Abstract:
A Hybrid Orbitless gearbox combines the high speed capabilities of an Orbitless first stage with the high ratio of a Coupled Orbitless second stage. The two stages share a common set of carriers and offset members for high compactness and simplicity. A Coupled Orbitless second stage may also function on its own. Its all-pinion design supports a variety of engaging members that include gears, chains, sprockets, belts, cables and pulleys, among others. Stepped engaging members further amplify the reduction ratio and variable pitch diameter engaging members provide an infinitely variable transmission ratio.

Description:
REFERENCE TO EARLIER FILED APPLICATIONS 
       [0001]    This application claims priority to U.S. Provisional Application No. U.S. 62/048,776 filed Sep. 10, 2014. This patent application is incorporated herein entirely by reference. This application improves upon International Application No. PCT/CA2015/050423 filed May 11, 2015 which discloses an Orbitless gearbox. 
     
    
     TECHNICAL FIELD 
       [0002]    The disclosure herein relates to a gearbox comprising a plurality of gears or other engaging members. More particularly, it relates to an apparatus providing a drive member that rotates at a different rate as a driven member. 
       BACKGROUND 
       [0003]    An Orbitless gearbox comprises a central gear and a number of offset crankshaft pinions, carried by a pair of offset carriers. It has lower pitch velocity, bearing speed, and windage than a Planetary gearbox but produces a lower speed ratio. It is, therefore, more energy efficient, but requires a greater volume for a given speed ratio. 
         [0004]    A Coupled Orbitless gearbox comprises coupling members which engage the central and offset members whereby they rotate in a common direction. This amplifies and inverts the speed ratio so that the roles of the input and output members are interchanged. 
         [0005]    Since the carriers are the output of an Orbitless reduction gearbox and the input of a Coupled Orbitless reduction gearbox, integrating an Orbitless first stage with a Coupled Orbitless second stage, allows a common set of carriers and offset members to be shared by both stages. A Hybrid Orbitless gearbox combines the superior efficiency and high-speed characteristics of an Orbitless gearbox with the high reduction ratio of a Coupled Orbitless gearbox. 
       SUMMARY 
       [0006]    Certain exemplary embodiments comprise a reference member, a first and second carrier, a second central member, one or more offset members, one or more coupling members, and a number of coupling axes equal to the number of coupling members. The second central member and all offset and coupling members are engaging members. The reference member comprises a central axis and a first and second carrier axis. Each carrier comprises a rotation axis and a number of offset axes equal to the number of offset members. Each offset member comprises a first and second member axis. All axes are parallel. The first and second carrier axes and all associated first and second member axes are spaced apart by the carrier distance. Each offset axis and the associated rotation axis are spaced apart by an offset distance. All offset axes are arranged circumferentially around the associated rotation axis. The second central member and the central axis, the first rotation axis and the first carrier axis, the second rotation axis and the second carrier axis, each first member axis and a different first offset axis, each second member axis and a different second offset axis, and each coupling member and a different coupling axis, are co-axial and rotatably coupled. The coupling axes are arranged whereby the coupling members simultaneously engage the second central member and all offset members. 
         [0007]    Certain exemplary embodiments further comprise a first central member which is an engaging member which is co-axial and rotatably coupled with the central axis. 
         [0008]    In certain exemplary embodiments, the first central member simultaneously engages all offset members. 
         [0009]    In certain exemplary embodiments, the first central member simultaneously engages all coupling members. 
         [0010]    In certain exemplary embodiments, each offset member is a stepped engaging member. 
         [0011]    In certain exemplary embodiments, each coupling member is a stepped engaging member. 
         [0012]    In certain exemplary embodiments, one of the first or second carriers and all coupling axes are integral. The associated carrier axis and the central axis are co-axial. 
         [0013]    Certain exemplary embodiments further comprise a third carrier comprising a third rotation axis. The third carrier and all coupling axes are integral. The third rotation axis and the central axis are co-axial and rotatably coupled. 
         [0014]    Certain exemplary embodiments further comprise a variable speed ratio between the second central member and the offset members. 
         [0015]    Certain exemplary embodiments comprise a reference member, a first and second carrier, a first and second central member, one or more offset members, and one or more coupling members. The first and second central member and all offset and coupling members are engaging members. The reference member comprises a central axis and a first and second carrier axis. Each carrier comprises a rotation axis and a number of offset axes equal to the number of offset members. Each offset member comprises a first and second member axis. All axes are parallel. The first and second carrier axes and all associated first and second member axes are spaced apart by the carrier distance. Each offset axis and the associated rotation axis are spaced apart by an offset distance. All offset axes are arranged circumferentially around the associated rotation axis. The first central member and the central axis, the second central member and the central axis, the first rotation axis and the first carrier axis, the second rotation axis and the second carrier axis, each first member axis and a different first offset axis, and each second member axis and a different second offset axis, are co-axial and rotatably coupled. The first central member simultaneously engages all offset members. The coupling members simultaneously engage the second central member and all offset members. 
         [0016]    In certain exemplary embodiments, each coupling member is a stepped engaging member. 
         [0017]    Certain exemplary embodiments further comprise a variable speed ratio between the second central member and the offset members. 
         [0018]    In certain exemplary embodiments, a reference member, a first and second carrier, a first and second central member, one or more offset members, and one or more coupling members are provided. The first and second central members and all offset and coupling members are provided with an engaging means. The reference member is provided with a central axis and a first and second carrier axis. Each carrier is provided with a rotation axis and a number of offset axes equal to the number of offset members. Each offset member is provided with a first and second member axis. All axes are located whereby they are all parallel. The first and second carrier axes and all associated first and second member axes are spaced apart by the carrier distance. Each offset axis and the associated rotation axis are spaced apart by an offset distance. All offset axes are arranged circumferentially around the associated rotation axis. The first central member and the central axis, the second central member and the central axis, the first rotation axis and first carrier axis, the second rotation axis and second carrier axis, each first member axis and a different first offset axis, and each second member axis and a different second offset axis, are co-axially located and rotatably coupled. The coupling members are simultaneously engaged with the second central member and all offset members. 
         [0019]    In certain exemplary embodiments, the first central member is simultaneously engaged with all offset members. 
         [0020]    In certain exemplary embodiments, the first central member is simultaneously engaged with all coupling members. 
         [0021]    In certain exemplary embodiments, each offset member is provided with a first engaging step and a second engaging step. 
         [0022]    In certain exemplary embodiments, each coupling member is provided with a first engaging step and a second engaging step. 
         [0023]    In certain exemplary embodiments, one of the first or second carriers is provided with a number of coupling axes equal to the number of coupling members. Each coupling member and a different coupling axis are co-axially located and rotatably coupled. The associated carrier axis and the central axis are co-axially located. 
         [0024]    In certain exemplary embodiments, a third carrier is provided which is provided with a third rotation axis and a number of coupling axes equal to the number of coupling members. Each coupling member and a different coupling axis, and the third rotation axis and the central axis, are co-axially located and rotatably coupled. 
         [0025]    In certain exemplary embodiments, a variable speed ratio is provided between the second central member and the offset members. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0026]      FIGS. 1A-1D  are respectively, a schematic side view, two partial front views, and an exploded perspective view, in accordance with a first exemplary embodiment depicting the present invention comprising gear engaging members. 
           [0027]      FIGS. 1E-1F  are respectively a rear view of an offset member, and a perspective view of an engaged offset and coupling member, in accordance with the first exemplary embodiment of the present invention. 
           [0028]      FIG. 2  is a partial front view in accordance with a second exemplary embodiment depicting the present invention comprising two coupling members engaging each offset member. 
           [0029]      FIGS. 3A-3B  are respectively, a schematic side view and an exploded perspective view, in accordance with a third exemplary embodiment depicting the present invention comprising stepped coupling members. 
           [0030]      FIG. 4  is a schematic side view in accordance with a fourth exemplary embodiment depicting the present invention comprising a ring first central member engaging stepped coupling members. 
           [0031]      FIG. 5  is a schematic side view in accordance with a fifth exemplary embodiment depicting the present invention comprising three non-co-axial carriers. 
           [0032]      FIG. 6  is a schematic side view in accordance with a sixth exemplary embodiment depicting the present invention comprising stepped offset members. 
           [0033]      FIGS. 7A-7B  are respectively, an exploded perspective view and a partial front view, in accordance with a seventh exemplary embodiment depicting the present invention comprising flexible coupling members. 
           [0034]      FIG. 7C  is a perspective view of a stepped second central member, in accordance with the seventh exemplary embodiment of the present invention. 
           [0035]      FIG. 8  is a partial front view in accordance with an eighth exemplary embodiment depicting the present invention comprising two serpentine coupling members, each engaging a pair of adjacent offset members. 
           [0036]      FIG. 9  is a partial front view in accordance with a ninth exemplary embodiment depicting the present invention comprising one flexible coupling member and one serpentine coupling member. 
           [0037]      FIGS. 10A-10B  are respectively, a schematic side view and an exploded perspective view in accordance with a tenth exemplary embodiment depicting the present invention comprising an integral first drive-shaft and first carrier. 
           [0038]      FIG. 11  is a schematic side view in accordance with an eleventh exemplary embodiment depicting the present invention comprising an integral first drive-shaft and second carrier, providing offset first and second drive-shafts. 
           [0039]      FIG. 12  is a schematic side view in accordance with a twelfth exemplary embodiment depicting the present invention comprising multiple second drive-shafts, each providing a different speed ratio. 
       
    
    
     REFERENCE NUMERALS 
       [0040]      
         [0000]    
       
         
               
             
           
               
                   
               
             
             
               
                 0-central axis 
               
               
                 1-first carrier axis 
               
               
                 2-second carrier axis 
               
               
                 3-first rotation axis 
               
               
                 4-second rotation axis 
               
               
                 5-third rotation axis 
               
               
                 6-first offset axis 
               
               
                 7-second offset axis 
               
               
                 8-first member axis 
               
               
                 9-second member axis 
               
               
                 10-coupling axis 
               
               
                 11-first drive-shaft 
               
               
                 12-second drive-shaft 
               
               
                 13-first shaft 
               
               
                 14-second shaft 
               
               
                 15-coupling shaft 
               
               
                 21-first carrier 
               
               
                 22-second carrier 
               
               
                 23-third carrier 
               
               
                 30-reference member 
               
               
                 31-first central member 
               
               
                 32-second central member 
               
               
                 33-offset member 
               
               
                 34-coupling member 
               
               
                 40-carrier distance 
               
               
                 41-offset distance 
               
               
                 42-coupling distance 
               
               
                 51-first stage 
               
               
                 52-second stage 
               
               
                 53-front 
               
               
                 54-rear 
               
               
                   
               
             
          
         
       
     
       Definitions 
       [0041]    A gear, sprocket, chain, pulley, belt, cable, friction or magnetic coupling, or any other member that engages and transmits energy to a mate is defined as an engaging member. 
         [0042]    An engaging member that engages and transmits energy between two or more engaging members is defined as a coupling member. 
         [0043]    A chain, belt, cable, or any other coupling member that changes shape while transmitting energy is defined as a flexible coupling member. 
         [0044]    A flexible coupling member that simultaneously couples three or more engaging members is defined as a serpentine coupling member. 
         [0045]    A flexible coupling comprising two counter-acting, pre-loaded cables that are fixedly attached to two pulleys is defined as a capstan cable coupling. 
         [0046]    An engaging member that engages on its exterior surface is defined as a pinion. 
         [0047]    An engaging member that engages on its interior surface is defined as a ring. 
         [0048]    A member that is coupled to an axis by three or more encircling engaging members but by no other mechanical means is defined as floating. 
         [0049]    Two parallel, offset shafts integrated into a common member is defined as a crankshaft. 
         [0050]    An apparatus that scales the relative speed and torque of a drive and driven member is defined as a gearbox, whether or not it comprises any gears. 
         [0051]    A gearbox that reduces velocity and amplifies torque is defined as a reduction gearbox. 
         [0052]    A gearbox that amplifies velocity and reduces torque is defined as an overdrive gearbox. 
         [0053]    A gearbox that may function as either a reduction or an overdrive gearbox is defined as back-drivable. 
         [0054]    A gearbox comprising a reference member, two offset carriers, a central member and one or more crankshaft offset members is defined as an Orbitless gearbox. 
         [0055]    An Orbitless gearbox further comprising one or more coupling members is defined as a Coupled Orbitless gearbox. 
         [0056]    A gearbox which integrates two or more Orbitless and/or Coupled Orbitless gearboxes with a common set of carriers is defined as a Hybrid Orbitless gearbox. 
       DESCRIPTION OF EMBODIMENTS 
       [0057]    Wherever possible, the same reference numerals are used throughout the accompanying drawings and descriptions to refer to the same or similar parts. Components such as bearings, retainers and fasteners that do not substantially contribute to the understanding of the invention are neglected for the sake of simplicity. 
         [0058]    Although spur gears, pulleys, belts and cables are depicted in the accompanying drawings, it is understood that many other engaging means would suffice, such as conical, radial, offset, spiral, helical, double helical, herring-bone, or roller tooth gears, friction or magnetic couplings, and chain drives. It is also understood that associated gears may comprise any face width, tooth profile, pressure angle, or module and may be made from metal, plastic, or any other appropriate material. 
         [0059]    Although a male shaft and female race are used to depict a rotatable coupling in the accompanying drawings, it is understood that any other means will suffice, such as anti-friction bearings, bushings, or low friction coatings, materials, surface treatments or lubricants. It is also understood that the male and female members of a rotatable coupling may often be interchanged. 
         [0060]    Although a shaft is used to depict a drive or driven member in the accompanying drawings, it is understood that any other means will suffice, such as an engaging member, a keyed, splined, or threaded hole, or a magnetic or electrostatic coupling. 
         [0061]    Although three or four offset members  33  are depicted in certain accompanying drawings, it is understood that any number of offset members  33  may be included, as long as they do not mechanically interfere. 
         [0062]    Although two stages are depicted sharing a common set of carriers in certain accompanying drawings, it is understood that any number of stages may be included, as long as they do not mechanically interfere. 
         [0063]    It is understood that multiple gearboxes may be joined in series or in parallel or combined with any other type of gearbox to provide a desired speed ratio or other characteristic. 
         [0064]    It is understood that a back-drivable gearbox may provide either a reduction or an overdrive ratio by interchanging the roles of its drive and driven members. In fact, the roles of the reference member, drive member and driven member may all be interchanged to obtain a desired speed ratio, or to cause the drive and driven members to rotate in the same or opposite directions. Similarly, if any one is used as a drive member and the remaining two are used as driven members, a differential mechanism is obtained. Reduction, overdrive, differential, and reverse gearboxes are all contemplated. 
         [0065]    It is understood that any one of the reference member  30 , the first central member  31 , the second central member  32 , an offset member  33 , a coupling member  34 , or the first, second, or third carrier  21 ,  22 ,  23 , may act as the reference with any other member acting as the drive or driven member. 
         [0066]    Although certain exemplary embodiments depict the first drive-shaft  11  and the first or second carrier  21 ,  22  as integral, all carriers  21 ,  22 ,  23  rotate in unison so the first drive-shaft  11  could be integral with any of the first, second or third carriers  21 ,  22 ,  23 . 
         [0067]    It is understood that the individual offset members  33  may have non-uniform first and second member axes  8 ,  9  as long as the associated first and second offset axes  6 ,  7  are similarly non-uniform, although additional vibration may result. 
         [0068]    Although certain exemplary embodiments depict all offset axes  6 ,  7  as being circumferentially equally spaced around the associated rotation axis  3 ,  4 , it is understood that they may be unequally spaced, although additional vibration may result. 
         [0069]    Although certain exemplary embodiments depict a first, second or third carrier  21 ,  22 ,  23 , that is rotatably coupled about its center, it is understood that rotational coupling could be provided between the interior of the case  30  and the exterior of the associated carrier  21 ,  22 ,  23 . Alternatively, a first, second or third carrier  21 ,  22 ,  23 , that is rotatably coupled to the central axis  0 , may be a floating carrier which is not explicitly coupled to the case  30 . Similarly, the first or second central member  31 ,  32 , may be floating members. 
         [0070]    A representative sample of embodiments is included in the accompanying drawings for exemplary purposes only. A great number of kinematic arrangements, types of engaging members, and combinations of disclosed features are also contemplated. The scope of the present invention is not limited to the embodiments included but spans all possible combinations anticipated by the specification and claims. 
         [0071]      FIGS. 1A-1F  illustrate a first exemplary embodiment of the present invention providing a reduction ratio between a first drive-shaft  11  and a second drive-shaft  12 . 
         [0072]    The first exemplary embodiment comprises a reference member  30 , a first carrier  21 , a second carrier  22 , a first central member  31 , a second central member  32 , three offset members  33 , and three coupling members  34 . 
         [0073]    The reference member  30  acts as the case of the gearbox and comprises a central axis  0 , a first carrier axis  1 , and a second carrier axis  2 , all of which are parallel. The first carrier axis  1  and the central axis  0  are co-axial. The second carrier axis  2  and the central axis  0  are spaced apart by a carrier distance  40 . 
         [0074]    The first carrier  21  comprises a first rotation axis  3 , three first offset axes  6 , and three coupling axes  10 . All first offset axes  6  are circumferentially equally spaced. Each first offset axis  6  and the first rotation axis  3  are spaced apart by an offset distance  41 . All coupling axes  10  are circumferentially equally spaced. Each coupling axis  10  and the first rotation axis  3  are spaced apart by a coupling distance  42 . 
         [0075]    The second carrier  22  comprises a second rotation axis  4  and three second offset axes  7 . All second offset axes  7  are circumferentially equally spaced. Each second offset axis  7  and the second rotation axis  4  are spaced apart by the offset distance  41 . 
         [0076]    The first rotation axis  3  and the first carrier axis  1  are co-axial and rotatably coupled. The second rotation axis  4  and the second carrier axis  2  are co-axial and rotatably coupled. 
         [0077]    Each offset member  33  comprises a co-axial first shaft  13  defining a first member axis  8 , and an offset second shaft  14  defining a second member axis  9 , which are parallel, spaced apart by the carrier distance  40 , and together define a crankshaft. Each coupling member  34  comprises a co-axial coupling shaft  15 . 
         [0078]    Each first member axis  8  and a different first offset axis  6  are co-axial and rotatably coupled. Each second member axis  9  and a different second offset axis  7  are co-axial and rotatably coupled. Each coupling shaft  15  and a different coupling axis  10  are co-axial and rotatably coupled. 
         [0079]    The first central member  31  and first drive-shaft  11  are co-axial and integral. The second central member  32  and second drive-shaft  12  are co-axial and integral. The first central member  31  and the central axis  0  are co-axial and rotatably coupled. The second central member  32  and the central axis  0  are co-axial and rotatably coupled. 
         [0080]    The first central member  31 , second central member  32 , all offset members  33 , and all coupling members  34  are pinion gears. The first central member  31  simultaneously engages all offset members  33 . Each coupling member  34  simultaneously engages the second central member  32  and a different offset member  33 . Together, the coupling members  34  co-operate to simultaneously engage the second central member  32  and all offset members  33 . 
         [0081]    The first central member  31 , all offset members  33 , and the carriers  21 ,  22 , together define a first stage  51  which is an Orbitless gearbox. The second central member  32 , all offset members  33 , all coupling members  34 , and the carriers  21 ,  22 , together define a second stage  52  which is a Coupled Orbitless gearbox. The offset members  33  and carriers  21 ,  22  are shared by the first and second stages  51 ,  52 , which together define a Hybrid Orbitless gearbox. 
         [0082]      FIG. 1E  illustrates non-uniform placement of the second shafts  14   a - 14   c  on the associated offset members  33   a - 33   c  that is required for the first exemplary embodiment to be assemble-able. The requirement for non-uniform second shaft  14  placement depends on the particular pitch diameters and spacing of the associated engaging members. 
         [0083]      FIG. 1F  illustrates a detail view of an offset member  33  and an engaged coupling member  34 . The offset member  33  has a large face width, a portion of which is engaged by the first stage  51 , and a portion of which is engaged by the second stage  52 . 
         [0084]      FIG. 2  illustrates a second exemplary embodiment of the present invention which is similar to the first exemplary embodiment except two redundant coupling members  34   a ,  34   b  simultaneously engage the second central member  32  and each offset member  33 . Both coupling members  34   a ,  34   b  are depicted with uniform pitch diameters. If the coupling members  34   a ,  34   b  are non-uniform, non-uniform coupling distances  42  are required for the associated coupling members  34   a ,  34   b.    
         [0085]      FIGS. 3A-3B  illustrate a third exemplary embodiment of the present invention which is similar to the first exemplary embodiment except each coupling member  34  is a stepped coupling member comprising a first step  34   a , and a second step  34   b . An offset member  33  engages each first step  34   a  and the second central member  32  simultaneously engages all second steps  34   b . In addition, the second carrier  22  is located in front of the offset members  33  and the second central member  32  is located behind the first carrier  21 , which is a floating carrier. 
         [0086]      FIG. 4  illustrates a fourth exemplary embodiment of the present invention which is similar to the first exemplary embodiment except each coupling member  34  is a stepped coupling member comprising a first step  34   a  and a second step  34   b . The first central member  31  is a ring which simultaneously engages all first steps  34   a  and each second step  34   b  simultaneously engages the second central member  32  and an offset member  33 . 
         [0087]      FIG. 5  illustrates a fifth exemplary embodiment of the present invention which is similar to the first exemplary embodiment except it further comprises a third carrier  23  which is integral with all coupling axes  10  and comprises a third rotation axis  5 . The third rotation axis  5  and the central axis  0  are co-axial and rotatably coupled, the second carrier  22  is located in front of the offset members  33 , each first shaft  13  and the associated offset member  33  are non-co-axial, and the first carrier axis  1  and the central axis  0  are non-co-axial. 
         [0088]      FIG. 6  illustrates a sixth exemplary embodiment of the present invention which is similar to the first exemplary embodiment except each offset member  33  is a stepped offset member comprising a first step  33   a , and a second step  33   b . All first steps  33   a  simultaneously engage the first central member  31  and each second step  33   b  engages a coupling member  34 . 
         [0089]      FIGS. 7A-7C  illustrate a seventh exemplary embodiment of the present invention which is similar to the sixth exemplary embodiment except all offset members  33  are stepped offset members  33  comprising a gear first step  33   a  and a pulley second step  33   b , all coupling members  34  are flexible coupling members  34 , there are no coupling axes  10 , and the second central member  32  is a stepped pulley. 
         [0090]      FIG. 7B  depicts the second stage  52  of the seventh exemplary embodiment. 
         [0091]      FIG. 7C  illustrates a detail view of the second central member  32  comprising three steps  32   a - 32   c  which each engage a different flexible coupling member  34 . All steps  32   a - 32   c  have a common pitch diameter and are included to avoid mechanical interference. 
         [0092]      FIG. 8  illustrates an eighth exemplary embodiment of the present invention which is an alternative configuration of the second stage  52  of the seventh exemplary embodiment. It comprises four offset members  33   b  and two serpentine coupling members  34 , each simultaneously engaging the second central member  32  and two offset members  33 . 
         [0093]      FIG. 9  illustrates a ninth exemplary embodiment of the present invention which is an alternative configuration of the second stage  52  of the seventh exemplary embodiment. It comprises three offset members  33   b , one of which further comprises a third step  33   c . A serpentine engaging member  34   a  simultaneously engages all offset member second steps  33   b . A flexible engaging member  34   b  simultaneously engages the second central member  32  and the offset member third step  33   c . Providing the second central member  32  and the offset member third step  33   c  with a variable pitch diameter results in an infinitely variable speed ratio. 
         [0094]      FIGS. 10A-10B  illustrate a tenth exemplary embodiment of the present invention which is similar to the first exemplary embodiment except the first central member  31  is absent, the first and second carriers  21 ,  22  are located in front of the offset members  33 , and the first drive-shaft  11  and the first carrier  21  are co-axial and integral. The absence of the first central member  31  eliminates the first stage  51  altogether, and leaves only the second stage  52 , which is a Coupled Orbitless gearbox. 
         [0095]      FIG. 11  illustrates an eleventh exemplary embodiment of the present invention which is similar to the tenth exemplary embodiment except the first drive-shaft  11  and second carrier  22  are co-axial and integral. This embodiment provides offset first and second drive-shafts  11 ,  12 . 
         [0096]      FIG. 12  illustrates a twelfth exemplary embodiment of the present invention which is similar to the first exemplary embodiment except the first central member  31  is a ring, the first central member  31  and an additional second drive-shaft  12   a  are co-axial and integral, the first and second carriers  21 ,  22  are located in front of the offset members  33 , and the first drive-shaft  11  and the first carrier  21  are co-axial and integral. The first and second stages  51 ,  52 , each depict a Coupled Orbitless gearbox which both reside in a common plane and each comprise a second drive-shaft  12   a ,  12   b  which each deliver a different speed ratio, and together depict a 2-speed Coupled Orbitless gearbox. 
       EXAMPLES 
       [0097]    As illustrated by the arrows in  FIG. 1B , the first through ninth exemplary embodiments each comprise a first stage  51  comprising a first central member  31  and offset members  33  which are engaged whereby they counter-rotate with respect to the first carrier  21 . Each of these exemplary embodiments depict an Orbitless first stage  51 . 
         [0098]    As illustrated by the arrows in  FIGS. 1C, 2, 7B, 8 and 9 , the first through twelfth exemplary embodiments each comprise a second stage  52  comprising a second central member  32  and offset members  33  which are engaged whereby they rotate in a common direction with respect to the first carrier  21 . Each of these exemplary embodiments depict a Coupled Orbitless second stage  52 . 
         [0099]    In each of the examples herein, two gearbox speed ratios, R and R′ are defined where T 1  is the number of turns of the first drive-shaft  11  and T 2  is the corresponding number of turns of the second drive-shaft  12 , all with respect to the reference member  30 . 
         [0000]    
       
         
           
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         [0100]    For each of the first and second stages  51 ,  52 , two corresponding speed ratios, R 1 , R 1 ′, R 2 , and R 2 ′, are defined where T C  is the number of turns of the carriers  21 ,  22 ,  23 , which all rotate in unison with respect to the reference member  30 . 
         [0000]    
       
         
           
             
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         [0101]    A Hybrid Orbitless gearbox comprising an Orbitless first stage  51  and a Coupled Orbitless second stage  52  provides the following reduction ratio: 
         [0000]    
       
         
           
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               = 
               
                 
                   
                     
                       T 
                       1 
                     
                     
                       T 
                       C 
                     
                   
                    
                   
                     
                       T 
                       C 
                     
                     
                       T 
                       2 
                     
                   
                    
                   
                     : 
                   
                    
                   1 
                 
                 = 
                 
                   
                     R 
                     1 
                   
                    
                   
                     R 
                     2 
                     ′ 
                   
                    
                   
                     : 
                   
                    
                   1 
                 
               
             
           
         
       
     
         [0102]    Speed ratios are computed from P 1 , P 2 , P o , P a , and P b  which are the pitch diameters of the first central member  31 , second central member  32 , offset members  33 , coupling member first steps  34   a , and coupling member second steps  34   b , respectively. Only stepped coupling members  34  alter the speed ratio. When an engaging member is a gear with a module of 1, the pitch diameter is equal to the number of teeth. 
         [0103]    In each first stage  51 , the first central member  31  and all offset members  33  are engaged whereby they counter-rotate and provide the following speed ratios: 
         [0000]    
       
         
           
             
               R 
               1 
             
             = 
             
               
                 1 
                 + 
                 
                   
                     
                       P 
                       o 
                     
                     
                       P 
                       1 
                     
                   
                    
                   
                     : 
                   
                    
                   1 
                    
                   
                       
                   
                    
                   
                     R 
                     1 
                     ′ 
                   
                 
               
               = 
               
                 
                   
                     P 
                     1 
                   
                   
                     
                       P 
                       1 
                     
                     + 
                     
                       P 
                       o 
                     
                   
                 
                  
                 
                   : 
                 
                  
                 1 
               
             
           
         
       
     
         [0104]    In each second stage  52 , the second central member  32  and all offset members  33  are engaged whereby they rotate in a common direction and provide the following speed ratios: 
         [0000]    
       
         
           
             
               R 
               2 
             
             = 
             
               
                 1 
                 - 
                 
                   
                     
                       P 
                       o 
                     
                     
                       P 
                       2 
                     
                   
                    
                   
                     : 
                   
                    
                   1 
                    
                   
                       
                   
                    
                   
                     R 
                     2 
                     ′ 
                   
                 
               
               = 
               
                 
                   
                     P 
                     2 
                   
                   
                     
                       P 
                       2 
                     
                     + 
                     
                       P 
                       o 
                     
                   
                 
                  
                 
                   : 
                 
                  
                 1 
               
             
           
         
       
     
         [0105]    The following speed ratios result when the following conditions are met: 
         [0106]    R 2 ′=P 2 :1 P o =P 2 −1 
         [0107]    R 2 ′=−P 2 :1 P o =P 2 +1 
         [0108]    The following speed ratios result when the coupling members  34  are stepped: 
         [0000]    
       
         
           
             
               R 
               2 
             
             = 
             
               
                 1 
                 - 
                 
                   
                     
                       
                         P 
                         o 
                       
                        
                       
                         P 
                         b 
                       
                     
                     
                       
                         P 
                         2 
                       
                        
                       
                         P 
                         a 
                       
                     
                   
                    
                   
                     : 
                   
                    
                   1 
                    
                   
                       
                   
                    
                   
                     R 
                     2 
                     ′ 
                   
                 
               
               = 
               
                 
                   
                     
                       P 
                       2 
                     
                      
                     
                       P 
                       a 
                     
                   
                   
                     
                       
                         P 
                         2 
                       
                        
                       
                         P 
                         a 
                       
                     
                     - 
                     
                       
                         P 
                         o 
                       
                        
                       
                         P 
                         b 
                       
                     
                   
                 
                  
                 
                   : 
                 
                  
                 1 
               
             
           
         
       
     
         [0109]    The following speed ratios result when the following conditions are met: 
         [0110]    R 2 ′=P 2   2 :1 P o =P 2 −1 P a =P 2  P b =P 2 +1 
         [0111]    R 2 ′=P 2   2 :1 P o =P 2 +1 P=P 2  P b =P 2 −1 
         [0112]    A first example considers the first and second exemplary embodiments illustrated in  FIGS. 1-2  where each coupling member  34  is a non-stepped pinion gear. 
         [0000]    
       
         
           
             
               P 
               1 
             
             = 
             
               
                 27 
                  
                 
                     
                 
                  
                 
                   P 
                   2 
                 
               
               = 
               
                 
                   21 
                    
                   
                       
                   
                    
                   
                     P 
                     o 
                   
                 
                 = 
                 20 
               
             
           
         
       
       
         
           
             
               R 
               1 
             
             = 
             
               
                 1 
                 + 
                 
                   
                     P 
                     o 
                   
                   
                     P 
                     1 
                   
                 
               
               = 
               
                 
                   1.74 
                    
                   
                     : 
                   
                    
                   1 
                    
                   
                       
                   
                    
                   
                     R 
                     2 
                     ′ 
                   
                 
                 = 
                 
                   
                     P 
                     2 
                   
                   = 
                   
                     
                       21 
                        
                       
                         : 
                       
                        
                       1 
                        
                       
                           
                       
                        
                       R 
                     
                     = 
                     
                       
                         
                           R 
                           1 
                         
                          
                         
                           R 
                           2 
                           ′ 
                         
                       
                       = 
                       
                         37 
                          
                         
                           : 
                         
                          
                         1 
                       
                     
                   
                 
               
             
           
         
       
     
         [0113]    A second example considers the third exemplary embodiment illustrated in  FIG. 3  where each coupling member  34  is a stepped pinion gear. 
         [0000]    
       
         
           
             
               P 
               1 
             
             = 
             
               
                 25 
                  
                 
                     
                 
                  
                 
                   P 
                   2 
                 
               
               = 
               
                 
                   19 
                    
                   
                       
                   
                    
                   
                     P 
                     o 
                   
                 
                 = 
                 
                   
                     20 
                      
                     
                         
                     
                      
                     
                       P 
                       a 
                     
                   
                   = 
                   
                     
                       19 
                        
                       
                           
                       
                        
                       
                         P 
                         b 
                       
                     
                     = 
                     18 
                   
                 
               
             
           
         
       
       
         
           
             
               R 
               1 
             
             = 
             
               
                 1 
                 + 
                 
                   
                     P 
                     o 
                   
                   
                     P 
                     1 
                   
                 
               
               = 
               
                 
                   1.8 
                    
                   
                     : 
                   
                    
                   1 
                    
                   
                       
                   
                    
                   
                     R 
                     2 
                     ′ 
                   
                 
                 = 
                 
                   
                     P 
                     2 
                     2 
                   
                   = 
                   
                     
                       361 
                        
                       
                         : 
                       
                        
                       1 
                        
                       
                           
                       
                        
                       R 
                     
                     = 
                     
                       
                         
                           R 
                           1 
                         
                          
                         
                           R 
                           2 
                           ′ 
                         
                       
                       = 
                       
                         650 
                          
                         
                           : 
                         
                          
                         1 
                       
                     
                   
                 
               
             
           
         
       
     
         [0114]    A third example considers the seventh exemplary embodiment illustrated in  FIG. 7  where all engaging members in the second stage  52  are pulleys and belts. The absence of gear teeth makes a very high reduction ratio practical. Note that if P 2 =P o  then R=R 2   1 =00:1. 
         [0000]    
       
         
           
             
               P 
               1 
             
             = 
             
               
                 19 
                  
                 
                     
                 
                  
                 
                   P 
                   2 
                 
               
               = 
               
                 
                   20.1 
                    
                   
                       
                   
                    
                   
                     P 
                     o 
                   
                 
                 = 
                 20 
               
             
           
         
       
       
         
           
             
               R 
               1 
             
             = 
             
               
                 1 
                 + 
                 
                   
                     P 
                     o 
                   
                   
                     P 
                     1 
                   
                 
               
               = 
               
                 
                   2.05 
                    
                   
                     : 
                   
                    
                   1 
                    
                   
                       
                   
                    
                   
                     R 
                     2 
                     ′ 
                   
                 
                 = 
                 
                   
                     
                       P 
                       2 
                     
                     
                       
                         P 
                         2 
                       
                       - 
                       
                         P 
                         o 
                       
                     
                   
                   = 
                   
                     
                       201 
                        
                       
                         : 
                       
                        
                       1 
                        
                       
                           
                       
                        
                       R 
                     
                     = 
                     
                       
                         
                           R 
                           1 
                         
                          
                         
                           R 
                           2 
                           ′ 
                         
                       
                       = 
                       
                         413 
                          
                         
                           : 
                         
                          
                         1 
                       
                     
                   
                 
               
             
           
         
       
     
         [0115]    A fourth example considers the second stage  52  of the ninth exemplary embodiment illustrated in  FIG. 9 . The second central member  32  and the offset member third step  33   c  have a variable pitch radius defined by the ratio N. In practice, the pitch diameters of the offset member  33   c  and the second central member  32  may be manipulated to maintain a constant length of the flexible coupling member  34   b . The variable pitch second stage  52  provides the following speed ratios: 
         [0000]    
       
         
           
             
               R 
               2 
             
             = 
             
               
                 1 
                 - 
                 
                   N 
                    
                   
                     : 
                   
                    
                   1 
                    
                   
                       
                   
                    
                   
                     R 
                     2 
                     ′ 
                   
                 
               
               = 
               
                 
                   
                     1 
                     
                       1 
                       - 
                       N 
                     
                   
                    
                   
                     : 
                   
                    
                   1 
                    
                   
                       
                   
                    
                   N 
                 
                 = 
                 
                   
                     P 
                     o 
                   
                   
                     P 
                     2 
                   
                 
               
             
           
         
       
     
         [0116]    When N varies from 0.5 to 1, R 2 ′ varies from 2:1 to ∞:1, which corresponds to a stopped second drive-shaft  12  (T 2 =0 for any T c ). When N varies from 1 to 2, R 2 ′ varies from ∞:1 to −1:1 which corresponds to a direction reversal of the second drive-shaft  12 . 
         [0117]    N=½→1 R 2 ′=2:1→∞:1 
         [0118]    N=1→2 R 2 ′=∞:1→−1:1 
         [0119]    A fifth example considers the tenth and eleventh exemplary embodiments illustrated in  FIGS. 10-11  which depict a Coupled Orbitless gearbox. 
         [0120]    P 2 =21 P o =20 
         [0121]    R=R 2 ′=P 2 =21:1 
       Advantages 
       [0122]    The exemplary embodiments disclosed herein have a number of advantageous properties. 
         [0123]    Certain exemplary embodiments comprise two gearing stages with a single set of carriers which provides low cost and complexity. 
         [0124]    Certain exemplary embodiments provide a high speed ratio in a small volume. 
         [0125]    Certain exemplary embodiments provide multiple speed ratios. 
         [0126]    Certain exemplary embodiments provide an infinitely variable speed ratio. 
         [0127]    Certain exemplary embodiments provide low pitch velocity and bearing speed which may accommodate a high input speed. 
         [0128]    Certain exemplary embodiments comprise flexible coupling members with a high contact ratio and high torque capacity. 
         [0129]    Certain exemplary embodiments comprise offset or co-axial drive axes. 
         [0130]    Other advantages are apparent from the disclosure herein.