Patent Publication Number: US-2015087464-A1

Title: Two mode continuously variable transmission

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 61/881,078 filed Sep. 23, 2013. The disclosure of the above application is incorporated herein by reference. 
    
    
     FIELD 
     The present disclosure relates to automatic transmissions and more particularly to a two mode continuously variable transmission. 
     BACKGROUND 
     The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art. 
     A continuously variable transmission (“CVT”) typically includes a belt and pulley system that operatively couples a rotary power source, such as an engine or electric motor, to a double gear final drive unit. The belt and pulley system generally includes first and second pairs of pulley cones having a torque transmitting belt or chain extending between the cone pairs. Each pulley cone pair includes an axially stationary pulley member and an axially movable pulley member. Each movable pulley member is axially adjustable with respect to the stationary pulley member by a hydraulic system. The hydraulic system provides primary and secondary hydraulic pressures to the respective movable pulley members to adjust the running radius of the first and second pulley cone pairs which in turn controls the output/input ratio of the continuously variable transmission. Movement of the cones steplessly or continuously varies the ratio of an input speed to an output speed. With the continuously variable transmission, small but effective ratio changes can be attained. This is in contrast to a fixed gear ratio unit where any ratio changes are step values. 
     CVT axial length and mass significantly impact its power density and efficiency. Accordingly, there is a constant need for improved CVT designs that minimize axial length and mass while providing sufficient performance characteristics. 
     SUMMARY 
     A two mode CVT is provided that for a motor vehicle. The two mode CVT includes a speed change device connected to a pulley and belt assembly. The pulley and belt assembly is also connected to a planetary gear set arrangement. The planetary gear set arrangement generally includes two planetary gear sets, one brake and two clutches. The planetary gear set arrangement is connected to a final drive unit. 
     In another aspect of the present invention, a transmission for a motor vehicle is provided having a transmission input member, a transmission output member, a continuously variable unit, a first transfer gear, a second transfer gear, a planetary gear set assembly, a first clutch, a second clutch, a brake, whereby torque is transferred from the input member to the output member through selective engagement of one of the first clutch and the second clutch thereby selectively connecting the second pulley to the planetary gear set assembly. 
     In yet another aspect of the present invention, the continuously variable unit has a first pulley, a second pulley and an endless member wrapped around the first pulley and the second pulley. 
     In yet another aspect of the present invention, the first transfer gear is connected for common rotation with the input member. 
     In yet another aspect of the present invention, the second transfer gear is in mesh with the first transfer gear and connected for common rotation with the first pulley of the continuously variable unit. 
     In yet another aspect of the present invention, the planetary gear set assembly has first, second, third and fourth members. 
     In yet another aspect of the present invention, the first clutch selectively connects the second pulley to the first member of the planetary gear set assembly. 
     In yet another aspect of the present invention, the second clutch selectively connects the second pulley to the fourth member of the planetary gear set assembly. 
     In yet another aspect of the present invention, the brake selectively connects the third member of the planetary gear set assembly to a stationary member. 
     In still another aspect of the present invention, the planetary gear set assembly includes a first planetary gear set and a second planetary gear set. The first planetary gear set has a sun gear connected for common rotation to a sun gear of the second planetary gear set and a carrier member connected for common rotation to the ring gear of the second planetary gear set. The first clutch is connected to the ring gear of the first planetary gear set, the second clutch is connected to the sun gear of the first planetary gear set and the brake is connected to carrier member of the second planetary gear set and the output member is connected for common rotation to the ring gear of the second planetary gear set. 
     In still another aspect of the present invention, the planetary gear set assembly has a first planetary gear set and a second planetary gear set. The first planetary gear set has a carrier member connected for common rotation to a carrier member of the second planetary gear set and the carrier member of the second planetary gear set has a first and a second set of pinion gears. The first set of pinion gears intermesh with the sun gear of the first planetary gear set and the second set of pinions. The second set of pinions intermesh with the ring gear of the second planetary gear set and the first set of pinion gears. The first clutch is connected to the sun gear of the first planetary gear set, the second clutch is connected to the sun gear of the second planetary gear set and the brake is connected to carrier member of the first planetary gear set. The output member is connected for common rotation to the ring gear of the second planetary gear set. 
     In still another aspect of the present invention, the planetary gear set assembly includes a first planetary gear set and a second planetary gear set. The first planetary gear set has a carrier member connected for common rotation to a ring gear of the second planetary gear set and a ring gear of the first planetary gear set is connected for common rotation to a carrier member of the second planetary gear set. The first clutch is connected to the sun gear of the first planetary gear set, the second clutch is connected to the sun gear of the second planetary gear set and the brake is connected to carrier member of the first planetary gear set and ring gear of the second planetary gear set. The output member is connected for common rotation to the carrier member of the second planetary gear set. 
     In still another aspect of the present invention, the planetary gear set assembly has a first planetary gear set and a second planetary gear set in a stacked arrangement. The first planetary gear set and a second planetary gear set share a common member. The common member functions as a ring gear in the first planetary gear set and functions as a sun gear in the second planetary gear set. Additionally, the first planetary gear set and a second planetary gear set share a common carrier member having a first pinion gear that intermeshes with the sun gear of the first planetary gear set and the common member and a second pinion gear that intermeshes with the ring gear of the second planetary gear set and the common member. The first clutch is connected to the common member, the second clutch is connected to the sun gear of the first planetary gear set and the brake is connected to ring gear of the second planetary gear set. The output member is connected for common rotation with the common carrier member. 
     In still another aspect of the present invention, the planetary gear set assembly includes a first planetary gear set and a second planetary gear set. The first planetary gear set has a carrier member connected for common rotation to a carrier member of the second planetary gear set and a ring gear of the first planetary gear set is connected for common rotation to a ring gear of the second planetary gear set. The first clutch is connected to the ring gear of the first planetary gear set and ring gear of the second planetary gear set, the second clutch is connected to the sun gear of the first planetary gear set and the brake is connected to sun gear of the second planetary gear set. The output member is connected for common rotation to the carrier member of the first and second planetary gear sets. 
     Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       The drawings described herein are for illustration purposes only and is not intended to limit the scope of the present disclosure in any way. 
         FIG. 1  is a schematic diagram of a powertrain according to the principles of the present invention; 
         FIG. 2  is a lever diagram of an exemplary transmission according to the principles of the present invention; 
         FIG. 3  is a diagrammatic illustration of another embodiment of a transmission according to the principles of the present invention; 
         FIG. 4  is a diagrammatic illustration of yet another embodiment of a transmission according to the principles of the present invention; 
         FIG. 5  is a diagrammatic illustration of still another embodiment of a transmission according to the principles of the present invention; 
         FIG. 6  is a diagrammatic illustration of still another embodiment of a transmission according to the principles of the present invention; 
         FIG. 7  is a diagrammatic illustration of still another embodiment of a transmission according to the principles of the present invention; and 
         FIG. 8  is a truth table presenting an example of a state of engagement of various torque transmitting elements to produce multiple forward and at least one reverse speed or gear ratios of the transmissions illustrated in  FIGS. 1-7 . 
     
    
    
     DETAILED DESCRIPTION 
     The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. 
     With reference to  FIG. 1 , a powertrain for a motor vehicle is generally indicated by reference number  10 . The powertrain  10  generally includes an engine  12  interconnected with a transmission  14 . The engine  12  may be a conventional gasoline, Diesel, or flex fuel internal combustion engine, a hybrid engine, or an electric motor, or any other type of prime mover, without departing from the scope of the present disclosure. The engine  12  supplies a driving torque to the transmission  14  through, for example, a flexplate (not shown) or other connecting device or a starting device  15  such as a hydrodynamic device or launch clutch. 
     The transmission  14  is a variable diameter pulley or sheave drive continuously variable transmission (CVT). The transmission  14  includes a typically cast, metal housing  16  which encloses and protects the various components of the transmission  14 . The housing  16  includes a variety of apertures, passageways, shoulders and flanges which position and support these components. Generally speaking, the transmission  14  includes a transmission input shaft  20  and a transmission output shaft  22 . Connected between the transmission input shaft  20  and the transmission output shaft  22  is a speed change device  23 , a pulley assembly  24 , and a gearbox  26  that cooperate to provide forward and reverse speed or gear ratios between the transmission input shaft  20  and the transmission output shaft  22 . The transmission input shaft  20  is functionally interconnected with the engine  12  through the starting device  15  and receives input torque or power from the engine  12 . The transmission output shaft  22  is preferably connected with a final drive unit  28 . The transmission output shaft  22  provides drive torque to the final drive unit  28 . The final drive  28  unit may include a differential, axle shafts, and road wheels (not shown). 
     The transmission input shaft  20  is connected to the speed change device  23 . The speed change device  23 , as well as the various gearbox  26  arrangements described below, are illustrated in a lever diagram format. A lever diagram is a schematic representation of the components of a mechanical device such as meshing gear sets or planetary gear sets. Each individual lever represents a planetary gear set or meshed gear pair. The three basic mechanical components of the planetary gear are each represented by a node while the gear pairs are represented by a node and the rotation change represented by a node fixed to ground. Therefore, a single lever contains three nodes. In a planetary gear set, one node represents the sun gear, one the planet gear carrier, and one the ring gear. In a meshed gear pair, one node represents a first gear, one a second gear, and the third the rotational direction change between the meshed gears. In some cases, two levers may be combined into a single lever having more than three nodes (typically four nodes). For example, if two nodes on two different levers are interconnected through a fixed connection they may be represented as a single node on a single lever. The relative length between the nodes of each lever can be used to represent the ring-to-sun ratio of each respective gear set. These lever ratios, in turn, are used to vary the gear ratios of the transmission in order to achieve an appropriate ratios and ratio progression. Mechanical couplings or interconnections between the nodes of the various planetary gear sets are illustrated by thin, horizontal lines and torque transmitting devices such as clutches and brakes are presented as interleaved fingers. Further explanation of the format, purpose and use of lever diagrams can be found in SAE Paper 810102, “The Lever Analogy: A New Tool in Transmission Analysis” by Benford and Leising which is hereby fully incorporated by reference. 
     For example, the speed change device  23  includes a first node  23 A, a second node  23 B, and a third node  23 C. The first node  23 A is coupled to the transmission input shaft  20 . The second node  23 B is fixed to ground representing a change in rotational direction. The third node  23 C is coupled to a first transfer shaft or member  29  that is connected to the pulley assembly  24 . The first node  23 A preferably represents a first gear while the third node  23 C preferably represents a second gear meshed with the first gear. The gears may be co-planar or partially axially offset. In a preferred embodiment, the speed change device  23  is an overdrive speed change device  23  that increases the speed of the first transfer shaft  29  relative to the transmission input shaft  20  while decreasing the torque. In a second preferred embodiment, the speed change device  23  is an underdrive speed change device  23 . In a third preferred embodiment, the speed change device  23  acts as a direct drive coupling member with no relative speed change. 
     The pulley assembly  24  includes a first pulley or sheave pair  30  and a second pulley or sheave pair  32 . The first pulley  30  includes a first truncated conical sheave or member  30 A and second truncated conical sheave or member  30 B in axial alignment with the first truncated conical sheave  30 A. The second sheave  30 B is directly connected for rotation with the first transfer member  29  and may be integrally formed with the first transfer member or shaft  29 . The first sheave  30 A is moveable axially relative to the second sheave  30 B by a hydraulic control system (not shown) or other actuating system. It should be appreciated that the sheaves  30 A and  30 B may be axially switched without departing from the scope of the present invention. 
     The second pulley  32  includes a first truncated conical sheave or member  32 A and second truncated conical sheave or member  32 B in axial alignment with the first truncated conical sheave  32 A. The second sheave  32 B is directly connected for rotation with a second transfer shaft or member  34  or may be integrally formed with the second transfer shaft  34 . The first sheave  32 A is moveable axially relative to the second sheave  32 B by a hydraulic control system (not shown) or other actuating system. It should be appreciated that the sheaves  32 A and  32 B may be axially switched without departing from the scope of the present invention. 
     A torque transmitting belt or chain  36  having a V-shaped cross section is mounted between the first pulley pair  30  and the second pulley pair  32 . It should be appreciated that other types of belts, including positive engagement devices, may be employed without departing from the scope of the present invention. Drive torque communicated from the transmission input shaft  20  is transferred via friction between the sheaves  30 A and  30 B and the belt  36 . The ratio of the input pulley  30  to the output pulley  32  is adjusted by varying the spacing between the sheaves  30 A and  30 B and between the sheaves  32 A and  32 B. For example, to change the ratio between the pulleys  30  and  32 , the axial distance between sheaves  30 A and  30 B may be reduced by moving sheave  30 A towards sheave  30 B while simultaneously the axial distance between sheave  32 A and  32 B may be increased by moving sheave  32 A away from sheave  32 B. Due to the V-shaped cross section of the belt  36 , the belt  36  rides higher on the first pulley  30  and lower on the second pulley  32 . Therefore the effective diameters of the pulleys  30  and  32  change, which in turn changes the overall gear ratio between the first pulley  30  and the second pulley  32 . Since the radial distance between the pulleys  30  and  32  and the length of the belt  36  is constant, the movement of the sheaves  30 A and  32 A must occur simultaneously in order to maintain the proper amount of tension on the belt  36  to assure torque is transferred from the pulleys  30 ,  32  to the belt  36 . 
     The pulley assembly  24  transfers torque to the gearbox  26  via the second transfer shaft  34 . The gearbox  26  comprises one of several planetary gear set transmissions or arrangements, as will be described in greater detail below. The gearbox  26  outputs torque from the pulley assembly  26  to the transmission output shaft  22  and then to the final drive unit  28 . 
     Turning now to  FIG. 2 , the planetary gear set transmissions or arrangements of gearbox  26  is shown in lever diagram format. The gearbox  26  includes a first planetary gear set  50  and a second planetary gear set  52 . The first planetary gear set  50  has three nodes: a first node  50 A, a second node  50 B and a third node  50 C. Each of the nodes represents a member of the planetary gear set, i.e.: a sun gear, a ring gear or a planet gear carrier. The second planetary gear set  52  has three nodes: a first node  52 A, a second node  52 B and a third node  52 C. Nodes  50 B and  52 A have been combined into a single node  50 B,  52 A and nodes  50 C and  52 C have been combined into a single node  50 C,  52 C. The aforementioned nodes may be combined since a member (a sun gear, a ring gear or a planet gear carrier) of the first gear set  50  is continuously coupled or permanently connected with a member of the second planetary gear set  52 . 
     The transmission output shaft or member  22  is continuously coupled to node  50 B,  52 A. A brake  56  selectively connects the node  52 B of the second planetary gear set  52  with the stationary element or transmission housing  16 . A first clutch  58  selectively connects the node  50 A of the first planetary gear set  50  with the second transfer shaft  34 . A second clutch  60  selectively connects the combined node  50 C,  52 C of the first and second planetary gear sets  50  and  52  with second transfer shaft  34 . 
     Turning now to  FIGS. 3-7  stick diagrams present schematic layouts of embodiments of the gearbox  26  according to the present invention. In  FIGS. 3-7  the numbering from the lever diagram of  FIG. 2  are carried over. The clutches and couplings are correspondingly presented whereas the nodes of the planetary gear sets now appear as components of planetary gear sets, such as, sun gears, ring gears, planet gears and planet gear carriers. 
     With specific reference to  FIG. 3 , a transmission  100  having an example of a gearbox  26  configuration is illustrated. Transmission  100 , in accordance with the present invention, includes the speed change device  23  having a first gear  23 A in mesh with a second gear  23 C. Second gear  23 C is rotatably coupled through first transfer member or shaft  29  to pulley assembly  24 . Planetary gear set  50  includes a ring gear member  50 A, a planet carrier member  50 B and a sun gear member  50 C. The ring gear member  50 A is connected for common rotation with a first shaft or interconnecting member  62 . The planet carrier member  50 B is connected for common rotation with a second shaft or interconnecting member  64  and rotatably supports a set of planet gears  50 D (only one of which is shown). The planet gears  50 D are each configured to intermesh with the ring gear member  50 A and the sun gear member  50 C. The sun gear member  50 C is connected for common rotation with a third shaft or interconnecting member  66  and a fourth shaft or interconnecting member  68 . 
     Planetary gear set  52  includes a ring gear member  52 A, a planet carrier member  52 B and a sun gear member  52 C. The ring gear member  52 A is connected for common rotation with the second shaft or interconnecting member  64  and output member or shaft  22 . The planet carrier member  52 B is connected for common rotation with a fifth shaft or interconnecting member  70  and rotatably supports a set of planet gears  52 D (only one of which is shown). The planet gears  52 D are each configured to intermesh with the ring gear member  52 A and the sun gear member  52 C. The sun gear member  52 C is connected for common rotation with the fourth shaft or interconnecting member  68 . 
     Moreover, torque-transmitting mechanisms including brake  56  and clutches  58  and  60  are provided to allow for selective interconnection of the shafts or interconnecting members, members of the planetary gear sets and the housing. The torque-transmitting mechanisms are friction, dog or synchronizer type mechanisms or the like. For example, the brake  56  is selectively engageable to connect the fifth shaft or interconnecting member  70  with the transmission housing  16  in order to restrict relative rotation of the member  70  and therefore the carrier member  52 B. The first clutch  58  is selectively engageable to connect the second transfer shaft  34  with the first shaft or interconnecting member  62  and the ring gear  50 A. The second clutch  60  is selectively engageable to connect the second transfer shaft  34  with the third shaft or interconnecting member  66  and the sun gear  50 C. 
     With specific reference to  FIG. 4 , a transmission  110  having an alternate gearbox  26 A arrangement is illustrated. The transmission  110  is similar to transmission  100  shown in  FIG. 3  and therefore like components are indicated by like reference numbers. Gearbox  26 A includes a first planetary gear set  80  and a second planetary gear set  82 . 
     Planetary gear set  80  includes a carrier member  80 B and a sun gear  80 C. The planet carrier member  80 B is connected for common rotation with a first shaft or interconnecting member  84  and a second shaft or interconnecting member  86  and rotatably supports a set of planet gears  80 D (only one of which is shown). The planet gears  80 D are each configured to intermesh with the sun gear member  80 C. The sun gear member  80 C is connected for common rotation with a third shaft or interconnecting member  88 . 
     Planetary gear set  82  includes a ring gear member  82 A, a planet carrier member  82 B and a sun gear member  82 C. The ring gear member  82 A is connected for common rotation with output member or shaft  22 . The planet carrier member  82 B is connected for common rotation with the second shaft or interconnecting member  86  and rotatably supports a first set of planet gears  82 D (only one of which is shown) and a second set of planet gears  82 E (only one of which is shown). The first set of planet gears  82 D are each configured to intermesh with the sun gear member  82 C and the second set of planet gears  82 E. The second set of planet gears  82 E are each configured to intermesh with the ring gear member  82 A and the first set of planet gears  82 D. The sun gear member  82 C is connected for common rotation with the fourth shaft or interconnecting member  90 . 
     Gearbox  26 A further includes torque-transmitting mechanisms including brake  92  and clutches  94  and  96  are provided to allow for selective interconnection of the shafts or interconnecting members, members of the planetary gear sets and the housing. The brake  92  is selectively engageable to connect the first shaft or interconnecting member  84  with the transmission housing  16  in order to restrict relative rotation of the member  84  and therefore the carrier members  80 B and  82 B. The first clutch  94  is selectively engageable to connect the second transfer shaft  34  with the third shaft or interconnecting member  88  and the sun gear  80 C. The second clutch  96  is selectively engageable to connect the second transfer shaft  34  with the fourth shaft or interconnecting member  90  and the sun gear  82 C. 
     With specific reference to  FIG. 5 , a transmission  120  having an alternate gearbox  26 B arrangement is illustrated. The transmission  120  is similar to transmission  100  shown in  FIG. 3  and therefore like components are indicated by like reference numbers. Gearbox  26 B includes the first planetary gear set  50  and a second planetary gear set  52 , as described above. However, the interconnections to clutches  58  and  60  and brake  56  have been reconfigured, as described hereinafter. Ring gear  50 A is now connected to a first interconnecting member  102 . Carrier member  50 B is now connected to a second interconnecting member  104 . Sun gear  50 C is now connected to a third interconnecting member  106 . Moreover, ring gear  52 A is now connected to the second interconnecting member  104 . Carrier member  52 B is now connected to the first interconnecting member  102 . Sun gear  52 C is now connected to a fourth interconnecting member  108 . Accordingly, first clutch  58  is selectively engageable to connect the second transfer shaft  34  with the third shaft or interconnecting member  106  and the sun gear  50 C. The second clutch  60  is selectively engageable to connect the second transfer shaft  34  with the fourth shaft or interconnecting member  108  and the sun gear  52 C. The brake  56  is selectively engageable to connect the second shaft or interconnecting member  104  with the transmission housing  16  in order to restrict relative rotation of the member  104  and therefore the carrier member  50 B and ring gear  52 A. 
     With specific reference to  FIG. 6 , a transmission  130  having an alternate gearbox  26 C arrangement is illustrated. The transmission  130  is similar to transmission  100  shown in  FIG. 3  and therefore like components are indicated by like reference numbers. The transmission  130 , however, does not have the speed change device  23 . Instead, input torque is received directly from the engine. Gearbox  26 C includes a first planetary gear set  112  and a second planetary gear set  114 . The first planetary gear set  112  and the second planetary gear set  114  are radially stacked. Radially stacked herein means that the planetary gear sets  112  and  114  share a common member  116  and have planet gears that are supported by a shared carrier member  118 . Common member  116  is a gear that has gear teeth on an inner surface and gear teeth on an outer surface of the gear. Common member  116  is connected for common rotation to a first interconnecting member  122 . Additionally, planetary gear set  112  has a ring gear  112 A connected to a second interconnecting member  124 . Planetary gear set  114  has a sun gear  114 C connected to a third interconnecting member  126 . Shared carrier member  118  is connected for common rotation with output shaft  22 . The shared carrier member  118  rotatably supports a first set of planet gears  118 D and a second set of planet gears  118 E. The first set of planet gears  118 D intermesh with the gear teeth on the outer surface of common member  116  and with ring gear  112 A. The second set of planet gears  118 E intermesh with the gear teeth on the inner surface of common member  116  and with sun gear  114 C. 
     Accordingly, first clutch  58  is selectively engageable to connect the second transfer shaft  34  with the first shaft or interconnecting member  122  and the common member  116 . The second clutch  60  is selectively engageable to connect the second transfer shaft  34  with the third shaft or interconnecting member  126  and the sun gear  114 C. The brake  56  is selectively engageable to connect the second shaft or interconnecting member  124  with the transmission housing  16  in order to restrict relative rotation of the member  124  and therefore ring gear  112 A. 
     With specific reference to  FIG. 7 , a transmission  140  having an alternate gearbox  26 D arrangement is illustrated. The transmission  140  is similar to transmission  100  shown in  FIG. 3  and therefore like components are indicated by like reference numbers. Gearbox  26 D includes the first planetary gear set  50  and a second planetary gear set  52 , as described above. However, the interconnections to clutches  58  and  60  and brake  56  have been reconfigured, as described hereinafter. Ring gear  50 A is now connected to a first interconnecting member  132  and to a second interconnecting member  134 . Carrier member  50 B is now connected to a third interconnecting member  136 . Sun gear  50 C is now connected to a fourth interconnecting member  138 . Moreover, ring gear  52 A is now connected to the second interconnecting member  144 . Carrier member  52 B is now connected to the third interconnecting member  136  and with output member  22 . Sun gear  52 C is now connected to a fifth interconnecting member  139 . Accordingly, first clutch  58  is selectively engageable to connect the second transfer shaft  34  with the first shaft or interconnecting member  132  and the ring gear  50 A. The second clutch  60  is selectively engageable to connect the second transfer shaft  34  with the fourth shaft or interconnecting member  138  and the sun gear  50 C. The brake  56  is selectively engageable to connect the fifth shaft or interconnecting member  139  with the transmission housing  16  in order to restrict relative rotation of the member  139  and therefore the sun gear  52 C. 
     Referring now to  FIG. 8 , a truth table presenting an example of a state of engagement of various torque transmitting elements to produce multiple forward and at least one reverse speed or gear ratios of the transmissions illustrated in  FIGS. 1-7  is shown. The state of engagement of the torque transmitting elements or mechanisms (brake  56  and clutches  58  and  60 ) is indicted by the presence of an “X” in the appropriate box in the table of  FIG. 8 . For example, a reverse gear ratio is produced by engaging the brake  56  and the second clutch  60 . Of course, an infinite number of ratios may be produced by the transmissions of the present invention through the adjustment of the pulley assembly  24 , as described above, and the selection of at least two of the torque transmitting elements or mechanisms, i.e.: brake  56  and clutches  58  and  60 , as shown in  FIG. 8 . 
     The description of the invention is merely exemplary in nature and variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.