POWER TRANSMISSION SYSTEM WITH CONTINUOUSLY VARIABLE

SPEED CONTROL

TECHNICAL FIELD

[0001] 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's lowest and highest ratio via a secondary input member and its low friction, rolling engagement with the device's members.

POWER TRANSMISSION SYSTEM WITH CONTINUOUSLY VARIABLE

SPEED CONTROL

BACKGROUND OF THE INVENTION

[0002] 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.

[0003] 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 maybe 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.

[0004] 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.

[0005] 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 ^{u,, j} — * ^{„+:„ „} . ^{,„+„„,„} These present continuously variable transmission systems provide a

significant advantage over conventional systems; however, these systems are not without their own drawbacks.

[0006] 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.

[0007] 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, hi 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 , 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'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.

[0008] 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.

[0009] 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 nput 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.

[0010] 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

[0011] 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.

[0012] It is another object of the present invention to provide an apparatus for power transmission that is extremely compact in size.

[0013] It is another object of the present invention to provide an apparatus for power transmission that is light in weight.

[0014] It is another object of the present invention to provide an apparatus for power transmission that is exceptionally efficient.

[0015] It is another object of the present invention to provide an apparatus for power transmission that is extremely reliable.

[0016] It is another object of the present invention to provide an apparatus for power transmission that has an excellent power to size ratio.

[0017] It is another object of the present invention to provide an apparatus for power transmission that can transmit extremely high torque loads.

[0018] It is another object of the present invention to provide an apparatus for power transmission that is extremely durable.

[0019] It is another object of the present invention to provide an apparatus for power transmission that is highly cost effective to manufacture.

[0020] 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 r>f ttrπi _^ r fnr ci λIπHP 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.

[0021] 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.

[0022] 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's speed increases, the output shaft's speed correspondingly decreases until its rotation is completely eliminated. Furthermore, as the secondary input member'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 ut member.

[0023] 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'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.

[0024] 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.

[0025] 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.

[0026] 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, hi 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.

[0027] 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 ower 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.

[0028] hi 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

[0029] Applicant'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.

[0030] Figure 1 is a cross-sectional view of the apparatus of the present invention.

[0031] Figure 2 is a cross-sectional view of an alternate embodiment of the present invention.

[0032] Figure 3 is a cross-sectional view of a second alternate embodiment of the present invention.

[0033] Figure 4 is a cross-sectional view of a third alternate embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0034] Referring to figures 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.

[0035] A first embodiment of the present invention is seen in figure 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 figure 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 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'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).

[0036] Continuing along the power path, and referring to figure 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).

[0037] Still referring to figure 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).

[0038] Next, still referring to figure 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, hi 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).

[0039] 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.

[0040] m 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'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).

[0041] 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).

[0042] 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.

[0043] Referring next to figure 2, a second embodiment of the present invention is shown, hi 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 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.

[0044] 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 factional 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).

[0045] 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 figure 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.

[0046] Next, referring to figure 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.

[0047] Still referring to figure 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).

[0048] Continuing with figure 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). hi 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.

[0049] Referring finally to figure 4, in the fourth embodiment, similar to the third embodiment, a power input means is coupled both to pump member (414) and innπt 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.

[0050] Still referring to figure 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).

[0051] Still referring to figure 4, as in the previous embodiment, the speed of output member (454) is further controlled by controlling the flow of hydraulic fluid ^■ (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'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.

[0052] 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.

[0053] 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.