels is absorbed by the leaf springs, and is thus prevented from being transmitted to the guide frame and the bogie. Accordingly, the running stability of the bogie is improved, and the vehicle can give a passenger a more comfortable ride. An impact on the first and second guide wheels themselves is also reduced by the leaf springs, so that the operating life of the first and second guide wheels can be extended. 
     Moreover, since the leaf springs, which are not a wear component, are used to connect the guide wheel supporting member to the guide frame, the replacement cycle becomes longer, and the maintainability is also improved. 
     Also, in the bogie for the guide rail type vehicle bogie according to the present invention, the bogie further includes the first link which connects the first pair of guide wheels to each other, and is arranged tilting relative to the guide rail; the first link support which is provided at the vehicle body end side portion of the guide frame so as to extend toward the vehicle body end side in the vehicle front and rear direction, and the first link being rotatably mounted to the first link support via the first shock-absorbing mechanism having the restoration function; the second link which connects the second pair of guide wheels to each other, and is arranged tilting relative to the guide rail; and the second link support which is provided at the vehicle body center side portion of the guide frame so as to extend toward the vehicle body center side in the vehicle front and rear direction, and the second link being rotatably mounted to the second link support via the second shock-absorbing mechanism having the restoration function. Thus, when the bogie runs along the curved section of the guide rail or the joint of the guide rail or the like, an impact on the first and second guide wheels is absorbed by the rotating first and second links, and is thus prevented from being transmitted to the guide frame and the bogie. Accordingly, the running stability of the bogie is improved, and the vehicle can give a passenger a more comfortable ride. An impact on the first and second guide wheels themselves is also reduced by the rotating first and second links, so that the operating life of the first and second guide wheels can be extended. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a plan view of a bogie on the front side in the vehicle front and rear direction of a guide rail type vehicle according to a first embodiment of the present invention. 
         FIG. 2  is a front view of the bogie in  FIG. 1  as viewed from the vehicle body end side. 
         FIG. 3  is a side view of the bogie in  FIG. 1  as viewed from the vehicle lateral direction. 
         FIG. 4  is a plan view of a bogie on the front side in the vehicle front and rear direction of a guide rail type vehicle according to a second embodiment of the present invention. 
         FIG. 5  is a plan view of a bogie on the front side in the vehicle front and rear direction of a guide rail type vehicle according to a third embodiment of the present invention. 
         FIG. 6  is a side view of the bogie in  FIG. 5  as viewed from outside in the vehicle lateral direction. 
         FIG. 7  is a plan view of a bogie on the front side in the vehicle front and rear direction of a guide rail type vehicle according to a fourth embodiment of the present invention. 
         FIG. 8  is a plan view of a bogie on the front side in the vehicle front and rear direction of a guide rail type vehicle according to a fifth embodiment of the present invention. 
         FIG. 9  is a plan view of a bogie on the front side in the vehicle front and rear direction of a guide rail type vehicle according to a sixth embodiment of the present invention. 
         FIG. 10  are views illustrating a modification of a guide rail of the guide rail type vehicle according to the present invention:  FIG. 10(   a ) is a plan view of the guide rail; and  FIG. 10(   b ) is a sectional view of the guide rail. 
         FIG. 11  is a plan view of a bogie on the front side in the vehicle front and rear direction of a conventional guide rail type vehicle. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     First Embodiment 
     In the following, a bogie for a guide rail type vehicle according to a first embodiment of the present invention will be described with reference to the drawings.  FIG. 1  is a plan view of a bogie on the front side in the vehicle front and rear direction of a guide rail type vehicle according to the first embodiment of the present invention.  FIG. 2  is a front view of the bogie in  FIG. 1  as viewed from the vehicle body end side.  FIG. 3  is a side view of the bogie in  FIG. 1  as viewed from outside in the vehicle lateral direction. 
     As shown in  FIGS. 1 and 2 , a vehicle  1  includes a bogie  2  at each of a front portion and a rear portion (the rear portion is not shown) in the vehicle front and rear direction, and runs along a predetermined guideway  3 . A guide rail  4  having an H shape in section is laid on a substantially center part in the vehicle lateral direction of the guideway  3 . 
     As shown in  FIGS. 1 and 2 , the bogie  2  includes a turn frame  5  assembled in a rectangular parallelepiped shape so as to have a rectangular shape in a plan view and a side view. The turn frame  5  includes an upper rectangular frame  6 , a lower rectangular frame  7 , and a plurality of connecting frames  8  that extend in the vehicle vertical direction and connect between the upper rectangular frame  6  and the lower rectangular frame  7 . 
     As shown in  FIGS. 1 and 2 , the bogie  2  includes an axle  9  that extends in the vehicle lateral direction. A pair of running wheels  10  is mounted to both end parts in the vehicle lateral direction of the axle  9 . Also, the axle  9  is arranged so as to pass through the inside of the turn frame  5  in the vehicle lateral direction. An arc-shaped bearing  11  (for example, an R guide) is arranged between the axle  9  and the upper rectangular frame  6  of the turn frame  5 . Meanwhile, an arc-shaped bearing  12  (for example, an R guide) is also arranged between the axle  9  and the lower rectangular frame  7  of the turn frame  5 . Accordingly, the axle  9  can be turned along the alternating long and short dashed line (see  FIG. 1 ) relative to the turn frame  5  with a center axis O 1  of the axle  9  as the rotation center. 
     As shown in  FIGS. 1 to 3 , a guide frame  13  is provided on a lower surface  9   a  of the axle  9 . The guide frame  13  is formed in a rectangular shape in a plan view, and includes two longitudinal frames  14  extending in the vehicle front and rear direction, and two lateral frames  15  connecting the two longitudinal frames  14  at both end parts in the vehicle front and rear direction thereof. 
     As shown in  FIGS. 1 to 3 , at a vehicle body end side portion  13   a  in the vehicle front and rear direction of the guide frame  13 , a first pair of guide wheels  16  is provided so as to face each other with the guide rail  4  therebetween. Each of the first guide wheels  16  is laterally arranged so as to contact an outer side surface  4   a  of the guide rail  4 . A center portion thereof is rotatably mounted to the guide frame  13  via a rotation shaft  17 . 
     Also, at a vehicle body center side portion  13   b  in the vehicle front and rear direction of the guide frame  13 , a second pair of guide wheels  18  is provided so as to face each other with the guide rail  4  therebetween. Each of the second guide wheels  18  is laterally arranged so as to contact the outer side surface  4   a  of the guide rail  4 . A center portion thereof is rotatably mounted to the guide frame  13  via a rotation shaft  19 . 
     As shown in  FIGS. 2 and 3 , a suspension frame  21  is provided on a lower surface  20   a  of a vehicle body  20  of the vehicle  1  at a position corresponding to the bogie  2 . The suspension frame  21  is formed so as to extend in the vehicle front and rear direction, and an extension part  21   b  is provided at a vehicle body center side portion  21   a  of the suspension frame  21  so as to extend downward. 
     As shown in  FIG. 3 , the extension part  21   b  of the suspension frame  21  and a vehicle body center side portion  6   a  of the upper rectangular frame  6  of the turn frame  5  are connected to each other by two traction links  22 . Here, an end part  22   a  on the vehicle body end side of the traction link  22  is rotatably mounted to the upper rectangular frame  6  via a joint  23 , and an end part  22   b  on the vehicle body center side of the traction link  22  is rotatably mounted to the extension part  21   b  of the suspension frame  21  via a joint  24 . 
     Also, the extension part  21   b  of the suspension frame  21  and a vehicle body center side portion  7   a  of the lower rectangular frame  7  of the turn frame  5  are connected to each other by two traction links  25 . Here, an end part  25   a  on the vehicle body end side of the traction link  25  is rotatably mounted to the lower rectangular frame  7  via a joint  26 , and an end part  25   b  on the vehicle body center side of the traction link  25  is rotatably mounted to the extension part  21   b  of the suspension frame  21  via a joint  27 . 
     In the present embodiment, as shown in  FIGS. 2 and 3 , a stopper  28  is provided on an upper surface (a side surface on the vehicle body  20  side)  9   b  of the axle  9  so as to project toward the vehicle body  20 . The stopper  28  is formed in a rectangular parallelepiped shape, and is arranged so as to extend in the vehicle front and rear direction. A pair of rubber stopper receivers  29  is also provided on the suspension frame  21  so as to project toward the axle  9 . The pair of stopper receivers  29  is formed in a rectangular parallelepiped shape, and arranged facing each other at intervals from the stopper  28  in the vehicle lateral direction. 
     Although not shown in the drawings, in the present embodiment, the bogie on the rear side of the vehicle  1  has the same features as those in the aforementioned embodiment. 
     The bogie for the guide rail type vehicle according to the present embodiment includes the turn frame  5  connected to the vehicle body  20 , the axle  9  turnably mounted to the turn frame  5  via the bearings  11  and  12 , the guide frame  13  mounted to the axle  9  and formed so as to extend in the vehicle front and rear direction, the first pair of guide wheels  16  rotatably provided at the vehicle body end side portion  13   a  in the vehicle front and rear direction of the guide frame  13 , the second pair of guide wheels  18  rotatably provided at the vehicle body center side portion  13   b  in the vehicle front and rear direction of the guide frame  13 , the stopper  28  provided so as to project from the upper surface  9   b  on the vehicle body side of the axle  9  toward the vehicle body  20 , and the pair of stopper receivers  29  arranged facing each other at intervals from the stopper  28  in the vehicle lateral direction, and provided so as to project from the vehicle body  20  toward the axle  9 . Thus, when the bogie  2  passes through a curved section of the guide rail  4 , the guide frame  13  is guided by the guide rail  4 , and the axle  9  and the guide frame  13  are turned together. Accordingly, the axle  9  and the guide frame  13  are turned in the same manner in both the cases of a right-hand curve and a left-hand curve, so that the steering angles of the running wheels  10  become equal. A tire can be thereby prevented from wearing unevenly. 
     Also, even when the bogie  2  is displaced in the vehicle lateral direction when passing through the curved section of the guide rail  4 , the stopper  28  provided on the axle  9  abuts against the stopper receivers  29  on the vehicle body side, and the displacement of the bogie  2  in the vehicle lateral direction can be suppressed. Thus, the displacement of the vehicle body  20  in the vehicle lateral direction is also suppressed, and as a result, the vehicle  1  can give a passenger a more comfortable ride. In addition, since the pair of stopper receivers  29  is arranged at intervals from the stopper  28  in the vehicle lateral direction, an impact from the running wheels  10  or the guide wheels  16  and  18  of the bogie  2  is prevented from being transmitted to the vehicle body  20 . As a result, the vehicle  1  can give a passenger a much more comfortable ride. That is, a large displacement in the vehicle lateral direction is suppressed, and other impacts such as vibrations are not transmitted to the vehicle body. 
     Second Embodiment 
     In the following, a bogie for a guide rail type vehicle according to a second embodiment of the present invention will be described with reference to the drawings.  FIG. 4  is a plan view of a bogie on the front side in the vehicle front and rear direction of a guide rail type vehicle according to the second embodiment of the present invention. In this embodiment, the same symbols are applied to elements that are the same as those explained in the above-described embodiments, and repeated explanation thereof is omitted. 
     In the present embodiment, as shown in  FIG. 4 , at a vehicle body end side portion  7   b  of the lower rectangular frame  7  of the turn frame  5 , a pair of arms  30  is provided so as to be formed extending toward the vehicle body end side. An end part  30   a  on the vehicle body end side of the right arm  30  relative to the vehicle running direction, and a vehicle body end side portion  14   a  of the longitudinal frame  14  of the guide frame  13  are connected to each other by a turn damper  31  that extends in the vehicle lateral direction. The turn damper  31  suppresses the rapid turning operation of the guide frame  13  when the vehicle  1  passes through the curved section (not shown) of the guide rail  4 . 
     Also, an end part  30   a  on the vehicle body end side of the left arm  30  relative to the vehicle running direction, and a vehicle body end side portion  14   a  of the longitudinal frame  14  of the guide frame  13  are connected to each other by a restoration rod  32  that extends in the vehicle lateral direction. The restoration rod  32  restores the guide frame  13  to a straight-running state after the turning operation of the guide frame  13  (after the vehicle  1  passes through the curved section of the guide rail  4 ). 
     Although not shown in the drawings, in the present embodiment, the bogie on the rear side of the vehicle  1  has the same features as those in the aforementioned embodiment. 
     As described above, the bogie for the guide rail type vehicle according to the present embodiment includes the turn damper  31  arranged so as to connect the guide frame  13  and the turn frame  5 , to suppress the turning operation of the guide frame  13 , and the restoration rod  32  arranged so as to connect the guide frame  13  and the turn frame  5 , to restore the guide frame  13  to the straight-running state after the turning operation of the guide frame  13 . Thus, when the bogie  2  passes through the curved section of the guide rail  4 , the rapid turning of the axle  9  and the guide frame  13  is suppressed by the turn damper  31 . As a result, the bogie  2  can be prevented from vibrating when passing through the curved section of the guide rail  4 . In addition, the guide frame  13  is immediately restored to the straight-running state by the restoration rod  32  after the bogie  2  passes through the curved section of the guide rail  4 . Accordingly, the bogie  2  can stably run along a portion in which the guide rail  4  is changed from a curve line to a straight line. 
     Third Embodiment 
     In the following, a bogie for a guide rail type vehicle according to a third embodiment of the present invention will be described with reference to the drawings.  FIG. 5  is a plan view of a bogie on the front side in the vehicle front and rear direction of a guide rail type vehicle according to the third embodiment of the present invention.  FIG. 6  is a side view of the bogie in  FIG. 5  as viewed from outside in the vehicle lateral direction. In this embodiment, the same symbols are applied to elements that are the same as those explained in the above-described embodiments, and repeated explanation thereof is omitted. 
     In the present embodiment, as shown in  FIGS. 5 and 6 , the guide frame  13  is arranged at an offset position relative to the center axis O 1  of the axle  9  toward the vehicle body end side in the vehicle front and rear direction such that a distance L 1  between the center axis O 1  of the axle  9  and the first pair of guide wheels  16  is greater than a distance L 2  between the center axis O 1  of the axle  9  and the second pair of guide wheels  18 . Although not shown in the drawings, in the present embodiment, the bogie on the rear side of the vehicle  1  has the same features as those in the aforementioned embodiment. 
     As described above, in the bogie for the guide rail type vehicle according to the present embodiment, the guide frame  13  is arranged at an offset position relative to the center axis O 1  of the axle  9  toward the vehicle body end side in the vehicle front and rear direction such that the distance L 1  between the center axis O 1  of the axle  9  and the first pair of guide wheels  16  is greater than the distance L 2  between the center axis O 1  of the axle  9  and the second pair of guide wheels  18 . Thus, for example, when the bogie  2  on the front side of the vehicle  1  passes through the curved section of the guide rail  4 , the running wheel  10  is turned by a predetermined angle (a slip angle) toward the inside of the curve relative to the tangential direction of the curve at the position of the running wheel  10 . Accordingly, a cornering force is generated in the tire of the running wheel  10  toward the inside of the curve. That is, when the bogie  2  on the front side passes through the curved section of the guide rail  4 , a cornering force is generated in the direction opposite to a centrifugal force acting on the bogie  2 . The load acting on the first and second guide wheels  16  and  18  is thereby reduced. As a result, the service life of the first and second guide wheels  16  and  18  can be further extended. 
     In addition, for example, in the case of the bogie  2  on the front side, the distance L 1  between the center axis O 1  of the axle  9  and the first pair of guide wheels  16  is greater than the distance L 2  between the center axis O 1  of the axle  9  and the second pair of guide wheels  18 . Thus, the load acting on the first guide wheels  16  is reduced based on a lever ratio, and as a result, the service life of the first guide wheels  16  can be further extended. 
     Also, for example, in the case of the bogie  2  on the front side, the guide frame  13  is arranged frontward from the center axis O 1  of the axle  9 . Thus, the guide frame  13  is guided by the guide rail  4  slightly before the axle  9 , and a trailing effect is generated such that the axle  9  easily follows the guide frame  13 . Accordingly, the running stability of the bogie  2  is further improved. 
     Fourth Embodiment 
     In the following, a bogie for a guide rail type vehicle according to a fourth embodiment of the present invention will be described with reference to the drawings.  FIG. 7  is a plan view of a bogie on the front side in the vehicle front and rear direction of a guide rail type vehicle according to the fourth embodiment of the present invention. In this embodiment, the same symbols are applied to elements that are the same as those explained in the above-described embodiments, and repeated explanation thereof is omitted. 
     In the present embodiment, as shown in  FIG. 7 , at the vehicle body end side portion  13   a  of the guide frame  13 , a first pair of guide wheel supports  33  is provided so as to be arranged facing each other with the guide rail  4  therebetween. Each of the first guide wheel supports  33  is arranged so as to extend toward the vehicle body end side in the vehicle front and rear direction. A vehicle body center side portion  33   a  of each of the first guide wheel supports  33  is rotatably mounted to the guide frame  13  via a rotation shaft  34 . Also, the first guide wheel  16  is rotatably mounted to a vehicle body end side portion  33   b  of each of the first guide wheel supports  33  via the rotation shaft  17 . 
     In the present embodiment, as shown in  FIG. 7 , the vehicle body end side portions  33   b  of the first pair of guide wheel supports  33  are connected to each other by a shock-absorbing rod  35  that extends in the vehicle lateral direction. A stopper (not shown) is provided on the shock-absorbing rod  35 , so that each of the first guide wheel supports  33  is prevented from rotating toward the inner side of the vehicle, and the interval between the first guide wheel supports  33  is thus not reduced. That is, the shock-absorbing rod  35  acts only against a force in the vehicle outer direction from the first guide wheels  16 , and widens the interval between the first guide wheel supports  33  when the force acts thereon. 
     Also, in the present embodiment, as shown in  FIG. 7 , at the vehicle body center side portion  13   b  of the guide frame  13 , a second pair of guide wheel supports  36  is provided so as to be arranged facing each other with the guide rail  4  therebetween. Each of the second guide wheel supports  36  is arranged so as to extend toward the vehicle body center side in the vehicle front and rear direction. A vehicle body end side portion  36   a  of each of the second guide wheel supports  36  is rotatably mounted to the guide frame  13  via a rotation shaft  37 . Also, the second guide wheel  18  is rotatably mounted to a vehicle body center side portion  36   b  of each of the second guide wheel supports  36  via the rotation shaft  19 . 
     Also, in the present embodiment, as shown in  FIG. 7 , the vehicle body center side portions  36   b  of the second pair of guide wheel supports  36  are connected to each other by a shock-absorbing rod  38  that extends in the vehicle lateral direction. A stopper (not shown) is provided on the shock-absorbing rod  38 , so that each of the second guide wheel supports  36  is prevented from rotating toward the inner side of the vehicle, and the interval between the second guide wheel supports  36  is thus not reduced. That is, the shock-absorbing rod  38  acts only against a force in the vehicle outer direction from the second guide wheels  18 , and widens the interval between the second guide wheel supports  36  when the force acts thereon. 
     Although not shown in the drawings, in the present embodiment, the bogie on the rear side of the vehicle  1  has the same features as those in the aforementioned embodiment. 
     As described above, in the bogie for the guide rail type vehicle according to the present embodiment, the first pair of guide wheel supports  33  is rotatably provided at the vehicle body end side portion  13   a  of the guide frame  13  so as to be arranged facing each other in the axle direction. Each of the first pair of guide wheels  16  is mounted to the vehicle body end side portion  13   a  of the guide frame  13  via each of the first pair of guide wheel supports  33 . The first pair of guide wheels  16  is connected to each other by the shock-absorbing rod  35 . The second pair of guide wheel supports  36  is rotatably provided at the vehicle body center side portion  13   b  of the guide frame  13  so as to be arranged facing each other in the axle direction. Each of the second pair of guide wheels  18  is mounted to the vehicle body center side portion  13   b  of the guide frame  13  via each of the second pair of guide wheel supports  36 . The second pair of guide wheels  18  is connected to each other by the shock-absorbing rod  38 . Thus, when the bogie  2  runs along the curved section of the guide rail  4  or a joint of the guide rail  4  or the like, an impact on the first and second guide wheels  16  and  18  is absorbed by the shock-absorbing rods  35  and  38 , and is thus prevented from being transmitted to the guide frame  13  and the bogie  2 . Accordingly, the running stability of the bogie  2  is improved, and the vehicle  1  can give a passenger a more comfortable ride. An impact on the first and second guide wheels  16  and  18  themselves is also reduced by the shock-absorbing rods  35  and  38 , so that the operating life of the first and second guide wheels  16  and  18  can be extended. 
     Fifth Embodiment 
     In the following, a bogie for a guide rail type vehicle according to a fifth embodiment of the present invention will be described with reference to the drawings.  FIG. 8  is a plan view of a bogie on the front side in the vehicle front and rear direction of a guide rail type vehicle according to the fifth embodiment of the present invention. In this embodiment, the same symbols are applied to elements that are the same as those explained in the above-described embodiments, and repeated explanation thereof is omitted. 
     In the present embodiment, as shown in  FIG. 8 , at the vehicle body end side portion  13   a  of the guide frame  13 , a first pair of leaf springs  39  is provided so as to be arranged facing each other with the guide rail  4  therebetween. The first pair of leaf springs  39  is arranged extending toward the vehicle body end side, and a first split-type wheel receiver (a guide wheel supporting member)  40  is mounted to vehicle body end side portions  39   a  of the first pair of leaf springs  39 . 
     The first split-type wheel receiver  40  includes a pair of guide wheel mounting parts  41  arranged at both end parts in the vehicle lateral direction, and a middle support part  42  arranged between the guide wheel mounting parts  41 . The first guide wheel  16  is rotatably mounted to each of the guide wheel mounting parts  41  via the rotation shaft  17 . Also, the vehicle body end side portion  39   a  of each of the first leaf springs  39  is held between each of the guide wheel mounting parts  41  and the middle support part  42 . 
     Also, in the present embodiment, as shown in  FIG. 8 , at the vehicle body center side portion  13   b  of the guide frame  13 , a second pair of leaf springs  43  is provided so as to be arranged facing each other with the guide rail  4  therebetween. The second pair of leaf springs  43  is arranged extending toward the vehicle body center side, and a second split-type wheel receiver (a guide wheel supporting member)  44  is mounted to vehicle body center side portions  43   a  of the second pair of leaf springs  43 . 
     The second split-type wheel receiver  44  includes a pair of guide wheel mounting parts  45  arranged at both end parts in the vehicle lateral direction, and a middle support part  46  arranged between the guide wheel mounting parts  45 . The second guide wheel  18  is rotatably mounted to each of the guide wheel mounting parts  45  via the rotation shaft  19 . Also, the vehicle body center side portion  43   a  of each of the second leaf springs  43  is held between each of the guide wheel mounting parts  45  and the middle support part  46 . 
     Although not shown in the drawings, in the present embodiment, the bogie on the rear side of the vehicle  1  has the same features as those in the aforementioned embodiment. 
     As described above, in the bogie for the guide rail type vehicle according to the present embodiment, the first pair of guide wheels  16  is supported by the first split-type wheel receiver  40 . The first pair of leaf springs  39  are provided at the vehicle body end side portion  13   a  of the guide frame  13  so as to be arranged facing each other in the axle direction. The first split-type wheel receiver  40  is mounted to the vehicle body end side portion  13   a  of the guide frame  13  via the first pair of leaf springs  39 . The second pair of guide wheels  18  is supported by the second split-type wheel receiver  44 . The second pair of leaf springs  43  is provided at the vehicle body center side portion  13   b  of the guide frame  13  so as to be arranged facing each other in the axle direction. The second split-type wheel receiver  44  is mounted to the vehicle body center side portion  13   b  of the guide frame  13  via the second pair of leaf springs  43 . Thus, when the bogie  2  runs along the curved section of the guide rail  4  or the joint of the guide rail or the like, an impact on the first and second guide wheels  16  and  18  is absorbed by the first and second leaf springs  39  and  43 , and is thus prevented from being transmitted to the guide frame  13  and the bogie  2 . Accordingly, the running stability of the bogie  2  is improved, and the vehicle  1  can give a passenger a more comfortable ride. An impact on the first and second guide wheels  16  and  18  themselves is also reduced by the first and second leaf springs  39  and  43 , so that the operating life of the first and second guide wheels  16  and  18  can be extended. 
     Moreover, the leaf springs, which are not a wear component, are used to connect the first and second split-type wheel receivers  40  and  44  and the guide frame  13 . Thus, the replacement cycle becomes longer, and the maintainability is also improved. 
     Sixth Embodiment 
     In the following, a bogie for a guide rail type vehicle according to a sixth embodiment of the present invention will be described with reference to the drawings.  FIG. 9  is a plan view of a bogie on the front side in the vehicle front and rear direction of a guide rail type vehicle according to the sixth embodiment of the present invention. In this embodiment, the same symbols are applied to elements that are the same as those explained in the above-described embodiments, and repeated explanation thereof is omitted. 
     In the present embodiment, as shown in  FIG. 9 , at the vehicle body end side portion  13   a  of the guide frame  13 , a first link support  47  is provided so as to extend toward the vehicle body end side. The first link support  47  is formed in a trapezoidal shape in a plan view. At a vehicle body end side portion  47   a  of the first link support  47 , a first link  48  is mounted so as to tilt relative to the guide rail  4 . 
     The first pair of guide wheels  16  is rotatably mounted to both end parts in the vehicle lateral direction of the first link  48  via the rotation shafts  17 . Each of the first guide wheels  16  contacts with the outer side surface  4   a  (see  FIG. 2 ) of the guide rail  4  in the state in which the first link  48  tilts relative to the guide rail  4 . 
     Also, the first link  48  is rotatably mounted to the first link support  47  via a first rubber vibration isolator (a shock-absorbing mechanism)  49  having a restoration function. The first link  48  is returned to an original tilting position by the restoration function of the first rubber vibration isolator  49  after rotation. The inner width between the first guide wheels  16  mounted to the both end parts of the first link  48  has a maximum value when the first link  48  is perpendicular to the guide rail  4 , and is not structurally widened any more. That is, such a structure itself as to mount the first link  48  rotatably to the first link support  47  also works as a stopper to limit the inner width between the first guide wheels  16 . 
     Also, in the present embodiment, as shown in  FIG. 9 , at the vehicle body center side portion  13   b  of the guide frame  13 , a second link support  50  is provided so as to extend toward the vehicle body center side. The second link support  50  is formed in a trapezoidal shape in a plan view. At a vehicle body center side portion  50   a  of the second link support  50 , a second link  51  is mounted so as to tilt relative to the guide rail  4 . 
     The second guide wheels  18  are rotatably mounted to both end parts in the vehicle lateral direction of the second link  51  via the rotation shafts  19 . Each of the second guide wheels  18  contacts with the outer side surface  4   a  (see  FIG. 2 ) of the guide rail  4  in the state in which the second link  51  tilts relative to the guide rail  4 . 
     Also, the second link  51  is rotatably mounted to the second link support  50  via a second rubber vibration isolator (a shock-absorbing mechanism)  52  having a restoration function. The second link  51  is returned to an original tilting position by the restoration function of the second rubber vibration isolator  52  after rotation. The inner width between the second guide wheels  18  mounted to the both end parts of the second link  51  has a maximum value when the second link  51  is perpendicular to the guide rail  4 , and is not structurally widened any more. That is, such a structure itself so as to mount the second link  51  rotatably to the second link support  50  also works as a stopper to limit the inner width between the second guide wheels  18 . 
     Although not shown in the drawings, in the present embodiment, the bogie on the rear side of the vehicle  1  has the same features as those in the aforementioned embodiment. 
     As described above, in the bogie for the guide rail type vehicle according to the present embodiment, the first pair of guide wheels  16  is connected to each other by the first link  48  arranged tilting relative to the guide rail  4 . The first link support  47  is provided at the vehicle body end side portion  13   a  of the guide frame  13  so as to extend toward the vehicle body end side. The first link  48  is rotatably mounted to the first link support  47  via the first rubber vibration isolator  49  having the restoration function. The second pair of guide wheels  18  is connected to each other by the second link  51  arranged tilting relative to the guide rail  4 . The second link support  50  is provided at the vehicle body center side portion  13   b  of the guide frame  13  so as to extend toward the vehicle body center side. The second link  51  is rotatably mounted to the second link support  50  via the second rubber vibration isolator  52  having the restoration function. Thus, when the bogie  2  runs along the curved section of the guide rail  4  or the joint of the guide rail  4 , an impact on the first and second guide wheels  16  and  18  is absorbed by the rotating first and second links  48  and  51 , and is thus prevented from being transmitted to the guide frame  13  and the bogie  2 . Accordingly, the running stability of the bogie  2  is improved, and the vehicle  1  can give a passenger a more comfortable ride. An impact on the first and second guide wheels  16  and  18  themselves is also reduced by the rotating first and second links  48  and  51 , so that the operating life of the first and second guide wheels  16  and  18  can be extended. 
     Also, even when an abnormal load is applied to the first and second guide wheels  16  and  18 , the first and second links  48  and  51  can be more reliably restored to the original tilting position by using the first and second rubber vibration isolators  49  and  52 . 
     Moreover, the inner widths between the first and second guide wheels  16  and  18  mounted to the both end parts of the first and second links  48  and  51  have a maximum value when the first and second links  48  and  51  are perpendicular to the guide rail  4 , and are not structurally widened any more. That is, such a structure itself as to respectively mount the first and second links  48  and  51  rotatably to the first and second link supports  47  and  50  also works as a stopper to limit the inner widths between the first and second guide wheels  16  and  18 . 
     The embodiments of the present invention have been described above. It should be noted that the present invention is not limited to the aforementioned embodiments, and various modifications and changes may be made therein based on the technical concepts of the present invention. 
     Although the guide rail  4  is formed in an H shape in section in the aforementioned first to sixth embodiments, a guide rail  53  may be formed in a U shape in section as shown in  FIGS. 10  ( a ) and ( b ). 
     In this case, as shown in  FIG. 10(   a ), the first pair of guide wheels  16  is arranged at the guide frame  13  so as to be adjacent to each other in the axle direction. Similarly, the second pair of guide wheels  18  is arranged at the guide frame  13  so as to be adjacent to each other in the axle direction. Also, as shown in  FIG. 10(   b ), the first and second guide wheels  16  and  18  contact with inner side surfaces  53   a  of the guide rail  53 . 
     Although the stopper  28  and the stopper receivers  29  are formed in a rectangular parallelepiped shape in the aforementioned first to sixth embodiments, any other shape may be employed as long as the displacement of the bogie in the vehicle lateral direction is suppressed. 
     Although the stopper  28  is provided on the upper surface  9   b  of the axle  9  and the pair of stopper receivers  29  is provided on the suspension frame  21  in the aforementioned first to sixth embodiments, the present invention is not limited thereto. A pair of stopper receivers may be provided on the axle  9 , and a stopper may be provided on the suspension frame  21 . 
     Although the stopper is provided on the shock-absorbing rods  35  and  38  in the aforementioned fourth embodiment, the first and second guide wheel supports  33  and  36  may be prevented from rotating toward the inner side of the vehicle without using the stopper. For example, the configuration may be such that when the first and second guide wheel supports  33  and  36  rotate toward the inner side of the vehicle, the guide frame-side end parts of the first and second guide wheel supports  33  and  36  contact with the guide frame  13 , whereby the first and second guide wheel supports  33  and  36  are prevented from rotating toward the inner side of the vehicle. 
     Although the first rubber vibration isolator  49  and the second rubber vibration isolator  52  are used as the shock-absorbing mechanism in the aforementioned sixth embodiment, the present invention is not limited thereto. As long as the first link  48  and the second link  51  are returned to the original tilting position after rotating, any other member having a torsion action, such as a torsion spring, may be used. 
     REFERENCE SYMBOLS LIST 
     
         
           1  Vehicle 
           2  Bogie 
           3  Guideway 
           4 ,  53  Guide rail 
           4   a ,  53   a  Side surface of guide rail 
           5  Turn frame 
           6  Upper rectangular frame 
           6   a  Vehicle body center side portion of upper rectangular frame 
           7  Lower rectangular frame 
           7   a  Vehicle body center side portion of lower rectangular frame 
           7   b  Vehicle body end side portion of lower rectangular frame 
           8  Connecting frame 
           9  Axle 
           9   a  Lower surface of axle 
           9   b  Upper surface of axle 
         Running wheel 
           11 ,  12  Bearing 
         Guide frame 
           13   a  Vehicle body end side portion of guide frame 
           13   b  Vehicle body center side portion of guide frame 
           14  Longitudinal frame 
           14   a  Vehicle body end side portion of longitudinal frame 
           15  Lateral frame 
           16 ,  18  Guide wheel 
           17 ,  19 ,  34 ,  37  Rotation shaft 
           20  Vehicle body 
           20   a  Lower surface of vehicle body 
           21  Suspension frame 
           21   a  Vehicle body center side portion of suspension frame 
           21   b  Extension part 
           22 ,  25  Traction link 
           22   a ,  25   a  End part on vehicle body end side of traction link 
           22   b ,  25   b  End part on vehicle body center side of traction link 
           23 ,  24 ,  26 ,  27  Joint 
           28  Stopper 
           29  Stopper receiver 
           30  Arm 
           30   a  End part on vehicle body end side of arm 
           31  Turn damper 
           32  Restoration rod 
           33 ,  36  Guide wheel support 
           33   a ,  36   b  Vehicle body center side portion of guide wheel support 
           33   b ,  36   a  Vehicle body end side portion of guide wheel support 
           35 ,  38  Shock-absorbing rod 
           39 ,  43  Leaf spring 
           39   a  Vehicle body end side portion of leaf spring 
           40 ,  44  Split-type wheel receiver 
           41 ,  45  Guide wheel mounting part of split-type wheel receiver 
           42 ,  46  Middle support part of split-type wheel receiver 
           43   a  Vehicle body center side portion of leaf spring 
           47 ,  50  Link support 
           48 ,  51  Link 
           49 ,  52  Rubber vibration isolator 
           61  (Conventional) guide rail type vehicle 
           62  (Conventional) bogie 
           63  (Conventional) guide rail 
           64  (Conventional) guide frame 
           65 ,  66  (Conventional) guide wheel 
           67  (Conventional) running wheel 
           68  (Conventional) steering lever 
           69 ,  71  (Conventional) link lever 
           70 ,  72  (Conventional) rotation shaft 
           73  (Conventional) tie rod 
           74  (Conventional) actuator 
           75  (Conventional) steering rod 
         O 1  Center axis of axle 
         L 1  Distance between center axis of axle and first pair of guide wheels 
         L 2  Distance between center axis of axle and second pair of guide wheels