Patent Publication Number: US-2005126055-A1

Title: Crawler type traveling apparatus

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      This invention relates to a crawler type traveling apparatus.  
      2. Description of the Related Art  
      Vehicles such as bulldozers, excavators, crawler cranes and the like include crawler type traveling apparatuses arranged on the right and left sides thereof.  
      In the excavators among them, a final reduction gear inclusive of a sprocket and an hydraulic motor are arranged in most cases at an end part of a track frame of the crawler type traveling apparatus and the hydraulic motor is connected to a hydraulic source of a vehicle main body through hydraulic piping arrangements to constitute a compact crawler type traveling apparatus.  
      In the vehicles in which traction is of importance such as in a bulldozer, the crawler type traveling apparatuses are arranged in some cases on both right and left sides of the vehicle in such a fashion as to be capable of rocking up and down through respective pivot shafts as is well known in the art. In consequence, the right and left crawler type traveling apparatuses reliably catch the ground even on the ground having three-dimensional undulation, thereby giving large traction.  
      As a result, a crawler type traveling apparatus that is compact in size and has large traction can be accomplished when crawler type traveling apparatuses are arranged on both right and left sides of a vehicle through respective pivot shafts in such a fashion as to be capable of rocking up and down and a final reduction gear inclusive of a sprocket and a hydraulic motor are arranged at an end part of a track frame of each crawler type traveling apparatus.  
      In this case, however, the problem yet remains unsolved in that piping arrangements having a predetermined length and high flexibility such as hydraulic hoses are necessary as means for connecting the hydraulic motor arranged on the track frame that rocks up and down to the hydraulic source of the vehicle main body. In this case, the piping arrangements are likely to come into contact with sand and rocks and are likely to be damaged.  
      As an example of means for solving the problem, the following non-patent reference  1  illustrates a construction in which a hydraulic motor and a final reduction gear are arranged on a track frame rocking up and down, and a construction in which hydraulic piping arrangements for connecting the hydraulic motor and a hydraulic source of a vehicle main body are compactly constituted and are protected from sand and rocks.  
      Non-Patent Reference 1:  
      LIEBHERR Co. (LIEBHERR-EXPORT A.G.) PR712 Type, Operation and Maintenance Manual PR712, Litronic, Germany, P. O. Box 54, CH-5415, Nussbaumen, Manual No. IRM-710-06, P. 2-6  
      As a referential example for similarly solving the problem described above, the following patent reference  1  describes a construction in which hydraulic piping arrangements for connecting a hydraulic cylinder arranged on a track frame rocking up and down to a hydraulic source of a vehicle main body are inserted into hollow pivot shafts and are protected from sand and rocks.  
      Patent Reference 1:  
      Japanese Utility Model Laid-Open No. 113585/1990 (pages 3 to 5, FIG. 1)  
      An example of the crawler type traveling apparatus according to the related art will be explained on the basis of the example illustrated in the non-patent reference 1 described above with reference to  FIGS. 5 and 6  of the accompanying drawings.  
       FIG. 5  is a side view of a bulldozer to which the crawler type traveling apparatuses according to the related art are applied, and  FIG. 6  is an exploded sectional perspective view of the crawler type traveling apparatus and is a view as viewed from Q in  FIG. 5 .  
      Referring initially to  FIG. 5 , the bulldozer  61  has at its center a main frame  62  elongated in a longitudinal direction. Right and left crawler type traveling apparatuses  70 ,  70  are fitted to respective pivot shafts  63 , that are provided to the main frame  62  on its right and left sides so as to protrude from the main frame  62 , in the manner that they can oscillate around the pivot shaft axis P 2 . Each crawler type traveling apparatus  70  includes a track frame  71  elongated in the longitudinal direction, an idler  6  arranged at the front end part of the track frame  71 , a predetermined number of track rollers  7  disposed on the lower surface of the track frame  71 , a predetermined number of carrier rollers  8  disposed on the upper surface, a sprocket  81  disposed at the rear end part, and a belt  9  so fitted as to wind the idler  6 , the track rollers  7 , the carrier rollers  8  and the sprocket  81 .  
      Next, in  FIG. 6 , a boss portion  71   a  arranged at a rear end part of the track frame  71  is rotatably inserted into the pivot shaft  63  fastened by a bolt to a left side plate  62   a  of the main frame  62  so that the track frame  71  can rock up and down. A final reduction gear  80  inclusive of a sprocket  81  is fitted to a vehicle inner side surface of a bracket portion  71   b  at the rear end part of the track frame  71 . A hydraulic motor  90  is fitted to a vehicle outer side surface of the final reduction gear  80 .  
      In  FIG. 6 , a predetermined number of hydraulic passages  91   b ,  92   b ,  93   b  and  94   b  are formed at an axial center portion of the pivot shaft  63  in such a fashion as to extend from the outer end face of the pivot shaft  63  towards its inner end face. A gallery block  95  is mounted to the outer end face. Hydraulic hoses  91   a  and  92   a  connected to a suction port and a discharge port, not shown, of the hydraulic motor  90  are communicated with a discharge port and a suction port of an hydraulic pump, disposed inside the main frame  62  and not shown, through the gallery block  95  and through the hydraulic passages  91   b  and  92   b , respectively.  
      Similarly, a hydraulic hose  93 a connected to a speed control port, not shown, of the hydraulic motor  90  and a hydraulic hose  94   a  connected to a brake release port of a parking brake, not shown, inside the reduction gear  80  are communicated with an operation valve, disposed inside the main frame  62  and not shown, through the gallery block  95  and through the hydraulic passages  93   b  and  94   b , respectively.  
      A cover  96  is fitted so as to protect the gallery block  95  and the hydraulic hoses  91   a ,  92   a ,  93   a  and  94   a.    
      In the construction shown in  FIGS. 5 and 6 , the hydraulic motor  90  is first arranged outside the vehicle at the bracket portion  71   b  at the rear end of the track frame  71 . On the other hand, required ports of hydraulic appliances such as a hydraulic pump (not shown) inside the main frame  62  are communicated with the gallery block  95  fitted to the outer end face of the pivot shaft  63  through the hydraulic passages  91   b    92   b ,  93   b  and  94   b  inside the pivot shaft  63  so that hydraulic hoses  91   a ,  92   a ,  93   a  and  94   a  having a small length can connect the hydraulic motor  90  and the gallery block  95  in a compact manner. As a result, the crawler type traveling apparatus  70  can achieve a compact piping arrangement construction.  
      However, the construction of the crawler type traveling apparatus according to the related art shown in  FIGS. 5 and 6  involves the following problems because the hydraulic motor  90  is disposed on the more outer side of the vehicle than the final reduction gear  80  inclusive of the sprocket  81 . 
      (1) The outer side surface of the crawler type traveling apparatus  70  often come into touch with obstacles such as surrounding grounds and pavement when the vehicle moves back and forth and turns and also impinges in many cases against rolling rocks from a mucking mound of sediment and/or rolling rocks from a wall of a bench-cut. For this reason, the possibility is large that the hydraulic motor  90  arranged close to the outer side surface of the crawler type traveling apparatus  70  and the hydraulic hoses  91   c ,  92   c ,  93   c  and  94   c  connected to the hydraulic motor  90  are damaged. As a result, the crawler type traveling apparatus  70  has low reliability.     ( 2 ) The depth of each hydraulic passage  91   b ,  92   b ,  93   b ,  94   b  formed in the pivot shaft  63  must be great so as to reach the inside of the side plate  62   a  of the main frame  62  from the outer end face of the pivot shaft  63 . Therefore, a specific machine tool such as a gun drill and an extended machining time are necessary for forming each hydraulic passage  91   b ,  92   b ,  93   b ,  94   b , and the crawler type traveling apparatus  70  has an expensive piping construction.    

     SUMMARY OF THE INVENTION  
      In view of the problems described above, the invention aims at providing a crawler type traveling apparatus having a compact size, a low cost piping construction and high reliability in a crawler type traveling apparatus so arranged on each side of a vehicle as to be capable of rocking up and down through each pivot shaft, and including a track frame rocking round the pivot shaft and a final reduction gear inclusive of a sprocket and an hydraulic motor that are provided at an end part of the track frame.  
      To accomplish this object, a first invention of this application provides a crawler type traveling apparatus so arranged on each side of a vehicle as to be capable of rocking up and down through each pivot shaft and including a track frame rocking round the pivot shaft, and a final reduction gear inclusive of a sprocket and an hydraulic motor that are provided at an end part of the track frame, wherein the hydraulic motor is fitted on a vehicle inner side relative to the final reduction gear.  
      According to the first invention, the strong final reduction gear is arranged on the outer surface side of the crawler type traveling apparatus, and the hydraulic motor and piping arrangements connected to the hydraulic motor are arranged on the inner side of the final reduction gear. Therefore, when the crawler type traveling apparatus operates, the hydraulic motor and the piping arrangements connected to the hydraulic motor do not come into contact with the surrounding ground and pavement explained with reference to  FIG. 6  (that explains the related art technology) and do not either impinge against rolling rocks from the mucking mound and/or from the wall of the bench-cut. Accordingly, the crawler type traveling apparatus has high reliability.  
      In the first invention described above, the second invention provides a construction in which hydraulic passages communicating with the hydraulic motor, etc, are defined in the pivot shaft.  
      In addition to the operation and effect of the first invention, the second invention provides the effect that the piping arrangements extending from the hydraulic appliances such as the hydraulic pump disposed inside the vehicle to the hydraulic motor and the like of the crawler type traveling apparatus can be arranged near the hydraulic motor without being exposed to the outside, and the piping construction that is compact and has high reliability can be acquired.  
      In the crawler type traveling apparatus according to the second invention, the third invention provides a construction in which a predetermined number of hydraulic piping arrangements connected to the hydraulic motor, etc are defined on an outer peripheral surface of the pivot shaft.  
      In addition to the operation and effect of the second invention, the third invention provides the following operation and effect. 
      (1) The piping arrangements such as the hydraulic hoses are extended from an arbitrary outer peripheral surface of each pivot shaft protruding in the transverse direction in front of the hydraulic motor to the hydraulic motor. In consequence, the hydraulic passages inside the pivot shaft can be connected to the hydraulic motor, etc and an extremely compact piping construction can be obtained.     (2) The length of each hydraulic passage formed inside the pivot shaft need not be the length that reaches the outer end face of the pivot shaft, and can be drastically reduced. Therefore, the hydraulic passages to be formed inside the pivot shaft can be easily machined by ordinary drilling, or the like, and an economical piping construction can be obtained.    

      As a result, in a crawler type traveling apparatus so arranged on each side of a vehicle as to be capable of rocking up and down through each pivot shaft and including a track frame rocking round the pivot shaft, and a final reduction gear inclusive of a sprocket and a hydraulic motor that are provided at an end part of the track frame, the invention can provide a crawler type traveling apparatus that has a compact size, a low cost piping construction and high reliability. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a side view of a bulldozer to which crawler type traveling apparatuses according to the invention are applied;  
       FIG. 2  is a top view of principal portions of the crawler type traveling apparatus according to the invention and is a sectional view taken along a line L-L of  FIG. 1 ;  
       FIG. 3  is a perspective view of a pivot shaft and is useful for explaining hydraulic passages;  
       FIG. 4  is a side view of principal inner portions of the crawler type traveling apparatus according to the invention and is a sectional view taken along a line M-M in  FIG. 2 ;  
       FIG. 5  is a side view of a bulldozer to which crawler type traveling apparatuses according to the prior art are applied; and  
       FIG. 6  is a sectional perspective view of principal portions of the crawler type traveling apparatus according to the related art and is a view from Q in  FIG. 5 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
      A crawler type traveling apparatus according to the invention will be hereinafter explained in detail about a bulldozer by way of example with reference to FIGS.  1  to  4 .  
       FIG. 1  is a side view of the bulldozer to which the crawler type traveling apparatuses according to the invention are applied.  FIG. 2  is a top view of principal portions of the crawler type traveling apparatus and is a sectional view taken along a line L-L in  FIG. 1 .  FIG. 3  is a perspective view of a pivot shaft and is useful for explaining hydraulic passages.  FIG. 4  is a side view of principal inner portions of the crawler type traveling apparatus according to the invention and is a sectional view taken along a line M-M in  FIG. 2 . Incidentally, like reference numerals as those used in  FIGS. 5 and 6  will be used to identify like constituent elements and explanation of such constituent elements will be omitted.  
      Referring initially to  FIG. 1 , the bulldozer  1  has at its center a main frame  2  that is elongated in a longitudinal direction. Pivot shafts  3  are fixed to the main frame  2  in such as fashion as to protrude from the main frame  2  on both right and left sides. Right and left crawler type traveling apparatuses  10  and  10  are fitted to the right and left pivot shafts  3 , respectively, in such a fashion as to be capable of rocking at respective track frames  11  and  11  round the axes P 1  of the pivot shafts  3 . Incidentally, explanation will be hereinafter given on only the crawler type traveling apparatus  10  on the left side, and explanation on the crawler type traveling apparatus  10  on the right side will be omitted because it has the same construction as the crawler type traveling apparatus  10  on the left side.  
      Next, in  FIG. 2 , a boss portion  11   a  arranged at the rear part of the track frame  11  is rotatably fitted into the pivot shaft  3  protruding from a left side plate  2   a  of the main frame  2  and the track frame  11  can rock up and down. A final reduction gear  20  including a sprocket  21  is fitted to a vehicle outer side surface of a bracket portion  11   b  at the rear end of the track frame  11 , and a hydraulic motor  30  is fixed to a vehicle inner side surface of the final reduction gear  20 .  
      Referring next to  FIG. 3 , hydraulic passages  31   c ,  32   c ,  33   c ,  34   c  and  35   c  are so formed in the pivot shaft  3  as to extend from the inner end face of the pivot shaft  3  in the axial direction. Ports  31   b ,  32   b ,  33   b ,  34   b  and  35   b  for fitting piping arrangements (hereinafter merely called “inner ports”), respectively communicating with these hydraulic passages  31   c ,  32   c ,  33   c ,  34   c , and  35   c  are formed in an outer peripheral surface of the pivot shaft  3  within a range C protruding to the inside of the main frame left side wall  2   a . Similarly, ports  31   d ,  32   d ,  33   d ,  34   d  and  35   d  for fitting piping arrangements (hereinafter merely called “outer ports”), respectively communicating with the hydraulic passages  31   c ,  32   c ,  33   c ,  34   c  and  35   c  are formed within a range D protruding to the outside of the main frame left side wall  2   a.    
      An inner end face opening of each of the hydraulic passages  31   c ,  32   c ,  33   c ,  34   c  and  35   c  is sealed through a plug  31   f ,  32   f ,  33   f ,  34   f  and  35   f  shown in  FIG. 2 .  
      Referring to FIGS.  2  to  4 , piping arrangements  31   a  and  32   a  to be connected to a discharge side and a suction side of the hydraulic pump, not shown, a drain piping arrangement  33   a  to be connected to an operation oil tank, not shown, and piping arrangements  34   a  and  35   a  to be connected to an operation valve, not shown, are coupled with inner ports  31   b ,  32   b ,  33   b ,  34   b  and  35   b  of the pivot shaft  3 , respectively, inside the left side plate  2   a  of the main frame  2 .  
      Outside the left side plate  2   a  of the main frame  2 , hydraulic hoses  31   e  and  32   e  are coupled with the outer ports  31   d  and  32   d  of the pivot shaft  3  through a gallery block  36 , respectively. The hydraulic hoses  31   e  and  32   e  are connected at their other end with a suction port and a discharge port, not shown, of the hydraulic motor  30 , respectively. Similarly, hydraulic hoses  33   e ,  34   e  and  35   e  are coupled with the outer ports  33   d ,  34   d  and  35  of the pivot shaft  3 , respectively. These hydraulic hoses  33   e ,  34   e  and  35   e  are connected at their other end with a drain port and a speed control port, not shown, and a brake release port of a parking brake  22  of the final reduction gear  20 , respectively.  
      Further, covers  38  and  39  are so adapted as to protect the hydraulic motor  30  and the hydraulic hoses  31   e ,  32   e ,  33   e ,  34   e  and  35   e.    
      In the construction shown in FIGS.  1  to  4 , the following operation and effect can be obtained. 
      (1) The hydraulic motor  30  is arranged the vehicle inner side with respect to the final reduction gear  20 , and the strong final reduction gear  20  is arranged close to the outer side surface of the crawler type traveling apparatus  10 . While the crawler type traveling apparatus operates, the hydraulic motor  30  arranged close to the inner side surface of the crawler type traveling apparatus  10  and the hydraulic hoses  31   e ,  32   e ,  33   e ,  34   e  and  35   e  coupled with the hydraulic motor  30  do not come into contact with the ground and the pavement described above with reference to  FIG. 6  (that explains the related art technology) and are free from impingement with rolling stones from the mucking mound and/or from the wall surface of a bench cut.     (2) The hydraulic passages  31   c ,  32   c ,  33   c ,  34   c  and  35   c  communicating with the hydraulic motor  30 , etc are defined inside the pivot shaft  3 . Therefore, the piping arrangements that are so disposed as to extend from the hydraulic appliances arranged inside the left side plate  2   a  of the main frame such as the hydraulic pump towards the hydraulic motor  30  and the like of the crawler type traveling apparatus  10  can be arranged near to the hydraulic motor  30  without being exposed to the outside. Accordingly, the piping construction that is hardly damaged from the outside can be acquired.     (3) The ports  31   d ,  32   d ,  33   d ,  34   d  and  35   d  to be connected to a predetermined number of hydraulic piping arrangements coupled with the hydraulic motor  30  are formed in the outer peripheral surface of the pivot shaft  3 . Therefore, an extremely compact piping construction can be obtained by connecting the hydraulic hoses  31   e ,  32   e ,  33   e ,  34   e  and  35   e  to the hydraulic motor  30  from an arbitrary outer peripheral surface of the pivot shaft  3  so arranged as to protrude to the right or left in front of the hydraulic motor  30 .     (4) For the same reason as described in (3), the length of the hydraulic passages  31   c ,  32   c ,  33   c ,  34   c  and  35   c  to be arranged inside the pivot shaft  3  need not be the length extending to the outer end face of the pivot shaft  3  but may be within the range B shown in  FIG. 3  and can be drastically reduced. Consequently, the hydraulic passages  31   c ,  32   c ,  33   c ,  34   c  and  35   c  can be easily machined by ordinary drilling and the like and an economical piping construction can be obtained eventually.    

      As described above, in a crawler type traveling apparatus so arranged on each side of a vehicle as to be capable of rocking up and down through each pivot shaft and including a track frame rocking round the pivot shaft and a final reduction gear inclusive of a sprocket and a hydraulic motor that are arranged at an end part of the track frame, the invention can provide a crawler type traveling apparatus having a compact and economical piping arrangement and achieving high reliability.  
      The crawler type traveling apparatus according to the invention has thus been explained about the crawler type traveling apparatus of the bulldozer by way of example, but the crawler type traveling apparatus according to the invention is not limited to the bulldozer but can be versatilely applied to crawler type traveling apparatuses of other machines in the same way and can obtain similar operation and effects.