WO2009101637A2

WO2009101637A2 - A variable length crank-arm based drive system

Info

Publication number: WO2009101637A2
Application number: PCT/IN2009/000104
Authority: WO
Inventors: Manoj Kumar Mondal
Original assignee: Manoj Kumar Mondal
Priority date: 2008-02-15
Filing date: 2009-02-13
Publication date: 2009-08-20
Also published as: WO2009101637A3

Abstract

A slidingly variable length crank arm assembly for particular use in manually driven vehicles including a slidably extendable crank arm provision to effect a selective change of length of the pedal arm during its rotary motion and in the process adapted such that the torque generated by the pedal-crank assembly of the invention is significantly multiplied to nearly two times the torque generated from conventional pedal-crank system involving arms of fixed and equal lengths ensuring that movement of the foot of the driver while using the slidingly variable length crank assembly is maintained in circular path, for example, in case of bicycle the driver's foot moves in the same circular path as in comparable fixed length crank assembly. A simple and cost effective manner of improving the torque generated through pedal-crank systems which would favour diverse and efficient application of such pedal-crank systems in variety of mechanically driven subjects.

Description

A VARIABLE LENGTH CRANK-ARM BASED DRIVE SYSTEM

FIELD OF THE INVENTION

The present invention relates to a slidingly variable length crank arm assembly and, in particular, to a pedal-crank system for converting force into torque so as to cause rotational movement, as for example in manually driven vehicles such as bicycle, rickshaws, trolleys and other such vehicles and implements wherein manual energy is transferred from the pedal to the wheels through a chain-sprocket system or a belt system. Importantly, the pedal-crank system of the present invention includes a slidably extendable crank arm provision to effect a selective change of length of the pedal arm during its rotary motion and in the process adapted such that the torque generated by the pedal-crank assembly of the invention is significantly multiplied to nearly two times the torque generated from conventional pedal-crank system involving arms of fixed and equal lengths. The movement of the foot of the driver while using the slidingly variable length crank assembly is in circular path, for example, in case of bicycle the driver's foot moves in the same circular path as as in comparable fixed length crank assembly. The invention is thus directed to improve the torque generated through pedal-crank system in manually driven vehicles such as bicycles, rickshaws and the like and machines or implements where force is used to create torque using a crank assembly and thereby favour improving the efficiency of such vehicles or machines. Advantageously, the invention proposes a simple and cost effective manner of improving the torque generated through pedal-crank systems which would favour diverse and efficient application of such pedal-crank systems in variety of mechanically driven subjects including vehicle such as bicycles, rickshaws and the like while the pedal movement remains in circular path. In other embodiments, a handle may be used in place of the pedal as the support means for applying the force for rotary motion.

BACKGROUND ART

It is well known that manually driven vehicles such as bicycles, rickshaws, trolleys and other such vehicles involve application of manual energy on operating pedals which is transferred on to the wheels through a chain - sprocket system or a belt system thereby set the vehicle in motion using manual energy. It is thus obvious that the vehicle motion is basically dependent on the force exerted by the foot of the driver on the pedal considering that the other constructional features remain the same. In particular, it is known that the torque generated in such a pedal-crank assembly is equal to the force (F) exerted by the foot of the driver multiplied by the fixed length (L) of the pedal arm i.e., F X L.

Considering that in the presently available pedal-crank system of manually driven vehicles such as bicycles, tricycles, rickshaws, trolleys and other such vehicles have the pedal-arm of a fixed length, it is obvious that the torque is solely dependent on the force exerted by the driver's foot on the pedal.

Attempts have been made in the past to achieve variable length of the crank arm to facilitate the driving of such manually driven vehicles with limited success and in most such cases the movement of the foot is not in circular path.

The United States Patent No. 4,807,491 describes a crank assembly which has a telescoping crank arm to facilitate variation in the length of the crank arm. In this invention the rider needs to slide the crank arm manually to the extended and retracted positions during the cycle of pedaling. Even though there is provision for limited enlargement of the crank arm the increased attention necessary from the driver is substantial and a cause for concern.

U.S. Patent No. 6640662 explains a mechanism to slide an extra arm with the pedal during the pedaling cycle, which also extends the arm to a certain extent. However, to accommodate necessary clearance at the top and bottom of the crank assembly the extra arms shrinks towards the center making the foot movement in elliptical path. Forcing the leg to move in elliptical path.

In U.S. Patent. No. 6,152,471 for a variable length crank arms the crank is suggested to be mounted to a position offset from the spindle which appears too complicated for manufacturing, even though there is limited increase in crank arm length. There is practical difficulty in implementing and controlling. U.S. Patent No. 7093516 also explains a self-extending and retracting crank arm which offers limited increase of crank arm and the movement of foot is in elliptical path.

U.S. Patent No. 7350796 describes a crank apparatus wherein a secondary crank arm slides within the primary crank arm. The secondary arm holds the pedal and expand and contract in length to give effective expansion and contraction in crank length. US Patenet No. 7093516 describes somewhat similar invention though it suffers from serious limitations. The possibility of expansion of the crank is limited and the movement of driver's foot is not in circular path in both cases.

Several other inventions disclosure describe means to expand crank arm for increased torque, however, either they have been able to achieve limited incremental torque or the foot movement is not in circular path or both.

It may therefore be seen that there is a need for invention of a crank arm assembly that can increase the torque to a larger extent and at the same time the foot of the driver should follow a circular path. The invention described here addresses all these issues.

Thus while there has been some attempts to achieve the variable length of the crank arm for such manually driven vehicles, it would be well apparent from the above systems that the same either involves complex mechanism with variety of linkages or complex profiles to achieve such purpose or are adapted to favour some limited extension of the arm length of the crank during its forward stroking motion.

Considering that the power /torque generated in such manually driven vehicles is equal to the force (F) exerted by the foot of the driver multiplied by the length (L) of the pedal arm i.e., F X L, it is important that the length of the arm be extended to the extent possible such as to achieve the maximum torque on application of the same force. Moreover, it is equally important that such arrangement for variable extension of length of the crank arm is attended with the least possible complexity so that operation of the vehicle or the device connected thereto is simple and easy and also the production of such crank-pedal assembly is less complex and cost-effective for wide scale use and application.

Importantly also such manually driven vehicles and the like involving pedal-crank systems such as bicycles, rickshaws, trolleys and other such vehicles have their own utilities and preferences vis-a-vis other forms of vehicles involving fuel/electrical energy consumption and thus the need for exertion of manual energy while operating such manually driven vehicles is always required to be made operator friendly such that the operator is provided with best possible comfort expending the minimum of energy to drive such vehicle. OBJECTS OF THE INVENTION

It is thus the basic object of the present invention to provide for an efficient and simple to obtain variable pedal-crank system for use in manually driven vehicles such as bicycles, rickshaws, trolleys and the like which would enable achieving higher torque than the presently available pedal-crank system for like purposes exerting the same manual effort by the driver.

Another object of the present invention is directed to provide for a simple and cost effective manner of improving the torque generated in pedal-crank based manually driven vehicles such as bicycles, rickshaws, trolleys and like which would facilitate providing better comfort and convenience for the driver to operate such vehicles exerting manual energy thereby favouring making such manually driven vehicle more operator friendly requiring less manual energy to drive the same.

Yet another object of the present invention is directed to an improve energy efficient pedal-crank system for manually driven vehicles/operative units wherein manual energy is converted to operate wheels the like through a chain-sprocket system or a belt system which would be simple to obtain and readily adapt to operate such vehicles and like operative systems thereby making such manually driven vehicles/operative units more convenient and comfortable to operate/drive.

Yet further object of the present invention is directed to provide for an improvement in the petal-crank system of manually driven vehicles such as bicycles, rickshaws, trolleys and the like wherein by exerting the same manual energy/effort it would be possible to achieve the required torque to operate such vehicles more than twice that achieved involving the conventional pedal-crank systems presently in use.

SUMMARY OF THE INVENTION

Thus according to the basic aspect of the present invention there is provided a slidingly variable length crank-arm assembly based drive system comprising :

crank-pedal/support for applying force assembly comprising a pair of rotatable crank- pedal/ support for applying force means operatively connected to an axle for generating a rotary motion of the axle which is adapted to rotate based on the force applied alternatively to the crank-pedal/ support for applying force at the front of the axle during its rotary motion,

said crank pedal/ support for applying force assembly adapted such that during the forward motion of the respective pedal/ support for applying force -crank means the crank arm assumes a maximum length there between the axle and the pedal/ support for applying force to thereby favour generating maximum torque based on the increased length of the crank arm during the pedals/ support for applying force forward motion while the operators driving force motion is maintained in circular path.

Importantly, in the variable length crank-pedal assembly based drive system the pedal means of the respective crank-pedal means are adapted to rotate along parallel and concentrically disposed respective circular paths of same diameter with the axle operatively connecting the said pair of crank arms disposed there between towards the rear and away from the center of the said respective circular pathways preferably close to the periphery of the said circular pathways.

In accordance with a preferred aspect the variable length crank-pedal assembly based drive system comprises:

said parallel and concentrically disposed respective circular paths defined by a pair of circular rings defining the circular pathways for the rotary motion of said respective crank-pedal means ;

axle means disposed there between the said pair of circular rings and operatively connected at its sides to a bracket means having slot there through , a free end of the crank arm adapted to pass there through said slotted bracket with its other end having the pedal means connected to the corresponding circular ring at the circumference thereof such that on rotary motion of the crank -pedal the attached circular ring also rotates and in the process the free end of the crank arm reciprocated to and fro through the slotted bracket thereby favouring providing for said increased length of the crank arm during its forward motion and retracted reduced length during its rearward motion along the circular path of the rings. Preferably, each said circular ring is adapted to guide the respective pedal along its periphery such as to in the process attain the variable length of the crank length with said circular rings in turn supported on stationary support means.

The said rotatable axle is supported and maintained in place by fixing to said stationary support and/or any other stationary member of the vehicle/ system to be operated by the axle motion.

As usual in case of any manual driven vehicle such as a bicycle and the like , the said axle is operatively connected to a sprocket and chain arrangement for transmission of the rotary motion generated by the crank-pedal motion.

Preferably, the said pedal end of the crank-pedal arm is connected to the circular ring by means of bearing arrangement for facilitating the application of the force on the pedal for rotating alongwith the respective circular ring.

Importantly, in the above variable length crank-pedal assembly based drive system the effective increase in the length of the crank arm of the pedal in the front is maximum as it reaches horizontal position from where the length starts reducing and to the minimum when it again reaches the horizontal position behind the axle point.

Also in the above variable length crank-pedal assembly based drive system the said pedal end region of the crank is connected to the circular ring by a pin and bearing arrangement.

The said slotted bracket is maintained rotatable alongwith the axle rotation based on the pedal motion.

The cross-section of the crank arm is of any configuration including round, rectangle. Advantageously, the variable length crank-pedal assembly based drive system of the invention can comprise a crank and pedal assembly of a manually driven vehicle including bicycles, rickshaws and trolleys.

In accordance with another aspect of the invention there is provided a power generating/drive system for operating any system and/or machines and/or vehicles comprising said variable length crank-pedal assembly based drive system as disclosed herein involving atleast one said pair of the rotatable crank-pedal means and wherein the power generated at the axle is adapted to drive any cooperative link requiring such operative drive power to operate the system/machine/vehicle.

Details of the invention, its object and advantages are explained hereunder in greater details in relation to non-limiting exemplary illustration of the crank-pedal assembly based drive system of the present invention in relation to the following accompanying figures wherein :-

Figure 1 is a line diagram illustrating the various operative components of the slidingly variable length crank-arm assembly based drive system of the present invention;

Figure 2 is a line diagram illustrating the first stage (crank in horizontal position)of variable length disposition of the crank pedal assembly based drive system of the present invention showing the disposition of the crank-pedal when the variable length of the crank assumes the desired maximum length upon reaching the horizontal position of the pedal during its forward stroke;

Figure 3 is a line diagram illustrating to the second stage (crank displaced by 45° to the horizontal position)of variable length disposition of the crank pedal assembly based mechanical drive system of the present invention showing the disposition of the crank- pedal when the same moves ahead of its first stage disposition during the circular rotary motion;

Figure 4 is a line diagram illustrating to the third stage (crank displaced by 90° to the horizontal position)of variable length disposition of the crank pedal assembly based drive system of the present invention showing the disposition of the crank-pedal when the same moves ahead of its second stage disposition during the circular rotary motion;

Figure 5 is a line diagram illustrating to the fourth stage (crank displaced by 135° to the horizontal position)of variable length disposition of the crank pedal assembly based drive system of the present invention showing the disposition of the crank-pedal when the same moves ahead of its third stage disposition during the circular rotary motion; Figure 6 illustrates the mounting of the slidingly variable length pedal-arm assembly on a vehicle, for example, a bicycle in accordance with the present invention.;

Reference is first invited to accompanying Figure 1 wherein the arrangement of the variable length crank-pedal assembly based mechanical drive system of the present invention is illustrated.

As clearly shown in the figure for the purpose of assuming the desired slidingly variable length of the crank-arm assembly the system basically comprises of a pair of rotatable crank (3 ) - Pedal (4) operatively connected with the axle (9) for generating a rotary motion on the axle (9). Importantly, as is usual in such rotatable crank-pedal especially for manual drives, torque generated in such a pedal-crank assembly is equal to the force (F) exerted by the foot of the rider multiplied by the length (L) of the pedal arm i.e., the distance between the axle at one end and pedal at the other end of the crank (3).

In particular, in order to achieve greater torque in the pedal-crank assembly of the invention the pedal arm i.e. the crank (3) length is adapted to vary such that when the pedal moves forward with respect to the center of the crank set, the effective length of the crank increases. It reaches to the maximum as it reaches horizontal position from where the length starts reducing and to the minimum when it again reaches to the horizontal position behind the crank set.

In order to achieve such a variable length of the crank arm and attain greater torque on application of the same force, the crank pedal assembly system has been developed. In particular, the crank pedal assembly is adapted such that during the forward motion of the respective pedal crank means the crank arm assumes a maximum length there between the axle and the pedal to thereby favour generating maximum torque based on the increased length of the crank arm during the pedals forward motion.

As further shown in the figures, the pedal means of the respective crank pedal means are adapted to rotate along parallel and concentrically disposed respective circular path of same diameter with the axle (9) operatively connected to the pair of crank arms (3). The circular path way for the pedal is defined by a pair of circular rings (7). In order to ensure that the pedal of the respective cranks move along the circular paths and at the same time enable the crank arms to assume the variable length, the crank pedal assembly of the invention is provided with an arrangement which is discussed hereunder in further detail.

As shown in the figure the system includes a pair of circular rings (7) which is provided to guide the pedal/crank along respective circular paths. The axle means (9) is disposed between the said pair of circular rings and operatively connected at its size to a bracket means (2) having slots there through. The free ends of the respective crank arms are adapted to pass there through said slotted bracket (2) while its other ends is connected to the pedal means (4) connected to the corresponding circular rings (7) at the circumference thereof such that on rotary motion of the cranks-pedal, the attached circular rings (7) also rotates and in the process the free end of the crank arms reciprocates to and fro through the slotted bracket 2 thereby favouring providing for said variable increase length of the crank arms during its forward motion and retracted reduced length during its rearward motion along the circular path of the rings.

Reference is invited to accompanying figures 2 to 5 which clearly and sufficiently illustrate the variable disposition of the length of the crank assembly during its clockwise rotary motion along the circular ring(7) supported on frame(6,8) to generate the rotary motion of the axle.

Importantly, as also clearly illustrated in the accompanying figures in the slidingly variable crank-pedal assembly based drive system, the axle (9) can be operatively connected to a sprocket (1) and chain arrangement for transmission of the rotary motion generated by the crank pedal arrangement of the invention. In particular, the rotatable stationary disposition of the axle can be achieved by supporting the same with respect to a fixed structure of the vehicle to be driven such as to the bi-cycle frame as is done in case of conventional bi-cycle frame connection to the axle of the chain and sprocket drive mechanism.

As is further illustrated in the accompanying figures the pedal end of the crank pedal arm is connected to the circular ring by means of bearing arrangement for facilitating the application of the force on the pedal for rotating alongwith the respective circular ring.

The pedal end region of the crank is connected to the circular ring by a pin and bearing arrangement(lθ). Preferably, to facilitate the guided circular motion of the pedal (4) along the circular ring, the circular ring is provided as a guide for the rotary motion of the pedal. In accordance with an embodiment of the pedal-crank system of the invention such slidable increase of the length of the pedal arm selectively during its rotary motion is possible by way of providing the pedal arm to slide within a guide while the pedal- crank system rotates. For the purpose the pivot of the pedal-crank assembly is placed behind the center of a circular ring and very close to said circular ring with a pin on each pedal arm opposite to the pedal foot rest inserted through a ball bearing into a groove in said circular ring. The other end of the pedal arm is maintained free and the whole arm is adapted to slide within a guide/slotted bracket. By way of such an arrangement when one of the pedal arm is horizontal the one with the foot rest extending forward will have an effective length of up to almost 2Lwhile the other will have almost up to nil effective length. Thus, even though the foot of the driver rotates within the same circular path of a conventional pedal-crank, almost double the torque of a conventional pedal-crank is generated by way of the pedal-crank system of the invention.

The cross section of the crank arm can be of any suitable configuration including round or rectangular, square or any regular or irregular shaped configuration.

Fig. 6 depicts as to how the slidingly variable length pedal-crank assembly is mounted on a vehicle, for example, a bicycle. This is only to illustrate the relative positions of different component vis. a vis. a vehicle and the bicycle has been shown only as an example and not to limit its multifarious application possibilities.

As apparent from the disclosure herein, the variable length crank pedal assembly based drive system of the invention can be adapted for driving any system including more specifically manually driven vehicles including bicycles, rickshaws and trolleys.

Advantageously, in keeping with further aspect of the invention the variable length crank pedal assembly based drive system of the invention can be adapted as variety of power generating/drive systems to operate any other system and/or machine and/or any other manually driven vehicle. In such case it is possible to use one or plurality of such pairs of rotatable crank-pedal means to achieve greater torque in driving the other system/machine or vehicle.

Advantageously, as would be clearly apparent from the figures that the effective increase in the length of the crank arm of the pedal in the front is maximum as it reaches horizontal position from where length starts reducing and to the minimum when it again reaches the horizontal position behind the axle point. Thus the present invention provides an energy efficient pedal-crank system adapted to be fitted on any bicycle, rickshaw, trolley or any other manually driven vehicle/like wheel operation comprising a pedal arm adapted to effect selective increase of length of the pedal arm selectively during its forward rotary motion such that the torque generated by such pedal-crank assembly which is based on the force exerted and the length of the pedal arm can be increased /multiplied several times vis-a-vis conventional pedal-crank system with fixed arm length. In one of the embodiments, the slidingly variable length crank assembly can be mounted to a machine or a vehicle, say for example a bicycle, at higher altitude/elevation compared to the traditional altitude/elevation of the pedal-crank system(with respect to the body of the vehicle) with higher diameter of the guiding ring up to which the leg can accommodate to gain further torque. This arrangement is to avoid the limitation of the ground clearance that is a key parameter for determining the size of crank. In such embodiments the generated torque can be much more than two times that generated in a fixed length pedal-crank system.

In particular, it is well known that the torque generated in pedal-crank assembly is equal to the force (F) exerted by the foot of the driver multiplied by the length (L) of the pedal arm i.e., F X L. In accordance with the present invention the pedal-crank system is adapted such that the pedal arm is about two times the length of a traditional pedal arm i.e., 2L. Thus, under the proposed pedal-crank system/assembly of the invention when the same is fitted to a vehicle, torque generated is close to 2L X F under the same force F. It is important to note that the movement of foot of the driver is in circular path in this case.

In accordance with yet another embodiment of the above disclosed pedal-crank system of the invention, it is possible to provide an effective length of the pedal much more than two times the length of a traditional pedal and the torque in such case is much more than double of the torque generated in a conventional pedal. In such an embodiment and elliptical ring is provided in the pedal-crank system instead of the circular ring.

The above disclosed pedal-crank assembly of the invention is adapted such that it can be fixed in a manually driven vehicle such as a cycle or a rickshaw or any other machine or implement where force is exerted to create torque and the energy from the crank could be transferred to the driving wheel through a conventional chain-sprocket mechanism or the like. Advantageously, by way of the present invention the effective length of the pedal can be made even much more than two times the length of the conventional pedal and torque generated in such case would be much more than double the torque generated under a conventional pedal. In such case the ring is provided in elliptical form.

It is thus possible by way of the present invention to provide for and efficient pedal- crank system for use in manually driven vehicles such as bicycles, rickshaws, trolleys and the like which would enable achieving higher torque than the presently available pedal- crank system for like purposes exerting the same manual effort by the driver.

Importantly, the invention would favour better comfort and convenience for the driver of such manually driven vehicles to operate such vehicles exerting manual energy thereby making such manually driven vehicles more operator friendly requiring less manual energy to drive the same.

Claims

WE CLAIM:

1. A slidingly variable length crank-arm assembly based drive system comprising : crank-pedal/support for applying force assembly comprising a pair of rotatable crank-pedal/ support for applying force means operatively connected to an axle for generating a rotary motion of the axle which is adapted to rotate based on the force applied alternatively to the crank-pedal/ support for applying force at the front of the axle during its rotary motion,

said crank pedal/ support for applying force assembly adapted such that during the forward motion of the respective pedal/ support for applying force -crank means the crank arm assumes a maximum length there between the axle and the pedal/ support for applying force to thereby favour generating maximum torque based on the increased length of the crank arm during the pedals/ support for applying force forward motion while the operators driving force motion is maintained in circular path..

2. A variable length crank-arm assembly based drive system as claimed in claim 1 wherein the support for applying force/ pedal means of the respective crank- pedal/ support for applying force means are adapted to rotate along parallel and concentrically disposed respective circular paths of same diameter with the axle operatively connecting the said pair of crank arms disposed there between towards the rear and away from the center of the said respective circular pathways preferably close to the periphery of the said circular pathways.

3. A variable length crank-arm assembly based drive system as claimed in anyone of claims 1 or 2 comprising:

said parallel and concentrically disposed respective circular paths defined by a pair of circular rings defining the circular pathways for the rotary motion of said respective crank-pedal means; axle means disposed there between the said pair of circular rings and operatively connected at its sides to a bracket means having slot there through , a free end of the crank arm adapted to pass there through said slotted bracket with its other end having the pedal means connected to the corresponding circular ring at the circumference thereof such that on rotary motion of the crank -pedal the attached circular ring also rotates and in the process the free end of the crank arm reciprocated to and fro through the slotted bracket thereby favouring providing for said increased length of the crank arm during its forward motion and retracted reduced length during its rearward motion along the circular path of the rings.

4. A variable length crank-arm assembly based drive system as claimed in anyone of claims 1 to 3 wherein each said circular ring is adapted to guide the respective pedal along its periphery such as to in the process attain the variable length of the crank length with said circular rings in turn supported on stationary support means.

5. A variable length crank-arm assembly based drive system as claimed in anyone of claims 1 to 4 wherein said rotatable axle is supported and maintained in place by fixing to said stationary support and/or any other stationary member of the vehicle/ system to be operated by the axle motion.

6. A variable length crank-arm assembly based drive system as claimed in anyone of claims 1 to 5 wherein said axle is operatively connected to a sprocket and chain arrangement for transmission of the rotary motion generated by the crank-pedal motion.

7. A variable length crank-arm assembly based drive system as claimed in anyone of claims 1 to 6 wherein said pedal end of the crank-pedal arm is connected to the circular ring by means of bearing arrangement for facilitating the application of the force on the pedal for rotating alongwith the respective circular ring.

8. A variable length crank-arm assembly based drive system as claimed in anyone of claims 1 to 7 wherein the effective increase in the length of the crank arm of the pedal in the front is maximum as it reaches horizontal position from where the length starts reducing and to the minimum when it again reaches the horizontal position behind the axle point.

9. A variable length crank-arm assembly based drive system as claimed in anyone of claims 1 to 8 wherein the said pedal end region of the crank is connected to the circular ring by a pin and bearing arrangement.

10. A variable length crank-arm assembly based drive system as claimed in anyone of claims 1 to 9 wherein said slotted bracket is rotatable alongwith the axle rotation based on the pedal motion.

11. A variable length crank-arm assembly based drive system as claimed in anyone of claims 1 to 10 wherein the cross-section of the crank arm is of any configuration including round, rectangle, square or any regular or irregular configuration.

12. A variable length crank-arm assembly based drive system as claimed in anyone of claims 1 to 11 comprising a crank and pedal assembly of a manually driven vehicle including bicycles, rickshaws and trolleys.

13. A variable length crank-arm assembly based drive system as claimed in anyone of claims 1 to 12 wherein the ring guiding the pedal -crank is circular in shape to ensure foot movement in circular path.

14. A variable length crank-arm assembly based drive system as claimed in anyone of claims 1 to 13 wherein the slidingly variable length crank arm assembly is mounted to a machine or a vehicle, preferably a bicycle, at higher altitude/elevation compared to the traditional altitude/elevation of the pedal-crank system with respect to the body of the vehicle with higher diameter of the guiding ring up to which the leg can accommodate to gain further torque preferably much more than two times that generated in a fixed length pedal-crank system.

15. A power generating/drive system for operating any system and/or machines and/or vehicles comprising said variable length crank-pedal assembly based drive system as claimed in anyone of claims 1 to 14 involving at least one said pair of the rotatable crank-pedal means and wherein the power generated at the axle is adapted to drive any cooperative link requiring such operative drive power to operate the system/machine/vehicle.

16. A variable length crank-arm assembly based drive system and a power generating/drive system involving the same substantially as hereindescribed and illustrated with reference to the accompanying figures.