Abstract:
A multiple-speed chain driving device includes a shaft, a rotors&#39;assembly, a chain driving sprocket, and a shifting assembly. The rotors&#39;assembly is mounted on the shaft and includes three rotors which are vertically mounted on each other and enclosed within the sprocket. The shifting assembly is also mounted on the shaft and located parallel with respect to the rotors&#39; assembly. The device can be made in either 3-speed or 2-speed design and enables a few slightly different configurations for both designs. The device enables a smooth shifting process and allows only one sprocket to produce the full range of speeds presently obtained by a front sprocket assembly in a bicycle.

Description:
BACKGROUND OF THE INVENTION 
     A front set of chain sprockets used in a bicycle comprises two or three chain sprockets which drive a chain that further transmits pedaling power to chain sprockets mounted on an axle in a rear bicycle wheel. Since each of the front sprockets has a different number of teeth, they enable different rotating speeds of the rear sprockets and thereby provide different bicycle driving speeds. In order to change driving ratios the chain has to be replaced from one sprocket to another by a derailleur which is mounted proximate to the front chain sprockets. 
     The sprockets have significantly different diameters which, in turn, makes the chain replacement relatively abrupt and difficult. Even the most sophisticated derailleurs cannot provide smooth shifting and eliminate the related stress and power loss. Every time the chain is displaced from one sprocket and mounted on another sprocket it causes an interruption of power flow and related loss of pedaling power. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a device which will enable an uninterrupted flow of pedaling power from a crankshaft to a drive chain of a bicycle or similar pedal propelled vehicles. The present invention comprises a rotor assembly wherein three members are provided within the front chain sprocket of the bicycle and mounted in a manner which enables all of them to work in concert with each other. An inner rotor is located within a middle rotor and the middle rotor is located within an outer rotor. The inner rotor has a certain number of lobes while the inner opening of the middle rotor has a certain higher number of pockets which receive the lobes during the rotation. The middle rotor also has a certain number of lobes on its outer circumference while the outer rotor&#39;s inner opening has a certain higher number of pockets which receive the lobes of the middle rotor. 
     The inner rotor and the outer rotor rotate around the same axis while the middle rotor rotates around a different axis. This enables the middle rotor to rotate eccentrically with respect to the inner and outer rotors which, in turn, enables the middle rotor to transfer the rotating force between the inner and outer rotors. The inner and outer rotor rotate around the same axis as the front chain sprocket which rotates around the outer rotor. An overrunning clutch connects the inner rotor to the bicycle crankshaft and this rotor serves as a power input member during the slowest speed. The inner rotor is also directly connected to the chain sprocket by mechanical means to serve as the power transfer member during the fastest speed, as explained later in this specification. The outer rotor is by mechanical means also connected to the bicycle crankshaft and serves as an input member during the 2 nd  and 3 rd  speed. 
     According to the process of the invention, when the inner rotor is pushed by the rotational force of the crankshaft, its lobes exert force onto the pockets inside the middle rotor and force the middle rotor to rotate in the same direction but at a slower speed. Further, the middle rotor&#39;s lobes force the outer rotor to rotate in the same direction at a lower speed. The rotating force of the outer rotor is over an overrunning clutch further transmitted onto the chain sprocket. Since the inner rotor has less lobes than the pockets in the middle rotor and the middle rotor has less lobes than the pockets in the outer rotor, the outer rotor rotates at the rate defined by the difference between the lobes and the pockets in all rotors. The rotating speed of the outer rotor is slower than the rotating speed of both other rotors and this speed of the outer rotor corresponds to the slowest possible rotating speed, hereinafter referred to as the “1 st  speed”. 
     When the outer rotor is connected to the crankshaft, the overrunning clutch which connects the inner rotor to the crankshaft is disconnected and the sprocket is (over the overrunning clutch) forced to rotate at the speed of the outer rotor which equals the rotating speed of the crankshaft. The obtained rotating speed is faster and hereinafter referred to as the “2 nd  speed”. During the time when the outer rotor is firmly connected to the crankshaft, the inner rotor rotates at a faster rate with respect to the outer rotor. When the inner rotor is directly connected to the sprocket while the outer rotor is connected to the crankshaft, the rotating speed of the sprocket equals the rotating speed of the inner rotor and the sprocket is forced to rotate at the fastest possible rate, hereinafter referred to as the “3 rd  speed”. 
     The present invention provides a few different versions of a speed changing device which can be used on bicycles or similar pedal-propelled vehicles. The versions presented in this specification include these which provide 3 output speeds and these which provide 2 output speeds. All versions operate apply the same operating principles wherein the change in output rotating speeds is obtained by alternately providing different connections between the crankshaft, rotors, and chain sprocket and wherein the different number of the rotors&#39; lobes and pockets results in different rotating ratios of the rotors. The features and advantages of the present invention will become apparent from the following brief description of the drawings and a detailed description of the invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side cut-away view of the rotors&#39; assembly showing the rotors&#39; and sprocket arrangement for the 3-speed version of the invention wherein the free-wheel clutch is used to connect the shaft and the inner rotor and the overrunning clutch is used to connect the outer rotor and the sprocket. 
     FIG. 2 is a side cut-away view of the rotors&#39; assembly showing the rotors&#39; and sprocket arrangement for the 3-speed version of the invention wherein one free-wheel clutch is used to connect the shaft and the inner rotor and another free-wheel clutch is used to connect the outer rotor and the sprocket. 
     FIG. 3 is a side cut-away view of the rotors&#39; assembly showing the rotors&#39; and sprocket arrangement for the 3-speed version of the invention wherein one overrunning clutch is used to connect the shaft and the inner rotor and another overrunning clutch is used to connect the outer rotor and the sprocket. 
     FIG. 4 is a back cut-away view for the 3-speed version of the invention in the situation when the 1 st  speed is engaged. 
     FIG. 5 is a back cut-away view for the 3-speed version of the invention in the situation when the 2 nd  speed is engaged. 
     FIG. 6 is a back cut-away view for the 3-speed version of the invention in the situation when the 3 rd  speed is engaged. 
     FIG. 7 is a back cut-away view for the 3-speed version of the invention showing the alternative arrangement wherein the balls are used to provide the connection between the crankshaft and the outer rotor and the connection between the inner rotor and the sprocket. 
     FIG. 8 is a back cut-away view for the 3-speed version of the invention showing yet another alternative arrangement wherein the friction rings are used to provide the connection between the crankshaft and the outer rotor and the connection between the inner rotor and the sprocket. 
     FIG. 9 is a perspective view of the inner rotor and its disc. 
     FIG. 10 is a perspective view of the middle rotor and its support ring. 
     FIG. 11 is a perspective view of the outer rotor and its engaging section. 
     FIG. 12 is a perspective view of the shaft showing its outer section and shaft disc. 
     FIG. 13 is a perspective view of the shifting unit&#39;s base. 
     FIG. 14 is a perspective view of the shifting disc. 
     FIG. 15 is a perspective view of the crankshaft showing its outer section, shaft disc, and eccentric disc. 
     FIG. 16 is the cut-away view of the crankshaft and the eccentric disc along the section wherein the eccentric disc is mounted onto the crankshaft. 
     FIG. 17 is the side cut-away view of the eccentric disc mounted between the crankshaft and the middle rotor. 
     FIG. 18 is the side cut-away view of the alternative version of the eccentric disc mounted between the crankshaft and the middle rotor. 
     FIG. 19 is a perspective view of the 3 rd  speed ring. 
     FIG. 20 is a perspective view of the 2 nd  speed ring. 
     FIG. 21 is a side cut-away view of the rotors&#39; assembly showing the rotors&#39; and sprocket arrangement for the first 2-speed version of the invention wherein the sprocket has a minimum number of teeth. 
     FIG. 22 is a back cut-away view of the invention for the first 2-speed version of the invention in the situation when the 1 st  speed is engaged. 
     FIG. 23 is a perspective view of the shifter&#39;s base for the 2-speed version of the invention. 
     FIG. 24 is a back cut-away view of the invention for the first 2-speed version of the invention in the situation when the 2 nd  speed is engaged. 
     FIG. 25 is a side cut-away view of the rotors&#39; assembly showing the rotors&#39; and sprocket arrangement for the second 2-speed version of the invention wherein the sprocket has a maximum number of teeth. 
     FIG. 26 is a back cut-away view of the invention for the second 2-speed version of the invention in the situation when the 1 st  speed is engaged. 
     FIG. 27 is a back cut-away view of the invention for the second 2-speed version of the invention in the situation when the 2 nd  speed is engaged. 
     FIG. 28 is a side cut-away view of the rotors&#39; assembly showing the rotors&#39; and sprocket arrangement for the third 2-speed version of the invention wherein the sprocket has a maximum number of teeth and the outer rotor is an integral part of the sprocket. 
     FIG. 29 is a back cut-away view of the invention for the third 2-speed version of the invention in the situation when the 1 st  speed is engaged. 
     FIG. 30 is a back cut-away view of the invention for the third 2-speed version of the invention in the situation when the 2 nd  speed is engaged. 
     FIG. 31 is a side cutaway view of the invention wherein the gears are used instead of the rotors. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     As shown in FIGS. 1,  2 , and  3 , the first version of the present invention comprises three rotors  2 ,  3 , and  4  mounted between a crankshaft  1  and a chain driving sprocket  5 . As shown in FIG. 1, the preferred design provides one star-shaped inner rotor  2  mounted onto the crankshaft  1  and connected to the crankshaft by an overrunning clutch  11  shown in FIG.  4 . The overrunning clutch  11  comprises a plurality of pawls  10  and a plurality of pawls engaging teeth  22  and engages the rotor only when the rotating speed of the crankshaft  1  exceeds the rotating speed of the rotor  2 . As also shown in FIG. 1, the middle rotor  3  is designed to have a plurality of lobe receiving pockets along its inner circumference and a plurality of lobes along its outer circumference. The pockets within the middle rotor  3  are designed to receive the lobes of the inner rotor  2  as shown in FIGS. 1,  2  and,  3 . 
     As also shown in FIGS. 1,  2 , and  3 , the outer rotor  4  is designed to have a plurality of pockets along its inner circumference and these pockets are designed to receive the lobes of the middle rotor  3 . The chain driving sprocket  5  is mounted onto the outer rotor  4  and connected to this rotor  4  by a plurality of self-engaging rollers  40  which act as an overrunning clutch which provides a firm connection in any situation when the speed of the outer rotor  4  exceeds the speed of the sprocket. As shown in FIGS. 1,  2  and  3 , the sprocket  5  has a plurality of openings  50  which extend through the sprocket  5 . The function of these openings  50  will be explained later in this description. The present invention assumes that the sprocket  5  has a number of teeth which represents a middle sprocket in existing bicycle front set of sprockets. 
     As shown in FIG. 2, the present invention can also be designed to apply a plurality of pawls  43  mounted onto the outer rotor  4  instead of the self-engaging rollers  40  as described above. The pawls  43  perform an identical function as the self-engaging rollers  40 , i. e. they connect the rotor  4  to the sprocket  5  when the speed of the rotor  4  exceeds the speed of the sprocket  5 . It is yet another proposal of the present invention to provide two sets of self-engaging rollers as shown in FIG. 3, wherein one set of self engaging rollers  15  connects the crankshaft  1  to the inner rotor  2  and another set of self-engaging rollers  40  connects the outer rotor  4  to the sprocket  5 . In any case, the rollers  15  and  40  or pawls  10  and  43  perform exactly the same operation and act as overrunning clutches. 
     As shown in FIGS. 4,  5 ,  6 ,  7 , and  8 , the rotors  2 ,  3 , and  4  are mounted onto the crankshaft  1  proximate to the crank  81  while the shifting unit assembly  6  and  62  is mounted onto the bottom bracket  61 . A shaft disc  11  is firmly connected to the crankshaft  1  or made as an integral part of the crankshaft  1  as shown in FIGS. 4,  12 , and  14 . As shown in FIGS. 12 and 15, the shaft disc  11  comprises a smaller circular elevated section  18  and a larger circular elevated section  17 . The elevated section  18  carries a eccentric disc  31  as shown in FIGS. 4 and 15 and can be made either having a flat surface as shown in FIG. 12 or having a toothed surface (gear)  180  as shown in FIGS. 15 and 17. The elevated section  17  is designed to carry a ball bearing  12  as shown in FIG. 4. A roller bearing  25  is provided within the elevated section  18  as shown in FIGS. 4 and 12 and this bearing is located proximate to the inner rotor  2 . As shown in FIG. 12, pawl seats  101  can also be made within the crankshaft  1  and the disc  11  has a plurality of openings  16  as shown in FIGS. 12 and 15. As shown in FIG. 4, the openings  16  are designed to receive the 2 nd  speed&#39;s shifting ring  49  pins  45  shown also in FIG.  20 . 
     As shown in FIG. 4, the inner rotor  2  is mounted onto the crankshaft  1  between the crank  81  and the shaft disc  11  and it comprises a disc  20  which extends along the outer side of the middle rotor  3  and the outer rotor  4 . The disc&#39;s  20  outer circumference corresponds to the circumference of the sprocket  5  and it can be made as an integral part of the inner rotor  2  as shown in FIGS. 4 and 9. The disc  20  has a plurality of grooves  21  proximate to its outer circumference as also shown in FIGS. 4 and 9. These grooves  21  are designed to receive the 3 rd  speed ring&#39;s  68  pins  67  as explained later in this description. As shown in FIG. 9, the plurality of pawl engaging teeth  22  can also be incorporated within the central opening of the rotor  2 . 
     The middle rotor  3  encompasses the inner rotor  2  as shown in FIGS. 1 and 4 and it has a side-mounted support ring  30  which is either attached to the rotor  3  or made as an integral part of this rotor  3  as shown in FIG.  10 . As shown in FIGS. 1,  4 ,  15 ,  17 , and  18 , the ring  30  of the middle rotor  3  is mounted onto the eccentric disc  31  and rotates around this disc  31 . The eccentric disc  31  forces the middle rotor to rotate on an axis which is different from the rotating axis of the inner rotor  2  and the outer rotor  4 . As shown in FIGS. 16 and 17, the eccentric disc  31  has two gears  32  mounted proximate to its inner opening which mesh with the gear  180  on the elevated section  18 . The gears  32  mesh with the gear  180  on the elevated section  18  as shown in FIG. 16, so as to ensure that the eccentric disc  31  is always kept in the same position with respect to both the inner  2  and outer rotors  4 . 
     In order for the invention to work, it is necessary that the middle rotor  3  always rotates around the same axis which is different with respect to the rotating axis of both other rotors  2  and  4 . Therefore, it is necessary to provide the eccentric disc  31  which has the same axis as the middle rotor  3 . Since without the eccentric disc  31  the middle rotor  3  will actually orbit around the inner rotor  2 , the movement of the middle rotor  3 , when mounted onto the eccentric disc, can not cause the eccentric disc  31  to rotate around the crankshaft&#39;s elevated section  18 . Namely, the force which would be applied by the middle rotor  3  to the eccentric disc  31  is pointed at an sharp angle which cannot be followed by the eccentric disc  31 . Consequently, provided that there is no significant friction resistance, the eccentric disc  31  will remain in its position. Therefore, the elevated section  18  and the inner circumference of the eccentric disc  31  can be made flat with a ball bearing provided between them as shown on FIG. 17 so as to allow the crankshaft  1  to turn inside the eccentric disc  31 . In any case, it is considered advantageous to provide the gears  32  to absolutely ensure that the eccentric disc  31  is always kept in its proper position. 
     As shown in FIGS. 1 and 4, the outer rotor  4  is mounted both onto the middle rotor  3  and the ball bearing  12 . As shown in FIG. 4 and 11, the outer rotor  4  has a side ring that encompasses the ball bearing  12  which forces the rotor to rotate around the given axis. The side ring of the outer rotor  4  has a plurality of grooves  41  which receive the 2 nd  speed ring&#39;s  49  pins  45  and it also may have a plurality of roller seats  42  as shown in FIG.  11 . It is to be understood that the connection between the outer rotor  4  and the sprocket  5  can be obtained either by the self-engaging rollers  40  as shown in FIG. 1 or by an overrunning clutch mounted between the rotor  4  and the sprocket  5 . 
     As shown in FIGS. 1 and 4, the sprocket  5  encompasses the outer rotor  4  and rotates around the same axis as the inner rotor  2  and outer rotor  4 . The shifting unit assembly shown in FIG. 4 and 13, comprises a unit&#39;s base  6 , and a shifting disc  62 , wherein the unit&#39;s base  6  is mounted and firmly connected to the bottom bracket  61  by the bolt  82  as shown in FIG.  4 . The unit&#39;s base  6  encompasses the bottom bracket  61  and circularly extends along the rotors&#39;assembly while the shifting disc  62  is rotatably mounted onto the unit&#39;s base  6 . As shown in FIG. 14, the shifting disc  62  comprises two sets of cam sections  63  and  64 . The 2 nd  speed shifting ring  49  which has a plurality of pins  45 , shown in FIG. 20, is mounted proximate to the shaft disc  11  and its pins  45  are inserted within the openings  16  as shown in FIG. 4. A plurality of balls  65  are provided within openings  60  in the unit&#39;s base  6  between the shifting disc  62  and the shifting ring  46  as shown in FIG.  4 . 
     The shifting disc  62  is rotated in one direction by a shifting cord  71  which is connected to the shifting disc  62  over the pin  72  as shown in FIG.  14  and in another direction by a circular spring  84  shown in FIG.  4 . The spring  84  is at one end connected to the shifting disc  62  and at the other end to the shifting base unit  6 . As shown in FIG. 19, the 3 rd  speed shifting ring  68  has a plurality of pins  67  which are inserted within the openings  50  in the sprocket as shown in FIG.  4 . The 3rd speed shifting ring  68  is located proximate to the cam sections  64  in the shifting disc  62  and a plurality of balls  66  are provided between this ring  68  and the shifting disc  62 . Both sets of balls  65  and  66  are provided in order to allow a frictionless contact between the shifting disc  62  which is always stationary and the shifting rings  68  and  49  which always rotate together with the entire rotor assembly. As shown in FIG. 5, a circular retracting spring  7  is also mounted between the shifting ring  68  and the outer rotor  4 . 
     As shown in FIG. 7, the another design of the present invention can provide a connection between the shaft&#39;s disc  11  and the outer rotor  4  over the balls  65  without applying the 2 nd  speed ring  49 . In this configuration, the balls  65  which engage the 2 nd  speed are slidably housed within the shaft disc&#39;s openings  16  and shifting unit base openings  60  and pushed into the grooves  46  in the outer rotor  4  by the shifting disc  62 . As also shown in FIG. 7, the connection between the sprocket  5  and the inner rotor&#39;s disc  20  is also provided by a plurality of balls  69  which are slidably received within the openings  50  in the sprocket  5 . The balls  69  are located between the 3 rd  speed ring&#39;s  67  pins  68  and the inner rotor&#39;s disc  20  in the openings  50  as shown in FIG.  7 . 
     As shown in FIG. 8, it is yet another alternative proposal of the present invention to provide one friction ring  48  in the 2 nd  speed ring  49  and another friction ring  47  in the outer rotor  4  in order to establish the connection between the shaft disc  11  and the outer rotor  4 . This design uses the friction ring  47  instead of the grooves  41  to connect the outer rotor  4  to the shaft disc  11  over the balls  65  and the 2 nd  speed ring&#39;s pins  45 . The design shown in FIG. 8 also proposes that another friction ring  24  is provided within the inner rotor&#39;s disc  20  instead of grooves  21 . In such case, the connection between the sprocket  5  and the disc  20  is established when the outer ends of the 3 rd  speed ring&#39;s pins  67  are pushed against the friction ring  47 . 
     It is to be understood that regarding the connections between the shaft disc  11  and the outer rotor  4  and the connections between the sprocket  5  and the inner rotor&#39;s disc  20 , any of the above described combinations can be applied either as presented in FIGS. 4,  7 , and  8  or in any other combination. It is also to be understood that both of said connections can be obtained by applying some other similar connecting means, such as pawls or rollers. 
     The following description of the process for the present invention assumes that all members are positioned as shown in FIG. 4 which represents the situation that produces the slowest possible sprocket rotating speed, hereinafter defined as the “1 st  speed”. According to the process of the present invention, the device is powered by rotating the crank  81  which, in turn, forces the crankshaft  1  and shaft disc  11  to rotate at the same speed and in the same direction. When the crankshaft  1  starts to turn forwards, the pawls  10  engage the toothed sections  22  and provide firm connection between the crankshaft  1  and the inner rotor  2  which is also forced to turn in the same direction. The lobes of the inner rotor  2  further force the middle rotor  3  to rotate around the eccentric disc in the same direction. Also, as the crankshaft  1  rotates, its gear  180  turns the gears  32  in the eccentric shaft  31  and this action keeps the eccentric disc  31  in its position at all times. 
     As shown in FIG. 4, some lobes of the middle rotor  3  are always positioned to act against the pockets in the outer rotor  4  and they transmit the force onto the outer rotor  4 . This action forces the outer rotor  4  to rotate in the same direction and over the clutch  40  engage the sprocket  5  which is also forced to rotate in the same direction. The edge of the outer rotor  4  is mounted onto the ball bearing  12  as shown in FIG. 4, and the ball bearing  12  keeps the outer rotor  4  turning around the proper axis. Since the inner rotor  2  has less lobes than the middle rotor&#39;s  3  pockets and the middle rotor  3  has less lobes than the outer rotor&#39;s pockets, the sprocket  5  is rotating at a rate slower than the rotating rate of the crankshaft. The difference in the rotating ratio between the crankshaft and the sprocket is defined by the difference between the number of lobes and number of pockets. 
     The above described process presents the situation wherein the sprocket  5  rotates at minimum possible speed with respect to the speed of the crankshaft  1  and this situation presents the 1 st  speed. When the shifting cord  71 , shown in FIG. 14, is pulled by one step, it forces the shifting ring  62  to rotate counterclockwise which, in turn, brings the cam sections  63  into the position shown in FIG.  5 . This action causes the cam sections  63  to displace the balls  65  which further act against the ring  49  and force the pins  54  into the grooves  41  as also shown in FIG.  5 . When the pins  45  enter the grooves  41 , they  45  create the firm connection between the shaft disc  11  and the outer rotor  4 . As the result, the outer rotor  4  is forced to rotate together with the shaft disc  11 , i. e. at a faster rate than during the previous process. 
     Since the outer rotor  4  starts rotating at the same rate as the shaft  1  and since its connection over the middle rotor  3  to the inner rotor  2  causes the inner rotor to start rotating faster, the overrunning clutch  10  disengages the connection between the shaft  1  and the inner rotor  2 . Over the overrunning clutch  40 , the outer rotor  4  forces the sprocket  5  to rotate at the same speed which is identical to the rotating speed of the shaft  1  and represents the 2 nd  speed. The inner rotor  2  now rotates faster than the sprocket  5  but it is not able to influence the sprocket&#39;s rotating speed and the disc  20  rotates idly around the sprocket  5 . When the shifting cord  71  is pulled by one more step, it forces the shifting ring  62  to further rotate counterclockwise which causes the cam sections  64  into the position shown in FIG.  6 . The cam sections  63  are designed with the longer surfaces and they still keep the balls  65  displaced into the grooves  41 , thereby still providing a firm connection between the shaft ring  11  and the outer rotor as also shown in FIG.  6 . 
     When the cam sections  64  are pulled into the position as shown in FIG. 6, they displace the balls  66  which further act against the 3 rd  speed ring  68  and force the pins  67  to enter the grooves  21 . This results in the firm connection between the sprocket  5  and the disc  20  which causes the sprocket  5  to rotate at the same speed as the inner rotor  2  and its disc  20 . Since a firm connection between the shaft disc  11  and the outer rotor  4  still exists, the rotating speed of the inner rotor  2  and the disc  20  is faster than the rotating speed of the outer rotor. Also, since the sprocket  5  starts rotating at the speed rate of the inner rotor  2 , the overrunning clutch  40  disengages the connection between the outer rotor  4  and the sprocket  5 . Consequently, the sprocket rotates at the fastest speed which represents the 3 rd  speed. 
     Shifting back to the lower gears is performed when the shifting cord  71  is released by one step which enables the spring  84  to pull the shifting disc  62  back so that the cam sections  64  return to their starting position. When the cam sections  64  return to their starting positions, the disc  20  pushes the pins  67  out of the groves  21  which are shaped in a manner that enable such action. The pins  67  and the ring  68  return the balls  66  to their starting position and the connection between the sprocket  5  and the disc  20  ceases to exist as shown in FIG.  5 . When the sprocket  5  and the disc  20  are disconnected, the power is again transmitted from the outer rotor  4  to the sprocket  5  over the overrunning clutch  40  which is engaged again. The sprocket  5  again rotates at the rate which corresponds to the 2 nd  speed and all members are positioned as shown in FIG.  5 . The ring  68  is kept into its starting position by the circular spring  7  which prevents the ring  68  and the pins  67  to lean against the disc  20  when they are not pushed by the cam sections  64 . 
     When the shifting cord  71  is released by one more step, the spring  84  pulls the shifting disc  62  back so that the cam sections  63  return to their starting position. As the cam sections  63  return to their starting positions, the outer rotor  4  displaces the pins  45  out of the groves  41  and the ring  49  return the balls  60  to their starting position as shown in FIG.  4 . This eliminates the connection between the outer rotor  4  and the shaft disc  11  and the overrunning clutch  10  engages the inner rotor  2  again. The power is again transmitted from the inner rotor  2  to the outer rotor  4  over the middle rotor  3  and further to the sprocket  5  over the overrunning clutch  40 . The sprocket  5  again rotates at the rate which corresponds to the 1 st  speed and all members are again positioned as shown in FIG.  4 . 
     Regarding the alternative designs shown in FIGS. 7 and 8, the entire up and down shifting process is identical as described above. The only difference is that, in the case of the design shown in FIG. 7, the connection between the shaft disc  11  and the outer rotor  4  is established over the balls  65  which are pushed by the cam sections  63  into the grooves  46 . This results in the 2 nd  speed according to the same operating principles as described above. Also, the connection between the disc  20  and the sprocket  5  is provided by the balls  69  which are displaced into the grooves  23 . This action also produces the 3 rd  speed according to the same operating principles as described above. 
     With regard to the design shown in FIG. 8, the difference is that the connection between the outer rotor  4  and the shaft disc  11  is established over the friction surfaces (rings)  48  and  47  shown in FIG.  8 . Such connection also results in the 2 nd  speed according to the same operating principles as described above. Also, the connection between the sprocket  5  and the disc  20  is established by providing the contact between the pins  67  and friction surfaces  24  in the disc  20 . The displacement of the pins  67  toward the friction surfaces  24  is identical to the above described process and also results in the 3 rd  speed. Shifting back into the lower speeds is also in all said instances identical to the above described process. 
     As shown in FIGS. 21,  22 ,  23 , and  24 , the present invention also provides a design which represents a 2-speed device for use in bicycles and similar pedal-powered vehicles. As in the case of the previously presented designs, this design also comprises the shaft  1 , the shifting disc  62 , the shifting base unit  6 , the sprocket  5 , and the rotor assembly comprising the inner rotor  2 , middle rotor  3 , and the outer rotor  4 . As shown in FIG. 22 and 24, this design uses only one shifting ring  68  and has a different shifting base unit as shown in FIGS. 22 and 23. As shown in FIGS. 21,  22 , and  24 , the rotor assembly is structured identically as described for the previous designs while the inner rotor  2  is mounted onto the shaft  1  over the bearing  70  which enables the completely free rotation of the inner rotor  2  with respect to the shaft  1 . 
     As shown in FIG. 22 and 24, the shaft disc  11  is firmly connected to the outer rotor  4 , which forces the outer rotor  4  to always rotate at the same speed as the shaft  1 . The shifting base unit  6  is firmly connected to the bottom bracket  61  and it has eccentric grooves  83  as shown in FIGS. 22 and 23. Inner portions of the shifting disc  62  are inserted into the grooves  83  as shown in FIGS. 22 and 24 in a manner which enables the groove  83  to drive the shifting disc  62  into the positions shown in FIGS. 22 and 24. When the shifting disc  62  is turned clockwise, it travels towards the rotor assembly and forces the ring  68  and pins  67  to travel in the same direction and into the position as shown in FIG.  24 . When the shifting disc  62  is turned back, the grooves  83  forces it to travel outwards into the starting position as shown in FIG.  22 . 
     According to this design, the shifting disc  62  has only one set of the cam sections  64  as shown in FIGS. 22 and 24. These cam sections  64  are designed to also permanently hold the balls  66  in the same position with respect to the cam sections  64 . The balls  66  rotate within the cam sections  64  and exert force against the ring  68  when carried by the cam sections  64  towards the rotor assembly. 
     According to the process for this design of the present invention, when the shaft  1  is turned forward by the crank  81 , it forces the outer rotor  4  to rotate in the same direction and at the same speed. Over the overrunning clutch  40 , the outer rotor  4  further forces the sprocket  5  to rotate in the same direction and at the same speed. The overrunning clutch is designed to engage the sprocket  5  in any situation when the speed of the outer rotor  4  exceeds the speed of the sprocket  5 . In this case, the rotating speed of the sprocket represents the 1 st  speed which is equal to the shaft input rotating speed. This design also assumes that the sprocket  5  has the minimum number of teeth, i. e. 39 teeth in the situation when this device is supposed to replace the sprocket assembly wherein one sprocket has 39 teeth and another sprocket has 54 teeth. 
     When the shifting disc  62  is pulled by the shifting cord  71 , it is driven inwards by the grooves  83  and the balls  66  push the ring  68  until the pins  67  enter the grooves  21  in the disc  20  as shown in FIG.  24 . This results in a firm connection between the sprocket  5  and the disc  20  which is rotating faster because the outer rotor  4  forces the inner rotor  2  to rotate at a higher rate. Since the outer rotor  4  has more pockets than the middle rotor  3  lobes and the middle rotor  3  has more pockets than the inner rotor  2  lobes, the inner rotor  2  rotates faster than the outer rotor  4 . The overrunning clutch  40  disengages the sprocket  5  and the rotating speed of the sprocket  5  equals the rotating speed of the inner rotor  2  which represents the 2 nd  speed. 
     When the cord  71  is released, the spring  84  drives the shifting disc  62  into its starting position thereby enabling the disc to push the pins  67  out of the grooves  21  which results in disconnecting the disc  20  from the sprocket  5 . When the connection between the disc  20  and the sprocket  25  is terminated, the overrunning clutch  40  engages the sprocket  5  again and the sprocket  5  starts rotating at the same speed as the outer rotor  4  which corresponds to the 1 st  speed. All members are again positioned as shown in FIG.  22  and the output sprocket&#39;s  5  speed is equal to the rotating speed of the shaft  1 . 
     As shown in FIGS. 25,  26 , and  27 , the present invention also provides a design which represents the 2-speed device wherein the sprocket has a maximum number of teeth. While having the identical rotors&#39;assembly and shifting unit configuration as described for the previous design, this design uses the overrunning clutch  10  to connect the shaft  1  and the inner rotor  2  as described for the 3-speed designs. It also does not provide the firm connection between the shafts disc  11  and the outer rotor  4  but enables the outer rotor  4  to rotate around the shaft disc  11  as also described for the 3-speed designs and shown in FIGS. 26 and 27. 
     According to the process for this design of the invention, the 1 st  speed is produced when the inner rotor  2  is firmly connected to the shaft  1  over the overrunning clutch  10  and it transmits power to the outer rotor  4  over the middle rotor  3 . The outer rotor  4  further transmits power to the sprocket over the overrunning clutch  40  which engages as soon as the speed of the outer rotor  4  exceeds the speed of the sprocket  5 . This situation is depicted in FIG.  26 . As shown in FIG. 27, the 2 nd  speed is produced when the sprocket is firmly connected to the disc  20  which is obtained by the process of driving the shifting disc  62  in a manner that is identical as described for the previous 2-speed design. The process to disengage the 2 nd  speed is also identical as described for said previous design. 
     As shown in FIGS. 28,  29 , and  30 , the present invention provides yet another design for the 2-speed device wherein the sprocket  5  has the maximum number of teeth. This design comprises the identical rotors&#39; assembly and shifting unit configuration as presented for the previously described design and does not require the overrunning clutch  40 . As shown in FIGS. 28,  29 , and  30 , the sprocket  5  is directly mounted onto the middle rotor  3  and it has the plurality of the lobes receiving pockets provided within its inner circumference. In sum, the sprocket is driven directly by the middle rotor  3  and it rotates on the bearing  12  mounted onto the shaft disc  11 . 
     According to the process of this design, the 1 st  speed is produced when the inner rotor  2  is connected to the shaft  1  over the overrunning clutch  10  and forced to drive the sprocket  5  over the middle rotor  3 . The 2 nd  speed is produced when the pins  67  establish the firm connection between the sprocket  5  and the disc  20  which is also obtained by the process of driving the shifting disc  62  in a manner that is identical as described for the previous 2-speed designs. Since the overrunning clutch  40  is eliminate in this design, the entire rotor assembly is locked together and all members rotate together during the 2 nd  speed rotation. The process to disengage the 2 nd  speed is also identical as described for said previous designs. 
     As shown in FIG. 31, the present invention also provides a design wherein the gears  92 ,  93 , and  94  are used instead of the rotors and perform the same functions in the same manner as done by the rotors. The inner gear  92  substitutes the rotor  2 , the middle gear  93  substitutes the middle rotor  3 , and the outer gear  94  substitutes the rotor  4 . This design proposes that all other members and all aspects of the invention are identical as previously described in this specification. It is assumed that this gear-driven design can be applied for all above described designs and that all above described shifting processes are identical as presented in this specification. In sum, the only difference regarding any of the presented designs is that the gears are used instead of the rotors. 
     While the above is the description of different embodiments of the present invention, various modifications may be employed. Accordingly, the invention should not be limited by the specific described embodiments and the true scope of the invention should be determined from the following claims.