"Mechanism for generating a motion of rotation with double thrust lever having variable arm"

FIELD OF APPLICATION

[0001] The present invention relates to a mechanism for generating a rotation movement with double thrust lever having variable arm.

[0002] In particular, this mechanism may find application in the movement mechanism of a bicycle. Advantageously, the mechanism according to the invention may also find other applications involving generating a rotation movement through two pedal cranks or hand cranks, for instance in nautical craft such as pedal boats or in double crank winches .

STATE OF THE ART

[0003] A known mechanism for generating a rotation movement with double thrust lever comprises two rods, each of which forms a thrust lever. Each rod is secured at a first end portion to a rotation pin around which the rotation movement develops and bears associated to a second end portion, opposite the first, a thrust appendage which is destined to receive an external force suitable to determine the rotation movement of the rod and of the associated rotation pin. The two thrust rods are keyed to the two opposite ends of the same hub or rotation pin, to extend in length (orthogonally to the axis of rotation) in diametrically opposite positions relative to one another. The motion generated by the rotation of the rods and of the rotation pin is transmitted by transmission means kinematically connected to the rotation pin or to one of the rods, for example by means of a toothed wheel/ chain assembly. The complete rotation motion of each rod is divided into two phases (each extending to about a half- revolution) : a thrust phase, in which the rod and the relative thrust appendage are active in generating the movement, and a recovery phase, in which the rod and the relative thrust appendage are passively dragged in rotation by the movement of the other rod (which is in the thrust phase) until brought back to the thrust phase once again .

[0004] The rotation speed is a function of the thrust impressed to the rod and the length (or arm) of said rod, understood as the distance between the rotation pin and the thrust appendage. The rotation speed can be varied only by varying the thrust impressed on the rod. It is in fact not possible to vary the arm, that is, the length of the rod, this being made in one single piece. This embodiment is dictated by requirements of mechanical robustness and simplicity of construction. The realization of a variable arm mechanism would in fact be too complex both from a construction point of view, and from a point of view of operational management understood as the adaptation of the length of the arm to operational needs.

[0005] A typical application of the generation mechanism described above is in the bicycle. The mechanism comprises two pedal cranks (rods) , each of which bears at its end a pedal (thrust appendage) . The two pedal cranks are keyed to the two opposite ends of a hub, to extend in length in diametrically opposite positions relative to one another. A toothed wheel is associated to one of the two cranks, on which wheel the driving belt to the rear wheel is kinematically associated. The complete rotation of each pedal crank divides into two phases: a thrust phase and a recovery phase.

[0006] As is known, the pedal cranks are in one piece and rigid. Assuming no change of the gear ratio, the rotation speed can be changed only by changing the thrust impressed on the pedals, as it is not possible to vary the arm of the pedal crank.

[0007] To date mechanisms for generating a rotation movement with double thrust lever having variable arm characterized by mechanical robustness (i.e. reliability) and simple construction, and which can therefore be exploited on a mechanically simple application such as bicycles, pedal boats or winches, without interfering in the regularity of pedalling or, in general, the rotation movement are not available .

PRESENTATION OF THE INVENTION

[0008] Consequently, the purpose of the present invention is to eliminate entirely or in part the drawbacks of the prior art mentioned above, by providing a mechanism for generating a rotation movement with double thrust lever having variable arm which is operationally reliable and at the same time simple to construct.

[0009] A further purpose of the present invention is to make available a mechanism for generating a rotation movement with double thrust lever having variable arm, which allows the application of the external thrust force on a point that moves along a circular or substantially circular traj ectory.

[0010] A further purpose of the present invention is to make available a mechanism for generating a rotation movement with double thrust lever having variable arm which can replace the traditional pedal crank/pedal generation mechanism of a bicycle, allowing the rider to further exploit the thrust impressed during the active rotation phase of each pedal, without interfering in the regularity of pedalling.

DESCRIPTION OF THE DRAWINGS

[0011] Further characteristics and advantages of the present invention will be more clearly understandable from the description given below of its preferred and non-limiting embodiments, wherein:

[0012] -Figure 1 shows a schematic view of a mechanism for generating a rotation movement with double thrust lever having variable arm according to a preferred embodiment of the invention, shown in an installation condition on a bicycle;

[0013] -Figure 2 shows four different positions adopted by a thrust lever with the relative thrust appendage and with the relative kinematic guide element in the mechanism for generating a rotation movement according to a preferred embodiment of the invention, respectively in the circular movement, a first position being shown at 3 o'clock, a second at 6 o'clock, a third at 9 o'clock and a fourth position at 12 o'clock;

[0014] -Figure 3 shows an orthogonal cross-section view of the thrust lever with the relative thrust appendage and with the relative kinematic guide element shown in Figure 2 according to the cross-section plane III-III indicated therein;

[0015] -Figure 4 shows a cross-section orthogonal view of the thrust lever illustrated in figure 2, along the cross- section plane IV-IV indicated in figure 3;

[0016] -Figure 5 shows a cross-section view of the kinematic guide element illustrated in figure 2, along the cross- section plane V-V indicated in figure 3;

[0017] -Figure 6 shows an enlarged view of the thrust lever with the relative thrust appendage and with the relative kinematic guide element shown in Figure 2 in the 3 o'clock position;

[0018] - Figure 7 shows a rear perspective view of the thrust lever shown in Figure 6;

[0019] -Figure 8 shows an enlarged view of the thrust lever with the relative thrust appendage and with the relative kinematic guide element shown in Figure 2 in the 6 o'clock position;

[0020] - Figure 9 shows a rear perspective view of the thrust lever shown in Figure 8;

[0021] -Figure 10 shows an enlarged view of the thrust lever with the relative thrust appendage and with the relative kinematic guide element shown in Figure 2 in the 9 o'clock position;

[0022] - Figure 11 shows a rear perspective view of the thrust lever shown in Figure 10;

[0023] -Figure 12 shows an enlarged view of the thrust lever with the relative thrust appendage and with the relative kinematic guide element shown in Figure 2 in the 12 o'clock position;

[0024] - Figure 13 shows a rear perspective view of the thrust lever shown in Figure 12.

DETAILED DESCRIPTION

[0025] With reference to the above drawings, reference numeral 1 globally denotes a mechanism for generating a rotation movement with double thrust lever having variable arm according to the present invention.

[0026] As will be explained in the rest of the description, the mechanism 1 according to the invention finds particular application as a movement mechanism of a bicycle.

[0027] The mechanism 1 according to the invention may also find other applications different from a bicycle, involving the generation of a circular movement through two pedal cranks or hand cranks, such as a handbike, in nautical craft such as pedal boats, or in double crank winches .

[0028] According to a general embodiment of the invention, the mechanism for generating a rotation movement with double thrust lever having variable arm 1 comprises two thrust levers 11 and 12.

[0029] As shown in the appended drawings, each thrust lever 11, 12 is associated at a first end portion 11' to a rotation pin 2, around which the aforementioned rotation movement develops so as to be rotationally integral with said pin 2 relative to the rotation axis XI of the pin.

[0030] Each thrust lever 11, 12 bears at a second end portion thereof 11", opposite the first, a thrust appendage 13, 14 which is destined to receive an external force such as to determine the rotation movement of the lever 11, 12.

[0031] The two thrust levers 11 and 12 are fixed to two opposite ends of the same common rotation pin 2 to extend in length, orthogonally to the rotation axis XI of the pin 2, in diametrically opposite positions with respect to the rotation axis XI. Their movement is thus in phase opposition, always staggered by 180°.

[0032] Operationally, the complete rotation movement of each thrust lever 11, 12 is divided into two phases, each corresponding to about one half revolution (about 180°):

[0033] - a thrust phase, in which the thrust lever 11 or 12 is active in the generation of motion; and

[0034] - a recovery phase, in which the thrust lever 11 or 12 is dragged passively by the rotation movement of the other lever 12 or 11, which works in phase opposition.

[0035] According to a first aspect of the invention, each thrust lever 11, 12 has a variable length so that during the rotation movement of the thrust lever 11, 12 around the common rotation pin 2 the arm B, defined by the distance between the thrust appendage 13, 14 and the rotation axis XI of the pin 2, can vary.

[0036] According to a further aspect of the present invention, the mechanism 1 comprises, coupled to each thrust lever 11, 12, a kinematic guide element suitable to guide the movement of variation in length of the coupled thrust lever 11, 12.

[0037] Each of the kinematic guide elements is constituted by an elongated body 111, which is associated at a first end portion 111 ¹ to said common rotation pin 2 in a rotationally neutral manner around the axis of rotation XI.

[0038] The rotationally neutral connection prevents the kinematic guide element from transferring thrust to the rotation pin 2 by means of the relative elongated element 111. Only the thrust lever 11, 12 is suitable to transfer to the rotation pin the force impressed on the thrust appendage 13, 14 as the angular momentum of rotation.

[0039] Advantageously, the kinematic guide element is associated to the rotation pin 2 by means of a rotatable connection with anti-friction means.

[0040] As shown in the appended drawings, the elongated body 111 of each kinematic guide element bears at its second end portion 111", opposite the first, a rotating support body 112, rotatably associated to the elongated body 111 at the second end portion 111" to rotate around a second axis X2 parallel to the axis of rotation XI of the common pin 2.

[0041] Preferably, the aforesaid rotating support body 112 is associated to the elongated body 111 by antifriction means 113, such as bearings, ball or roller bearings or lubricating gaskets.

[0042] In particular, as shown in figure 5, the elongated body 111 is defined by a rod provided at its second end 111 ¹ ' with a circular ring inside which an annular flange, which constitutes the rotating support body 112, is rotatably inserted around the second axis X2.

[0043] The thrust appendage 13, 14 of each thrust lever 11, 12 is rigidly fixed to the rotating support body 112 of the respective kinematic guide element in a radially eccentric position with respect to the second axis X2 so as to associate kinematically the kinematic guide element to the respective thrust lever 11, 12 by means of the aforesaid rotating support body 112.

[0044] In the appended figures the attachment point of the thrust appendage 13, 14 on the rotating support body 112 is indicated as X3. The rigid attachment of the thrust appendage 13, 14 to the rotating support body 112 is designed to prevent a relative rotation between the two parts and thus make them integral in rotation. To such purpose, according to a particular embodiment, the aforesaid rotating support body 112 may be in one piece with the respective thrust appendage 13, 14.

[0045] Preferably, each thrust appendage 13, 14 engages the rotating support body 112 of the respective kinematic guide element in a direction parallel to the axis of rotation XI of the pin 2.

[0046] Preferably, the rotation plane of each thrust lever 11, 12 is parallel to the rotation plane of the respective kinematic guide element. In particular, the rotation plane of each of the thrust levers 11, 12 is perpendicular to the axis of rotation XI of the pin 2.

[0047] Operationally, as shown schematically in figure 2, during the rotation of the thrust lever 11, 12 around the pin 2 - thanks to the rotation of the rotating support body 112 and the positioning eccentricity E of the thrust appendage 13, 14 with respect . to the second axis X2 - the thrust appendage 13, 14 performs a complete circular motion (illustrated with the circumference C2) , eccentric with respect to the rotation axis XI of the pin 2, the centre 0 of which is radially shifted toward the arc of circumference corresponding to the thrust half-revolution made by the kinematic guide element around the axis XI of the pin 2. In Figure 2 the circumference that describes the circular movement of the kinematic guide element (or rather of the centre X2 of the rotating support body 112) is indicated as CI.

[0048] Figure 2 refers in particular to the case where the mechanism 1 is inserted in a bicycle: the arrow A indicates the direction of advancement of the bicycle; the arrows R indicate the direction of rotation of the thrust lever 11, 12.

[0049] The thrust appendage 13, 14 - in its movement of rotation around the axis X2 integrally with the rotating support body 112 - drags alternately in axial lengthening and axial shortening the respective thrust lever 11, 12 imposing on the second end 11" of the thrust lever 11, 12 a circular movement. As can be seen in Figure 2, this movement brings the thrust lever 11, 12 to oscillate alternately with respect to the longitudinal axis of the elongated body 111 of the kinematic guide element around the axis XI.

[0050] This way, in the thrust phase (i.e. when the thrust lever 11, 12 is active and generates motion) upon the varying of the angular position around the rotating support body 112 the arm B (defined by the distance between the attachment point X3 of the thrust appendage 13, 14 on the rotating support body 112 and the rotation axis XI of the pin 2) progressively increases up to a maximum value equal to the sum of the eccentricity E with the distance D between the axis X2 and the axis XI (see figures 6 and 7) . As can be seen in Figure 2, this maximum value is reached in about half of the thrust half-revolution; having exceeded this maximum, the lever value B starts to decrease again .

[0051] In the recovery phase (i.e. when the thrust lever is dragged and generates no motion) upon the varying of the angular position around the rotating support body 112 the arm B progressively decreases to a minimum value equal to the distance D between the axis X2 and the axis XI of the pin 2 less the eccentricity E (see figures 10 and 11) . As can be seen in Figure 2, this maximun value is reached in about half of the recovery half-revolution; having exceeded this minimum, the lever value B starts to increase again .

[0052] This way, in the mechanism 1 according to the invention, in the thrust phase (i.e. when the rod is active and generates motion) being the force applied to the thrust appendage 13, 14 equal, a greater speed is obtained thanks to the increased arm B of the thrust lever. Conversely, in the recovery phase (i.e. when the rod is dragged and generates no motion) , the arm B of the thrust lever is reduced .

[0053] In the appended figures, the distance between the second axis X2 of the rotating support body 112 and the rotation axis XI of the pin 2 is indicated as "D", while the eccentricity of the attachment point X3 of the thrust appendage on the rotating support body is indicated as "E" . For the purposes of the present invention, the attachment point X3 of the thrust appendage on the rotating support body can be considered substantially coincident with the point where the thrust received by the thrust appendage 13, 14 is discharged onto the thrust lever 11, 12.

[0054] In Figure 2, the mechanism 1 according to the invention is illustrated with the thrust phase which corresponds to the position adopted in the 3 o'clock position (maximum value of the arm) and with the recovery phase which corresponds, instead, to the position adopted by the thrust appendage 13 in the 9 o'clock position (minimum value of the arm) . The other two positions (12 o'clock and 6 o'clock) illustrate the thrust lever (with relative thrust appendage and kinematic guide element) in the two positions of passage respectively from the recovery phase to the thrust phase and from the thrust phase to the recovery phase.

[0055] The thrust appendage 13, 14 naturally adopts the positions described above, in the thrust phase and in the recovery phase, thanks to the free rotation of the rotating support body 112 and to the fact that the thrust appendage 13, 14 cannot rotate with respect to the rotating support body 15, 16.

[0056] More specifically, the application of the force on the thrust appendage during the thrust phase tends to move the same appendage 13, 14 outwards and downwards, thereby favouring the direction of rotation of the second end 11" of the thrust lever around the rotating support body and its elongation. During the recovery phase, the thrust appendage does not substantially undergo the application of external force to the mechanism. This allows the appendage and the rotating body to follow the same circular trajectory started by the appendage in the thrust phase.

[0057] From all this it derives that a mechanism for generating a rotation movement with double thrust lever having variable arm according to the invention allows the application of the external thrust force on a point (thrust appendage) that moves along a circular or substantially circular trajectory.

[0058] According to an embodiment of the invention not illustrated in the appended figures, each thrust lever 11, 12 is variable in length thanks to the fact of having an extensible telescopic structure which extends axially along the longitudinal axis of said lever.

[0059] According to the alternative embodiment of the invention illustrated in the appended figures, each thrust lever 11, 12 is axially rigid and is variable in length thanks to the fact of being slidingly associated to the rotation pin 2 parallel to the longitudinal extension axis of said lever. The sliding stroke of the thrust lever with respect to the rotation pin determines the variation in length of the arm B of the thrust lever. Preferably, the thrust lever is equipped in this case with a limit stop 19.

[0060] The thrust lever 11, 12 can be attached indirectly to the rotation pin 2 by means of a support base 15, as illustrated in the appended figures, or may be attached directly to the rotation pin, for example by direct keying.

[0061] Advantageously, as shown in particular in figure 3, also the kinematic guide element may be indirectly associated to the rotation pin 2 by said support base 15, although in a manner such as to ensure a neutral rotatable connection to the rotation pin. Alternatively, the kinematic guide element can be attached directly to the rotation pin 2.

[0062] Preferably, as illustrated in the appended figures, the thrust lever 11, 12 is slidingly attached to the rotation pin 2 by means of the aforesaid support base 15, so as to make assembly on the rotation pin 2 easier.

[0063] According to the embodiment illustrated in the appended figures, each of thrust levers 11, 12 is defined by two rods 16, 17 which are parallel to the longitudinal extension axis of the thrust lever 11, 12. Preferably, the two rods 16, 17 are fixed to the rotation pin 2 in such a way that the rotation axis XI is placed on the centreline between said two rods. This way there is a balanced distribution of the forces.

[0064] More specifically, said two rods 16, 17 are connected to each other:

[0065] - at the first end 11· of the thrust lever 11, 12 by means of the aforesaid support base 15; and

[0066] - at the second end 11" of the thrust lever by means of a fork body 18, to which the respective thrust appendage 13,14 is also rotatably pivoted.

[0067] Preferably, as illustrated in the appended figures, the two rods 16, 17 are slidingly associated to the support base 15, so that the thrust lever can vary its length and thus the arm offered by it. Alternatively, the variation in length of the thrust lever may be obtained by equipping both rods 16, 17 with an axial telescopic structure.

[0068] According to an alternative embodiment not illustrated in the appended figures, each thrust lever 11, 12 can be defined by a single rod. The change in length of the thrust lever may be obtained by connecting the single rod slidingly to the rotation pin (preferably by means of a support base) , or by equipping the single rod with an axial telescopic structure.

[0069] Advantageously, the mechanism 1 according to the invention comprises transmission means of the rotation movement generated by the two thrust levers 11 and 12 on the rotation pin 2. The aforesaid transmission means of the movement can be kinematically associated directly to the rotation pin 2 or to one of the two thrust levers 11 or 12. These transmission means may be of any type suitable for the purpose and are not described here since they are known to a person skilled in the art. By way of example they may consist of a toothed crown concentric with the axis of rotation XI of the pin and by a chain or belt transmission kinematically coupled to the toothed wheel.

[0070] The mechanism for generating a rotation movement with double thrust lever having variable arm according to the invention is particularly suitable to be used in applications that provide for the application of force by a human .

[0071] In the case in which the force applied to the thrust appendages is applied through the feet of a user, the two thrust levers 11, 12 are pedal crank and the relative thrust appendages 13, 14 are pedals.

[0072] A particularly preferred application of the mechanism 1 according to the invention is in bicycles and in general in pedal-operated vehicles. Figure 1 shows a frame S of a bicycle, where P indicates the toothed crown and Q the transmission chain. The arrow A indicates the direction of advancement of the bicycle, while the arrows R indicate the direction of rotation of the thrust lever/ pedal crank.

[0073] Considering the characteristics set out above, the mechanism 1 according to the invention is suitable very well to replace the traditional pedal crank/pedal mechanisms having a fixed arm pedal crank and pedal rotating with respect to the pedal crank. In fact, compared to the aforesaid traditional mechanisms the mechanism 1 according to the invention allows the cyclist, being the force applied equal, to increase the speed thanks to the increase of the arm in the thrust phase. At the same time, the regularity of pedalling is not substantially influenced by the mechanism 1 given that the pedals (thrust appendages) follow a circular or substantially circular trajectory.

[0074] In other words, the mechanism 1 according to the invention allows the cyclist to perform regular and traditional pedalling, but to exercise a variable thrust action, more intense in the thrust phase, further exploiting the thrust impressed on the pedal.

[0075] Typically, a conventional pedal crank has a useful length/arm (distance between pin/hub and the pedal axis) of about 170 mm. Thanks to the invention, the pedal crank/ thrust levers 11, 12 of the mechanism 1 according to the invention in the thrust phase can increase the useful arm by about 60 - 80 mm, bringing the useful arm to 230-250 mm. In the recovery phase, the pedal cranks/ thrust levers 11, 12 of the mechanism 1 according to the invention shorten the arm by about 60 - 80 mm.

[0076] What has been described above in relation to the application of the mechanism 1 on a bicycle, in terms of benefits and construction features, is understood as automatically extended - mutatis mutandis - to other applications .

[0077] The present invention relates to a pedal- operated vehicle comprising a mechanism for generating a rotation movement with double thrust lever having variable arm according to the invention and in particular as described above, in which the aforesaid two thrust levers 11, 12 are pedal cranks and the relative thrust appendages 13, 14 are pedals.

[0078] Preferably, the aforesaid pedal-operated vehicle is a bicycle.

[0079] Advantageously, the aforesaid pedal-operated vehicle may also be a nautical vehicle, in particular a pedal boat.

[0080] In the case in which the force applied to the thrust appendages 13, 14 is applied by the hands of a user, the two thrust levers 11, 12 are hand cranks and the relative thrust appendages 13, 14 are hand grips. In this case the mechanism 1 according to the invention may be applied in various actuating devices, such as double crank winches. The operational and structural advantages mutatis mutandis - are similar to those already set forth with reference to the application to a bicycle.

[0081] In particular, the present invention relates to a handbike comprising a mechanism for generating a rotation movement with double thrust lever having variable arm according to the invention and in particular as described above, in which the aforesaid two thrust levers 11, 12 are hand cranks and the relative thrust appendages 13, 14 are hand grips .

[0082] In particular, the present invention relates to a double crank winch comprising a mechanism for generating a rotation movement with double thrust lever having variable arm according to the invention and in particular as described above, in which the aforesaid two thrust levers 11, 12 are hand cranks and the relative thrust appendages 13, 14 are hand grips.

[0083] The present invention also relates to a pedal crank assembly for pedal-operated vehicles, and in particular for a bicycle, comprising:

[0084] - a thrust lever 11, 12, suitable to be associated, at a first end portion 11' to a rotation pin so as to be rotationally integral with said pin during a rotation movement around the axis of rotation XI of the pin; and [0085] - a pedal 13, 14 associated with the thrust lever at a second end portion 11" of the thrust lever, opposite the first.

[0086] In particular, the pedal 13, 14 is rotatably associated with the second end portion 11 " of the thrust lever 11, 12.

[0087] According to a first aspect of the invention, the aforesaid thrust lever 11, 12 is variable in length so that during said rotation movement of the thrust lever 11, 12 around the aforesaid rotation pin the arm B, offered by the thrust lever and defined by the distance between the pedal 13, 14 and the rotation axis XI, can vary.

[0088] According to a further aspect of the invention, the aforesaid pedal crank assembly comprises a kinematic guide element suitable to guide the movement of variation in length of the thrust lever 11, 12.

[0089] The aforesaid kinematic guide element consists of an elongated body 111 suitable to be associated at a first end portion 111' to said rotation pin in a rotationally neutral manner around the axis of rotation XI of said rotation pin 2.

[0090] The elongated body 111 bears at a second end portion 111" thereof, opposite the first, a rotating support body 112, rotatably associated to the elongated body 111 at the second end portion 111" to rotate around a second axis X2 parallel to the axis of rotation XI of the common pin 2.

[0091] The pedal 13, 14 is rigidly fixed to the rotating support body 112 of the kinematic guide element in a radially eccentric position with respect to the second axis X2. This way, the pedal 13, 14 associates kinematically in rotation the kinematic guide element to the thrust lever 11, 12 by means of the aforesaid rotating support body 112.

[0092] Advantageously, the pedal crank assembly for a pedal- operated vehicle, and in particular for a bicycle, according to the invention is a component of the mechanism for generating a rotation movement with double thrust lever having variable arm according to the invention and in particular as described above.

[0093] Advantageously, the pedal crank assembly for a pedal- operated vehicle, and in particular for a bicycle, can be considered as a separate element and be used to perform a retrofitting of an existing mechanism of the traditional type, replacing the traditional fixed-arm pedal cranks.

[0094] The pedal crank assembly according to the invention may be of a simple type without a toothed crown or may comprise a toothed crown P associated to the thrust lever 11, 12 at the first end portion 11'. Preferably, as illustrated in the appended figures, the toothed crown P may be associated to a support body 15 by means of which the thrust lever and the kinematic guide element can be associated to the rotation pin 2.

[0095] The invention permits numerous advantages to be achieved, in part already described.

[0096] The mechanism for generating a rotation movement with double thrust lever having variable arm according to the invention is operationally reliable and simple to construct .

[0097] In fact, in use the useful thrust arm varies automatically without the need for adjustment, increasing in the thrust phase of the single thrust lever (i.e. when the thrust lever is active in the generation of motion) , and decreasing in the recovery phase of the single thrust lever (i.e. when the thrust lever is not used for the generation of motion) .

[0098] As amply described above, the constructive simplicity of the mechanism 1 according to the invention is linked to the fact that compared to similar traditional mechanisms it entails: - realising the thrust lever as a variable- length element; and - coupling to each thrust lever, a kinematic guide element provided at its free end with a rotating support body which is connected eccentrically to the thrust lever by means of the thrust appendage. Such kinematic guide element has the function of guiding the elongation and the shortening of the thrust lever imposing a circular cyclicity related to the rotation of the rotating support body. The realization of such a system does not involve particular constructional or assembly difficulties .

[0099] The operational reliability of the mechanism 1 is related to the fact that the mechanism does not require any adjustment system and to the fact that it allows the application of the external thrust force on a point that moves along a circular or substantially circular trajectory. In other words, the mechanism 1 according to the invention does not affect the method of application of the external force, resulting from this point of view equivalent to traditional mechanisms.

[00100] The mechanism according to the invention finds a particularly preferred application as a mechanism generating movement for bicycles, in substitution of the traditional mechanisms with fixed arm pedal cranks. More specifically, the mechanism according to the invention allows the cyclist to better exploit the thrust impressed during the active rotation phase of each pedal, without however interfering with the regularity of pedalling.

[00101] The invention thus conceived thereby achieves the intended objectives.

[00102] Obviously, its practical embodiments may assume forms and configurations different from those described while remaining within the sphere of protection of the invention .

[00103] Moreover, all the details can be replaced by technically equivalent elements and the dimensions, forms and materials used may be any as needed.