Abstract:
The present invention is directed toward an apparatus for continuous speed variation of an output member with respect to a primary input member. In particular, the present invention provides a device having an output that rotates at reduced speed and increased torque relative to its prime input through the low friction, rolling engagement of its members, or alternatively, at increased speed and reduced torque for overdrive applications. Furthermore, the speed of the output member may be varied continuously and infinitely between the apparatus&#39;s lowest and highest ratio via a secondary input member and its low friction, rolling engagement with the device&#39;s members.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of co-pending U.S. application Ser. No. 11/535,286, filed Sep. 26, 2006 and entitled “POWER TRANSMISSION SYSTEM WITH CONTINUOUSLY VARIABLE SPEED CONTROL,” the disclosure of which is incorporated herein by reference in its entirety. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention is directed toward an apparatus for continuous speed variation of an output member with respect to a prime input member. In particular, the present invention provides a device having an output that rotates at reduced speed and increased torque relative to its prime input through the low friction, rolling engagement of its members, or alternatively, at increased speed and reduced torque for overdrive applications. Furthermore, the speed of the output member may be varied continuously and infinitely between the apparatus&#39;s lowest and highest ratio via a secondary input member and its low friction, rolling engagement with the device&#39;s members. 
       BACKGROUND OF THE INVENTION 
       [0003]    The ability to vary the power between an input and output shaft is vital to industries and economies throughout the world. Industries dependent on variable power transmission range from energy exploration and power generation to transportation and construction. Consequently, the applications range from stationary to mobile equipment, but the desired result remains the same, that is, to achieve the desired output of torque or speed in the most efficient manner possible. 
         [0004]    In order to achieve these desired power transmission results a number of systems have developed over the years to vary the desired rotational speed output with respect to the prime input member in the most efficient manner possible. Most, if not all, such current systems may be classified as either stepped, conventional power transmission systems or step-less, continuously variable power transmission systems. Each of the presently available systems, whether conventional or continuously variable, have distinct advantages and corresponding disadvantages associated therewith. 
         [0005]    First, conventional power transmission systems employ the use of multiple gear sets and clutching devices. Such systems, typically, receive input from a single source, and the speed ratio changes are accomplished in discrete steps by engaging different gears in the power transmission pathway until the output is in the vicinity of that which is desired. The output speed variation between two of the “geared” speed ratios is obtained by varying the input speed supplied by the prime mover. Consequently, the prime mover cannot always operate at its most efficient speed, resulting in a less than ideal power transmission system. 
         [0006]    To the contrary, continuously variable transmission systems provide continuously variable speed ratio change between the minimum and maximum available speed ratios. With this type of power transmission system, the prime mover may be operated at its optimum speed for peak performance or efficiency. Presently available continuously variable transmission systems include belt systems, toroidal systems, and hydrostatic systems. These present continuously variable transmission systems provide a significant advantage over conventional systems; however, these systems are not without their own drawbacks. 
         [0007]    Belt driven continuously variable transmissions consist essentially of a drive pulley, a belt, a driven pulley, and a control system. The drive pulley is driven by the prime mover and consists of two cones facing each other. The driven pulley transfers power to the output, and it also consists of two cones facing each other. The belt rides in the groove between the two cones of each pulley. When the two cones of the pulley are far apart (when the diameter increases), the belt rides lower in the groove, and the radius of the belt loop going around the pulley gets smaller. When the cones are close together (when the diameter decreases), the belt rides higher in the groove, and the radius of the belt loop going around the pulley gets larger. Such a continuously variable transmission system may use hydraulic pressure, centrifugal force, or spring tension to create the force necessary to adjust the pulley halves. This type of system works well for its intended purpose and provides many advantages including its efficiency and simplicity; however, several drawbacks of the belt driven continuously variable transmission exists as well. First, this type of system is typically limited to small, relatively low horsepower applications because of its reliance on the belt for full power transmission. In such a system, the belt can stretch (resulting in slippage and efficiency loss) or break resulting in complete power failure. Additionally, the system is limited by its size. The typical belt system is large in size and weight, limiting its useful applications to light stationary or light mobile equipment. 
         [0008]    Toroidal continuously variable power transmissions works similarly to the belt system, but it replaces the belt and pulleys with discs and power rollers. The input disc is driven by the prime mover, and the output disc transfers power to the output. Rollers are located between the discs acting like the belt, in a belt system, transmitting power from the input disc to the output disc. In operation, the rollers can rotate along two separate axes. Each roller may spin around the horizontal axis and tilt in or out around the vertical axis, which allows the roller to contact the discs in different areas. When the rollers are in contact with the input disc near the center, they must contact the output disc near the rim, resulting in a reduction in speed and an increase in torque. When the rollers contact the input disc near the rim, they must contact the output disc near the center, resulting in an increase in speed and a decrease in torque. Therefore, any tilt of the rollers incrementally changes the gear ratio, providing for an infinite variation in speed ratios between the corresponding system&#39;s minimum and maximum ratio. This type of system, similarly to the belt system, suffers from drawbacks associated with its limited size and scope. Toroidal continuously variable power transmissions are unable to handle large torque loads, and are quite heavy, limiting it to light stationary and mobile equipment as well. 
         [0009]    Finally, hydrostatic continuously variable transmission systems use variable displacement pumps to vary the fluid flow into hydrostatic motors. In this system, the rotational motion of the prime mover operates a hydrostatic pump on the input side. The pump converts the rotational motion into fluid flow; then, with a hydrostatic motor located on the output side, the fluid flow is converted back into rotational motion. However, hydrostatic drives also have several drawbacks. The hydrostatic power transmission systems are noisy and operate at very low efficiency. Therefore, they are generally used only for low speed applications such as agricultural machinery and construction equipment. Additionally, hydrostatic power transmission systems are prone to contamination, which can result in efficiency loss or catastrophic system failure. 
         [0010]    More recent developments in step-less, continuously variable power transmission systems involve the use of electromechanical transmission systems. Many such systems operate on a power-split concept similar to hydrostatic drives. Furthermore, the typical electromechanical power transmission system integrates either single or compound planetary gear trains to achieve a continuously variable transmission of power. However, a number of inherent deficiencies exist in this type of mechanical gear train that are well known in the art. For instance, the efficiency and performance of this type of system is detrimentally impacted by the sliding frictional forces generated during its operation. In order to transfer torque, planetary gear systems depend on the sliding engagement of individual gear teeth. It is well known that this sliding produces high frictional forces between the teeth, which can lead to total destruction of the system if not continuously and properly lubricated. Furthermore, proper transfer of torque in these planetary gear systems is totally reliant on the strength of each individual gear tooth. As the input member of the system rotates at a given torque, the force from each single tooth of the input is transferred, one at a time, to each single tooth of the mating gear. As a result, each individual tooth must be designed to transfer the entire force of the system including any impact loads that may be introduced at any particular time. Additionally, any tooth breakage can lead to catastrophic failure of the entire system. Finally, traditional means of manufacturing housing and components of current planetary gear systems are not only expensive and time consuming to set up and modify, but they are also expensive and time consuming to manufacture and produce. The housing for such a system consists of two or more cast parts assembled together; therefore, in order to either originally produce housings or modify existing designs, either new molds must be manufactured or modifications must be made to existing molds. Likewise, expensive tooling and highly skilled personnel are required for both the gears themselves and other major components of a planetary gear system. 
         [0011]    In view of the limitations of products currently known in the art, a tremendous need exists for a continuously variable transmission system that is compact, efficient, durable, reliable, cost-effective, and able to handle high power applications. 
       SUMMARY OF THE INVENTION 
       [0012]    In view of the foregoing, it is an object of the present invention to provide an apparatus for power transmission that allows continuously variable speed control of the output with respect to the input. 
         [0013]    It is another object of the present invention to provide an apparatus for power transmission that is extremely compact in size. 
         [0014]    It is another object of the present invention to provide an apparatus for power transmission that is light in weight. 
         [0015]    It is another object of the present invention to provide an apparatus for power transmission that is exceptionally efficient. 
         [0016]    It is another object of the present invention to provide an apparatus for power transmission that is extremely reliable. 
         [0017]    It is another object of the present invention to provide an apparatus for power transmission that has an excellent power to size ratio. 
         [0018]    It is another object of the present invention to provide an apparatus for power transmission that can transmit extremely high torque loads. 
         [0019]    It is another object of the present invention to provide an apparatus for power transmission that is extremely durable. 
         [0020]    It is another object of the present invention to provide an apparatus for power transmission that is highly cost effective to manufacture. 
         [0021]    In satisfaction of these and other related objectives, the present invention provides an apparatus for power transmission with continuously variable speed control of the output. This system provides for highly efficient transfer of power from a prime input member to an output member with output speed controlled via a secondary input member. As will be discussed in the specification to follow, practice of the present invention involves a combination of components so aligned to provide efficient transfer of power for a wide range of horsepower ratings and a wide range of applications, while allowing for infinite variation in output speed from a maximum speed through zero output rotation to reverse or negative output rotation, if desired. 
         [0022]    The preferred embodiment of the present invention incorporates a power input shaft, driven by a prime mover, configured for low-friction, rolling engagement with dual, offset driver discs. In operation, as the power input shaft rotates in a given direction each driver disc is pushed outward against another low friction, rolling mechanism, driving a second member to rotate in the same direction about the input shaft and at a reduced speed and corresponding torque increase. This increased torque is further transferred via low friction, rolling engagement with a set of dual, offset driven discs. These discs, in operation, are also pushed outward against a final low friction, rolling mechanism, driving an output member to rotate in the same direction as the second member at a further reduced speed and corresponding torque increase. Hence, the result being, an output member configured to operate in the same direction as the input member, but at reduced speed and increased torque, while being operated completely through low friction, rolling engagement of their respective members. 
         [0023]    Additionally, a second system is incorporated into the first in order to continuously vary the output speed from the maximum speed obtainable through the elimination of rotation of the output shaft in its entirety to reverse output rotation, if desired. This second system incorporates a secondary input device, driven by a secondary power source. This secondary input is configured to drive a hollow shaft member, with which the power input shaft has near frictionless engagement, while extended therethrough. This secondary input shaft incorporates two sets of dual eccentric lobe members configured for rolling engagement with the inner surfaces of the driving and driven discs of the primary system respectively. In operation, as this secondary shaft is rotated in the opposite direction of the primary, power shaft. This action, in turn, further slows the rotation of both the driving and driven disc members about the input shaft, resulting in a greater speed reduction in the output shaft. Thus, as the secondary input member&#39;s speed increases, the output shaft&#39;s speed correspondingly decreases until its rotation is completely eliminated. Furthermore, as the secondary input member&#39;s speed is further increased, the output shaft rotates in the opposite direction from that of its original direction of rotation, thus, providing breaking for the device attached to the output member. 
         [0024]    The result is a continuously variable transmission system with capabilities unmatched by the prior art. First, through a novel configuration of components, the present invention allows the prime mover to continuously operate at the user&#39;s desired speed and torque, whether the application requires a particularly high transmission of torque throughout its specified operating speeds or whether the application calls for the prime mover to operate at its peak efficiency for maximum fuel economy. That is, in operation, the present system allows for the prime mover to be set and held at the optimum speed for which the application calls. When the secondary input member is fixed to prevent rotation of the secondary input shaft, the speed is reduced through the two (or more) stage reduction system of low friction rollers to the maximum output speed and corresponding desired torque increase of the output shaft. While holding the prime mover constant, the secondary input member, which may be driven by either an electric or hydraulic motor, is ramped up, resulting in a further reduction in speed of the output member, while keeping the output member at a constant torque. Therefore, the system allows for an infinitely variable, step-less, variation in output speed, while maintaining the prime mover at a constant speed and while maintaining the available torque to the output member at a constant level as well. Furthermore, the system can be used to retard speed or provide breaking to a device connected to the output member by continuing to ramp up the speed of the secondary input until the rotation of the output member is reversed. 
         [0025]    Secondly, because of its compact design, and the robustness of its component parts, the present invention is able to transmit much higher torque and horsepower than current continuously variable transmission systems, while maintaining a much smaller envelope and lighter operating weight. Current continuously variable operating systems depend on sets of conical discs and either belts or rollers to transmit the torque loads. These types of systems, as previously mentioned, result in large, heavy systems compared to the torque loads they are capable of transmitting. By contrast, the present invention has an extremely high torque to size/weight ratio because the present invention is merely dependent upon the size of the driver and driven discs and the eccentricity of each. Further, because torque is transmitted by a series of low-friction rolling members, large torque transmitting members are not necessary. 
         [0026]    Additionally, the mechanical efficiency of the present invention is extremely high because of the near elimination of friction within the system as compared to current continuously variable power transmission systems. Whereas, most continuously variable transmission systems depend on friction for the transmission of the torque, most of the newer, electromechanical systems use planetary gear systems, as previously mentioned. In the former, a reduction in friction results in slippage and a corresponding reduction in efficiency, while in the latter, a significant amount of efficiency is lost due to the “sliding” friction generated between the mating teeth. By contrast, all torque transfer in the present system is accomplished through low-friction, rolling engagement; therefore, because the present invention completely eliminates the “sliding” or slipping friction effects of the prior art, the present invention is able to operate at a significantly higher efficiency. 
         [0027]    The present invention is also able to withstand much higher loading (including impact loading) than prior art continuously variable transmission systems. In belt systems, all loading is transferred via belts; thus, the system is limited by the tensile strength of belt materials. In toroidal systems, all loading is transferred via friction rollers; thus, the system is limited by the frictional loading between the rollers and the discs. Finally, in electromechanical gearing systems, all loading is transferred via a single gear tooth; thus, these systems are limited by the strength of materials and the loading that a single gear tooth can withstand. In the present invention, loading is evenly distributed among multiple, rolling members, which, in turn, allows the system to withstand much higher loading than its traditional counterparts. Not only does this result in a more robust system (compared to the size of the system), but it also results in a more reliable system because damage to one rolling member does not result in total system failure whereas a broken gear tooth, belt, or roller does lead to total system failure in the known prior art systems. Therefore, the present design is much more durable and reliable than currently available continuously variable transmission systems. 
         [0028]    Finally, the present invention, in its preferred embodiment, is extremely cost effective in view of the prior art of continuously variable transmission systems. The novel design of the present invention provides for a simple and cost-effective manufacturing process as opposed to more traditional manufacturing techniques applied to current power transmission systems. Whereas the traditional manufacturing methods of casting and extensive machining of a number of different sized components is laborious, time-consuming, and expensive, the present invention requires relatively very little in the way of lead or production costs. In the present invention, both the housing and the internal components of the device are laminated. That is, each component is comprised of a plurality of relatively thin pieces of source material, generally consisting of a metal alloy or some other suitably rigid material, which are individually cut and sandwiched together using an affixing means, such as pins, screws, or other bonding techniques, to form the final primary components. Production by way of lamination greatly reduces both start up time and cost as well as production time and cost without sacrificing strength or quality. Start up time and cost are reduced by eliminating the need for long-lead casting and machining equipment. Correspondingly, production time and cost are reduced by eliminating the need for stocking and using materials of multiple thicknesses and by eliminating the need for extensive machining and highly skilled machinists to produce final primary components. Thus, when compared to the prior art continuously variable power transmission systems, the present invention provides a substantially more cost-effective device than is presently available. 
         [0029]    In summary, the present invention provides a highly cost-effective, compact, and reliable continuously variable power transmission system capable of withstanding significantly higher torque loads than that of the prior art. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0030]    Applicant&#39;s invention may be further understood from a description of the accompanying drawings, wherein unless otherwise specified, like referenced numerals are intended to depict like components in the various views. 
           [0031]      FIG. 1  is a cross-sectional view of the apparatus of the present invention. 
           [0032]      FIG. 2  is a cross-sectional view of an alternate embodiment of the present invention. 
           [0033]      FIG. 3  is a cross-sectional view of a second alternate embodiment of the present invention. 
           [0034]      FIG. 4  is a cross-sectional view of a third alternate embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0035]    Referring to  FIGS. 1 through 4 , a device for continuously variable power transmission is disclosed and generally designated by numeral  10 . In the preferred embodiment, the primary components of the device are laminated. That is, each component is comprised of a plurality of relatively thin pieces of source material, generally consisting of a metal alloy or some other suitably rigid material, which are individually cut and sandwiched together using affixing or bonding means to form the final primary components. Accordingly, several different source materials may be laminated into a single part or assembly as needed for the particular application. Production by way of lamination greatly reduces both start up time and cost as well as production time and cost without sacrificing strength or quality. Start up time and cost is reduced by eliminating the need for long-lead casting and machining equipment. Correspondingly, production time and cost is reduced by eliminating the need for stocking and using materials of multiple thicknesses and by eliminating the need for extensive machining and highly skilled machinists to produce final primary components. 
         [0036]    A first embodiment of the present invention is seen in  FIG. 1 . This device contains a power input member  12  centrally, axially aligned with an output member  14 . Power input member  12  is supported on the input side of device  10  by input bearing member  16  and is configured for engaging with any number of prime movers, such as an internal combustion engine, electric motor, hydraulic motor, or turbine engine. Following the line of power transmission, input member  12  is attached to first stage adapter member  18  via any number of attachment means as known in the art. First stage adapter member  18  is further engaged with first stage roller members  20  via first stage pin members  22 . These first stage roller members  20  are configured to engage driver disc members  24  through low-friction, rolling engagement about a circular cutout machined through each driver disc  24 . As can be seen in  FIG. 1 , each driver disc member  24  is centrally offset from primary input member  12  by the same distance in diametrically opposing directions. Additionally, each driver disc member  24  is engaged with driver disc bearing members  26  about its respective inner diameter. Bearing members  26  may be ball or roller bearings, or alternatively, wraps of roller chains. The outer diameter of driver disc members  24  is machined with rounded cutouts, or alternatively, they are machined into a sprocket shape in order to allow a “walking” engagement with external roller mechanisms. Driver disc members  24 , in turn, alternately engage second roller members  28  at diametrically opposing points along the outer diameter of driver disc members  24 . Correspondingly, as driver disc members  24  are forced to revolve about input member  12  in the same direction as input member  12  by way of first stage adapter member  18 , driver disc members  24  are forced outward onto second roller members  28  forcing second stage adapter member  30 , through its rolling engagement with second pin members  32 , to rotate in the same direction as prime input member  12 , but at decreased speed with a corresponding increase in torque as it “walks” around the driver disc member&#39;s  24  perimeter. Second stage adapter member  30  is otherwise configured to rotate freely about first stage adapter member  18  through their respective engagement with one another via second stage bearing member  33 . 
         [0037]    Continuing along the power path, and referring to  FIG. 1 , second stage adapter member  30  engages driven disc members  34  through the engagement of third pin members  36  with second stage roller members  38  along circular cutouts machined through driven disc members  34 . Similar to driver disc members  24 , driven disc members  34  are centrally offset from prime input member  12  by the same amount in diametrically opposing directions. Again, similar to driver disc members  24 , driven disc members  34  engage driven disc bearing members  35  along the inner diameter of driven disc members  34 . Also similar to driver disc members  24 , the outer diameter of driven disc members  34  is machined with rounded cutouts, or alternatively, it is machined into a sprocket shaped form in order to allow a “walking” engagement with external roller mechanisms. Driven disc members  34 , in turn, alternately engage output roller members  40  at diametrically opposing points along the outer diameter of driven disc members  34 . Correspondingly, as driven disc members  34  are forced to revolve about input member  12  in the same direction as input member  12  by way of first stage adapter member  18  and second stage adapter member  30 , driven disc members  34  are forced outward onto output roller members  40  forcing outer ring member  42 , through its rolling engagement with output pin members  46  in the same direction as second stage adapter member  30 , but at decreased speed with a corresponding increase in torque. Alternatively, wraps of roller chain may be substituted for pins and rollers  28 ,  32 ,  46 ,  40 , respectively, in order to engage with a more sprocket shaped outer diameter of discs  24 ,  34 . 
         [0038]    Still referring to  FIG. 1 , and finishing out the power path, outer ring member  42  engages output ring  48  via first output ring pin members  52 . Further, this reduced speed and increased torque is carried to output member  14  through output engagement means  54 . Output engagement means  54  and output member  14  are otherwise configured to freely rotate about input member  12  and housing member  56  via output engagement bearing member  58  and output bearing member  60 . 
         [0039]    Next, still referring to  FIG. 1 , secondary input member  62  is configured within housing member  56 , supported by secondary input bearing members  64 . Secondary input member  62  is configured for engagement with a secondary input, such as an electric or hydraulic motor, which is used to variably reduce the output speed of device  10  from its maximum speed (attained through the above described reduction) through zero rotation to reverse rotation, if desired. In this first embodiment, continuing along the speed circuit, secondary input member  62  engages input sleeve  66  by way of belt member  68 , wherein input sleeve  66  is supported by and allowed to rotate freely about input member  12  through sleeve bearings  70 . Affixed to and centrally aligned with input sleeve  66  are support lobes  72  and  74  whose outer diameters engage the inner radius of outer ring member  42  and second stage adapter member  30 , respectively, through lobe bearing members  76 . 
         [0040]    Continuing along the speed control circuit, first stage eccentric lobe members  78 ,  79  and second stage eccentric lobe members  80 ,  81  are affixed to input sleeve  66 . Correspondingly, each pair of lobe members  78 - 81  has the center point of one lobe member  78 ,  80  offset from the central axis of input member  12  in one direction, while the other lobe member  79 ,  81  is centrally offset from the central axis of input member  12  an identical distance in the diametrically opposing direction. 
         [0041]    In operation, a power drive means is applied to input member  12  through a coupling engagement as known in the art. Assuming secondary input member  62  is constrained, the input speed and torque is directly transferred with minimal efficiency loss to first stage adapter member  18  because of input member&#39;s  12  low-friction, rolling support of input bearing member  16  with respect to housing member  56 , sleeve bearing members  70  with respect to constrained input sleeve  66 , second stage bearing member  33  with respect to second stage adapter member  30 , and output engagement bearing member  58  with respect to output engagement member  54 . Progressing along the power train, the input speed and torque transfers from first stage adapter member  18  to driver disc members  24  through low-friction, rolling engagement of pin members  22  and roller members  20 . As first stage adapter member  18  rotates at the same speed and torque as input member  12 , roller members  20  force driver disc members  24  to rotate about eccentric lobe members  78 ,  79 , and therefore input member  12  and constrained sleeve member  66 , in a “cam-type” fashion. The disc members are allowed to rotate about eccentric lobe members  78 ,  79  via their rolling engagement with eccentric lobe members  78 ,  79  through driver disc bearing members  26 . Correspondingly, as each driver disc member  24  rotates, it creates an eccentric sweep, which forces driver disc  24  outward onto roller  28 . This continued rotation of disc members  24  forces disc members  24  to “walk” along rollers  28 . This action forces second stage adapter member  30  to rotate (through low-friction, rolling engagement) about first stage adapter member  18  at a reduced speed and corresponding torque increase with very little efficiency loss, not only because of its low-friction rolling engagement with its driving members, but also because of its rolling engagement with central lobe member  74  via bearing member  76  and its rolling engagement with first adapter member  18  via second stage bearing member  33 . 
         [0042]    Continuing along the power train, the reduced speed and increased torque of second stage adapter member  30  is transmitted to driven disc members  34 , through the low-friction rolling engagement of pin member  36  and corresponding roller members  38 . The second stage speed reduction functions similarly to the first stage speed reduction. That is, as second stage adapter member  36  rotates at a reduced speed and increased torque from that of input member  12 , roller members  38  force driven disc members  34  to rotate about eccentric lobe members  80 ,  81 , and therefore input member  12  and constrained sleeve member  66 , in a “cam-type” fashion. The driven disc members  34  are allowed to rotate about eccentric lobe members  80 ,  81  via their rolling engagement with eccentric lobe members  80 ,  81  through lobe bearing members  35 . Furthermore, as each driven disc member  34  rotates, it creates an eccentric sweep, which forces driven disc  34  outward onto roller  40 . This continued rotation of disc members  34  forces them to “walk” along rollers  40 . Correspondingly, output ring member  42  is forced to rotate (through low-friction, rolling engagement) about second stage adapter member  30  at a reduced speed and corresponding torque increase with very little efficiency loss, not only because of its low-friction rolling engagement with its driving members, but also because of its rolling engagement with central lobe member  72  via bearing member  76 . Finally, this second stage reduced speed and increased torque is transmitted through output ring  48  and output engagement member  54  to output member  14  with very little efficiency loss because of the support and rolling engagement of bearing member  58  with respect to input member  12  and output bearing member  60  with respect to housing member  56 . 
         [0043]    As previously mentioned, additional speed control is attained through the secondary speed circuit. As secondary input member  62  speed is ramped up, input sleeve  66  is rotated in the opposite direction from input member  12 . Accordingly, eccentric lobe members  78 - 81  and central lobe members  72 ,  74  are forced to rotate at the same speed as input sleeve  66 . Further, because of the rolling engagement of the outer diameter of lobe members  78 - 81 ,  72 ,  74  with the inner diameter of disc members  24 ,  34  and adapter members  30 ,  42 , the rotation of the entire power system (excluding input member  12 ) is slowed. Therefore, by controlling the speed of secondary input member  62 , the output speed of device  10  may be varied from its maximum speed through zero output rotation to reverse rotation, if desired. 
         [0044]    Referring next to  FIG. 2 , a second embodiment of the present invention is shown. In this embodiment, a power driving means is not only coupled to input member  212 , but also engaged with hydraulic pump member  214 . Input member  212  is thus driven at the desired input speed and torque directly and transmits the same to first stage adapter  216  with minimal efficiency loss due to its being supported by low-friction, rolling engagement of sleeve bearings  218  with respect to input sleeve  220  and output engagement bearing  222  with respect to output engagement means  224 . Assuming input sleeve  220  is constrained and continuing along the power path, first stage adapter  216  transmits input speed and torque from input member  212  to driver discs  226  through low-friction, rolling engagement of first stage pin members  268  and first stage roller members  230 . As first stage adapter  216  rotates, first stage roller members  230  alternately engage and “walk” the outer diameter of driver disc members  226  at diametrically opposing points, as driver discs  226  (similar to the first embodiment) are centrally offset, with respect to input member  212 , the same distance in diametrically opposing directions. Therefore, as first adapter member  216  rotates, it forces driver discs  226  to eccentrically rotate at an increased speed and decreased torque about eccentric lobe members  228  via driver bearings  230  situated along the outer diameter of eccentric lobe members  228  and the inner diameter of driver discs  226 . Accordingly, as in the previous embodiment, eccentric lobe members  228  are attached to input sleeve  220 , and are centrally offset the same amount in diametrically opposing directions. 
         [0045]    Next, driver discs  226  transmit this speed and torque to driven discs  232  through the low-friction, rolling engagement of driver rollers  234 , driver pins  236  and driven rollers  238 . As driven discs  232  are forced to rotate, they create offsetting, eccentric sweeps about eccentric lobe members  240 , which are attached to input sleeve  220  and are centrally offset from the central axis of input sleeve  220  the same distance in diametrically opposing directions. Again, low-friction rolling engagement is attained between eccentric lobe members  240  and driven discs  232  via eccentric bearings  242 . Accordingly, each driven disc  232  is centrally offset, with respect to input member  212 , the same distance in diametrically opposing directions from one another as well. This eccentric sweeping motion forces the outer diameters of driven disc members  232  outwardly and causes engagement of the cutout or sprocket shape along second stage rollers  244  and second stage pins  246 , in turn, forcing second stage adapter  248  to rotate at reduced speed and corresponding increased torque. Accordingly, minimal frictional losses are attained because all engagement is via low-friction, rolling members as opposed to traditional sliding gear members. Second stage adapter  248  is also supported by adapter bearing  250  allowing second stage adapter to rotate freely about input sleeve  220 . Finally, this final speed and torque is transmitted directly through output ring  252  and output engagement member  224  to output member  254 . Frictional losses are again minimized through the rolling engagement of output engagement bearing  222  with respect to input member  212  and output bearing  266  with respect to housing member  256 . 
         [0046]    In operation, the optimum input speed and torque may be attained via control over a prime driving means. As previously mentioned, this driving means also drives pump member  214 . Pump member  214 , in turn, through hydraulic fluid transfer, drives motor member  258 . Still referring to  FIG. 2 , motor member  258  drives input sleeve  220  in the opposite direction of input member  212 . Correspondingly, input sleeve  220  forces eccentric lobe members  228 ,  240  to rotate in the same direction and at the same speed as input sleeve  220 . Similar to the first embodiment, as the input speed of input sleeve  220 ) is increased, the speed of disc members  226 ,  232  and second stage adapter  248  is correspondingly decreased through the engagement of the outer diameter of lobe members  228 ,  240  with the inner diameter of disc members  226 ,  232  and the engagement between input sleeve  220  and second stage adapter  248 . Hence, the output speed of the second embodiment may be controlled via manipulation of fluid flow from pump member  214  to motor member  258 , resulting in variation of output speed from its maximum through zero rotation to reverse rotation if necessary, while attaining constant speed and torque from the prime driving means. 
         [0047]    Next, referring to  FIG. 3 , in the third embodiment, similar to the second embodiment, the prime driving means is coupled both to pump member  314  and input member  312 . Again, minimal efficiency is lost in the initial speed and torque transfer from input member  312  to first stage adapter  316  because of the low-friction, rolling support from and engagement with input sleeve  320  through sleeve bearings  318  and second stage adapter  348  through second stage bearings  350 . Following the power line and assuming input sleeve  320  is constrained, the input speed and torque is transferred from first stage adapter  316  to driver discs  326  via the low-friction rolling engagement of first stage pins  318  and first stage rollers  330 . As in the previous embodiments, eccentric lobe members  328  are attached to input sleeve  320  and centrally offset by the same amount in diametrically opposing directions. Furthermore, low friction engagement between the outer diameter of eccentric lobe members  328  and driver discs  326  is achieved through lobe bearings  330 . Correspondingly, disc members  326  are also centrally offset by the same amount in diametrically opposing directions. Further, as first stage adapter  316  forces each driver disc  326  to rotate about input sleeve  320 , each driver disc  326  creates an eccentric sweep, forcing its cutouts or sprocket shaped outer diameter outward against second stage roller  334 , resulting in second stage adapter  370  rotating about input member  312  in a “walking” motion at a reduced speed and corresponding increase in torque. 
         [0048]    Still referring to  FIG. 3  and continuing along the power line, this reduced speed and increased torque is transmitted through second stage adapter  370  to driven discs  332  through its low friction, rolling engagement with driven pins  336  and driven rollers  338 . Similar to the first stage reduction, driven discs  332  are forced about their eccentric path along lobe bearings  342  and eccentric lobe members  340 , which are centrally offset by the same amount in diametrically opposing directions from input sleeve  320 . As the driven discs  332  rotate, each disc  332  is alternately forced outwardly into low-friction rolling engagement with output adapter  348  via output pins  346  and output rollers  344 . This, in turn causes output rollers  344  to “walk” along the cutout or sprocket shaped outer diameter of driven discs  332 , albeit at reduced speed and increased torque. Finally, this output torque is transmitted along output ring  352  through output engagement member  324  and to output member  354  with minimal efficiency loss due the low friction support and engagement through second stage bearing  382 , output engagement bearing  322 , and output bearing  366 . 
         [0049]    Continuing with  FIG. 3 , as in the previous embodiment, speed is controlled via pump member  314  flow control of motor member  358 . Motor member, in turn, controls the speed of rotation of input sleeve  320 . Input sleeve  320  is attached to eccentric lobe members  328 ,  340  and centrally mounted lobe member  380 . Each lobe member  328 ,  340 ,  380 , along its outer diameter, engages its corresponding disc member  326 ,  332  or adapter member  370  through rolling engagement of lobe bearings  330 ,  342 ,  382 . In operation, as the speed of input sleeve  320  increases, the speed of the corresponding members  326 ,  332 ,  370 ,  352  decreases due to their rolling engagement. Thus, the speed of output member  354  may be varied from its maximum speed through zero rotation to reverse rotation, all while keeping the speed and torque of the prime mover constant. 
         [0050]    Referring finally to  FIG. 4 , in the fourth embodiment, similar to the third embodiment, a power input means is coupled both to pump member  414  and input member  412 . Input speed and torque is transmitted along input member  412  to first adapter member with minimal efficiency losses due to low-friction rolling support and engagement with input sleeve  420  via sleeve bearings  418 , second stage adapter  470  via second stage bearings  472 , and output engagement  424  via output engagement bearings  422 . Still following the power line and assuming input sleeve  420  is constrained, first stage adapter member  416  transmits input speed and torque to driving disc members  426  through the low friction, rolling engagement of first stage pin members  468  and first stage roller members  430 . Furthermore, as in the previous embodiments, eccentric lobe members  428  are attached to input sleeve  420  and are centrally offset by the same distance in diametrically opposing directions. Because of this configuration, as driven discs  426  are forced to rotate about their corresponding eccentric lobe member  428  through the rolling engagement of lobe bearings  430 , the cutout or sprocket shaped outer diameter of driver discs  426  are forced into low-friction rolling engagement with second stage rollers  434 . As driver disc  426  rotation continues, the outer diameter of driver discs  426  “walk” second stage adapter  470  about the central axis of input member  412  forcing second stage adapter  470  to rotate at a reduced speed and corresponding torque increase. 
         [0051]    Still referring to  FIG. 4  and following the power line, as second stage adapter  470  rotates at its reduced velocity and increased torque, it engages the cutout or sprocket shaped outer diameter of driven discs  432  through low friction, rolling engagement of rollers  438  and pins  436 , alternately, causing each to rotate in an eccentric fashion about input sleeve  420 . This rotation, in turn, through its low-friction rolling engagement via output pins  446  and rollers  444 , forces output adapter  448  to rotate at increased velocity and decreased torque from that of second stage adapter  470 . This output speed and torque are further transmitted to output engagement member  424  through output ring  452  and output engagement member  424 , wherein, limited efficiency loss is attained because of the low-friction, rolling support of output adapter bearing  450  with respect to input sleeve  420 , output engagement bearing  422  with respect to output engagement member  424 , and output bearing  466  with respect to output member  454 . 
         [0052]    Still referring to  FIG. 4 , as in the previous embodiment, the speed of output member  454  is further controlled by controlling the flow of hydraulic fluid from pump member  414  to motor member  458 . Motor member  458 , in turn rotates input sleeve  420  in the opposite direction from that of the input member  412 . As the speed of input sleeve  420  ramps up, the rolling contact between the outer diameter of the attached lobe members  428 ,  440 ,  480  and the inner diameter of the driver discs  426 , driven discs  432 , and second stage adapter  470 , causes each of these components to rotate at a reduced velocity, translating in reduced output speed of output member  454 . Thus, through this control circuit, the output speed of device  10  may be manipulated between device&#39;s  10  maximum speed through zero rotation to reverse rotation of the output member, while retaining a constant speed and torque (as desired) of input member  412  and the prime power driving member. 
         [0053]    In summary, each of the embodiments described herein have displayed a double speed change and corresponding torque change in one manner or another. It is important to note that although particular stages may either increase or decrease the input torque, the size of driver discs  24 ,  226 ,  326 ,  426  and driven discs  34 ,  232 ,  332 ,  432 , the number of cutouts or spokes in the outer diameter of driver discs  24 ,  226 ,  326 ,  426  and driven discs  34 ,  232 ,  332 ,  432 , and the number of rollers  28 ,  40 ,  334 ,  344 ,  230 ,  244 ,  434 ,  438  situated along the outer perimeter of driver and driven discs  24 ,  34 ,  226 ,  232 ,  326 ,  332 ,  426 ,  432  dictate the specific ratio of speed reduction and torque increase achieved, or alternatively, speed increase and torque reduction in overdrive applications. Furthermore, one skilled in the art would also contemplate from the presented embodiments that the invention contemplates both additional stages of reduction in the power line of device  10  by the addition of lobe and disc members as well as numerous power line configurations based on the embodiments disclosed. 
         [0054]    Finally, although the invention has been described with reference to specific embodiments, this description is not meant to be construed in a limited sense. Various modifications of the disclosed embodiments, as well as alternative embodiments of the inventions will become apparent to persons skilled in the art upon reference to the description of the invention. It is, therefore, contemplated that the appended claims will cover such modifications that fall within the scope of the invention.