Abstract:
A mechanical transmission device for modifying torque and speed of rotation form torque input to torque output, more particularly a device capable of modifying torque and speed of rotation in a continuously variable fashion utilizing a single set of levers in conjunction with an abaxial ring.

Description:
This application claims priority of U.S. Provisional Application No. 60/144,648, filed under 35 C.F.R. 1.53(b)(2), on Jul. 20. 1999. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of The Invention 
     A mechanical transmission device for modifying torque and speed of rotation from torque input to torque output, more particularly a device capable of modifying torque and speed of rotation in a continuously variable fashion utilizing a single set of levers in conjunction with an abaxial ring. 
     2. Background Information 
     To expand the usefulness of rotary power sources, a variety of variable torque transmission and conversion devices have been developed. Among the most energy efficient variable transmission systems are the incrementally shiftable systems that employ multiple gears or chains and cogs, but these systems generally require an interruption in power during shifts, and where many ratios are required they can become complex, bulky, and difficult to manage. Continuously variable transmissions offer greater versatility and simplify shifting operations, but all have limitations which make them more suitable for some applications than others. 
     The hydraulic or electrical drives, where a motor is driven by a pump or generator, are among the most versatile continuously variable drives, but they tend to be massive and not very energy efficient, so their use has mostly been restricted to heavy industry and high-load work and transport machinery. 
     Limited slip differential drives employ a split in the torque path with a brake or clutch or something to provide variable drag to select between paths having different ratios. Energy efficiency is good when either path is fully selected, but there are friction losses in all intermediate positions and the intermediate ratios tend to be unstable because the constancy of a given ratio is only as good as the proportionality between the friction and the power load. 
     Traction drives—where a ring, disk, or belt frictionally engages a disk, cone, or sphere at varying radii—have stable ratios throughout their range and are often more energy efficient than limited-slip drives in the intermediate ratios, but the power is transmitted through a rolling frictional interface. This interface can slip if the shear load from the power exceeds the friction, and it tends to be a focal point for wear and energy loss problems. 
     Potentially some the most energy efficient of the continuously variable drives are the oscillation drives, where rotary power is converted to oscillating power and then back again to rotary power and variable gearing is achieved by varying the amplitude of the oscillations. Rotary power loses directionality when converted to oscillating power, so there is usually a directional freewheeling mechanism which imparts directionality when converting back to rotary power, so reversing the direction of the input rotary power will typically not reverse the direction of the output rotary power; and most oscillation drives are not symmetrical such that the roles of input and output elements can be swapped. To have continuous power transmission, there must be at least two oscillating elements, each to take the load while the other is returning. Also, oscillation drives tend not to be very compact. However, oscillation drives have stable ratios and they can entirely eliminate the frictional rolling interfaces that traction drives require, so the efficiency and durability can be good. The main design challenges of the oscillation drives have been to have the oscillating elements receive and deliver power as tangentially as possible to the rotary elements while keeping the total number of elements as few as possible. 
     The device of this application is a rotary transmission device with some, but not all, of the properties of a typical oscillation drive. Like most oscillation drives, the output power is unidirectional, and reversing the direction of rotary input power will merely freewheel the input torque element rather than drive the output element in reverse. Unlike most oscillation drives, however, applicants device is symmetrical in that it is arbitrary which is the drive element and which is the driven element. If applicants device is flipped end-for-end, it will operate to convert torque identically. 
     Applicants torque transmission device has utility, for example where an unlimited number of stable gear ratios over a certain range is of benefit and where high efficiency, reasonable simplicity, and compactness are desired. This can have applications in diverse areas including pumps (giving non-variable displacement pumps variable output); endless double-loop chain hoists; machinery and conveyance timing; mopeds and other low-power vehicles that currently employ belts and expandable pulleys; and many forms of human-powered vehicles. Probably the most familiar and common of these machines is the bicycle, so for purposes of illustration, this device is herein described with particular reference to bicycles with the understanding that it can have uses for other machines as well. 
     Despite several attempts to give bicycles continuously variable transmissions, virtually all contemporary multi-speed bicycles still shift in discrete steps; that is, they experience a jump in gearing when shifting from one gear ratio to another. An advantage is seen in having a torque transmission device which can operate on bicycles as they exist without requiring extensive modification of the basic bicycle form; which has energy efficiency similar to that of existing multi-speed drives; which drives when pedalling forward and freewheels when pedalling backward; which permits coasting (rolling without the application of power); which is compact and reasonably lightweight; and importantly, which can provide an unlimited number of stable gear ratios, continuously selectable over a finite range, which can be selected at any time whether stopped, coasting, or pedalling. Applicant proposes the device of this application as such a device. 
     SUMMARY OF THE INVENTION 
     Applicant&#39;s invention employs a rotating torque input element such as a drive ring or shaft on a primary axis (the primary axis being an arbitrary reference axis which may be coincident with the axis of a wheel, pulley, crank, gear, or any other rotatable element for delivering or receiving torque); a rotating torque output element such as a ring or shaft, also on the primary axis; a multiplicity of levers radiating from the primary axis, each rotatable about the primary axis; means by which to engage and disengage each lever with the input and output elements; an abaxial element such as a ring rotating on a secondary axis parallel to, but not coincident with the primary axis; and means by which to engage the abaxial element with each of the multiplicity of radiating rotatable levers and means to move abaxial with respect to the primary axis. 
     The multiple rotating levers bear, in succession, the input torque load from the drive element. The multiple rotating levers deliver, in succession, the output torque load to the driven element. Each lever will engage the driving and driven elements at different times through a rotation about the primary axis, with an unloaded cycle between each duty. Succession of load on the levers is determined by speed of rotation so that only the slowest and fastest rotating levers bear a load at any time. The load is conducted between the slowest and fastest levers via an abaxial ring, and it is by this ring acting on differing radii of these levers that modification of torque is achieved. 
     The principle of this torque converter is unaffected by the position of the devices on each lever which engage the input and output elements, but since loads and engagement lag times are reduced as the distance from the axis of rotation is increased, an advantage is seen in having the engagement devices, such as clutches, located away or distal from the axial end of each lever. The drive and driven elements will have radii corresponding to the position of their respective clutches, and so will typically take the form of disks or rings (hereafter referred to as the drive and driven rings). 
     This torque converter device functions the same whether the bearings for rotation are mounted within a housing or on an axle, but an advantage in terms of versatility and economy of design is seen in mounting the assembly on an axle. Further, the clutches can operate to obtain either an increase or decrease in torque with a corresponding decrease or increase in speed of rotation, respectively. If the fastest lever engages the drive ring and the slowest lever engages the driven ring, torque will be increased and speed will be decreased. If the slowest lever engages the drive ring and the fastest lever engages the driven ring, torque will be decreased and speed will be increased. For simplicity, the preferred embodiment utilizes directional clutches which engage and disengage according to the relative motion between the levers and the drive and driven rings. In this configuration, torque will be delivered from the slowest lever to the fastest lever, resulting in an increase in speed and a decrease in torque to the output elements, such as a wheel. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1A is a perspective view of the torque transmission device of applicant&#39;s invention, in exploded form. 
     FIG. 1B is a side elevational view of the torque transmission device. 
     FIG. 1C is a side elevational view of the torque transmission device, with the levers in the position as shown in FIG. 1B but with arrows showing the transmission of the torque load. 
     FIG. 1D is the same view as FIG. 1C but with the abaxial ring rotated about 18 degrees, with the resulting change of position of the levers. 
     FIG. 1E is the same view as FIG. 1C but with the abaxial ring rotated about 36 degrees from the position illustrated in FIG. 1C, with the resulting change of position of the levers. 
     FIG. 1F is the same view as FIG. 1C but with the abaxial ring rotated about 54 degrees from position illustrated in FIG. 1C, with the resulting change at the position of the levers. 
     FIG. 2A is an exploded perspective view of the abaxial ring and carriage assembly cooperating with the axle. 
     FIGS. 2B and 2C are side elevational cutaway views of the carriage assembly and abaxial ring, with FIG. 2B illustrating the abaxial ring coincident with the axle and FIG. 2C illustrating the abaxial ring displaced from the axle. 
     FIG. 3 is a cross-sectional view of the torque transmission device illustrated in conjunction with an external gear set, hub, and axle. 
     FIGS. 4A-4D illustrate various views of the levers apart from the rest of the device. 
     FIGS. 5A and 5B illustrate details, and elevational view, of two embodiments of ring engagement means. 
     FIGS. 6A and 6B are views to assist an explanation of the operation of applicant&#39;s device showing representative examples of torque input (FIG. 6A) in torque output (FIG. 6B) ranges. 
     FIG. 7 is a sectional view illustrating the torque transmission device used with an internal axle mounted gear set driving the hub of a wheel. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     With reference to the enclosed figures, it is seen that the levers radiate from and rotate around a common axis, namely, the axis of the axle, and each lever can rotate over a limited range independently of the other levers. Each lever typically has two clutches—one for torque input (drive ring engagement) and the other for torque output (driven ring engagement). If used, for example, in the rear hub of a bicycle, this device could be located between the rear cog (or cogset) and the hub body (or other internal gearing within the hub). In such an application, the directional torque-in clutches would be driven by the drive ring attached to the cog or cogset. These clutches would ensure that no lever can rotate slower than the cog or cogset, though any lever may rotate faster. Thus, where the levers have varying rotational speeds, the driving force will be imparted to the slowest lever. 
     The directional torque-out clutches ensure that the driven ring will rotate no slower than any lever, though it may rotate faster, thus where the levers have varying rotational speeds, the drive force will be imparted by the fastest lever. 
     In the body of each lever is a radial slot and operating in each slot is a drive stud of the abaxial ring. Force can be exerted between the lever and stud at any point along the slot. The drive studs are mounted to and spaced evenly around the abaxial ring. The abaxial ring is mounted on a bearing which can be displaced away from the common axis of the levers, the drive ring, and the driven ring. When the abaxial ring has the same axis as the levers, the levers will be evenly spaced and they will all have the same rate of rotation, so the load will pass directly from the torque-in clutches to the torque-out clutches and the load will bypass this device. As the abaxial ring is displaced away from the common axis, the levers will acquire varying rotation rates (in effect, oscillating relative to one another). The levers pointing toward the axis of the abaxial ring will have slower rates of rotation than those pointing away from it. The greater the displacement of the abaxial ring, the greater the difference in rotational speed between the slowest and fastest levers. Torque enters this device at the speed of the slowest lever and exits at the speed of the fastest lever, and with the increased speed comes a proportional drop in torque. 
     The load path is from the drive ring, to the torque-in (drive ring) clutch on the slowest lever, to the drive stud engaging that lever, and then around the abaxial ring to the stud engaging the fastest lever, and out the torque-out (driven ring) clutch on that lever to the driven ring. Power is conveyed from the drive ring to the slowest lever purely tangentially to the drive ring rotation. Power is conveyed between the levers and the abaxial ring not quite but nearly tangentially to the lever rotation. Power is conveyed from the fastest lever to the driven ring purely tangentially to the driven ring rotation. Friction losses between the clutches and rings and between the levers and studs should be minimal. The principle energy losses will most likely be flex losses and normal bearing losses at the abaxial ring and at the center of lever rotation. 
     The ratio between input and output speed is not perfectly consistent once the abaxial ring is displaced to some distance from the axis of the levers. This is because the distance of the drive stud from the axis of the levers is not precisely constant through each lever&#39;s turn at bearing the load. The amount of variation is a function of two factors: 1) the amount of displacement of the abaxial ring and 2) the number of levers in the device. The less the displacement and the greater the number of levers, the less gear ratio fluctuation there is. An odd number of levers is preferable to an even number because the fluctuation of the input lever will be out of phase with the fluctuation of the output lever. Such a device with five levers, restricted to a maximum overdrive ratio of about 1 to 1.43, would have a maximum gear fluctuation of less than 4%—an amount comparable to the radial fluctuation that is already found on the smallest cogs currently used on bicycles (owing to the fact that cogs are, in effect, polygons). 
     The chief benefit of this device is that it makes possible minute adjustments in the gear ratio so that the cyclist will be able to easily find the exact optimal ratio to match available strength to any given combination of terrain, wind, and cargo. Because of the limited range of this device, it will probably find its most practical application in conjunction with another gearing scheme to achieve a wide gearing range, but even so, it covers a wide enough range that it can confer benefits with respect to 1) reducing the complexity, weight, and cost of the alternate gearing scheme; 2) making the alternate scheme simpler to operate; and 3) for making possible total gear ranges that would be impractical using the alternate scheme alone. If, for example, this were to be used in conjunction with a derailleur scheme (which locates the drive chain onto cogs of various sizes), a rear cogset of four cogs could replace the sets of eight or nine cogs found on many current bikes, and yet still offer a broader total range. On racing style bikes, the extra front chainring, front derailleur, and its shifter could be eliminated without any reduction in total gear range currently available. If used in conjunction with epicyclic (internal hub) gearing, the steps could be made fewer and larger, which could reduce the number of epicyclic gearsets needed along with weight, cost, and losses of energy. The weight and cost savings in whatever alternate scheme is used could at least partially offset the weight and cost of this device. It is believed there are many cyclists for whom it would be worthwhile to gain simpler operation and an unlimited number of gear ratios over a wider range than is currently available even if there is some overall increase in cost and weight. 
     FIGS. 1A and 1B illustrate details of Applicant&#39;s torque converter  10 . The torque converter  10  is seen to include a drive ring  12  and a driven ring  14 , the drive and driven ring both engaging drive levers (here five in number, but that number may be smaller or larger), designated  16 A through  16 E. Engaging the levers is an abaxial ring  18 . A multiplicity of drive ring clutches  200  through  208  and driven ring clutches  220  through  228  complete the mechanism as illustrated in FIG.  1 B. 
     With reference to FIGS. 1A through 1F, further details of Applicant&#39;s present invention may be appreciated. 
     It is seen that Applicant&#39;s torque converter  10  includes a generally disk-shaped drive ring  12 , which drive ring engages the cogset or sprocket set B so as to move therewith. That is, when sprocket set B is driven through a chain from the bicycle crank set, the drive ring rotates about an axle C, the axle C extending through the hub D of wheel E. 
     With reference to FIGS. 1A through 1F, it is seen that Applicant&#39;s drive ring includes a perimeter lip  12 A which is circular about the disk-shaped body  12 D. 
     Applicant&#39;s driven ring  14  consists of a similar perimeter lip designed to engage through fasteners or be integral with or otherwise move another member or portion of the bicycle such that ultimately the driven ring will cause the wheel to move in a direction to propel the bike forward. 
     With reference to FIGS. 1A through 1F, it is seen that there are a series of levers, again numbering five, and designated levers  16 A through  16 E. Each lever is similarly (but not necessarily identically) shaped. Each lever has a near end (axis end)  160 A through  160 E. Likewise, each lever has a removed end  162 A through  162 E. Further, each lever has a body  164 A through  164 E between the near and the removed end. Finally, each lever has, in the body, walls defining a slot designated  166 A through  166 E. 
     An abaxial ring  18  has a series of studs  18 A through  18 E arranged around said ring at angular intervals, each stud engaging a slot  166 A through  166 E in levers  16 A through  16 E, respectively. 
     On the removed ends  162 A through  162 E of levers  16 A through  16 E, there is a multiplicity of drive ring clutches  200 ,  202 ,  204 ,  206 , and  208 , the drive ring clutches for engaging the perimeter lip  12 A of the drive ring. Also on the removed ends  162 A through  162 E of levers  16 A through  16 E are a series of driven ring clutches  220 ,  222 ,  224 ,  226 , and  228  for engaging driven ring  14 . That is, on the removed ends of each lever is a drive ring clutch and a driven ring clutch. 
     At the near end of each lever is a cut-out for a set of bearings. That is, each of the five (or whatever number) levers have at the near end cut-outs for needles, roller bearings, bushings, or other means by which they can articulate with axle C and revolve freely about said axle. 
     Further, it should be appreciated that the distance from the origin (axis) of the levers to the drive ring clutches on the removed ends of the levers for each of the levers is the same for all of the levers, and the distance from the origin of the levers to the driven ring clutches on the removed ends of the levers for each of the levers is the same for all of the levers. Further still, it is seen with reference to the figures that the studs of the abaxial ring may travel (for example, by sliding or rolling) in the slots of the levers. 
     Lastly, and importantly, it should be noted with reference to FIGS. 1A through 1F that in operation, the axis of rotation of the abaxial ring is not coincident with, but is parallel to, the common axis of rotation of the levers, drive ring, and driven ring. 
     With an understanding of the components as set forth with reference to the figures and explanations above, Applicant will again briefly summarize the operation of the torque converter. The condition of the abaxial ring will be such that its axis is not coincident with the axis of the axle (i.e., the device is acting to convert torque). 
     A bicycle rider through pedalling action causes to be applied to cogset B a torque which would tend to cause the cogset to be rotated in the direction indicated in FIG. 1A by the arrow adjacent the drive ring. The cogset is in turn coupled to the drive ring and causes the drive ring to rotate at the same speed and in the same direction that the cogset is rotating. 
     The rotating drive ring will cause to engage at least one of the drive ring clutches, namely that of the slowest rotating lever, and cause that lever to rotate at the same speed as the drive ring. The drive ring will not cause to engage the drive ring clutches of the levers rotating faster than the drive ring. The rotation of the slowest lever will cause abaxial ring  18  to rotate at an angular speed greater than that of the slowest lever, and abaxial ring  18  will in turn cause the fastest lever to rotate at an angular speed greater than that of the abaxial ring. The driven ring clutch of the fastest lever will engage the driven ring and cause it to rotate at the same rate as the fastest lever. The driven ring clutches of levers rotating slower than the driven ring will not engage the driven ring. 
     With this understanding and with reference to FIGS. 1A through 1F, and with reference to the notes on the figures, an explanation of torque transfer and conversion between the drive ring and the driven ring follows. 
     Turning to FIG. 1C, at the instant of time shown, clutch  200  is engaged with drive ring  12 , and through clutch  200 , lever  16 A is being urged to rotate about its axis by the drive ring at the same rate of rotation as the drive ring. The rotation of lever  16 A urges the rotation of the other levers through the studs on the abaxial ring. Further, it can be seen that lever  16 A is moving slower than levers  16 B through  16 E owing to the fact that the stud in the slot on lever  16 A is acting at a greater distance from the center of rotation of the levers than the distances of the studs acting on each of the other four levers. Because levers  16 B through  16 E are rotating faster than drive ring  12 , drive ring  12  cannot engage the drive ring clutches of levers  16 B through  16 E. By extension, it can be seen that at the instant illustrated in FIG. 1C, the fastest moving levers are levers  16 C and  16 D with equal velocities at this instant because the studs engaging  16 C and  16 D are acting at an equal distance from the axis of the levers, that distance being less than the distances for the studs acting on each of the other three levers. However, lever  16 C is accelerating while lever  16 D is decelerating. In the next instant lever  16 C will attempt to rotate faster than driven ring  14 , causing its clutch  224  to engage the driven ring. As lever  16 D decelerates, clutch  226  will not be able to keep up with the driven ring, and will release. 
     At the instant depicted in FIG. 1D the abaxial ring has advanced 18 degrees from FIG.  1 C. Lever  16 A has the slowest rate of rotation, so drive ring  12  drives lever  16 A via clutch  200 . No other drive clutch is engaged. Lever  16 C has the fastest rate of rotation, so lever  16 C drives driven ring  14  via clutch  224 . No other driven clutch is engaged. 
     At the instant depicted in FIG. 1E the abaxial ring has advanced 36 degrees from FIG.  1 C. It can be seen that levers  16 A and  16 E are matched for slowest rates of rotation. Lever  16 A is accelerating so clutch  200  is disengaging from drive ring  12 . Lever  16 E is decelerating so clutch  208  is engaging with drive ring  12 . Lever  16 C has the fastest rate of rotation so lever  16 C drives driven ring  14  via clutch  224 . 
     At the instant depicted in FIG. 1F, the abaxial ring has advanced 54 degrees from FIG.  1 C. Lever  16 E has the slowest rate of rotation so drive ring  12  drives lever  16 E via clutch  208 . Lever  16 C has the fastest rate of rotation so lever  16 C drives driven ring  14  via clutch  224 . Another 18 degrees rotation of the abaxial ring and each lever will then occupy the position of the lever that preceded it in FIG.  1 C and the cycle will repeat. 
     FIGS. 2A through 2C illustrate details of the Applicant&#39;s abaxial ring assembly  24 . The function of the abaxial ring assembly, of which abaxial ring  18  is a part, is to move the axis of the abaxial ring from a position of rotation coincident with the axis of the axle (and, therefore, of the drive ring, driven ring, and rotating levers) to a position non-coincident or spaced away from (but still parallel to) the axis of the axle, and thereby affecting the amount of torque conversion between the drive ring and the driven ring. Moreover, the distance of displacement between the two axes of rotation (the axis of the abaxial ring and the axis of the axle) will correspondingly vary the amount of speed differential (torque conversion) between the drive and driven rings. 
     The abaxial ring assembly  24  includes the abaxial ring  18  mounted to a carriage plate  36  through a series of ball (or roller, or other) bearings  28 . The carriage plate  36  does not rotate, but instead, is slideably mounted to the axle C through the use of a transverse section  30 , typically, a plate dimensioned to slideably engage walls  32  of cut-out  34  near the center of carriage plate  36 . 
     Turning down to FIGS. 2B and 2C, as well as continuing reference to FIG.  2 A, it is seen that carriage plate  36  may be caused to slide with respect to transverse section  30  (fixed to the axle) by the actuation of knuckle shift linkage  42 . 
     Normally, spring  40  will maintain plate  36  centered on axle C in the position indicated in FIG. 2B where the axis of rotation of the abaxial ring is the same as the axis of the axle, rotating levers, and the drive and driven rings. This position will provide no torque conversion between the drive and driven rings; that is, the torque will pass unmodified from the drive ring to the driven ring giving them the same rates of rotation while torque is applied. However, as force, such as that from a cable attached to a rider-actuated twist grip on the handlebar of a bike, is applied to actuator arm  42 C, plate  36  is removed toward the position indicated in FIG. 2C, which position locates the axis of rotation of the abaxial ring away from the axis of the axle (and, therefore, the axis of rotation of the drive ring, driven ring, and levers). 
     This is done through the use of shift linkage  42 , which shift linkage is knuckled and has a first end  42 A and a second end  42 B. The first end  42 A is rotatably pinned adjacent plate  36  and the second end is rotatably pinned adjacent transverse section  30 , such as on axis  44 . (See also FIG. 3.) With reference to knuckle  42 D and the remaining structure of shift linkage  42 , as seen in FIGS. 2A through 2C and FIG. 3, it may be appreciated that when a force is applied to  42 C, the configuration between the transverse section  30  and the carriage plate  36  (and, therefore, bearing  28  and abaxial ring  18 ) will move from that position illustrated in FIG. 2B to the position illustrated in FIG.  2 C. Further, when the force applied to  42 C is released, spring  40  will return carriage plate  36  back to the position illustrated in FIG.  2 B. This may be done as a smooth, continuous movement, such as through rider-actuated rotation of a handlebar-mounted twist grip (or lever) which the bicycle rider can use to move the carriage assembly to any position between the position shown in FIG. 2B (which represents no torque conversion) and the position shown in FIG. 2C (which represents maximal torque conversion) and thus correspondingly affect the amount of torque conversion between the drive and driven rings. 
     If this torque converter is used with an alternate gearing scheme (such as is represented by cogset B) then the rider may begin in a low gear with the carriage positioned as shown in FIG. 2B for no torque conversion, then gradually increase the amount of torque conversion as the rider&#39;s speed increases until he reaches the limit shown in FIG. 2C, at which point he may move it back to the position in FIG.  2 B and shift to a higher gear, and begin again to gradually increase the amount of torque conversion as his speed continues to increase. Conversely, if his speed is decreasing, he may gradually decrease torque conversion until the carriage reaches the limit shown in FIG. 2B, at which point he may move the carriage back to the position in FIG.  2 C and shift to a lower gear, and then begin again to gradually decrease the amount of torque conversion as his speed continues to decrease. 
     FIG. 3 illustrates the hub, torque converter and cogset in cross section. For simplification lever  16 A is shown as being directly opposite lever  16 C whereas in reality, with an odd number of levers, they would be only approximately opposite. The -drive and driven rings are shown to be of different diameters for reasons of axial compactness, as this makes possible an overlap between the drive and driven rings, but the drive and driven rings could just as well have the same diameter where radial compactness is desired. 
     It can be seen with reference to FIGS. 3 and 4A that the levers, at the near end thereof, may be forked (some of the levers may be forked and some may not be). FIG. 5A shows detail of a preferred directional ring clutch with spring  240 , cylindrical roller  242 , and inclined surface  244 , such a clutch serving for both drive and driven rings. When the ring moves relative to the clutch in the direction marked to engage, the roller wedges between inclined surface  244  and the ring surface. When the ring moves in the direction marked to release, the roller is no longer wedged and the ring can proceed in that direction relative to the clutch while spring  240  holds the roller in contact with the inclined surface and the ring surface. FIG. 5B shows detail of an alternate directional ring clutch with spring  240 , and cam  246  pivotable about axis  248 , such a clutch serving for both drive and driven rings. When the ring moves to engage, the pivot forces the cam face against the ring surface. When the ring moves to release, the spring holds the cam face against the ring surface. 
     FIG. 6A shows the approximate range of rotation of the levers through which drive ring clutches will be engaged with the drive ring, and FIG. 6B shows the range through which the driven ring clutches will be engaged with the driven ring. The angle of the range given in FIG. 6A decreases and the angle of the range given in FIG. 6B increases as the abaxial ring is displaced progressively away from the axis of the axle. FIG. 7 shows the torque converter used in conjunction with an internal gearing scheme, wherein driven ring  14  drives gears G which in turn drive the hub D. 
     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.