Abstract:
A gearbox arrangement includes a gearbox housing, a first shaft supported in bearings in the housing, the first shaft containing a cavity which extends eccentrically to the axis of rotation of the first shaft, a second shaft supported in the cavity for rotation and having an end region projecting from the cavity and being provided with gear teeth, and a third shaft supported in the gear box housing for rotation, with the axis of rotation of the third shaft cooperating with the axis of rotation of the first shaft to define a plane. Leakage of lubricant from the housing is prevented by fastening a plate to the first shaft so as to prevent axial movement of the second shaft while containing an opening for the end region of the second shaft. Sealing devices are provided for all of the openings of the gearbox housing as well as for the opening in the plate in order to prevent the escape of lubricant from the gearbox housing.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention concerns a gearbox arrangement with a gear box housing, a gearbox chamber enclosed by the gearbox housing, a first shaft supported in bearings in the gearbox housing, a cavity configured eccentrically to the axis of rotation with the center of gravity of its cross section, a second shaft supported in bearings, free to rotate, in the cavity of the first shaft which is provided with at least one area of gear teeth and a shaft end section projecting axially out of the cavity of the first shaft a, and a third shaft supported in bearings in the gearbox housing whose axis of rotation extends at an angle to the plane lying on the axis of rotation of the first shaft. 
       BACKGROUND OF THE INVENTION 
       [0002]    Gearbox arrangements are known in the state of the art that are provided with gear rations arranged at angles to each other with gearbox shafts arranged within each other. Gearbox arrangements with gearbox shafts arranged within each other represent, among other factors, compact configuration and the possibility of attaining eccentric drives. Gearbox arrangements with eccentric drives are applied, for example, in agriculture for drives of cutterheads on front mowing attachments for combines. 
         [0003]    Such a gearbox arrangement is disclosed, for example in U.S. Pat. No. 6,273,214 B1. The gearbox arrangement is provided with a gearbox housing in which a gearbox shaft is supported in bearings that can be driven by an angle drive stage and is provided with a cavity that is located eccentrically. An eccentric shaft is supported in bearings in the cavity and is connected with a journal. The gearbox arrangement disclosed is operated with lubricating grease. In order to assure a sufficiently large supply of lubricating grease to the cavity, a channel is provided that connects a region of the gearbox arrangement with the cavity of the shaft. The lubricating grease deposited in the gearbox chamber can reach the cavity through the channel. The difficulty here lies in the sealing of the cavity relative to the gearbox housing or the sealing of the eccentric shaft relative to the gear box shaft, which requires a costly configuration for the axial securing of the eccentric shaft and a large assembly cost connected with it. Moreover, a further disadvantage results from the fact that the lubricating grease can escape through the openings of the gearbox housing or the gearbox shaft after only a few hours of operation and that topping off of the lubricating grease results in very short maintenance intervals. Furthermore, it is difficult to verify whether there still is a sufficient supply of lubricating grease in the interior of the gearbox arrangement. 
         [0004]    The purpose of the invention is seen in the need to define a gearbox arrangement of the type noted initially, through which one or more of the aforementioned problems are overcome. 
       SUMMARY OF THE INVENTION 
       [0005]    According to the present invention, there is provided an improved gearbox arrangement, especially an arrangement for reliably containing lubricating grease. 
         [0006]    According to the invention, a gearbox arrangement of the kind noted initially is configured in such a way that the gearbox arrangement is provided with a plate fastened to the first shaft, fixed against rotation, for immobilizing the second shaft in the axial direction, where an opening is provided in the plate for the shaft end region and that openings of the gearbox housing as well as the opening in the plate are provided with sealing devices that seal the lubricant located in the gearbox housing in order to prevent its escape between the gearbox housing and the first and the third shaft or between the plate and the second shaft. Since a plate is provided to immobilize the second shaft in the axial direction, on the one hand the cost of the assembly can be reduced considerably and poorly accessible snap rings can be avoided, and on the other hand, a sealing device can be placed in the opening, that seals the second shaft to the outside so that no lubricant can escape through a clearance gap between the second and the first shaft. The other sealing devices at the openings of the housing at the exits of the first and second shaft correspondingly seal the gearbox housing as effectively. All told, the sealing devices prevent leakage of lubricant which require short maintenance intervals at gear box arrangements known in the state of the art. With a gearbox arrangement according to the invention, the loss of lubricant through leakage and the cost of assembly can be reduced considerably and the maintenance intervals can be lengthened significantly. 
         [0007]    In a preferred embodiment of the invention, the plate is bolted to the end face of a shaft end region of the first shaft. The plate can be assembled and disassembled easily by the use of threaded bores distributed over the circumference at the edge of the end face of the first shaft, preferably three bores are used. Moreover, a further sealing device can be provided between the end face of the first shaft and the plate so that here, too, an escape of lubricant can be prevented. In addition to accommodating the sealing device for the second shaft, the plate is also used to protect the clearance gap against intruding dirt. 
         [0008]    Preferably, the gearbox housing is provided with one or more closure plugs arranged along the axis of rotation of the first shaft. The closure plugs are used to fill the gearbox arrangement with lubricant, to check the quantity of lubricant remaining or to create a drain opening for the lubricant. In that way, a closure plug arranged at a relatively high level can be used to fill the housing with lubricant, on the other hand a closure plug arranged at a relatively lower level can be opened to permit a drainage of lubricant or to check whether lubricant drains out of that opening. If no lubricant drains from that closure plug, then there is insufficient lubricant in the housing and must be topped off. Thereby, a costly disassembly of components during the maintenance can be avoided. 
         [0009]    Alternatively, a measuring rod can also be arranged on the housing wall that extends into the interior of the housing. 
         [0010]    The sealing devices are preferably configured as shaft sealing rings, for example, as radial packing rings that are inserted into the gearbox housing or in the cavity of the first shaft and are forced by ring-shaped garter springs against sealing sleeves of oil-resistant artificial rubber and are used to seal openings for shafts against leakage of lubricant or entry of dust. However, other sealing devices can be applied that seal a rotating shaft relative to an opening. 
         [0011]    A gearbox arrangement according to the invention has the advantage that gear oil can be used as a lubricant so that the entire gearbox arrangement can be operated with gear oil. In contrast to lubricating grease, gear oil has more advantageous temperature characteristics. Moreover, the maintenance process is simplified by the use of gear oil for the lubrication of the gear arrangement, since with the use of the closure plugs the filling up, measurement of the oil level and draining of the gear oil can be performed without any cost. Due to the arrangement according to the invention of corresponding shaft sealing rings, or other sealing devices, any leakage of gear oil is prevented. It should be noted here that other types of lubricants, particularly lubricating grease, can also be applied for the operation of the gearbox arrangement. 
         [0012]    The plate provided for the immobilizing of the second shaft and for the location of a sealing device for the sealing of the second shaft is preferably arranged in such a way that a bearing arranged in the first bearing region of the second shaft is immobilized axially at the first shaft by the plate. Thereby, snap rings for the immobilizing of the bearing of the second shaft in the axial direction that are poorly accessible or other costly attachment measures for the bearing of the second shaft can be omitted. By pressing the plate, the bearing located in the bearing region of the second shaft is forced against a step of the first shaft and retained there or immobilized. 
         [0013]    The second shaft is supported in bearings, free to rotate, in the cavity of the first shaft, where the second shaft is preferably configured as a one-piece component. Since the second shaft is configured as a one-piece component and, in particular, the shaft end region is configured as a part of the shaft, connecting components are omitted, the susceptibility to failure is reduced and the manufacturing process and the assembly are simplified. Preferably the second bearing region is arranged between the gear tooth area and the shaft end region. The second shaft may be supported bin bearings by two bearing seats spaced axially in the cavity of the first shaft. Preferably, the first bearing region of the second shaft is equipped with a rolling contact bearing, particularly a needle bearing, where the first bearing seat is preferably arranged in the area of the cavity opening of the channel in the interior of the gearbox interior of the first shaft. In view of the relatively small dimensions of a needle bearing, a compact configuration can be attained. The second bearing seat for a second rolling contact bearing is preferably arranged at a cavity opening located at the outside of the first shaft. The second rolling contact bearing is configured, for example, as a ball bearing and is located in the second bearing region of the second shaft. Obviously other combinations are conceivable with other types of rolling contact bearings. Moreover, it is conceivable that the bearing areas are also arranged directly alongside each other so that the shaft end region as well as the gear tooth area are freely arranged in bearings. Preferably the second shaft is configured in such a way that the maximum outside diameters in the various regions increase towards the shaft end region. Thereby, a shaft end region with a relatively large outside diameter is attained whereby a shaft step towards the shaft end region is used as an axial security device for the second rolling contact bearing. Moreover, a simple pre-assembly of the second rolling contact bearing on the shaft is thereby attained, so that the second shaft can be assembled in one working cycle and particularly the assembly time or the maintenance time for the gearbox arrangement are shortened. 
         [0014]    The gear tooth region configured between the at least one bearing region and the shaft end region meshes with a set of gear teeth connected to the gearbox housing, fixed against rotation, preferably an internal gear. For this purpose, the cavity of the first shaft is provided with a radial opening that extends over a part of the circumference of the first shaft and partially frees the gear tooth region. 
         [0015]    A rotation of the second shaft can be attained in itself in the cavity of the first shaft by the meshing of the gear tooth region with the set of gear teeth connected, fixed against rotation, with the gearbox housing, so that a superposition of an eccentric movement of the second shaft about the axis of rotation of the first shaft can be attained with a rotational movement of the second shaft about its own axis of rotation. 
         [0016]    The gearbox arrangement is provided with a third shaft, supported in bearings in the gearbox housing, whose axis of rotation extends at an angle to the plane lying on the axis of rotation of the first shaft. Preferably, the third shaft is arranged in such a way that the axes of rotation of the first shaft and that of the third shaft intersect in a point and thereby lie in a common plane and extend at an angle of approximately 90°. It is also possible, however, to arrange the third shaft in an offset position, so that the axes of rotation of the first and the third shafts do not lie in a common plane. Moreover, it is also possible to arrange the shafts so that they extend at a larger or a smaller angle to each other. 
         [0017]    The third shaft is preferably supported in bearings axially loose in a first bearing, where the first bearing of the third shaft is configured as a roller bearing, in particular a needle bearing. Here is it also possible to apply other types of rolling contact bearings, for example, a ball bearing that is immobilized axially in both directions on a shaft or in a bearing seat and the shaft is supported in bearings so that it is axially loose. The use of a needle bearing as a loose bearing has the advantage that the shaft can be configured very compactly and simply. 
         [0018]    The third shaft is preferably immobilized axially in both directions in the gearbox housing in a second bearing. Preferably the second bearing of the third shaft is configured as a rolling contact bearing, particularly a ball bearing, that is immobilized axially by a step on the gearbox housing towards the interior of the gearbox housing and by a snap ring at the gearbox housing to the outside of the gearbox housing. By immobilizing it in both directions of the gearbox hosing by means of a snap ring, it is possible to pre-assemble the third shaft and to insert it into the gearbox housing in a single working cycle. Thereby, assembly time and maintenance time can be reduced. 
         [0019]    The gearbox arrangement is provided with a gear arranged on the third shaft that can be immobilized in one direction axially by a snap ring. With the use of a snap ring for the fastening of a gear, a step on the shaft that is costly to manufacture can be avoided whereby the entire shaft can be configured more simply and as a result the manufacturing cost can be reduced. 
         [0020]    A gear fastened to the first shaft meshes with the gear fastened to the third shaft, where the gear of the first shaft is immobilized in the first bearing of the first shaft radically to the axis of rotation of the first shaft and applies an axial force with respect to the third shaft. 
         [0021]    The third shaft is immobilized in both directions by the axial force and the snap ring arranged at the gearbox housing for the second bearing of the third shaft. 
         [0022]    The interior of the gearbox hosing is connected with the surroundings of the gearbox housing by a ventilation arrangement provided on the gearbox housing, for example, on a gearbox hosing cover, the ventilation arrangement may be a ventilation opening, a small ventilation tube, a ventilation valve, an over-pressure valve or the like. Through the connection with the surroundings, a pressure equalization can take place between the interior of the gearbox arrangement and the surroundings, so that operating temperatures can be reduced and the durability can be increased. 
         [0023]    The gearbox arrangement is preferably provided with a journal that extends axially out of the shaft end section axially and eccentrically to the axis of rotation of the second shaft. Here the journal may be a part of the on-piece second shaft or it may be connected to the second shaft by connecting devices. The rotation of the first and the second shafts results in a superposition of an eccentric rotational movement of the axis of rotation of the second shaft about the axis of rotation of the first shaft and an additional eccentric rotational movement of the journal about the axis of rotation of the second shaft. Thereby, the journal is used to transmit the superimposed eccentric movements into corresponding linear movements on an arrangement that can be drive, for example, a cutter head. 
         [0024]    In order to transmit the rotational movements, the journal is preferably equipped with a rolling contact bearing that can be connected with a bearing pan which is connected with an arrangement that can be driven. Depending on the rotational speed of the journal or the shafts and the forces to be transmitted, a sliding bearing could be used instead of the rolling contact bearing, the sliding contact bearing may, for example, be provided in the form of a sliding bushing. The rolling contact bearing of the journal may be configured as a roller bearing. The rolling contact bearing is enclosed in a bushing that is preferably configured in the shape of a ring and is provided with a spherically bowed outer surface. The rolling contact bearing is taken up in the bushing by means of a race of the rolling contact bearing that is pressed into the inner surface of the bushing. The spherically bowed outer surface in turn, is taken up by a bearing pan that is configured with an inner surface congruent to the outer surface of the bushing. The spherical surfaces permit a relative movement of the parts to each other so that an angle of inclination of the parts to each other can be adjusted between the journal and the arrangement to be driven or between the longitudinal axis of the journal and the rotational axis of symmetry of the bearing pan, whereby tolerance problems during the transmission of movements can be overcome. Moreover, it is possible to configure the bearing as a ball bearing whose outer race is engaged in a corresponding bushing. Here a needle bearing is used that includes an outer race with a spherically bowed outer surface. Another type of rolling contact bearing could also be used, for example, a ball bearing or a roller bearing could be provided with an outer race with such a shape. 
         [0025]    The bushing that engages the outer race as well as the bearing pan that encloses the bushing are configured as closed around their circumference. Recesses or openings are provided on the bearing pan located opposite each other in the radial direction and that extend axially to the axis of rotational symmetry of the bearing pan along the inner surface of the bearing pan. The openings are dimensioned in such a way that when the bushing engages the bearing pan the bushing can be inserted in its width transverse to its axis of rotational symmetry and by pivoting through 90° the outer surface of the bushing is oriented to the inner surface of the bearing pan and brought into bearing position. Previous configurations are provided with a bushing that is open around its circumference or is slotted, mostly of plastic, that is engaged by a bearing pan with an open configuration. The slotted bushing is stretched around the rolling contact bearing of the journal by a stretching arrangement at the bearing pan. Since the bushing and the bearing pan are configured as closed around their circumference, on the one hand the connection between the rolling contact bearing and the bushing or the bearing pan can be made without any costly stretching arrangements, on the other hand stronger materials and materials more resistant to wear can be used and thereby the maintenance intervals can be lengthened and the susceptibility to failure can be reduced. Moreover, the result is also a lower bearing clearance. A gearbox arrangement with a rolling contact bearing for the journal and the use of a bushing and a bearing pan that are configured as closed in the above described configuration and are provided with spherical surfaces, can be seen as an independent invention 
         [0026]    The bearing pan for the rolling contact bearing of the journal is preferably connected to connecting devices, particularly connecting devices for the connection with a cutter head. For example, the bearing pan is connected directly with a guide rod or a drive rod, through which a cutter movement is brought about. The connection with the bearing pan can be made, for example, by welding or bolting. Moreover, it is possible to configure the bearing pan and the connecting device as a one-piece component, for example, to forge or to cast it. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0027]    The drawing shows and embodiment of the invention on the basis of which the invention as well as its advantages and the advantageous further developments and embodiments of the invention shall be explained and described in greater detail in the following. 
           [0028]      FIG. 1  is a cross sectional view of a gearbox arrangement constructed in accordance with the principles of the present invention. 
           [0029]      FIG. 2  is a side view of the gearbox arrangement of  FIG. 1 . 
           [0030]      FIG. 3  is a perspective view of the gearbox arrangement of  FIG. 1 . 
           [0031]      FIG. 4  is a detailed view of the second shaft of the gearbox arrangement of  FIG. 1 . 
           [0032]      FIG. 5  is a plan view of the shaft end section of the second shaft shown if  FIG. 4 . 
           [0033]      FIG. 6  is a side view of a journal arrangement of the gearbox arrangement of  FIG. 1 . 
           [0034]      FIG. 7  is a plan view of the journal arrangement of  FIG. 6 . 
           [0035]      FIG. 8  is a plan view of the plate of the gearbox arrangement of  FIG. 1  with an opening for the second shaft. 
           [0036]      FIG. 9  is a cross sectional view of the plate shown in  FIG. 8 . 
           [0037]      FIG. 10  is a cross sectional view of a bearing for a journal of the gearbox arrangement shown in  FIG. 1   
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0038]      FIGS. 1 through 3  show a gearbox arrangement  10  constructed in accordance with the present invention, with a gearbox chamber  12  of an angle gearbox  14  being surrounded by a housing  16 . The gearbox housing  16  extends generally rotationally symmetrical along an axis of rotation  18  of a first shaft  20 , where the axis of rotation  18  defines the longitudinal direction of the gearbox arrangement  10 . the gearbox chamber  12  is subdivided into a first gearbox chamber region  22 , that generally surrounds the first shaft  20 , and a second gearbox chamber region  24 , that generally surrounds a third shaft  26  arranged transverse to the longitudinal direction. The gearbox chamber regions  22 ,  24  are configured as adjoining each other in the longitudinal direction and are provided with a common cylindrical transition region  28 , that is arranged approximately in the center of the longitudinal extent of the gearbox housing  16  and coaxially to the axis of rotation  18 , and through which an axial connection of the gearbox chamber regions  22 ,  24  is defined. 
         [0039]    The gearbox housing  16  is provided with a first cylindrical opening  30  in the first gearbox chamber region  22 , that is oriented coaxially to the axis of rotation  18  and that opens the first gearbox chamber region  22  axially to the outside. Moreover, the gearbox housing  16  is provided with first, second and third cylindrical openings  32 ,  34  and  36 , respectively, in the second gearbox chamber region  24 . The second opening  32  is oriented coaxially to the axis of rotation  18  and opens the second gearbox chamber region  24  axially to the outside. the third and fourth openings  34 , and  36 , respectively are arranged to either side of the axis of rotation  18  and coaxially to an axis of rotation at the third shaft  26  arranged transverse to the axis of rotation  18 . 
         [0040]    A first bearing  40  is arranged in the common transition region  28 , and a second bearing  42  is arranged in the first opening  30  in the first gear box chamber region  22  for the first shaft  20 . A step  44  is formed onto the common transition region  24  which axially immobilizes the bearing  40  in the direction of the first opening  30 . A step  46  is formed onto the first opening  30  that axially immobilizes the bearing  42  in the direction of the common transition region  28 . The bearings  40 ,  42  are preferably configured as rolling contact bearings and as an example are pictured in  FIG. 1  as ball bearings. The first shaft  20  is supported in the bearings  40  and  42 , free to rotate, in the gearbox housing  16  or the first gearbox chamber region  22 . Moreover, a first shaft seal ring  47 , for example, a radial packing ring, is provided at the first opening  30  adjacent to the second bearing  42  that seals the clearance gap between the first opening  30  and the first shaft  20  to the outside. 
         [0041]    A housing cover  48  is provided in the second gearbox chamber region  24  at the second opening  32  that encloses the second gearbox chamber  12  axially to the surroundings. 
         [0042]    A first bearing  49  is arranged in the second gearbox chamber region  24  at the third opening  34 , and a second bearing  50  in the fourth opening  36  for the third shaft  26 . A step  52  is formed onto the fourth opening  36  that axially immobilizes the bearing  50  in the direction of the third opening  34 . Moreover, a ring groove  56  is formed onto the fourth opening  36  and is provided with a snap ring  54 , whereby the bearing  50  is also immobilized in the opposite direction. The bearing  49  is freely supported and arranged in the third opening  34 . The bearings  49 ,  50  are preferably configured as rolling contact bearings, where in the case of the bearing  49  a roller bearing in the form of a needle bearing is used, as can be seen in  FIG. 1 . In the form pictured, the bearing  50  is configured as a ball bearing, where here a roller bearing could also be applied. The third shaft  26  engages the bearing  49  and  50  and is supported in these bearings, free to rotate, in the gearbox housing  16  or in the second gearbox chamber region  24 . Moreover, a second shaft sealing ring  57 , for example, a radial packing ring sealing to the outside, is arranged at the fourth opening  36  adjacent to the snap ring  54 , that seals the clearance gap between the fourth opening  36  and the third shaft  26 . A bearing bushing  58 , provided at the third opening  34 , seals the third opening  34  to the outside. 
         [0043]    Moreover, a further step  59  is provided in the first gearbox chamber region  22  between the bearings  40 ,  42 , to which an internal gear  60  is fastened. The internal gear  60  is bolted to the gearbox housing  16  by means of screws  62  distributed around the circumference of the step  59  (see  FIG. 2 ). 
         [0044]    The first shaft  20  extends through the entire first gearbox chamber region  22  and is provided with a shaft end region  64  that projects out of the first opening  30  and essentially covers the entire diameter of the first opening  30 . Starting from the shaft end region  64 , a first shaft step  65  adjoins a shaft seal ring region  65 ′ for the first shaft seal ring  47 . Starting from the shaft end region  64  a second shaft step  66  is formed that adjoins a bearing region  68  for the second bearing  42 . A third shaft step  70  is formed adjoining the bearing region  68  that in turn adjoins a central shaft region  72 . The central shaft region  72  ends in a fourth shaft step  74 . The fourth shaft step  74  is followed by a fifth shaft step  76  that, in turn, adjoins a shaft journal  78 , where the shaft journal  78  extends through the common transition region  28  in the second gearbox chamber region  24 . A first bevel gear  80  is supported in bearings on the shaft journal  78 , it is connected, fixed against rotation, by means of a spring/groove connection  82  to the first shaft  20  or the shaft journal  78 . The shaft journal  78  is equipped with a shaft nut  84 . A bearing region  86  is configured on the first bevel gear  80  through which the first shaft  20  is engaged in the first bearing  40 . 
         [0045]    The first shaft  20  is provided with a cavity  88 . The cavity  88  is configured generally cylindrical about an axis of rotation  90  where the axis of rotation  90  is arranged parallel to the axis of rotation  18  and eccentrically to the first shaft  20 . The cavity  88  is provided with a cylindrical opening  92  that opens the cavity  88  to the shaft end  64  of the first shaft  20  axially to the axis of rotation  90 . Starting from the opening  92 , the cavity  88  is provided with first and second steps  94 ,  96  and ends in a cavity floor  98 . Between the first and the second steps  94 ,  96 , the cavity  88  is provided with an opening  100  at the level of the internal gear  60 , opening  100  extends radially and axially to the axis of rotation  90  along the wall of the cavity and opens a partial region of the wall of the cavity towards the internal gear  60 . 
         [0046]    A first bearing seat  102  is a configured to accept a first bearing  104  for a second shaft  206  between the second step  96  and the cavity  88  and the cavity floor  98 . A second bearing seat  108  is configured to accept a second bearing  110  for the second shaft  106  between the opening  92  of the cavity  88  and the step  94 . The second bearing  110  is secured axially by means of a plate  112  bolted to the end face  11  of the shaft end region  64 , in that the outer race of the second bearing  110  is pressed against the first step  94 . 
         [0047]    The first and second bearings  104 ,  110  for the second shaft  106  are configured as rolling contact bearings, where for the first bearing  104  a roller bearing is provided in the form of a needle bearing, and for the second bearing  110  a ball bearing is provided, as is shown in  FIG. 1 . 
         [0048]    The second shaft  106  extends through the entire cavity  88  of the first shaft  20  and is provided with a shaft end region  113  projecting out of the first opening  92  of the first shaft  20  (see  FIG. 4 ). Starting from the shaft end region  113 , the second shaft  106  is provided with a first shaft step  114  that adjoins a bearing region  116  for the second bearing  110 . Adjoining the bearing region  116 , a ring groove  116  is configured that accepts a snap ring  120  (shown in  FIG. 1 ). The ring groove  118  adjoins a second shaft step  122  that ends in a gear tooth area  124  of the second shaft  106 . The gear tooth region  124  of the second shaft  106  extends axially between the shaft steps  94 ,  96  of the cavity  88  and ends in a third shaft step  126 . The third shaft step  126  adjoins a shaft journal  128  on which a bearing region  130  for the first bearing  104  is provided. 
         [0049]    The third shaft  26  extends through the entire second gearbox chamber region  24  and is provided with a shaft end region  132  projecting out of the fourth opening  36  (see  FIG. 1 ). The shaft end region  132  is provided with a shaft nut  134 . Starting from the shaft end region  132 , the third shaft  26  is provided with a shaft region  136  that adjoins a ring groove  138  where a part of the shaft region  136  projects out of the fourth opening  36 . The ring groove  138  accommodates a snap ring  140 . A shaft step  142  is provided between the ring groove  138  and the third opening  34 , it adjoins a shaft journal  144 . A bearing region  146  is provided on the shaft journal  144  that engages the first bearing  49  of the second gearbox chamber region  24 . a second bevel gear  148  is supported in bearings on the shaft region  136 , it is connected with the third shaft  26 , fixed against rotation, by means of a spring/groove connection  150 . A bearing region  152  is configured on the second bevel gear  148  by means of which the third shaft is engaged in the second bearing  50 . Moreover, a belt pulley  154  is provided on the part of the shaft region  136  projecting out of the fourth opening  36 , the belt pulley is also connected to the third shaft  26 , fixed against rotation, by means of the spring/groove connection  150 . 
         [0050]    The shaft journal  78  of the first shaft  20  is equipped with a channel  156  that is provided, starting from the end of the shaft journal  78 , with a gearbox chamber opening  158  and a cavity opening  160 . 
         [0051]    The gearbox chamber opening  158  is arranged concentrically to the axis of rotation  18  of the first shaft  20 . The cavity opening  160  of the channel  156  is arranged eccentrically to the axis of rotation  18  of the first shaft  20  in the area of the cavity floor  98 . The gearbox chamber opening  158  is provided with a thread  161  and a component  162 , in particular a closure plug that is configured as an internal hex head or Allen head screw. The component  162  is provided with a bore  164 . The component  162  and the bore  164  are arranged concentrically to the axis of rotation  18 . 
         [0052]    The housing cover  48  is provided with a bore  166  into which a ventilation arrangement  168  is inserted. The ventilating arrangement  168  is configured in the form of a pipe arrangement and extends into the interior of the second gearbox chamber region  24  (see  FIG. 1 ). A filter  172  is arranged in the head  170  of the ventilating arrangement. 
         [0053]    The plate  112  arranged for the immobilizing of the second shaft  106  is pictured in  FIGS. 8 and 9 . Corresponding to the diameter of the shaft end region  64 , the plate  112  is configured cylindricalloy and concentric to the axis of rotation  18  and is provided with an opening  174  for the projection of the shaft end region  113  of the second shaft  106 . Corresponding to the eccentric movement of the second shaft  106 , the opening  174  is arranged eccentrically to the axis of rotation  18 . The opening  174  is provided with a step  176  in which a third shaft seal ring  178  is arranged, sealing to the outside, for example, a radial packing ring. The shaft seal ring  178  seals the clearance gap between the opening  174  and the second shaft  106 . Moreover, the plate  112  is provided with bores  180  that are arranged distributed around its circumference. In the embodiment shown, three bores  180  are provided. The bores  180  are used for the bolting of the plate  112  into threaded bores  182  provided correspondingly in the shaft end region  64 . A sealing layer or a coating(not shown) may be provided for the sealing of the plate  112  with respect to the end face  11  that prevents an escape of lubricant between the plate  112  and end face  111 . 
         [0054]    The shaft end region  113  of the second shaft  106  is provided with connecting devices  190  that are configured in the form of a flange arrangement connected radially, as is shown in  FIGS. 4  and . The connecting devices  190  include U-shaped projections  192  projecting axially from the shaft end region  113  of the second shaft  106  which are provided with two legs  194  extending transverse to the axis of rotation  90  on the end face of the shaft end region  113 . A free space  196  is developed between the legs  194 . Threaded bores  198  are provided on the end faces of the legs  194 , where the end faces of the legs  194  extend at an angle to the floor of the free space  196  that is less than 90°. The end face of the shaft region  113  is provided with a threaded bore  200 . 
         [0055]    Moreover, the gearbox arrangement  10  is provided with a journal arrangement  202  that is connected with the shaft end region  113  of the second shaft  106 . The journal arrangement  202  is shown in greater detail in  FIGS. 6 and 7 . The journal arrangement  202  is provided with a journal  204  with a journal axis  206  and connecting devices  208  in the form of a flange arrangement that provides a radial connection. The connecting devices  208  include a plate  210  on which a bridge  212  extended in the radial direction to the axis of the journal  2006 . The plate  210  is located at a height that corresponds generally to the height of the U-shaped projection  192 . The journal  204  extends axially to the journal axis  206  from the plate  210 . The bridge  212  is configured in such a way that it is generally provided with the shape and the height of the free space  196 . Connecting surfaces  214  are configured to the sides of the bridge  212 , these connecting surfaces being slightly chamfered relative to the faces of the legs  194 . The plate  210  is provided with bores  216  that conform in size and spacing to the threaded bores  198 . Moreover, the journal  204  is provided with a threaded bore  217  arranged on its end face concentric to the journal axis  206 . 
         [0056]    The journal arrangement  202  or the journal  204  is equipped with a bearing arrangement  232  (see  FIG. 10 ), it is connected by means of connecting devices  234  for the operation of a cutter head (not shown). The bearing arrangement  232  includes a rolling contact bearing  236  with an inner race  237 , and outer race  238  and a bushing  240  that is closed around its circumference, a bearing pan  242  closed around its circumference, where the bearing pan  242  establishes the connection with the connecting devices  234 , an attachment plate  244  and an attaching screw  246 . The rolling contact bearing  236  is configured as a roller bearing and engages the journal  204  with its inner race  237 . The bushing  240  engages the outer race  238 . The bushing  240  is supported in bearings in the bearing pan  242 . The bushing  240  is provided with an outer surface that is configured spherically curved to the outside and arranged radially to the axis of rotation  206  of the journal  204 . The bearing pan  242  is provided with an inner surface that is curved spherically inward congruent to the outer surface of the bushing  240  radially to the axis of rotation  206  of the journal  204 . The bearing pan  242  is provided with recesses located radially opposite each other (not shown) that extend axially to the axis of the journal  206  along the inner surface of the bearing pan  242 . Here the curvature of the spherical surfaces of the bushing  240  or the bearing pan  242  are provided with a radius of curvature that corresponds to the maximum outer radius of the bushing  240  or the maximum inner radius of the bearing pan  242 . The recesses are used for the insertion of the bushing  240  into the bearing pan  242 . The connecting device  234  is configured in the form of a guide rod that is rigidly connected to the bearing pan  242  or is configured as a one-piece component with the bearing pan  242 . The connecting device  234  is connected by means of a connecting rod and screws to a cuter head mechanism (not shown). 
         [0057]    The following will briefly go into the assembly as well as the relevant advantages of the gearbox arrangement  10 . 
         [0058]    Starting from the gearbox housing  16 , this is equipped with the fre space  60  and provided with the second bearing  42  for the first shaft  20  as well as the first shaft seal ring  47 . Following this, the first shaft is inserted into the first gearbox chamber region  22  through the first opening  30 , the first bevel gear  80 , preassembled with the second bearing  40  is guided over the shaft journal  78  over the second opening  32  of the second gearbox chamber region  24 . The bevel gear  80  and the shaft step  76  are clamped axially by the shaft nut  94  and the shaft step  76  and the first shaft  20  is secured axially. 
         [0059]    The second shaft  106  is preassembled with the first bearing  104  and the second bearing  110 , where the second bearing  110  is secured axially by the snap ring  120  in the ring groove  118 . The preassembled second shaft  106  is conducted into the cavity  88  of the first shaft  20  and immobilized axially by the plate  112  that was preassembled with the third shaft seal ring  178 . 
         [0060]    The third shaft  26  is preassembled to such a degree that the shaft journal  144  is equipped with the first bearing  49  and the second bevel gear  148  with the preassembled second bearing  50  is forced against the snap ring  140  fastened on the third shaft  26  in the ring groove  138 . Immediately following, the preassembled third shaft  26  is conducted over the fourth opening  36  in the second gearbox chamber region  24  and the second bearing  50  is immobilized with the snap ring  54  in the ring groove  56 . After installing the second shaft seal ring  57 , the belt pulley  154  is conducted over the shaft end  132  and forced against the second bevel gear  148 . The belt pulley  154  and the second bevel gear  148  are clamped against each other axially on the third shaft  26  by the shaft nut  134  and the snap ring  140   
         [0061]    The connecting devices  190 ,  208  of the shaft end region  113  and the journal arrangement  202  are connected to each other by inserting the bridge  212  into the free space  196  and by bolting the plate  210  to the legs  194  over the bores  198  and  216 . By connecting the connecting devices  190 ,  208  the journal  204  is immobilized eccentrically to the axis of rotation  90  of the second shaft  106 . 
         [0062]    The bearing arrangement  232  and the journal  202  are assembled by inserting the journal  202  into the inner race  237  of the rolling contact bearing  236 . The bushing  240  is inserted transverse to the bearing pan  242  into the recesses, so that the radii of the bushing  240  and the bearing pan  242  extend perpendicularly to each other, (until the center of the bushing lies approximately at the level of the center of the bearing pan). By subsequently orienting the busing  240  toward the bearing pan  242 , (so that the radii of the bushing  240  and the bearing pan  242  extend parallel to each other, then the bushing is brought into a position in which it is immobilized by the bearing pan  242  axially and radially to the axis of rotation of the journal  206 . However, the busing  240  may be rotated about any desirable axis of rotation that extends through the center of the bearing pan, that is located perpendicular to the axis of rotation  206 . Immediately following thereto the bushing  240  is slid over the outer race  238  and connected to the journal  204  along with the rolling contact bearing  236  together with the bushing  240  by means of the fastening disk  244  and the fastening screw  246 . The spherical configuration of the bushing  240  or the bearing pan  242  permits an equalization movement of the connecting devices  234  or the connecting rod about an axis extending perpendicularly to the axis of rotation  206  of the journal  204 . The closed configuration of the bushing  240  and the bearing pan  242  increase the stability and the resistance to wear of the bearing arrangement  232  and simplify the assembly, since conventional clamping arrangements for the bearing pan  242  can be omitted. 
         [0063]    The gearbox arrangement  10  is driven by means of the belt pulley  154  on the third shaft  26 . The first shaft  20  is driven about the axis of rotation  18  by means of the angle gearbox configured by the two bevel gears  80 ,  148 . The rotational movement of the first shaft  20  brings about, on the one hand, a rotational movement of the second shaft  106  itself about the axis of rotation  90 , since the second shaft  106  meshes with the cavity  60  over the gear tooth region  124  through the cavity opening  100 . The journal  204  connected to the shaft end region  113  of the second shaft  106  by means of the connecting devices  19 ,  208 , which is arranged eccentrically to the axis of rotation of the second shaft  106 , thereby experiences an eccentric rotational movement about the axis of rotation  18  of the first shaft  20  that is superimposed by an eccentric rotational movement about the rotational axis  90  of the second shaft  106 . 
         [0064]    As shown in  FIGS. 2 and 3 , closure plugs  252 ,  254  are provided that are spaced at intervals along the axis of rotation  18 , where an upper closure plug  252  is provided for the filling of the housing  16  with lubricant or gear oil, and a lower closure plug  254  is provided for draining the lubricant or gear oil. The closure plugs  252 ,  254  may be configured as screws that are screwed into the housing  16 . The position of the upper closure plug  252  represents a maximum fill level for the lubricant or gear oil and is selected in such a way that the gearbox housing  16  can be filled with lubricant or gear oil so as to reach the region of the third shaft  26 , on the other hand, the position of the lower closure plug  254  represents a minimum fill level for the lubricant or gear oil that is arranged in the common cylindrical transition region  28 . The cross section passage area of the channel  156  is clearly reduced by the component  162  inserted into the gearbox chamber opening  158  or the bore  164  provided in the component  162 . Since the cavity opening  160  is arranged eccentrically to the gearbox chamber opening  158  or to the axis of rotation  18 , a suction develops when the first shaft  20  rotates which conveys the existing lubricant from the gearbox chamber opening  158  through the channel  156  to the cavity opening  160 . The cross section passage area of the channel  156  reduced by the component  162  has the effect that a reduced amount of lubricant reaches the cavity  88 . By having the bore  164  conform to the needs, the lubricating effect can be made to conform to the power requirements of the gearbox arrangement in a simple manner so that the lubricant conveyed through the channel corresponds to an optimum amount. 
         [0065]    The ventilation arrangement  168  inserted into the housing cover  48  is used for the ventilation of the gearbox arrangement  10 . In contrast to conventional arrangements, it has the advantage that the pipe section is configured very long in comparison to the diameter of the head  170 . Thereby, the contamination of the filter element  172  can be slowed since, on the one hand, lubricant vapor ascending through the pipe can be deposited on the inside will of the pipe, one the other hand, foaming or splashing lubricant does not reach the filter so as directly to contaminate it. 
         [0066]    All in all, the embodiments according to the invention of the gearbox arrangement permit the maintenance intervals to be lengthened, the temperature and pressure relationships in the gearbox housing  16  to be clearly improved and the cost of assembly to be significantly reduced. 
         [0067]    Although the invention has been described on the basis of only one embodiment, anyone skilled in the art will perceive many varied alternative, modifications and variations, in the light of the foregoing description as well as the drawing, all of which fall under the present invention. 
         [0068]    Having described the preferred embodiment, it will become apparent that various modifications can be made without departing from the scope of the invention as defined in the accompanying claims.