A transmission for transmitting power from an input shaft to a driving wheel and changing rotating speed ratios is disclosed. The transmission comprises a drive shaft, a set of drive gears, a driven shaft, a set of driven gears, one counter gear, one return gear including a hub, a planetary gear and sprocket assembly, and a braking mechanism which alternates the operation of the planetary gear. By alternately engaging the different drive gears, the transmission enables the change of an input rotating speed and by stopping the ring gear in the planetary assembly it further multiplies the change of the input rotating speed. Within a very compact and user-friendly design, the transmission provides a fill range of speeds and enables smooth power flow resulting in the decrease of power loss in pedal propelled vehicles.

BACKGROUND OF THE INVENTION 
A bicycle transmission is used for changing the ratio between a crank 
operating speed and a driving wheel operating speed to best meet each 
particular driving situation. Bicycle transmissions known in the prior art 
use different size sprockets (chainwheels) and a driving chain to transmit 
a pedaling force to a driving (rear) wheel. They use two sets of 
sprockets, wherein one set of sprockets is mounted on a crank spindle and 
another on a rear axle. The chain rotates on one of the front sprockets 
and one of the rear sprockets and is displaced by derailleurs from one 
sprocket to another in order to change the driving wheel operating speed. 
The front derailleur is located proximate to the front sprockets and used 
to displace the chain on these sprockets. The rear derailleur is located 
proximate to the rear sprockets and used to displace the chain on these 
sprockets. 
In order to change the speed, the chain has to be displaced from at least 
one sprocket which causes interruptions in the power transmitting process 
and results in power loss. Due to their size and position the chain and 
sprockets cannot be properly lubricated without creating negative effects 
and are often exposed to environmental damage. The transmissions of the 
prior art do not allow an identical ratio of speed increase/decrease 
between two neighboring speeds, thereby creating negative effects 
regarding power flow. A rear set of sprockets (cogs' cassette) requires 
both chainstays and seatstays to be spaced wide apart to accommodate for 
the width of the sprockets which, in turn, creates negative aerodynamic 
effects. In sum, the transmissions of the prior art do not enable an 
efficient and uninterrupted flow of the pedaling force and negatively 
influence the aerodynamic properties of the bicycle. 
SUMMARY OF THE INVENTION 
The present invention comprises one gear box and a planetary gear located 
within a bottom bracket area and connected to a chain sprocket. The gear 
box comprises two sets of gears mounted on two shafts. One set of gears, 
hereinafter referred to as drive gears, is mounted on a crank spindle 
which serves as a power input (drive) shaft and another set of gears, 
hereinafter referred to as drive gears, is mounted onto the shaft which 
serves as a driven (counter) shaft. Each set comprises gears which have 
different diameters and are mounted to be in a constant-mesh position, 
wherein the largest drive gear meshes with the smallest driven gear and 
vice versa. The gears mounted onto the drive shaft are firmly connected to 
this shaft and all rotate at the same speed as the shaft. The gears 
mounted onto the driven shaft rotate independently and their rotating 
speed is proportional to the difference of their diameters with respect to 
the diameters of the corresponding drive gears. 
The driven shaft is drilled through and houses a shifting mechanism which 
alternately engages one of the driven gears. When engaged, the driven gear 
is connected to the driven shaft and forces the shaft to rotate at the 
same speed. Each pair of gears (one drive and corresponding driven gear) 
produces a rotating speed which is different from one which can be 
produced by two neighboring pairs of gears. One (counter) gear is firmly 
connected to the driven shaft and always rotates at the same speed as this 
shaft. This gear permanently meshes with and drives one (return) gear 
which is rotatably mounted on the drive shaft. The gear which is rotatably 
mounted on the drive shaft has a hub which extends along the drive shaft 
into a inner section of a chain sprocket and a inner section of a 
planetary gear. The hub drives either the sprocket or the planetary gear 
as explained later in a detailed description of the preferred embodiment. 
The present invention enables a chain to transmit a pedaling force without 
being displaced from one sprocket to another and, therefore, eliminates 
disadvantages related to existing power transmission systems. The chain is 
constantly mounted onto two sprockets and a shifting process is performed 
smoothly and efficiently. All major components are encased and can be 
properly lubricated at all times. Also, almost every component is 
performing only a one-way rotating motion which creates the smallest 
friction and wear, thereby enabling a maintenance-free operation. 
A smooth and uninterrupted shifting process and low friction create minimum 
power loss and a relatively small volume enables excellent aerodynamic 
properties. A shifting process can be performed by a single shifting cable 
or an electric step motor and produces a wide variety of identical 
shifting ratios. This transmission is also aesthetically pleasing, 
eliminates chain slipping problems inherent to bicycles with suspension 
systems, and regarding weight and volume does not exceed the parameters of 
the existing power transmitting systems.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
As shown in FIG. 1, the present invention comprises one set of gears 11, 
hereinafter identified as drive gears, mounted onto a drive shaft 10 and 
one set of gears 90-96, hereinafter identified as driven gears, mounted 
onto a driven (counter) shaft 2. Both sets of gears 11 and 90-96 are 
positioned so as to enable that each of the drive gears 11 constantly 
meshes with a corresponding driven gear 90-96. The drive gears 11 have 
different diameters and all of them are firmly attached to the drive shaft 
10. The driven gears 90-96 also have different diameters and each of these 
gears 90-96 is mounted in a manner which allows a completely independent 
rotation around the shaft 2. The driven shaft 2 and the drive shaft 10 are 
rotatably mounted within the housing 1 and only the end sections of the 
drive shaft 10 extend outside the housing 1. As shown in FIG. 1, two 
cranks 8 are mounted onto the end sections of the drive shaft 10. 
One counter gear 9 is mounted onto the driven shaft 2 as shown in FIG. 1, 
and it 9 is firmly connected into keyways 99 of the shaft 2 shown in FIGS. 
2 and 4. One return gear 12, shown in FIG. 1, is mounted onto the drive 
shaft 10. This gear 12 has a hub 122 which encircles one of the end 
sections of the drive shaft 10 and is able to freely rotate around the 
shaft 10. A planetary gear and sprocket assembly, which incorporates a sun 
gear 3, a chain driving sprocket 37, planet gears 34, a ring gear 35, a 
planet carrier 33, and two over-running clutches 31 and 32, is mounted 
onto the hub 122 of the return gear 12 as shown in FIG. 1. The sun gear 3 
is mounted onto the hub 122 in a manner which allows it 3 to freely rotate 
in any direction around the hub 122. The over-running clutches 31 and 32 
are able to freely rotate only in one direction as explained later in this 
specification. The planet carrier 33 is firmly connected to the hub 122 
and always rotates together with the hub 122. A brake 30 is located next 
to the ring gear as shown in FIG. 1 and used to stop the rotation of the 
ring gear 35 when required by the process of the invention as explained 
later in this specification. 
As shown in FIGS. 1, 2, 3, 4, 5, 6, and 7, the driven shaft 2 has a 
longitudinal opening 20 and a plurality of lateral openings 21 and 22. As 
shown in FIGS. 1, 7, 11, and 12, the longitudinal opening 20 houses a 
plurality of shifting plungers 5, 51, and 52, and a plunger holder 6 shown 
in FIGS. 1, 11, 12, and 14. The lateral openings 22 house intermediate 
balls 42 and the lateral openings 21 house rollers 41 as shown in FIGS. 1, 
5, 6, 7, 11, and 12. The balls 42 and rollers 41 are able to travel from 
the retracted position, as shown in FIGS. 4, 5, and 6, into the extended 
position as shown in FIG. 7. When the balls 42 are pushed outwards, they 
42 push the rollers 41 in the same direction and, consequently, the 
rollers 41 extend to the outer circumference of the counter shaft 2 as 
shown in FIG. 7. The plungers' holder 6, shown in FIGS. 1, 11, 12, and 14 
is inserted through the shifting plungers 5, 51, and 52 and firmly 
connected to the housing 1 as shown in FIG. 1. Its function is to prevent 
rotation of the plungers 5, 51, and 52 during the shifting process and, 
thereby, ensure their linear motion. 
The shifting plungers 5, 51, and 52 are located within the longitudinal 
opening 20 of the driven shaft 2 and each of them has sections which have 
different diameters as shown in FIGS. 1, 11, 12, and 15. The circumference 
of the sections having a larger diameter 56 corresponds to the 
circumference of the longitudinal opening 20 of the counter shaft 2 and 
these sections 56 displace the balls 42 and rollers 41 into their extended 
position as shown in FIG. 7. The circumference of the sections having a 
smaller diameter is smaller then the circumference of the longitudinal 
opening 20 of the counter shaft 2 and enables the balls 42 and rollers 41 
to return into their retracted position as shown in FIGS. 4, 5, and 6. The 
shifting plungers 5, 51, and 52 are mounted onto each other so that the 
middle plunger 51 encircles the inner plunger 5 and that the external 
plunger 52 encircles the middle plunger 51 as shown in FIGS. 1, 11, and 
12. The plungers 5, 51, and 52 extend through one end of the counter shaft 
2 and each of them has an end extension 53, 54, and 55 as shown in FIGS. 
1, 11, 12, and 15. The end extensions 53, 54, and 55 of the plungers 5, 
51, and 52 are inserted into a shifter 7 as shown in FIGS. 1, 11, and 12. 
The shifter 7, shown in FIGS. 1, 11, 12, and 13, has internal grooves 73, 
74, and 75 shown in FIG. 13. The grooves 73, 74, and 75 house the end 
extensions 53, 54, and 55 of the plungers and are curved so as to 
horizontally drive the plungers back and forth through the opening 20 when 
the shifter 7 is rotated as shown in FIGS. 11 and 12. 
As shown in FIGS. 6, 7, and 8, the driven gears 90-96 have a plurality of 
notches 98 machined within their inner openings 97. One engaging key 4 is 
located within each of the notches 98 in a manner which allows the keys 4 
to assume either an extended position as shown in FIG. 6 and 9 or a 
retracted position as shown in FIG. 7 and 10. The keys 4 are mounted onto 
an tension spring 43, as shown in FIGS. 6, 7, 9, and 10, which forces the 
keys 4 into the extended position and, consequently, enables the keys 4 to 
push the rollers 41 and balls 42 into their retracted position as shown in 
FIG. 6. When the keys 4 are in their extended position, as shown in FIG. 
6, they 4 enter rollers' openings 21 and lock the gear 90-96 to the 
counter shaft 2, thereby forcing the shaft 2 to rotate at the same speed 
as the corresponding gear 90-96. When the keys 4 are in their retracted 
position, as shown in FIG. 7, they allow the gear 90-96 and the shaft 2 to 
rotate at different speeds. The keys 4 also do not exert any influence in 
the case when the rotating speed of the shaft 2 exceeds the rotating speed 
of the gear 90-96. 
The following description of the process of the invention assumes that the 
shifting mechanism is positioned so as to result with the lowest (first) 
speed as shown in FIG. 1. Also, in this position the brake 30 is not 
blocking the ring gear 35 and this gear 35 can freely rotate in any 
direction. According to the process of the invention, when the cranks 8 
are turned forward they force the drive shaft 10 to rotate in the same 
direction. Since the drive gears 11 are firmly connected to the drive 
shaft 10 they also are forced to rotate in the same direction and at the 
same speed. Due to the constant-mesh position, the drive gears 11 force 
the driven gears 90-96 to rotate at the speed defined by the difference in 
diameter between each pair of the drive 11 and driven 90-96 gears. The 
plungers 5, 51, and 52 are in their ultimate inward position as shown in 
FIG. 1, and they are displacing the balls 42 and rollers 41 as shown in 
FIG. 1. In this instance only the balls 42 and rollers 41 corresponding to 
the largest driven gear 90 are not displaced from their inward position, 
shown in FIG. 5, and 6, and only the keys 4 corresponding to the largest 
driven gear 90 are able to engage the counter shaft 2 as shown in FIG. 6. 
According to the process of the present invention, all of the driven gears 
91-96 whose corresponding balls 42 and rollers 41 are displaced outwards 
by the plungers 5, 51, and 52, as shown in FIG. 7, are freely turning 
around the counter shaft 2 because the keys 4 corresponding to these gears 
91-96 cannot enter the lateral openings 21 and engage the shaft 2. 
Consequently, only the largest driven gear 90 is connected to the shaft 2 
and forces the shaft 2 to rotate at the same speed. Since the largest 
driven gear 90 meshes with the smallest drive gear 11, this situation 
results in the slowest rotating speed, hereinafter referred to as the 
first speed. The counter gear 9, which is firmly connected to the counter 
shaft 2, transmits the rotating force of the counter shaft 2 onto the 
return gear 12 which now rotates in the same direction as the drive shaft 
10. 
The rotating force is further transmitted by the return gear's hub 122 
which engages the one-way over-running clutch 32. The clutch 32 is able to 
turn faster but not slower than the hub 122 and, therefore, is forced to 
turn at the same speed as the hub 122. The over-running clutch 32 further 
engages the one-way over-running clutch 31 which is also able to turn 
faster but not slower than the clutch 32. The clutch 31 engages the chain 
sprocket 37 which, in turn, is forced to turn at the same speed and in the 
same direction as the hub 122 of the return gear 12. The rotating force is 
further transmitted to the driving wheel by a chain mounted onto the 
sprocket 37. During the above described power transmitting process the 
planetary gear assembly simply turns around at the same speed as the hub 
122 and does not perform any action. Due to the fact that the sun gear 3 
is firmly connected to the clutch 31 and that the planet carrier 33 is 
firmly connected to the hub 122, the entire planetary gear assembly turns 
as a single unit and does not create any friction losses. 
Shifting into a higher/slower speed is performed by rotating the shifter 7 
by a certain predetermined number of degrees which is performed by a 
shifting cord 71 connected to the shifter 7. The internal grooves 73, 74, 
and 75 of the shifter 7 are curved as shown in FIG. 13, and each of them 
houses one of the plungers' end extensions 53, 54, and 55. According to 
the process of the present invention, when the shifter 7 is turned by a 
certain number of degrees, one of the grooves 73, 74, or 75 forces one of 
the end extensions 53, 54, or 55 to move in accordance with the groove 
curvature and, thereby, pull/push one of the plungers 5, 51, or 52. 
Accordingly, the rotary motion of the shifter 7 is alternately translated 
into the linear motion of one of the plungers 5, 51, or 52. Each of the 
plungers 5, 51, and 52 is able to move within a length corresponding to 
two (2) driven gears 90-96 and the plungers are alternately pulled/pushed 
into one of two possible positions. The grooves 73, 74, and 75 are 
designed to engage one of the plungers 5, 51, or 52 at the point after the 
neighboring plunger is driven into an ultimate left/right position. 
When shifting from first to second speed is required, the shifter 7 drives 
the end extension 53 of the plunger 5 through the groove 73 into the 
position shown in FIG. 11. At this instant, the plunger's 5 position 
allows the balls 42 and rollers 41 corresponding to the second driven gear 
91 to be displaced into their retracted position by the keys 4 
corresponding to the second driven gear 91. Consequently, the keys 4 
corresponding to the second driven gear 91 are able to enter the lateral 
openings 21 located in the section covered by the second gear 91 and 
engage the counter shaft 2 as shown in FIGS. 6 and 11. Since the second 
driven gear 91 is always turning faster than the first driven gear 90, the 
shaft 2 starts turning at the speed of the second driven gear 91 and the 
keys 4 corresponding to the first gear 90 disengage the shaft 2 regardless 
of the fact that the rollers 41 and the balls 42 corresponding to the 
first driven gear 90 are able to remain in their retracted position. It is 
to be mentioned that in every situation when the counter shaft 2 turns 
faster than any driven gear 90-96, the keys 4 corresponding to that gear 
90-96 cannot engage the shaft 2. 
Shifting into the third speed is performed by driving the plunger 5 into 
the position as shown in FIG. 12, wherein the shifter drives the end 
extension 53 into its ultimate left position. Consequently, the keys 4 of 
the third driven gear 92 are able to displace the balls 42 and rollers 41 
and enter the lateral openings 21 as shown in FIGS. 6 and 12. This causes 
the third driven gear 92 to engage the shaft 2 and the second driven gear 
91 to disengage the shaft 2 which starts rotating faster than the second 
driven gear 91. The process of shifting up to the seventh speed (when the 
gear 96 is engaged) is performed by driving the plungers 51 and 52 in the 
same manner as described above for the plunger 5. Shifting into a lower 
gear is performed by driving the plunger back into the previous position, 
for example, driving the plunger 5 from the position shown in FIG. 12 into 
the position shown in FIG. 11. When driven one step backwards, every 
plunger forces the balls 42 and rollers 41 into the extended positions, 
shown in FIG. 7, which, in turn, displaces the keys 4 from the lateral 
openings 21 and disengages the previously engaged driven gear 90-96. In 
every case, as soon as the faster gear is disengaged, the shaft 2 slows 
down and enables the keys 4 of the slower gear to connect this (slower) 
gear to the shaft 2. 
The process of driving the plungers 5, 51, and 52, as explained above, 
produces the first seven speeds. Shifting into the eighth speed is 
performed by driving all plungers back into the starting position as shown 
in FIG. 1, i.e. into the same position as for the first speed. 
Simultaneously, the shifter pulls the cord 36 which, in turn, activates 
the brake 30 that stops rotation of the ring gear 35. As known from the 
prior art, when the ring gear 35 is blocked (its rotation stopped) the 
planet carrier 33 (which is firmly connected to the hub 122) starts 
forcing the planet gears 34 to rotate inside the ring gear 35, which 
results in faster rotation of the sun gear 3 than the rotation of the hub 
122. Since the sun gear 3 is firmly connected to the clutch 31, the speed 
of the sprocket 37 is increased with respect to the speed of the hub 122. 
An increased rotating ratio of the sun gear 3 is defined by a difference 
between the number of teeth of the ring gear 35 and number of teeth of the 
sun gear 3. According to the process of the invention, this ratio is 
settled at the point wherein the sun gear's 3 rotating speed is higher 
than the hub's 122 rotating speed when the fastest driven gear 96 is 
connected to the shaft 2 and the planetary gear set is allowed to rotate, 
i. e. the sun gear's 3 rotation is faster than the seventh speed and 
represents the eighth speed. 
As soon as the sun gear 3 starts rotating faster than the hub 122, the 
over-running clutch 31 disengages the cover of the over-running clutch 32. 
Further up- and down-shifting is performed identically as explained above 
for the first seven speeds with the ring gear 35 being blocked all the 
time. Shifting back into seventh speed is performed by driving all of the 
plungers 5, 51, and 52 into their ultimate left position and 
simultaneously releasing the brake 30 on the ring gear 35. As soon as the 
ring gear 35 is again allowed to rotate, the rotating speed of the 
sprocket 37 becomes equal to the rotating speed of the hub 122, i. e. the 
transmission can produce only seven lower speeds. In sum, seven lower 
speeds are produced when the planet carrier 33 cannot force the planet 
gears 34 to rotate inside the ring gear 35 and the seven higher speeds are 
produced when the planet carrier 33 forces the planet gears 34 to rotate 
inside the ring gear 3, thereby forcing the sun gear 3 to rotate faster 
than the hub 122. 
It is to be understood that the number of driven gears and possible speeds 
specified in the above description is defined only for the purpose of 
illustration. It is also to be understood that the shifter 7 can be 
operated by other means, such as an electric step motor. 
As obvious from the above description, the present invention discloses the 
transmission which will eliminate drawbacks inherent to the transmissions 
known in the prior art. While having a compact design, this transmission 
will enable smooth power flow resulting in smaller power loss and much 
more convenient application in any type of pedal powered vehicle. 
It is to be understood that the present invention has been described in 
relation to the particular embodiment, herein chosen for the purpose of 
illustration, and that the claims are intended to cover all changes and 
modifications, apparent to those skilled in the art, which do not 
constitute departure from the scope and spirit of the invention.