Abstract:
An adjusting device for positioning a load comprises a threaded spindle, which is connected in the region of a longitudinal end to a carrier toothed wheel so as to be fixed with respect to rotation relative to it and so as to be fixed with respect to displacement axially, and a spindle nut which is arranged on the spindle thread and which is displaceable axially by means of a rotation of the threaded spindle for positioning the load. A fastening portion of the threaded spindle which is formed in the region of the longitudinal end of the threaded spindle has, in addition to a cylindrical portion which is received by a cylindrical portion of the through-opening of the carrier toothed wheel and in which torque is transmitted between the carrier toothed wheel and the fastening portion by a key, another conical portion which is situated closer to the longitudinal center of the threaded spindle and which widens in direction of the longitudinal center of the threaded spindle and which is received by a conical portion of the through-opening of the carrier toothed wheel, wherein the conical portion of the fastening portion and the conical portion of the carrier toothed wheel are clamped against one another by a clamping nut.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     This application claims priority of Austrian Application No. GM 454/2005, filed Jul. 5, 2005, the complete disclosure of which is hereby incorporated by reference.  
       BACKGROUND OF THE INVENTION  
       [0002]     a) Field of the Invention  
         [0003]     The invention is directed to an adjusting device for positioning a load. The adjusting device comprises a threaded spindle which is connected in the region of a longitudinal end to a carrier toothed wheel, particularly in the form of a worm gear, so as to be fixed with respect to rotation relative to it and so as to be fixed with respect to displacement axially, which carrier toothed wheel is rotatably mounted in a gear unit housing and can be set in rotation by means of a driving toothed wheel, particularly in the form of a worm, whose teeth engage in the teeth of the carrier toothed wheel. The adjusting device further comprises a spindle nut which is arranged on the spindle thread and which is displaceable axially by means of a rotation of the threaded spindle for positioning the load. A fastening portion of the threaded spindle which is formed in the region of the longitudinal end of the threaded spindle and along which the spindle thread is at least partially turned penetrates a central opening through the carrier toothed wheel and is connected to the carrier toothed wheel by a key and, further, is provided with a screw thread in an end portion projecting out of the through-opening of the carrier toothed wheel, a clamping nut which clamps the threaded spindle against the carrier toothed wheel being screwed onto this screw thread.  
         [0004]     b) Description of the Related Art  
         [0005]     Adjusting devices of the type mentioned above are known and are also called spindle lifting gear units, spindle nut gear units, or actuating drive units. Adjusting devices of this type are used for positioning loads in the form of structural component parts or component groups. For example, these adjusting devices are used in lifting platforms, lifting jacks, vertically adjustable platforms, valves with valve slides that are adjustable by motor, forms for concrete that are adjustable by motor, and so on.  
         [0006]     In adjusting devices of this kind, rotational movements (of the drive motors or crank mechanisms) are transformed into linear movements either of the threaded spindle or of a spindle nut arranged on the thread of the threaded spindle. In the first instance, in contrast to the generic type, a carrying nut is rotatably mounted in a gear unit housing, and the threaded spindle, which is not rotatable, is displaced in axial direction by rotating the carrying nut. In the second instance, the threaded spindle is connected to a carrier toothed wheel, usually in the form of a worm gear, so as to be fixed with respect to rotation relative to it, this carrier toothed wheel being rotatably mounted in the gear unit housing. When the carrier toothed wheel, and therefore the threaded spindle, is rotated a spindle nut which is arranged on the thread of the threaded spindle and fixed with respect to rotation is displaced in axial direction of the threaded spindle.  
         [0007]     As regards spindle nut gear units in which the threaded spindle is rotatable and is connected to the carrier toothed wheel, usually a worm gear, so as to be fixed with respect to rotation relative to it, there are various known constructions for connecting the threaded spindle to the carrier toothed wheel.  
         [0008]     In a first conventional embodiment form, a threaded rod with a continuous thread (in the form of a trapezoid thread) which is turned along an end portion to form a cylindrical shaft is used as the starting product for the threaded spindle. A spacer sleeve is first slipped onto this end portion and contacts the step between the cylindrical shaft and the beginning of the thread. The carrier toothed wheel is then slipped onto the cylindrical shaft and contacts the spacer sleeve at one side. In the region of the free end of the shaft, this shaft is provided with a fine-pitch thread (i.e., a screw thread) on which the clamping nut is screwed. This clamping nut clamps the carrier toothed wheel and the spacer sleeve against the step between the shaft and the spindle thread of the spindle. Further, in order to prevent rotation, a key is inserted into the cylindrical shaft and engages in a corresponding recess in the carrier toothed wheel. While this connection between the spindle and the worm gear can be produced relatively simply and, further, a threaded rod which can be commercially obtained inexpensively as a piece good can be used as a starting product for the threaded spindle, the problem arises that the step between the spindle thread and the cylindrical shaft does not present a uniform contact surface for the spacer sleeve because of the turned, helically extending thread. The clamping of the carrier toothed wheel and the spacer sleeve against this shoulder can lead to axial bending between the longitudinal axis of the cylindrical shaft and the threaded portion of the threaded spindle resulting in unwanted eccentricity. However, it is not practicable to enlarge this step while reducing the diameter of the shaft at a given diameter of the threaded spindle because of the torques and possible tensile forces to be absorbed by the cylindrical shaft. Axial bearings are arranged on shoulders provided at both sides of the carrier toothed wheel for rotatable bearing support of the threaded spindle relative to a housing.  
         [0009]     Therefore, in another conventional adjusting device with a rotatable threaded spindle, a cylindrical shaft is used as starting material for the threaded spindle, a trapezoid thread being turned on this cylindrical shaft, specifically, substantially along the entire length of the threaded spindle with the exception of a fastening portion at one end of the shaft. This fastening portion at the end has a cylindrical portion adjoining the trapezoid thread of the threaded spindle, the outer diameter of the cylindrical portion lying between the inner radius and the outer radius of the trapezoid thread. Adjoining this cylindrical portion by a step is a cylindrical portion having a smaller diameter which carries the carrier toothed wheel (also constructed as a worm gear in this instance) that contacts the step between the two cylindrical portions. A key is again provided for preventing rotation between the carrier toothed wheel and the cylindrical portion having the smaller diameter. In the area of the end of the threaded spindle, a fine-pitch thread (screw thread) is cut into the cylindrical portion having the smaller diameter. A clamping nut which clamps the carrier toothed wheel against the shoulder is screwed onto this fine-pitch thread. Axial ball bearings mounted on shoulders of the worm gear are again provided for rotatable support of the threaded spindle. Further, a radial ball bearing is arranged between the housing and the cylindrical portion with the larger diameter. This construction is very costly to produce, particularly due to that fact that a pre-manufactured threaded rod cannot be used to produce the threaded spindle, and the threaded spindle must be manufactured from a cylindrical shaft, wherein the thread of the threaded spindles must be produced.  
         [0010]     In another embodiment form for connecting the threaded spindle to the carrier toothed wheel, the carrier toothed wheel has an internal thread by means of which it is screwed on the thread of the threaded spindle. In this case, special clampable lock nuts must be provided for securing the carrier toothed wheel to the threaded spindle and, further, the carrier toothed wheel must be provided with tolerance-compensating bushings to reduce the clearance between the threaded spindle and the carrier toothed wheel. While pre-manufactured threaded rods can be used for the threaded spindles because of these steps, the construction is very costly overall and the torque in its entirety must be transmitted via the clamped lock nuts.  
       OBJECT AND SUMMARY OF THE INVENTION  
       [0011]     It is the primary object of the invention to provide an adjusting device of the kind mentioned above with a connection between the threaded spindle and the carrier toothed wheel which is simple to produce and in which the occurring torques and forces are reliably transmitted, while ensuring the best possible parallel and concentric orientation of the longitudinal axis of the threaded spindle relative to the axis of rotation of the carrier toothed wheel.  
         [0012]     According to the invention, this object is met by an adjusting device for positioning a load, comprising a threaded spindle which is connected in the region of a longitudinal end to a carrier toothed wheel so as to be fixed with respect to rotation relative to it and so as to be fixed with respect to displacement axially, which carrier toothed wheel is rotatably mounted in a gear unit housing and can be set in rotation by means of a driving toothed wheel whose teeth engage in the teeth of the carrier toothed wheel, and a spindle nut which is arranged on a spindle thread of the threaded spindle and which is displaceable axially by means of a rotation of the threaded spindle for positioning the load, wherein a fastening portion of the threaded spindle which is formed in the region of the longitudinal end of the threaded spindle and along which the spindle thread is at least partially turned penetrates a central through-opening through the carrier toothed wheel and is connected to the carrier toothed wheel by a key and, further, is provided with a screw thread in an end portion which projects out of the through-opening of the carrier toothed wheel, a clamping nut which clamps the threaded spindle against the carrier toothed wheel being screwed onto this screw thread, and the fastening portion has, in addition to a cylindrical portion which is received by a cylindrical portion of the through-opening of the carrier toothed wheel and in which torque is transmitted between the carrier toothed wheel and the fastening portion by the key, another conical portion which is situated closer to the longitudinal center of the threaded spindle and which widens in direction of the longitudinal center of the threaded spindle and which is received by a conical portion of the through-opening of the carrier toothed wheel, wherein the conical portion of the fastening portion and the conical portion of the carrier toothed wheel are clamped against one another by the clamping nut.  
         [0013]     The key which extends at least along most of its length in the area of the cylindrical portion of the fastening portion of the threaded spindle serves to transmit torque between the carrier toothed wheel and the threaded spindle. However, torque can also be transmitted by means of the cooperating conical portions of the threaded spindle and of the carrier toothed wheel, which allows a compact construction with respect to height in spite of the different portions of the fastening portion of the threaded spindle. The cooperating conical portions also ensure the parallel orientation of the longitudinal axis of the threaded spindle and of the axis of rotation of the carrier toothed wheel without having to undertake special steps in assembly. This results in a very simple assembly process  
         [0014]     The threaded spindle of the adjusting device according to the invention can advantageously be produced from a standard rolled threaded rod which is obtainable as a stock item. The invention can be used not only for threaded spindles with trapezoid threads but also for threaded spindles with ball threads.  
         [0015]     Bevel seat connections in which the connection is carried out by means of the cooperation of conical connection parts are known per se. In particular, bevel seat connections of this kind are used to connect clamping chucks of drills to the drill shaft. It is also known to connect hubs to shafts by means of clamping cones. These commonly known bevel seat connections do not relate to generic devices.  
         [0016]     In an advantageous embodiment form of the invention, the fastening portion of the threaded spindle has a second cylindrical portion in addition to the first cylindrical portion in which the threaded spindle is connected to the carrier toothed wheel by the key. This second cylindrical portion lies closer to the longitudinal center of the threaded spindle than the conical portion and preferably directly adjoins the conical portion. This second cylindrical portion is received at least over a portion of its longitudinal extension by a second cylindrical portion of the through-opening of the carrier toothed wheel, wherein a sliding fit is preferably formed between the second cylindrical portions of the fastening portion and of the through-opening of the carrier toothed wheel, i.e., a fit with only very slight clearance. This leads to an additional radial support of the threaded spindle in the carrier toothed wheel. This further improves stability with respect to transverse forces. An optimal orientation of the longitudinal axis of the threaded spindle parallel to and concentric to the axis of rotation of the carrier toothed wheel is ensured in addition.  
         [0017]     As was already mentioned, the different portions of the fastening portion of the threaded spindle can be produced in the area of a longitudinal end, preferably by a defined turning of the threaded rod from which the threaded spindle is formed. In the conical portion, the thread of the threaded rod can be completely turned or a more or less large portion of the thread can remain along a more or less large longitudinal portion of the cylindrical portion depending on the outer diameter and core diameter (inner diameter of the thread) of the threaded rod that is used. In the area in which a portion of the outer thread remains, the turned outer surface of the thread forms the conical outer surface of the conical portion.  
         [0018]     Also, the thread of the threaded rod can be completely turned or only partially turned in the second cylindrical portion that is preferably provided. In the latter case, the cylindrically turned outer surface of the remaining portion of the thread forms the cylindrical outer surface of the cylindrical portion.  
         [0019]     However, in the (first) cylindrical portion which is arranged between the conical portion and the screw thread, the thread of the threaded rod used as starting material is preferably completely turned. Accordingly, there is a continuous cylindrical outer surface in this case.  
         [0020]     Other advantages and details of the invention are described in the following with reference to the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0021]      FIG. 1  shows a base unit comprising the gear unit housing and the toothed wheels which are rotatably supported therein in longitudinal section through the gear unit housing according to an advantageous embodiment form of the invention;  
         [0022]      FIGS. 2   a  and  2   b  show the fastening portion and an adjoining portion of the main portion of a threaded spindle which can be connected to the base unit of  FIG. 1  in two side views that are rotated by 90° (in a different scale than that shown in  FIG. 1 );  
         [0023]      FIG. 3  shows the adjusting device according to this embodiment example of the invention in the assembled state (the base unit is again shown in cross section, and the threaded spindle is shown in a side view in the area of the gear unit housing and schematically in the area of a spindle nut arranged on it) with a load to be adjusted, shown schematically;  
         [0024]      FIG. 4  shows a section along line AA of  FIG. 3 ;  
         [0025]      FIG. 5  and  FIG. 6  show views of the base unit of  FIG. 1  with threaded spindles which are inserted therein and which have different diameters than the threaded spindle shown in FIGS.  2  to  4 ; and  
         [0026]      FIG. 7  shows the base unit with an inserted threaded spindle which has a ball thread. 
     
    
       [0027]     Different scales are used in the drawings.  
       DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0028]      FIG. 1  shows the base unit of the adjusting device according to an advantageous embodiment form of the invention. This base unit comprises the gear unit housing  1  and the toothed wheels  2 ,  7  which are rotatably mounted therein. The carrier toothed wheel  2  serves to hold the threaded spindle  3  which is described in the following. In the present embodiment example, the carrier toothed wheel  2  is constructed as a worm gear and accordingly has an external worm toothing. Construction in the form of a different type of toothed wheel, for example, a bevel gear wheel, is conceivable and possible.  
         [0029]     The carrier toothed wheel  2  is mounted in the gear unit housing  1  so as to be rotatable by means of axial bearings  4 ,  5 .  
         [0030]     Further, the hub of the carrier toothed wheel  2  has an axial through-opening  6  serving to receive the threaded spindle  3 . The construction of this through-opening  6  will be described following the description of the threaded spindle  3 .  
         [0031]     The carrier toothed wheel  2  can be rotated by means of the driving toothed wheel  7  which is rotatably mounted in the gear unit housing  1  and whose teeth engage with the teeth of the carrier toothed wheel  2 . The driving toothed wheel  7  is constructed as a worm in the present embodiment example. Depending on the construction of the carrier toothed wheel  2 , other constructions are also conceivable and possible, for example, construction in the form of a bevel gear wheel.  
         [0032]     The driving toothed wheel  7  has a drive shaft, not shown in the drawing, which projects out of the gear unit housing  1  and by which it can be driven, particularly by means of a drive motor.  
         [0033]     The gear unit housing  1  has a housing base part  8  with an inner receiving space  9  for the rotatably supported toothed wheels  2 ,  7  and a housing cover  10  which is screwed into the housing base part  8  and which has an opening  11  as a through-guide for the threaded spindle  3 . The housing cover  10  has an annular flange  12  which surrounds the opening  11  and into which a bushing  13  is pressed. This bushing can be made of brass, for example.  
         [0034]     On the opposite side of the housing cover  10 , a cover  14  closes an opening of the housing base part  8 . Further, the gear unit housing  1  has a lubricating bore hole  15  and swivel bearing bushes  17  which are pressed into recesses  16 .  
         [0035]     The threaded spindle  3  is constructed as a trapezoid thread spindle in the embodiment forms according to FIGS.  2  to  6 . It comprises a main portion  18  along which the spindle thread  20  extends and with which the spindle nut  21  (see  FIG. 3 ) engages. The spindle nut  21  can be axially adjusted in the main portion  18  of the threaded spindle  3 . In the main portion  18 , there is no machining of the thread of the threaded rod from which the threaded spindle  3  is preferably produced.  
         [0036]     A fastening portion  19  comprising a plurality of portions  22 ,  25 ,  36 ,  29 ,  31  is formed in the area of a longitudinal end of the threaded spindle  3 .  
         [0037]     An end portion  22  which projects out of the through-opening  6  of the carrier toothed wheel  2  when the threaded spindle  3  is connected to the carrier toothed wheel  2  is provided with a screw thread (fine-pitch thread)  23  on which a clamping nut  24  (see  FIG. 3 ) can be screwed. This end portion  22  preferably directly adjoins the longitudinal end  37  of the threaded spindle  3 .  
         [0038]     A first cylindrical portion  25  of the fastening portion  19  is located closer to the longitudinal center of the threaded spindle  3  (that is, farther away from the adjoining longitudinal end  37 ). This first cylindrical portion  25  preferably adjoins the end portion  22  provided with the screw thread  23  by way of an expansion portion  36 . This first cylindrical portion  25  has a cylindrical outer surface  26  and is provided with a receiving groove  27  for a key  28  (see  FIGS. 3 and 4 ). The receiving groove  27  extending in direction of the longitudinal axis  41  of the threaded spindle  3  is not visible in the side view according to  FIG. 2   b,  but is indicated by a dashed line.  
         [0039]     A conical portion  29  is located closer to the longitudinal center of the threaded spindle  3  than the first cylindrical portion  25 . This conical portion  29  expands (i.e., increases in diameter) in direction of the longitudinal center of the threaded spindle  3  and has a conical outer surface  30 . The conical portion  29  preferably directly adjoins the first cylindrical portion  25 .  
         [0040]     In the embodiment example shown in FIGS.  2  to  4 , the diameter of the conical outer surface  30  at the end of the conical portion  29  facing the first cylindrical portion  25  is smaller than the core diameter d of the threaded spindle  3  (i.e., smaller than the inner diameter of the spindle thread  20 ), while the diameter of the conical outer surface  30  at the end of the conical portion  29  directed to the longitudinal center is greater than the core diameter d of the threaded spindle  3 . As a result, the spindle thread  20  is completely turned in a portion of the conical portion  29  adjoining the first cylindrical portion  25 , and the conical outer surface  30  is accordingly continuous. However, in an adjoining portion of the conical portion  29  in direction of the longitudinal center of the threaded spindle  3 , the spindle thread  20  is only partially turned. The conical outer surface is formed by the outer surface of the remaining threaded part so that the conical outer surface  30  has interruptions in this case.  
         [0041]     The smallest outer diameter of the conical portion  29  at the end of the conical portion  29  facing the adjoining longitudinal end  37  is at least as large as the outer diameter of the first cylindrical portion  25  and is the same size in the present embodiment example.  
         [0042]     In the present embodiment example, the receiving groove  27  for the key  28  extends into the conical portion  29 . In this case, the bottom of the receiving groove  9  in the first cylindrical portion  25  lies in the same plane as in the conical portion  29 . Because of the conical widening, the key  28  which likewise extends in the conical portion  29  in the assembled state of the adjusting device projects radially in the conical portion  29  as the distance  30  increases. In the present embodiment example, the receiving groove  27  and the key end approximately at the location of the conical portion  29  at which the key no longer projects over the conical outer surface  30 .  
         [0043]     The fastening portion  19  further comprises a second cylindrical portion  31  which lies closer to the longitudinal center of the threaded spindle  3  in relation to the conical portion  29 . The second cylindrical portion  31  preferably directly adjoins the conical portion  29 .  
         [0044]     In the present embodiment example of the invention, the second cylindrical portion  31  has two areas  32 ,  33  with different outer diameters. The first area  32  which lies on the side of the second cylindrical portion  31  situated closer to the conical portion  29  has a smaller diameter than the second area  33 .  
         [0045]     The outer diameter of the first area  32  is at least as large as the outer diameter of the conical portion  29  at its largest point (that is, at the end of the conical portion  29  facing the longitudinal center of the threaded spindle  3 ), but is smaller than the outer diameter D of the threaded spindle  3  in its main portion  18  (i.e., smaller than the outer diameter of the spindle thread  20 ) which extends over most of the length of the threaded spindle  3 .  
         [0046]     In the embodiment example according to FIGS.  2  to  4 , the spindle thread  20  is partially turned in the first area  32  of the second cylindrical portion  31 . The remaining portion of the spindle thread  20  forms a discontinuous cylindrical portion  34 .  
         [0047]     In the embodiment example according to FIGS.  2  to  4 , the spindle thread  3  has been turned very slightly in the second area  33  in order to compensate for manufacturing tolerances of the spindle thread and to form a defined cylindrical outer surface  35  (which has interruptions because it is formed by the outer surface of the remaining thread). This turning is so slight that it is not visible in  FIGS. 2 and 3 .  
         [0048]     The through-opening  6  of the carrier toothed wheel  2  has a first cylindrical portion  38  which serves to receive the first cylindrical portion  25  of the threaded spindle  3 , wherein there is only a slight clearance, preferably a sliding fit between the cylindrical portion  38  of the through-opening  6  and the cylindrical portion  25  of the threaded spindle  3 , and the clearance of this sliding fit is preferably less than 3/100 mm.  
         [0049]     Further, an axial receiving groove is formed in the first cylindrical portion  38  for receiving the key  28 .  
         [0050]     Further, the through-opening  6  has a conical portion  39  which serves to receive the conical portion  29  of the fastening portion  19  of the threaded spindle  3 , wherein the conical portion  29  of the fastening portion  19  contacts the wall of the through-opening  6  in its conical portion  39  in the assembled state of the adjusting device. The receiving groove for the key  28  preferably extends into this conical portion  39 , wherein the base of the receiving groove lies in the same plane in the cylindrical portion  38  and in the conical portion  39 , and the receiving groove extends up to the location of the conical portion  39  at which the base of the receiving groove reaches the outer surface area of the conical portion  39 .  
         [0051]     Further, in the present embodiment example, the through-opening  6  has a second cylindrical portion  40  serving to receive the second cylindrical portion  3  over its first area  32 . In this case, there is a close sliding fit with only a very slight clearance (preferably less than 2/100 mm).  
         [0052]     In the second cylindrical portion  31 , the threaded spindle  3  passes through the bushing  13 , specifically in the second area  33  of the second cylindrical portion  31 . There is a slight clearance between the inner surface of the bushing  13  and the cylindrical outer surface  35  which is preferably less than 8/100 mm, e.g., between 3/100 and 5/100 mm.  
         [0053]     In the absence of transverse forces, the threaded spindle  3  should not contact the bushing  13  as far as possible. When acted upon by transverse forces, the threaded spindle  3  is supported at the bushing  13 .  
         [0054]     The threaded spindle  3  is mounted by inserting it into the carrier toothed wheel  2  with the key  28  inserted until the end portion  22  projects from the through-opening  6 . With the cover  14  removed, the clamping nut  24  is screwed onto the screw thread  23  of the end portion  22  and tightened. Due to the contact of the conical outer surface  30  at the driving toothed wheel  7 , an axial fastening of the threaded spindle  3  is brought about in the area of the conical portion  39  of the through-opening  6  and its longitudinal axis  41  is oriented relative to the axis of rotation  42  of the carrier toothed wheel  2  so that their two axes  41 ,  42  are parallel and concentric to one another, i.e., coincide with one another.  
         [0055]     Further,  FIG. 3  schematically shows a load  43  which is connected to the spindle nut  21  and adjusted by the spindle nut  21  in that the latter is displaced axially along the threaded spindle  3 . The spindle nut  21  is fixed with respect to rotation by means of the connection of the spindle nut  21  to the load  43 .  
         [0056]      FIG. 5  shows the connection of a threaded spindle  3  to the base unit shown in  FIG. 1 , wherein this threaded spindle  3  has a greater core diameter d and therefore also a greater outer diameter D than the threaded spindle  3  shown in  FIG. 3 . The spindle thread  20  is completely turned in the fastening portion  19  of the threaded spindle  3  in order to form the portions  22 ,  25 ,  29 ,  31  of the fastening portion  19 .  
         [0057]      FIG. 6  shows a threaded spindle  3  which is connected to the base unit of  FIG. 1  and which has a greater core diameter d and outer diameter D compared to it.  
         [0058]      FIG. 7  shows a threaded spindle  3  mounted in the base unit of  FIG. 1  with a spindle thread  20  formed as a ball thread. In this case, the core diameter d of this threaded spindle  3  is slightly smaller than the diameter of the cylindrical outer surface  34  in the first area  32  of the second cylindrical portion  31 .  
         [0059]     Therefore, as is shown, threaded spindles  3  with different core diameters d and outer diameters D can be used in combination with the same gear unit housing  1  with toothed wheels  2 ,  7  which are rotatable therein by corresponding machining of the threaded spindles  3  in the fastening portion  19 . Commercially available standard spindles can be used as starting products for the threaded spindles  3 .  
         [0060]     The first area  32  and the second area  33  of the second cylindrical portion  31  can also have the same outer diameter.  
         [0061]     In principle, it would also be conceivable and possible for the fastening portion  19  to terminate after the conical portion  29  toward the longitudinal center of the threaded spindle  3 , so that the second cylindrical portion is dispensed with. The second cylindrical portion  40  of the carrier toothed wheel  2  could then likewise be omitted, and the threaded spindle  3  could exit from the gear unit housing  1  through the bushing  13  in the main portion  18  that is not machined.  
         [0062]     However, it is preferable that at least a second cylindrical portion  31  is provided with a first area  32  which cooperates with the second cylindrical portion  40  of the through-opening  6  in order to achieve additional support of the threaded spindle  3  relative to transverse forces and to improve centering of the threaded spindle  3 . Further, it is preferable that the threaded spindle  3  is also machined in a second area  33  of the second cylindrical portion  31  relative to the main portion  18  in order to enable a smaller clearance between the bushing  13  and the threaded spindle  3 .  
         [0063]     As follows from the preceding description, the field of the invention is not limited to the embodiment examples shown herein, but rather should be defined with reference to the appended claims together with their full range of possible equivalents. While the preceding description and drawings show the invention, it is obvious to the person skilled in the art that various modifications can be carried out without departing from the spirit of and field of the invention.  
       REFERENCE NUMBERS  
       [0000]    
       
           1  gear unit housing  
           2  carrier toothed wheel  
           3  threaded spindle  
           4  axial bearing  
           5  axial bearing  
           6  through-opening  
           7  driving toothed wheel  
           8  housing base part  
           9  receiving space  
           10  housing cover  
           11  opening  
           12  annular flange  
           13  bushing  
           14  cover  
           15  lubricating bore hole  
           16  recess  
           17  swivel bearing bush  
           18  main portion  
           19  fastening portion  
           20  spindle thread  
           21  spindle nut  
           22  end portion  
           23  screw thread  
           24  clamping nut  
           25  first cylindrical portion  
           26  cylindrical outer surface  
           27  receiving groove  
           28  key  
           29  conical portion  
           30  conical outer surface  
           31  second cylindrical portion  
           32  first region  
           33  second region  
           34  cylindrical outer surface  
           35  cylindrical outer surface  
           36  expansion portion  
           37  longitudinal end  
           38  first cylindrical portion  
           39  conical portion  
           40  second cylindrical portion  
           41  longitudinal axis  
           42  axis of rotation  
           43  load