Abstract:
A hydraulic pump device for a work vehicle having a transmission case that houses a PTO shaft ( 12 ) comprises: a hydraulic pump ( 35 ), a pump input shaft ( 36 ) of the hydraulic pump ( 35 ) that has a projecting shaft portion projecting into the transmission case ( 1 ), a first bevel gear ( 41 ), and a second bevel gear ( 42 ). The first bevel gear ( 41 ) is fitted on the PTO shaft ( 12 ) and the second bevel gear ( 42 ) is connected to the projecting shaft portion. A holder ( 38 ) for supporting the PTO shaft ( 12 ) is removably attached to the transmission case ( 1 ). The first bevel gear and the second bevel gear are supported to the holder for rotation about respective axes.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a hydraulic pump device for a work vehicle having a transmission case that houses a PTO axis. 
         [0003]    2. Description of the Related Art 
         [0004]    Some of the hydraulic pump devices for work vehicles, such as tractors include a hydraulic pump having its pump input shaft projected into a transmission case, a first bevel gear fitted onto a PTO axis, a second bevel gear which meshes with the first bevel gear and is connected with the pump input shaft of the hydraulic pump with the first and the second bevel gears provided within the transmission case. The rotational power of the PTO axis is taken out by the first and second bevel gears to rotate the pump input shaft of the hydraulic pump. An example of the hydraulic pump device for work vehicles of this conventional type is disclosed in JP Publication Of Application No. 2006-90476. In this device, a tubular support shaft projecting to the first bevel gear and a support shaft projecting to the second bevel gear are supported separately by a respective holder for rotation about an axis of rotation and a holder supporting the first bevel gear is different from a holder supporting the second bevel gear. 
       SUMMARY OF THE INVENTION 
       [0005]    Since the bearing case for supporting the first bevel gear is different from the holder supporting the second bevel gear in the conventional device, adjusting the positions of the first and second bevel gears for proper meshing takes time and efforts, and assembling the first and second bevel gears into the transmission case was also troublesome. 
         [0006]    An object of the present invention is to provide a hydraulic pump device which allows easy adjustment of the positions of the first and second bevel gears for proper meshing, and which also facilitates assembly of the first and second bevel gears into the transmission case. 
         [0007]    To achieve the objective described above, a hydraulic pump device, in accordance with the present invention, for a work vehicle having a transmission case that houses a PTO axis comprises: a hydraulic pump; a pump input shaft of the hydraulic pump, the pump input shaft having a projecting shaft portion projecting into the transmission case; a first bevel gear, and a second bevel gear that meshes with the first bevel gear, the first and second bevel gears being housed within the transmission case, the first bevel gear being fitted onto the PTO shaft, and the second bevel gear being coupled with the projecting shaft portion of the pump input shaft; a holder for supporting the PTO shaft, the holder being removably attached to the transmission case. The first bevel gear and the second bevel gear are supported to the holder for rotation about respective axes. 
         [0008]    In accordance with the present invention, since a holder for supporting the PTO shaft is removably attached to the transmission case and since the first and second bevel gears are supported to this holder for rotation about their respective axes, adjustment of the positions of the first and second bevel gears for proper meshing may be performed easily. In addition, if the holder is attached to the inside of the rear end of the front transmission case of the transmission case, the assembly of the first and second bevel gears to the transmission case would be facilitated. 
         [0009]    Other feature and advantages of the present invention will be clear from the description of the preferred embodiment of the present invention with reference to the attached drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is a side sectional view of a work vehicle according to one embodiment of the present invention and partially includes a rear sectional view, 
           [0011]      FIG. 2  is a sectional expanded view of a pump attaching portion of  FIG. 1 , and 
           [0012]      FIG. 3  is a rear sectional view of the pump attaching portion. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0013]    The preferred embodiment of the present invention is described next with reference to the attached drawings. 
         [0014]    As shown in  FIG. 1 , the tractor vehicle body has a transmission case  1 , whose main components are a front transmission case  3  which houses a gear type main speed change portion  2 , and a rear transmission case  4  in the rear which houses, among other things, a rear-wheel differential, and a PTO speed change portion. The rear edge  3   a  of the front transmission case  3  and the leading edge or the front edge portion  4   a  of the rear transmission case  4  are joined in the fore-and-aft direction. 
         [0015]    A clutch housing  8  is provided forwardly of and is connected to the front transmission case  3 , and this housing  8  is connected to a rear surface of an engine. 
         [0016]    Engine power is engaged and disengaged by the clutch and transmitted to a driving axis  11  the travel drive line, and the driving axis  11  has a tubular shaft structure and is divided into a front axis  11 A and a rear axis  11 B. The PTO axis  12  is inserted within the driving axis  11  and is coupled to the PTO speed change portion through the PTO clutch  13 . 
         [0017]    The travel drive line driving axis  11  is installed to the support holder  9  and the intermediate wall  10  of the front transmission case  3  by a bearing  14 , etc., and the speed change countershaft  15  is installed to the support holder  9  and the intermediate wall  10  by a bearing, in parallel with the axis  11 . 
         [0018]    In the present embodiment, the gear-type main speed change portion  2  is always in engagement, and is provided between the driving axis  11  and the speed change countershaft  15 . 
         [0019]    In more detail, the main speed change portion  2  includes a first shifter  18  which is located between and adapted to engage with either of the first and second driving speed change gears  16 ,  17  which are freely rotatably supported to an approximately central portion of the speed change countershaft  15 , a transmission gear  19  and a third driving speed change gear  20  both located in a forward region of the speed change countershaft  15 , and a reverse rotation gear  21  rotatably provided in the rear region of the speed change countershaft  15 . 
         [0020]    A drive gear  22  which engages with the transmission gear  19  on the countershaft  15  is provided on the front shaft  11 A of the travel drive line driving axis  11 . And a second shifter  23 , which directly links the gear  22  and the rear axis  11 B when moved in the direction shown by the arrow  4 F to provide a fourth speed position or gear ratio, is provided. This second shifter  23  enables the driven third speed change gear  24  to selectably engage with the third driving speed change gear  20  to provide a third speed position or gear ratio when moved in the arrow shown at  3 F. 
         [0021]    Further, first and second driven speed change gears  25  and  26 , which engage the first and second driving speed change gears  16  and  17 , are fixedly mounted to the rear axis  11 B in the driving axis  11 , and a wide transmission gear  27  which engages the reverse rotation gear  21  is also provided on the axis  11 . First and second speeds or gear ratios are obtained by shifting the first shifter  18  in the directions indicated by  1 F and  2 F respectively. 
         [0022]    A speed change output shaft  28  is installed to the front transmission case  3  through a bearing  29  and is parallel to the travel drive line driving axis  11  and the speed change countershaft  15 . A high-speed auxiliary speed change gear  30 , a low-speed auxiliary speed change gear  32 , and the reverse rotation gear  34  are provided to the speed change output shaft  28  and are operatively connected to the rear-wheel differential through the power transmission shaft  31 . 
         [0023]    And the rear-wheel differential is operatively connected to the rear wheels through a final reduction gear, and a front-wheel differential is operatively connected to the front wheels through the final reduction gear to provide a four-wheel-drive tractor. 
         [0024]    The PTO axis  12  transmits engine power to the PTO power transmission shaft  33  through a PTO clutch  13 . And this PTO power transmission shaft  33  is configured to transmit power to the PTO axis in the rear of the rear transmission case  4  through a PTO speed change mechanism. 
         [0025]    The PTO axis  12  and the PTO power transmission shaft  33  are arranged to meet end-to-end in a rear region of the front transmission case  3 , or a front region of the rear transmission case  4 . And each of the PTO axis  12  and the PTO power transmission shaft  33  is supported for independent rotation by bearings in the rear of the front transmission case  3 , or the front of the rear transmission case  4 . 
         [0026]    The pump power take off structure is described next. The structure is attached to the transmission case  1  as hydraulic pressure supply means for power steering for the tractor and also as hydraulic pressure supply means for supplying hydraulic pressure to the three-point link hitch mechanism installed in the tractor rear. 
         [0027]    As shown in  FIGS. 2 and 3 , the hydraulic pump  35  is removably attached to a right hand side surface in the rear of the front transmission case  3  with one or more tightening tools  37 , such as bolts. And the hydraulic pump  35  projects outwardly from the rear of the front transmission case  3 , and its pump input shaft  36  projects into within the rear portion of the front transmission case  3 . 
         [0028]    A holder  38  which supports the back end portion of the PTO axis  12  is provided in the rear of the front transmission case  3 , and the holder  38  is removably attached to an attachment boss of a rear edge  3   a  of the front transmission case  3  by one or more tightening tools  39 , such as bolts, so that the holder is attached to inside the rear or back end of the front transmission case  3 . 
         [0029]    A first bevel gear  41  fitted on the back end portion of the PTO axis  12  and a second bevel gear  42  connected to the pump input shaft  36  of the hydraulic pump  35  are provided within the rear of the front transmission case  3 , and the second bevel gear  42  meshes with the first bevel gear  41 . The first bevel gear  41  is arranged rearwardly of the second bevel gear  42 , and the first bevel gear  41  has a tubular support shaft  43  projected in the direction of its axis, and the tubular support shaft  43  is spline-fit to the back end portion of the PTO axis  12 . The second bevel gear  42  has a support shaft  46  projected in the direction of its axis. A support shaft  46  and the pump input shaft  36  of the 2nd bevel gear  42  are fixedly connected by a coupling  47 , so that the support shaft  46  rotates with the pump input shaft  36  in unison about the same axis. 
         [0030]    The holder  38  has a first support portion  51  and a second support portion  52  in the shape of an L, and a first attachment hole  53  is provided in the first support portion  51 , and a second attachment hole  54  is provided in the second support portion  52 . The back end portion of the PTO axis  12  and the support tubular shaft  43  of the first bevel gear  41  are inserted into the first attachment hole  53  of the first support portion  51  in the fore-and-aft direction, and are rotatably supported by the holder  38  through the bearing  44 . Thereby, the first bevel gear  41  and the back end portion of the PTO axis  12  are rotatably supported by the holder  38  for rotation about its axis, so that the back end portion of the PTO axis  12  is supported by the transmission case  1  through the first bevel gear  41  and the holder  38 . The support shaft  46  of the second bevel gear  42  is laterally inserted into or through the attachment hole  54  of the second support portion  52 , and is rotatably supported by the holder  38  through the bearing  45 . 
         [0031]    According to the embodiment described above, after assembling the PTO axis  12 , the speed change output shaft  28 , the countershaft  15 , each speed change gear, etc. all of which are located forwardly of the intermediate wall  10  of the front transmission case  3 , into the front transmission case  3 ; and with the first bevel gear  41  and the second bevel gear  42  assembled to the holder  38  for rotation about their axes, the holder  38  in the assembled state is then inserted into the front transmission case  3  from the upper or side direction (or any direction in-between) of the front transmission case  3 , and is attached to the rear edge  3   a  of the front transmission case  3  by one or more tightening tools  39 , such as bolts. Then, by inserting into the support tubular shaft  43  of the first bevel gear  41 , the PTO axis  12  is spline-fit to the support tubular shaft  43  of the first bevel gear  41 . And, by inserting the pump input shaft  36  of the hydraulic pump  35  into the front transmission case  3 , the support shaft  46  of the second bevel gear  42  and the pump input shaft  36  can be fixedly connected by coupling  47 . The hydraulic pump  35  can then be fixed to the front transmission case  3  by one or more tightening tools  37 , such as the bolts tightened from outside. 
         [0032]    Accordingly, since the first bevel gear  41  and the second bevel gear  42  are rotatably supported by one holder  38  for rotation about their axes, they can be assembled together before installing them to the transmission case  1 , and thus the positions of the bevel gears for proper meshing may be adjusted easily.