Abstract:
A cone disc infinitely-variable gearbox including a shaft, a cone disc preferably embodied in one piece with the shaft, a cone disc connected to the shaft in a non-rotating axially-displaceable manner, a bearing ring axially fixed onto the shaft at a separation from the rear face of the displaceable cone disc, a radial inner pressure chamber formed between the cone disc and the bearing ring, which may be altered in the axial direction and which may be pressurized with pressure medium, through an opening embodied in the shaft, for displacement of the cone disc and a radial outer pressure chamber which may be altered in the axial direction and which may be pressurized with pressure medium, through a further opening embodied in the shaft, for displacement of the cone disc.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This is a continuation of International Application Ser. No. PCT/DE03/01908, with an international filing date of Jun. 10, 2003, the entire contents of which is hereby incorporated by reference to the same extent as if fully rewritten. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The invention relates to a cone pulley CVT, a method for defining the spread width between the two cone pulleys of such a transmission, and a method for towing such a transmission. 
   2. Description of the Related Art 
   Recently the use of cone pulley CVTs in passenger cars has increased, due to the successful development of such transmissions with sufficient torque transmission capability, good acoustic properties and a long service life. 
   As the use of cone pulley CVTs increases, the significance of both cost and road capability increases. 
   It is the purpose of the invention to design cone pulley CVTs that are less costly and have better road capability. 
   SUMMARY OF THE INVENTION 
   A first solution is achieved with a cone pulley CVT that includes a shaft, a cone pulley that is preferably designed to form a single piece with the shaft, a cone pulley that is non-rotatably and axially movably connected to the shaft, a support ring that is axially immovably mounted to the shaft at a distance from a rear side of the axially movable cone pulley, a radially inner and axially variable pressure chamber that is formed between the cone pulley and the support ring and that can be pressurized via a passageway in the shaft for the purpose of moving the cone pulley, and a radially outer pressure chamber that is axially variable and can be pressurized via a further passageway for the purpose of moving the cone pulley, wherein the further passageway in the shaft is connected to the radially outer pressure chamber via a passageway in the axially movable cone pulley. 
   The further passageway in the shaft advantageously extends through an annulus located between the axially movable cone pulley and the shaft, to the passageway in the axially movable cone pulley. 
   Toward the axially movable cone pulley, the radially outer pressure chamber is bordered by the floor of an annular wall structure with an inner and an outer axially extending annular wall, the annular walls being sealed and axially movable relative to the support ring, and the passageway in the axially movable cone pulley extending through an opening in the annular wall structure to the radially outer pressure chamber. 
   The support ring advantageously includes a radially inner and a radially outer ring component, while areas of the radially outer ring component border the radially outer pressure chamber. 
   The ring components may be designed to form an integral component. 
   As an alternative, the ring components may be formed sheet-metal components that are press-fit connected to one another. 
   In one advantageous embodiment, the radially outer ring component is form-fittingly pushed onto the radially inner ring component when the radially outer pressure chamber is pressurized. 
   A coil spring without surface-ground coil ends may be positioned between the radially inner ring component and the axially movable cone pulley. 
   It is also advantageous to design the axially movable cone pulley, the support ring, the outer annular wall and the outer ring component identically in construction for the input and the output sides of the transmission, as this will reduce the number of different components and lower production costs. 
   The identical design will lead to another benefit, namely that the hood is mounted on the input side or on the output side. 
   This, however, requires that the end of the annular wall be provided with an appropriate form-fitting or force-locking component where the hood may be mounted. 
   Another solution to the task of the present invention is achieved by means of a cone pulley CVT that includes a pair of cone pulleys with a shaft, a cone pulley that preferably is integral with the shaft, a cone pulley that is non-rotatably connected to the shaft in an axially movable manner, a support ring that is axially immovably mounted to the shaft at a distance from a rear side of the axially movable cone pulley, a minimum of one pressure chamber that is formed between the support ring and the rear side of the axially movable cone pulley and that, by being pressurized with a hydraulic medium, allows the axially movable cone pulley to move, and an annulus in a push fit for movable sealing between the cone pulley and a stationary component that is equipped with a seal ring, the annulus turning into an annular gap toward one side and over a bevel, turning into a sealing gap toward the opposite side. 
   With regard to cost cutting, a method for defining the spread width of a pair of cone pulleys in a cone pulley CVT is advantageous, wherein the pair of cone pulleys includes one cone pulley that preferably is integral with a shaft and one cone pulley that is non-rotatably connected to the shaft in an axially movable manner, with the latter cone pulley being movable toward the other cone pulley by means of pressurization of a minimum of one pressure chamber that is located between its rear side and a support ring that is rigidly mounted to the shaft and the axially movable cone pulley, at its maximum distance from the other cone pulley, resting on the support ring, in which method the support ring, without being in contact with a radial shaft stop with a movable cone pulley resting on it, is mounted axially and non-rotatably to the shaft in such manner that a predetermined maximum spacing between the cone pulleys is maintained. 
   A cone pulley CVT according to the present invention includes a shaft, one cone pulley preferably designed to be integral with the shaft, one cone pulley that is non-rotatably connected to the shaft and in an axially movable manner, a support ring that is axially immovably mounted to the shaft at a distance from the rear side of the axially movable cone pulley, wherein the axially movable cone pulley is movable toward the other cone pulley via pressurization of a minimum of one pressure chamber that is formed between the rear side of the axially movable cone pulley and the support ring, and the axially movable cone pulley, at its farthest position away from the other cone pulley, rests on the support ring which, without being in contact with a radial shaft stop and the movable cone pulley resting on it, is axially immovably mounted to the shaft in such manner that a predetermined maximum spacing between the cone pulleys is maintained. 
   The support ring is advantageously welded to the shaft. 
   In an additional advantageous embodiment, the support ring is axially form-fittingly mounted to the shaft by a minimum of one component, which engages in a recess located in the outer circumference of the shaft and the inner circumference of the support ring. 
   Another cone pulley CVT according to the present invention includes a shaft, a cone pulley that advantageously is integral with the shaft, a cone pulley that is non-rotatably connected to the shaft and in an axially movable manner, a support ring at a distance from the rear side of the axially movable cone pulley, a minimum of one pressure chamber that is formed between the support ring and the rear side of the axially movable cone pulley, wherein pressurization of said pressure chamber with hydraulic medium pressure allows the axially movable cone pulley to move toward the other cone pulley, and a minimum of one mass body that is arranged in such manner, and acts together with both the axially movable cone pulley and the support ring in such a manner that, due to the centrifugal force acting upon it, a force is exerted on the movable cone pulley which counteracts the force resulting from the hydraulic pressure. 
   The mass body may be part of a lever, which is positioned between a component that is rigidly connected to the axially movable cone pulley and protrudes beyond the support wall on its far side to the movable cone pulley, and the support ring, and, with increasing shaft speed, presses the axially movable cone pulley toward the support ring. 
   In another embodiment, the mass body is connected to the axially movable cone pulley and the support ring by a minimum of one cable, in such manner that with increasing shaft speed, the axially movable cone pulley is pulled toward the support ring. 
   In another variation, the mass body is placed in a point of articulation between two levers, of which one is pivotally connected to a component that is rigidly connected to the axially movable cone pulley and that protrudes beyond the support wall on its far side to the axially movable cone pulley, and the other lever is connected to the support ring, so that with increasing shaft speed, the axially movable cone pulley is pressed toward the support ring. 
   In a further embodiment, the mass body is movable along an inclined plane that is rigidly connected to the support ring or to the axially movable cone pulley and that runs obliquely to the axial direction, in such manner that, with a radially outward motion of the mass body, the axially movable cone pulley is pushed toward the support ring. 
   In another embodiment, the mass body includes two gears that are adjacent to the shaft and parallel to its axial direction, and that are rotatable in a circumferential direction, relative to the axial direction, and that intermesh with one another and with each of the gear tooth systems, one being obliquely mounted to the support ring and the other being obliquely mounted to the axially movable cone pulley, and with radial motion away from the axis of the shaft, the gears force the axially movable cone pulley toward the support ring. 
   Advantageously, several mass bodies are mounted at a distance from each other around the shaft. 
   A further solution to the task of this invention is achieved with a cone pulley CVT that includes two pairs of cone pulleys that are positioned at a radial distance from one another and parallel to one another, each including a shaft, one cone pulley that preferably is integral with the shaft, one cone pulley that is non-rotatably connected to the shaft and in an axially movable manner, an axially stationary support ring that is mounted to the shaft at a distance from the rear side of the axially movable cone pulley, a minimum of one pressure chamber that is formed between the support ring and the rear side of the axially movable cone pulley, wherein pressurization of the pressure chamber with hydraulic pressure allows the axially movable cone pulley to move, and an endless torque-transmitting means that wraps around both cone pulley pairs while the pressure chamber may be pressurized in such manner that the spacings between the cone pulleys of either cone pulley pair, and hence the radii along which the endless torque-transmitting means runs on the tapered surfaces of the cone pulley pairs, change in the opposite direction. Furthermore, the cone pulley CVT includes a mechanism which, in case of hydraulic pressure failure, separates the cone pulleys of at least one cone pulley pair in such manner that the inner circumference of the endless torque-transmitting means comes in contact with an inner axially parallel peripheral area of the cone pulley pair. 
   Advantageously, the inner axial peripheral area of the cone pulley CVT is provided with an anti-friction coating. 
   The cone pulley pair that separates in case of pressure failure is preferably the one on the output side. 
   The mechanism for separating the cone pulleys may include a spring. 
   A further solution to the task of the present invention is achieved with a method for towing a cone pulley CVT with two cone pulley pairs that are placed at a radial distance from one another and parallel to one another, each including one shaft, one cone pulley that preferably is integral with the shaft, one cone pulley that is non-rotatably connected to the shaft and in an axially movable manner, an axially stationary support ring that is mounted to the shaft at a distance from the rear side of the axially movable cone pulley, a minimum of one pressure chamber that is located between the support ring and the rear side of the axially movable cone pulley, wherein pressurization of the same with a hydraulic medium allows the axially movable cone pulley to move, and an endless torque-transmitting means that wraps around both cone pulley pairs, wherein the pressure chamber may be pressurized in such manner that the spacings between the cone pulleys of either pair of cone pulleys, and hence the radii along which the endless torque-transmitting means runs on the tapered surfaces of the cone pulley pairs, change in the opposite direction. In this method, during towing of a cone pulley CVT, the cone pulleys of at least one cone pulley pair separate in such manner that the inner circumference of the endless torque-transmitting means comes in contact with an inner axially parallel peripheral area of the cone pulley pair. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the following description, embodiments of the invention are discussed based on schematic drawings, and more detail is provided: 
       FIG. 1  is a longitudinal sectional view through part of a cone pulley CVT, which to some extent is conventional, while other parts are according to the invention, 
       FIG. 2  is a detail view of region  11  in  FIG. 1 , 
       FIG. 3  is a longitudinal sectional view through part of a cone pulley CVT, which to some extent is conventional, while other parts are according to the invention, 
       FIG. 4  is a longitudinal sectional view through part of a cone pulley CVT modified according to the invention as shown in  FIG. 3 , 
       FIG. 5  shows two different embodiments (upper and lower half) of a detail of a portion of the embodiment shown in  FIG. 4 , 
       FIGS. 6   a  to  6   h  show different views of a part of a cone pulley CVT in a first embodiment of a mechanical centrifugal force mechanism, 
       FIGS. 7 to 17  show different embodiments of the mechanical centrifugal force mechanism, 
       FIG. 18  shows a portion of a cone pulley pair with a spring to increase the spacing between the cone pulleys, 
       FIG. 19  shows a cone pulley pair on the input side according to the invention, 
       FIG. 20  shows a complete cone pulley CVT according to the invention. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1  is a cutaway view of a cone pulley pair of a cone pulley CVT axial longitudinal section, wherein the lower half of  FIG. 1  shows a conventional design and the upper half shows a design according to the invention. A shaft  2  of a cone pulley pair of a cone pulley CVT, having an axis A-A, is designed to form a single component with a cone pulley  4 . At a distance from the cone pulley  4 , another cone pulley  6  is positioned on the shaft A in a non-rotatable and an axially movable manner. At a distance from the rear side of the cone pulley  6  a support ring  8  is rigidly connected to the shaft  2 , from which, in a radially medial area, an axially oriented cylindrical annular wall  10  protrudes toward the cone pulley  6 . In the radially outer portion of the rear side of the cone pulley  6 , an annular wall structure  12  rests against or is attached to it, which includes cylindrical annular walls  14  and  16  that are radially inside and outside and that extend axially. The inner annular wall  14  is in sealed sliding contact with the annular wall  10  by means of a seal ring  18  and the outer annular wall  16  is in sealed sliding contact with the outer circumference of the support ring  8  by means of a seal ring  20 . By this, an inner pressure chamber  22  is formed between the shaft  2  and the cone pulley  6  as well as the annular walls  10  and  14 , and an outer pressure chamber  26  is formed between the annular walls  10 ,  14 , and  16 , the floor  24  of the wall structure  12 , and the radially outer portion of the support ring  8 . The supply of pressurizing medium to the inner pressure chamber  22  is provided through a passageway  28  in the shaft  2 . Pressurization of the outer pressure chamber  26  takes place through passageways in the shaft  2  and a channel  30  that runs through the support ring  8 . As the design and function of such assembly are known, they will not be discussed herein any further. 
   Due to the channel  30 , the support ring  8  is a relatively complex component, in most cases a forged component, which must be sturdy enough to function as a support wall for the pressure chambers and the cone pulley  6  accordingly, and must also afford sufficient volume so that the channel  30 , which is usually branched, may be formed. 
   The difference between the upper and the lower halves of  FIG. 1  is that in the upper half the supply of pressurizing medium to the radially outer pressure chamber  26  is provided through passageways  32  and  34  in the shaft  2  via an annulus  36  through a channel or passageway  38  in the cone pulley  6 , and from there through an opening  40  in the floor  24  of the wall structure  12 , which leads into the outer pressure chamber  26 . It is understood that the annulus  36 , which is formed by recesses in the shaft  2  and/or the cone pulley  6 , must be of such axial length that the connection is maintained from the passageway  34  to the passageway  38  along the entire travel distance of the cone pulley  6 . The passageway  38  may be a transverse drill hole. 
   The supply of pressurizing medium to the outer pressure chamber  26  being provided through the axially movable cone pulley  6  offers great design freedom with regard to the support ring  8 . In the illustrated example at location  48 , the support ring  8  includes two formed sheet metal pieces  42  and  44 , which are, for example, pressed together in the same manner as they come out of the forming tool. The seat surfaces mating with the annular walls  14  and  16  of the wall structure  12  may be machined while mounted.  FIG. 1  does not show that, due to the pressure in the pressure chamber  26  during operation, the formed sheet-metal piece  44  is continuously pushed against the formed metal-sheet piece  42  (a form fit to the right side exists in the contact area with regard to an axial motion of the formed sheet-metal piece  44  according to  FIG. 1 ), so that it cannot become detached. 
   The two formed sheet-metal pieces may be joined to one another via spot welding. Alternatively, the support ring  8  may be formed as a single piece or designed otherwise. 
   As the support ring  8  does not have a pressure medium passageway, great design freedom exists, resulting in low costs. 
   At this point, reference is made to a hood  50  which extends from the outer annular wall  16  and forms a centrifugal oil chamber between itself and the support ring  8 , where hydraulic pressure builds as speed increases, counteracting the pressure in the pressure chambers  22 ,  26  with respect to the movement of the cone pulley  6 . 
   A further advantage of the invention, as illustrated in the upper half of  FIG. 1 , is that because of the increase in available space, a coil spring  52  without surface-ground coil ends may be used, which functions as a pressure spring and is located in the radially inner pressure chamber  22 . 
     FIG. 2  is an enlargement of the cutaway view  11  of  FIG. 1  and shows the design of a push-fit between the axially movable cone pulley  6  and the shaft  2 . Inside the inner circumferential area of the cone pulley  6  there is an annular groove  54 , in which a seal ring  56 , for example an O-ring, is placed. According to  FIG. 2 , the inner circumferential area of the cone pulley  6  is somewhat recessed on the left of the annular groove  54 , so that an annular gap  58  remains, where no mechanical component exists between the cone pulley  6  and the shaft  2 . On the far side of the annular gap  58 , the annular groove  54  passes over a bevel  60  into its cylindrical inner circumferential area, wherein a continuous flow of leakage pressure medium flows through the section b of the unit between the cone pulley and the shaft, preventing wear. The purpose of the bevel  60  is to shift the support force between the cone pulley  6  and the shaft  2  somewhat to the right of the bevel  60 , to eliminate the risk of material chipping in the area of the edge. 
   It is understood that the push-fit may be modified to the effect that the annular groove  54  is designed only in the shaft  2  or in the shaft  2  as well as the cone pulley  6 , wherein in the Fig. the annular gap  58  is located to the left of the formed annulus that accommodates the seal ring, and one or two bevels are located on the right side in transition to the contact surfaces. 
   The sliding seat design according to  FIG. 2  may also be applied to other push-fits as shown in  FIG. 1  and to any hydraulically operated cone pulley CVT. 
   One problem that arises with respect to conventional cone pulley CVTs is discussed with reference to  FIG. 3 . The design of the cone pulley pair in  FIG. 3  is identical to the one in the lower half of  FIG. 1 , and components of a like function have been assigned the same previous reference designations.  FIG. 3  shows an additional endless torque-transmitting means  61  in its radially outermost and its radially innermost positions. An important design dimension is the so-called spread width X, i.e., the maximum distance between the tapered surfaces of the cone pulleys  4  and  6  in the radially medial area of the tapered surfaces. This spread width X is defined by the difference of measures A and B. Measure A is the axial distance between a radial step  62  on the shaft and the radial center of the tapered surface of the axially fixed cone pulley  4 . The other measure B is the distance between the step  62  and the radial center of the tapered surface of the axially movable cone pulley  6 . Measure B equals the total axial thickness of the cone pulley  6 , which, with the greatest possible distance between the cone pulleys, rests against the support ring  8 , which is pressed onto the shaft  2  seated to the step  62 , and is fixed in this position. During transmission manufacture, tolerances occur in the production of the cone pulleys and the shaft, affecting the measure X. It is understood that the spread width may be defined at a location other than the radial center. 
   According to the invention, the shaft  2  is therefore designed without the step  62 , as shown in  FIG. 4 , and the support ring  8  with the movable cone pulley  6  resting against it is pressed onto the shaft  2  to such an extent that the measure X is maintained and fixed in this position on the shaft  2 . 
   Mounting of support ring  8  may be effected via welding  64  ( FIG. 5 ) or by means of a single-piece or multi-component lock ring  66 , which engages in corresponding recesses or grooves  68 ,  70 . The axial thickness of the lock ring/s is determined as the result of an appropriate measurement, so that a ring of the appropriate thickness or several rings of which the thickness adds to the relevant measure is/are used. 
   The solution to another problem existing with cone pulley CVTs is discussed with reference to  FIGS. 6 through 16 . 
   As discussed with  FIG. 1 , conventional cone pulley CVTs are provided with a hood  50 , between which hood and the outer side of the support ring  8  there is a centrifugal oil chamber that exerts a force on the cone pulley  6 , which counteracts the force resulting from pressure chambers  22  and  26 . Due to increasing centrifugal forces with speed increase, the forces from the pressure chambers  22  and  26  exerted on the cone pulley  6  and pushing it toward the cone pulley  4  increase. These forces are counteracted by the pressure underneath the centrifugal oil hood  50  to compensate for influences on speed. The cone pulley CVT design having a centrifugal oil hood and an additional oil pressure chamber is intricate. In the following, solutions are presented to compensate for influences on speed in a more simple and operationally sound manner. 
     FIG. 6   a  shows a sectional view through a cone pulley pair of a cone pulley CVT, wherein components of a like function have been assigned the same previous reference designations. 
   As is apparent, a mass body  80  is pivotally mounted between the free end of the outer annular wall  16  of the annular wall structure  12  and a shoulder  76  of the support ring  8 , wherein the center of gravity of this mass body relative to the pivot points is positioned in such a way that according to  FIG. 6   a , an upward centrifugal force tends to turn the mass body  80  clockwise, i.e., moving the outer annular wall  16  and also the axially movable cone pulley  6  to the right, against the pressure forces from the pressure chambers  22 ,  26 . The centrifugal force increases as speed increases, so that with increasing speed, an increasing pressure is compensated for in the pressure chambers. 
     FIG. 6   b  is a sectional view through the assembly according to  FIG. 6   a  in the plane b-b.  FIG. 6   c  is a front view of the assembly according to  FIG. 6   a  viewed in the direction of the arrows c-c. As is apparent, several mass bodies  80  are distributed along the circumference of the outer annular wall  16  and the shoulder  76 . It is understood that the mass bodies  80  must only be positioned at the shoulder  76  or preferably on the annular wall  16 , for example, by means of a spring ring attached to the annular wall. 
     FIG. 6   d  shows the assembly in the overdrive position of the cone pulleys,  FIG. 6   e  in top drive position,  FIG. 6   f  at a transmission ratio of 1:1, and  FIG. 6   g  in underdrive position.  FIG. 6   h  is the enlargement of the cutaway view h of  FIG. 6   b . The mechanical solution has the following advantages over the hydraulic centrifugal force compensation:
         It is more cost-efficient;   It requires less space in the mounting area (the dotted line in  FIG. 6   a  indicates the required space for a hydraulic solution);   Pressure oil or hydraulic medium consumption is reduced;   Mechanical pressure (a compression spring) is no longer necessary for towing, as the axially movable cone pulley is pulled away from the axially fixed pulley, due to the centrifugal force and by the endless torque-transmitting means during towing;   The form and weight of the mass body, which forms a lever in the illustrated example, may be selected as required;   The principle of mechanical centrifugal force compensation may also be used, e.g. for a torque sensor;   Mechanical centrifugal force compensation is always active; filling of the centrifugal oil chamber is not necessary;       
   In the subsequent drawings, the upper half shows the overdrive position (maximum possible pulley spacing) and the lower half shows the underdrive position of the axially movable cone pulley  6  (minimum cone pulley spacing). 
   In the embodiment according to  FIG. 7 , the mass body  80  is fastened at a pivot point  82 , wherein two levers  84  and  86  are pivotally connected, which are pivoted at  82  and  90  on the radial outer edge of the support ring  8  and the outer end of the annular wall  16 . As can be seen, with increasing centrifugal force F the levers  84  and  86  tend to move to the extended position, by which a force that increases with the centrifugal force according to  FIG. 7  is exerted on the cone pulley  6  to the right. It is understood that, as well as in the subsequent embodiment variations, several mass bodies  80  with associated levers are distributed around the circumference of the assembly. 
     FIG. 8  shows a modified embodiment wherein the mass body  80  is movably mounted in a radially outwardly oriented compartment  92  that is fastened to the support ring  8 , and through a cable  94  that is connected to the annular wall  16  by rollers  98  that are mounted to the compartment  92  or to a lug  96  of the support ring  8 . It can be clearly seen in  FIG. 8  that there is a line of force toward the right on the cone pulley  6  that is rigidly connected to the annular wall  16 , as the centrifugal force F acting on the mass body  80  increases. 
   In the embodiment illustrated in  FIG. 9 , the mass body  80  is fastened to a lever  116  in such manner that it, with increasing centrifugal force F, pushes the lever, which is pivoted at location  100  on the annular wall and rests on a surface  104  of the support ring  8  over a roller  102 , exerting an increasing clockwise force that causes the cone pulley  6  to be forced to the right. 
   In the embodiment illustrated in  FIG. 10 , the mass body  80  is mounted at the end of a lever  108 , which is pivoted on the support ring  8  at location  110  and has a longitudinal slot  112  or groove extending from the left top to the right bottom, in which a pin  114  runs, that is fastened to the free end of the annular wall  16 . It clearly shows that the centrifugal force F in this embodiment also causes a rightward force to act on the cone pulley  6 . 
   In the embodiment illustrated in  FIG. 11 , the annular wall  16  ends in a radially inwardly inclined plane  120 , along which the mass body  80  that is pivotally mounted at location  124  on the support ring  8 , is movable via a lever or a rod  122 . As is clearly shown, the inclined plane  120  is pressed against the mass body  80 , due to the force from the pressure chambers applied leftward onto the cone pulley  6 . With increasing centrifugal force F, the mass body  80 , which tends to move radially outward along the inclined plane  120 , counteracts this force. It is understood that the inclined plane  120  may be designed as a cone-shaped hood around the shaft  2 , against which several mass bodies  80  rest, that are distributed around the circumference. 
   The embodiment illustrated in  FIG. 12  is identical to  FIG. 11 , except that the mass body  80  is designed as a ball that may be rigidly connected to the rod  122  or be mounted at the rod  122 . It is understood that the ball may be substituted by a cylinder or by a mass body having a convex surface toward the inclined plane  120 . 
   In the embodiment illustrated in  FIG. 13 , another inclined plane  126  or a conically extending hood is mounted to the support ring  8  in addition to the inclined plane  120  at the end of the annular wall  16 . The mass body  80 , which in this example is a ball, is mounted between the inclined planes  120  and  126 , which extend radially outward toward one another. As can be seen, due to the centrifugal force F, the mass body  80  tends to move the inclined plane  126  away from the inclined plane  120 , which results in a rightward force being applied to the cone pulley  6 . 
   The embodiment illustrated in  FIG. 14  is identical to  FIG. 13 , except that the mass body  80  is not a ball, but is trapezoidal in cross-section, wherein the incline of the lateral surfaces of the trapezoid equals the incline of the inclined surfaces  120  or  126 . The function of the assembly illustrated in  FIG. 14  is identical to the one in  FIG. 13 . 
   The embodiment illustrated in  FIG. 15  is identical to  FIG. 13 , except that the inclined surface  126  is replaced by a radially extending surface  130 . 
   The embodiment illustrated in  FIG. 16  is identical to  FIG. 15 , except that the mass body is in the form of an inner cylinder and an outer cylinder, wherein the inner cylinder is inserted into the outer cylinder  134  as a shaft  132 . The inner cylinder or shaft  132  is somewhat longer than the outer cylinder  134  and rests on the inclined surface  120 , which is rigidly connected to the cone pulley  6 , while the outer cylinder rests on the radial wall  130 , which is rigidly connected to the support ring  8 . With the mass body formed by the two components it is achieved that the mass body acts as a slide bearing, although with friction, as the shaft  132  can turn relative to the outer cylinder  134 . 
   The embodiment illustrated in  FIG. 17  is identical to  FIGS. 13 and 14 , except that the mass body is provided as two intermeshing gears  132  and  134 , and that the inclined surfaces  120  and  126  are provided with teeth that engage with the teeth of the gears  132  and  134 . This will prevent sliding as compared with  FIGS. 13 and 14 . 
   Vehicles equipped with cone pulley CVTs must also be towable, e.g. when the transmission hydraulics is defective. As a known method, the axially movable cone pulleys are pushed toward the axially fixed pulleys by means of springs, so that the endless torque-transmitting means is in friction-locking contact pressure with the cone pulleys and does not slip. A spring of this kind may be e.g. the spring  52  in  FIG. 1 . 
   According to the invention, towing, i.e. driving the output cone pulley pair, is performed in a different way by the vehicle. In the case of hydraulic pressure failure, the cone pulleys of at least one cone pulley pair, preferably the cone pulley pair on the output side, are separated from one another in such a manner that the endless torque-transmitting means or the endless chain slides on the drive shaft of the cone pulley CVT that is preferably on the output side, and turns with the wheels of the towed vehicle. 
   An advantage over the conventional solution is that the endless chain assumes a well-defined position, independently of the towing speed. This allows easy and low-cost implementation. 
     FIG. 18  is a view similar to that of  FIG. 1  and shows a cutaway view of a cone pulley pair on the output side of such an embodiment. The annular wall structure  12  is rigidly connected to the cone pulley  6 , which is movable axially relative to the shaft. An inner pressure chamber  22  is formed between the cone pulley  6  and the support ring  8 . An outer pressure chamber  26  is formed between the support ring  8  and the wall structure  12 . The annular wall  16  of the wall structure  12  is extended above a hood  50 , which has a sliding seal facing a surface of the support ring  8 , so that another chamber  136  is formed. In the chamber  136  a spring  138  rests between the support ring  8  and the hood  50 , which pushes the hood  50  and simultaneously the axially movable cone pulley  6 , in the direction of the arrows, i.e., away from the axially fixed pulley that is rigidly connected to the shaft  2  (not shown). In a functional hydraulic system, the pressure in the pressure chambers  22  and  26  overpressures the spring  138 . When the hydraulic system fails, the spring  138  moves the axially movable cone pulley  6  rightward as shown in the drawing, so that the endless chain  61  comes into immediate contact with an outer surface of the shaft  2  and can slide on it with favorable friction. It is advantageous to apply a coating  140  of lubricant to the outer surface of the shaft  2 , at least in this area, to reduce friction and increase durability. 
     FIG. 19  shows a cone pulley pair on the input side according to the invention. In this embodiment, the support ring  8  and the outer ring component  44  are combined as a single component. 
   A complete cone pulley CVT is illustrated in  FIG. 20 . It can be seen that the components, such as the support ring  8 , the outer ring component  44 , the ring wall  16 , and the axially movable cone pulley  6  are identical in construction. The mounting location of the hood  50  is optional on either pulley pair. If the set of pulleys is not provided with a cover in the form of the hood  50 , the end of the annular wall  16  has a bevel according to region X 1 . 
   If the set of pulleys is covered with the hood  50 , according to region X 2 , an appropriate recess, e.g. in form of a groove that matches the wall thickness of the hood  50 , must be provided at the end of the annular wall  16 . 
   It is understood that the described design may be modified in many ways and that it is not restricted to systems that operate with two pressure chambers. 
   In the event of pressure failure, only the pulleys of the cone pulley pair on the output side (preferred solution) may be moved away from one another, or those of the cone pulley pair on the input side or those of both cone pulley pairs may be moved away from one another. For moving the cone pulleys of a cone pulley pair away from one another, a spring may be used, e.g. a coil spring (as illustrated), or a cup spring, etc., which acts at the appropriate location between the shaft or the support ring and the cone pulley or a component that is axially rigidly connected to the cone pulley. For pulling back the cone pulley, instead of a spring, or in addition to a spring, a system may be used that operates with centrifugal force (similar to the one in  FIGS. 6 to 17 ), and/or an additional hydraulic system may be used, that e.g. pressurizes the chamber  136 . 
   The patent claims submitted with the application are wording suggestions without prejudice to obtaining continued patent protection. The applicant reserves the right to claim further feature combinations that have been disclosed only in the description and/or drawings. 
   Back-references used in dependent claims refer to the further development of the subject matter of the main claim through the features of the respective dependent claim; they shall not be construed as a waiver of obtaining independent, objective protection for the feature combinations of the back-referenced dependent claims. 
   Since the subjects of the dependent claims with respect to state-of-the-art technology on the priority date may form own and independent inventions, the applicant reserves the right to make them the subject of independent claims or declarations of division. 
   They may continue to contain independent inventions that present a design that is independent of one of the subjects of the previous dependent claims. 
   The exemplary embodiments shall not be deemed a restriction of the invention. Rather, numerous variations and modifications are possible within the framework of the present disclosure, particularly such variants, elements and combinations and/or materials that by combination, modification of individual features, elements or procedural steps, in connection with those discussed in the general description, embodiments and claims and included in the drawings may be gathered by a person skilled in the art and may, through combinable features, lead to a new subject or to new procedural steps or procedures, including manufacturing, testing and operating methods.