Abstract:
A powershiftable reversing transmission for a vehicle with a drive engine arranged off-center and a telescopically extendable lifting arm. The reversing transmission has a shaft ( 4 ) for forward driving and a shaft ( 5 ) for reverse driving, with a clutch ( 9 ) for forward driving and a clutch ( 10 ) for reverse driving. Two fixed wheels ( 20, 21 ) are arranged on the shaft ( 4 ) for forward driving, while only one clutch and one fixed wheel are arranged on the other shafts.

Description:
[0001]    This application claims priority from German patent application serial no. 10 2014 219 106.8 filed Sep. 23, 2014. 
       FIELD OF THE INVENTION 
       [0002]    The invention concerns a powershiftable reversing transmission for a vehicle with a drive engine arranged off-center. 
       BACKGROUND OF THE INVENTION 
       [0003]    Powershiftable reversing transmissions of this type are used in working machines, such as vehicles with a telescopically extendable arm, so-termed telehandlers or telescopic vehicles. These vehicles often have a telescopic lifting arm arranged centrally in the vehicle, with the drive engine arranged on one side of the vehicle and the driver&#39;s cabin on the other side of the telescopic arm. 
         [0004]    Since the drive shafts to the front and rear axles of the vehicle often also extend centrally, it is necessary for the drive output of the gearshift transmission to be positioned almost centrally in the longitudinal direction of the vehicle. Because of this the distance between the drive engine and the drive output shafts of the transmission has to be bridged. 
         [0005]    DE 10131329 A1 discloses a powershiftable reversing transmission for a vehicle with a drive engine arranged off-center, in which, particularly in  FIG. 5  thereof, the drive input shaft of the gearshift transmission, which can be connected to the drive engine, is arranged a distance away from the drive output shaft of the gearshift transmission, whereby it is made possible for the drive output shaft to be arranged almost centrally in the vehicle, whereas the drive input shaft is arranged to one side in the area of the drive engine. Owing to the direct flange connection of the transmission to the drive engine, a great deal of fitting space in the vehicle&#39;s longitudinal direction is needed, which has to be provided by the lateral arrangement between the vehicle&#39;s wheels; in vehicles with a short wheel base, however, this is not possible. 
         [0006]    U.S. Pat. No. 6,152,253 discloses a drive unit for a vehicle with a drive engine arranged off-center and a lifting arm arranged centrally in the vehicle, wherein the drive engine and the transmission are arranged close to but a distance away from one another, the drive output shaft of the drive engine and the drive input shaft of the transmission are located on the same side, and the distance is bridged by a chain transmission. Although this arrangement is suitable also for vehicles with a short wheel base, the lifting arm has to be positioned at a very high level so as not to collide with the transmission housing, and this considerably restricts the vision from the driver&#39;s cabin. 
       SUMMARY OF THE INVENTION 
       [0007]    The purpose of the present invention is to provide a powershiftable reversing transmission for a vehicle with an drive engine arranged off-center and a centrally arranged lifting arm, which is suitable for vehicles with a short wheel base and which has no restrictive effect on the driver&#39;s vision from the driver&#39;s cabin. 
         [0008]    This objective is achieved with a powershiftable reversing transmission of the type in question which also embodies the characterizing features as described below. 
         [0009]    The invention is based on the recognition that a drive system with a drive engine, for example an internal combustion engine, arranged off-center, is only possible in a vehicle with a short wheel base if the drive output shaft of the drive engine and the drive input shaft of the powershiftable reversing transmission extend in the same direction and the drive engine and powershiftable reversing transmission are arranged close to but a distance away from, i.e. parallel to one another. The drive output shaft of the drive engine and the drive input shaft of the powershiftable reversing transmission can be connected by a connecting gear assembly, for example a spur gear assembly or a chain transmission. The main drive output shaft of the powershiftable reversing transmission should be designed such that the main drive output shaft of the powershiftable reversing transmission coincides with the front axle of the vehicle, i.e. the axle arranged near the free end of the lifting mast, since the front axle is the main drive output axle. The drive engine and the powershiftable reversing transmission should be arranged so that the drive output shaft of the drive engine and the drive input shaft of the powershiftable reversing transmission extend in the direction of the free end of the lifting mast and thus toward the front of the vehicle. In this way the part of the powershiftable reversing transmission having the largest diameter, namely the outer diameter of the housing that surrounds the hydrodynamic torque converter, is displaced toward the front end of the vehicle, thus creating more fitting space for a hydraulic cylinder that actuates the lifting arm and is arranged in the rear portion of the vehicle. To position the lifting arm even lower and thereby improve the driver&#39;s vision, the powershiftable reversing transmission must be moved even closer to the drive engine and the drive output shaft of the powershiftable reversing transmission must be a distance away from the drive input shaft of the powershiftable reversing transmission, whereby the drive output shaft is positioned almost centrally in the vehicle and the drive input shaft of the powershiftable reversing transmission is displaced laterally toward the drive engine. In that way the highest point of the housing surrounding the hydrodynamic torque converter is arranged outside the lifting arm. 
         [0010]    This is possible because the powershiftable reversing transmission comprises a drive input shaft and a drive output shaft that are arranged a distance away from one another and the distance is bridged by gearwheels on gearshift shafts and shafts for forward and reverse driving. In this case only one clutch is arranged on each shaft and, except for the shaft for forward driving, all the shafts have only one fixed wheel. In that the shaft for forward driving has two fixed wheels, the main drive output shaft on the transmission can be arranged on the same side as the drive input shaft and the front axle of the vehicle can be driven with the correct rotational direction for the drive output shaft. In addition, when the forward driving direction is engaged the drive unit has the best efficiency, since there are then fewer meshing gearwheel pairs. 
         [0011]    In a further design version of the invention, an additional drive output shaft can be arranged on the powershiftable reversing transmission, which can be connected to the rear axle of the vehicle, this additional drive output shaft being arranged either coaxially with the drive output shaft for the front axle, or by virtue of an additional spur gear stage at a distance away from the drive output shaft for the front axle. The additional drive output shaft for the rear axle can be driven permanently, or it can be disconnected by a clutch. When the drive output shaft is coaxial it can be connected to the main drive output shaft. 
         [0012]    Since only one clutch is arranged on the shafts, a powershiftable reversing transmission which is short in the axial direction is obtained, which bridges the distance between the drive input shaft and the drive output shaft of the powershiftable reversing transmission. Since both the clutch for forward driving and two fixed wheels are arranged on the shaft for forward driving, the drive output shaft for the front axle can be positioned on the same side as the drive input shaft in the powershiftable reversing transmission. In particular, a reversing transmission that can be fitted into a restricted space is obtained. 
         [0013]    Since during forward driving the drive unit can be realized with a small number of meshing gearwheels, the efficiency can be increased and gearing losses reduced. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0014]    Further characteristics emerge from the descriptions of the figures. 
           [0015]    These show: 
           [0016]      FIG. 1 : A schematic representation of the powershiftable reversing transmission; 
           [0017]      FIG. 2 : A spatial arrangement of the gearwheels and shafts of the powershiftable reversing transmission; 
           [0018]      FIG. 3 : A spatial arrangement of the gearwheels and shafts of the powershiftable reversing transmission; 
           [0019]      FIG. 4 : A spatial arrangement of the gearwheels and shafts of the powershiftable reversing transmission; 
           [0020]      FIG. 5 : An arrangement of the powershiftable reversing transmission in the vehicle; and 
           [0021]      FIG. 6 : A schematic representation of a cross-section through the vehicle. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     FIG.  1   
       [0022]    A drive input shaft  1  of the powershiftable reversing transmission can be driven by means of a hydrodynamic torque converter  29 , and a first fixed wheel  2  is connected rotationally fixed to the drive input shaft  1 . A fixed wheel is understood to mean a gearwheel connected to a shaft in a rotationally fixed manner. A loose wheel is understood to mean a gearwheel arranged on and able to rotate about a fixed shaft or a shaft rotating at a different rotational speed. A fourth loose wheel  26 , a fifth loose wheel  27  and a sixth loose wheel  28  are in permanent functional engagement with the first fixed wheel  2 . The fourth loose wheel  26  is mounted to rotate about the third gearshift shaft  8 , the fifth loose wheel  27  is mounted to rotate about the shaft  4  for forward driving and the sixth loose wheel  28  is mounted to rotate about the shaft  5  for reverse driving. The shaft  5  for reverse driving is connected in a rotationally fixed manner to a ninth fixed wheel  22 , which is in permanent functional engagement with the fourth fixed wheel  17  and with the eighth fixed wheel  21 . The fourth fixed wheel  17  is connected rotationally fixed to the third gearshift shaft  8 . The eighth fixed wheel  21  is connected rotationally fixed to the shaft  4  for forward driving. The seventh fixed wheel  20  is connected rotationally fixed to the shaft  4  for forward driving, and is in permanent functional engagement with the fifth fixed wheel  18 , which is connected rotationally fixed to the first gearshift shaft  6 . The eighth fixed wheel  21  is in permanent functional engagement with the second fixed wheel  15 , which is connected rotationally fixed to the second gearshift shaft  7 . The second loose wheel  24  is mounted to rotate about the second gearshift shaft  7  and is in permanent functional engagement with the third fixed wheel  16 , which is connected rotationally fixed to the drive output shaft  3 . The drive output shaft  3  can be connected to a front axle of the vehicle. The drive output shaft  3  and the drive input shaft  1  are arranged on the same side of the powershiftable reversing transmission. A further drive output shaft  30  can be connected directly to the drive output shaft  3  in a rotationally fixed manner, but a clutch can also be arranged between the further drive output shaft  30  and the drive output shaft  3 . The further drive output shaft  30  can be connected to a rear axle of the vehicle. It is also possible to bring the loose wheel  31  into engagement with the first loose wheel  23  and to connect a further drive output shaft  32  by way of a rear axle clutch  19  to the loose wheel. When the clutch  9  for forward driving is actuated in the closing direction, the fifth loose wheel  27  is connected in a rotationally fixed manner to the shaft  4  for forward driving and thus also to the seventh fixed wheel  20  and the eighth fixed wheel  21 . If the clutch  10  for reverse driving is actuated in the closing direction, the sixth loose wheel  28  is connected rotationally fixed to the shaft  5  for reverse driving and to the ninth fixed wheel  22 . When the first gearshift clutch  11  is actuated in the closing direction, the first loose wheel  23  is connected rotationally fixed to the first gearshift shaft  6  and to the fifth fixed wheel  18 . When the second gearshift clutch  12  is actuated in the closing direction, the second loose wheel  24  is connected rotationally fixed to the second gearshift shaft  7  and to the second fixed wheel  15 . If the third gearshift clutch  13  is actuated in the closing direction, the third loose wheel  25  is connected rotationally fixed to the drive output shaft  3  and to the third fixed wheel  16 . When the fourth gearshift clutch  14  is actuated in the closing direction, the fourth loose wheel  26  is connected rotationally fixed to the third gearshift shaft  8  and to the fourth fixed wheel  17 . Since the structure of the transmission is very narrow, an auxiliary power take-off  33  can be arranged on the reversing transmission, which is connected in a rotationally fixed manner to the input shaft in the converter. By appropriate actuation of the clutch  9  for forward driving, the clutch  10  for reverse driving, the first gearshift clutch  11 , the second gearshift clutch  12 , the third gearshift clutch  13  and the fourth gearshift clutch  14 , four gears in the forward direction and four gears in the reverse direction can be engaged. 
       FIG.  2   
       [0023]    The drive input shaft  1 , the third gearshift shaft  8 , the shaft  5  for reverse driving and the shaft  4  for forward driving are accommodated within the external radial dimensions of the housing  34  of the hydrodynamic torque converter. The drive output shaft  3 , the third fixed wheel  16  and the third loose wheel  26  are arranged outside the radial extension of the housing  34  of the hydrodynamic torque converter, whereby an axial distance can be realized between the drive input shaft  1  and the drive output shaft  3 . The shaft  5  for reverse driving, the shaft  4  for forward driving, the second gearshift shaft  7 , the drive output shaft  3 , the first gearshift shaft  6  and the further drive output shaft  32  are positioned below a plane  43  that extends horizontally in the vehicle, parallel to the ground on which the vehicle is standing and through the rotational axis of the drive input shaft  1 , whereas the third gearshift shaft  8  is arranged above that plane  43 . 
       FIG.  3   
       [0024]    The drive input shaft  1 , the third gearshift shaft  8 , the shaft  5  for reverse driving, the shaft  4  for forward driving and the further drive output shaft  32  are arranged within a radial extension of a housing  34  of the hydrodynamic torque converter, while the first gearshift shaft  6 , the second gearshift shaft  7  and the drive output shaft  3  are arranged outside this radial extension of the housing  34  of the hydrodynamic torque converter. The shaft  4  for forward driving, the second gearshift shaft  7 , the first gearshift shaft  6  and the drive output shaft  3  are positioned below a plane  43  that passes through the rotational axis of the drive input shaft  1 , whereas the third gearshift shaft  8  and the shaft  5  for reverse driving are above the plane  43 . Since the drive output shaft  3  is a distance away from the drive input shaft  1 , the lifting arm and its hydraulic cylinder can be positioned outside the housing  34  of the hydrodynamic torque converter, above the second fixed wheel  15 . In that way the lifting arm can be positioned lower down, which results in clearer vision in the vehicle. 
       FIG.  4   
       [0025]    The drive input shaft  1 , the third gearshift shaft  8 , the shaft  5  for reverse driving and the shaft  4  for forward driving are arranged within the radial extension of the housing  34  of the hydrodynamic torque converter. The first gearshift shaft  6 , the drive output shaft  3  and the second gearshift shaft  7  are arranged outside the housing  34 . The third gearshift shaft  8 , the shaft  5  for reverse driving, the shaft  4  for forward driving, the first gearshift shaft  6  and the drive output shaft  3  are arranged below a plane  43  passing through the rotational axis of the drive input shaft  1 . The second gearshift shaft  7  is arranged above the plane  43 . 
       FIG.  5   
       [0026]    The housing  34  of the hydrodynamic torque converter is connected, on the one hand, to a spur gear assembly  35  and, on the other hand, to the powershiftable reversing transmission. The drive output of the powershiftable reversing transmission is connected, on the one hand to a cardan shaft  42  for the front axle  38  and a cardan shaft  41  for the rear axle  37 . On the front axle  38  are arranged wheels  40  and on the rear axle  37  there are also wheels  40 . The vehicle has a frame  36 . 
       FIG.  6   
       [0027]    The frame  36  is recessed on one side so that the spur gear assembly  35  can connect the drive output of a drive engine (not shown) to the drive input of the powershiftable reversing transmission. The drive output shaft  3  of the powershiftable reversing transmission is arranged approximately centrally in order to drive the wheels  40  by way of a cardan shaft. The drive input shaft  1  of the powershiftable reversing transmission is both horizontally and vertically at a distance away from the drive output shaft  3 , whereby some fitting space is created above the powershiftable reversing transmission, in particular laterally, on the housing  34  of the hydrodynamic torque converter, in which space, the lifting arm or the lifting cylinder can be accommodated. The lifting cylinder of the vehicle is, on the one hand, articulated in the direction of the rear axle  37  on the vehicle frame  36  and, on the other hand, in the direction of the front axle  38  on the lifting arm. Since the components having the largest diameter, such as the housing  34  of the hydrodynamic torque converter, are arranged displaced toward the front axle  38 , the vehicle has more fitting space for the lifting cylinder. 
       INDEXES 
       [0000]    
       
           1  Drive input shaft 
           2  First fixed wheel 
           3  Drive output shaft 
           4  Shaft for forward driving 
           5  Shaft for reverse driving 
           6  First gearshift shaft 
           7  Second gearshift shaft 
           8  Third gearshift shaft 
           9  Clutch for forward driving 
           10  Clutch for reverse driving 
           11  First gearshift clutch 
           12  Second gearshift clutch 
           13  Third gearshift clutch 
           14  Fourth gearshift clutch 
           15  Second fixed wheel 
           16  Third fixed wheel 
           17  Fourth fixed wheel 
           18  Fifth fixed wheel 
           19  Rear axle clutch 
           20  Seventh fixed wheel 
           21  Eighth fixed wheel 
           22  ninth fixed wheel 
           23  First loose wheel 
           24  Second loose wheel 
           25  Third loose wheel 
           26  Fourth loose wheel 
           27  Fifth loose wheel 
           28  Sixth loose wheel 
           29  Torque converter 
           30  Further drive output shaft 
           31  Loose wheel 
           32  Further drive output shaft 
           33  Auxiliary power take-off 
           34  Housing of the hydrodynamic torque converter 
           35  Spur gear assembly 
           36  Frame 
           37  Rear axle 
           38  Front axle 
           39  Wheels 
           40  Wheels 
           41  Cardan shaft 
           42  Cardan shaft 
           43  Plane