Patent Publication Number: US-2009223500-A1

Title: Device for launching a projectile or a launch object in general

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application claims the benefit of Italian Patent Application RM2008A000130 filed on Mar. 10, 2008 and PCT patent application PCT/IB2008/054053, both of which are incorporated herein by reference in their entirety. 
    
    
     FIELD 
     The present disclosure refers to a device for launching a projectile, or an arrow, or a bolt, or a launch object in general. More specifically, it refers to a perfected type of archery crossbow. 
     BACKGROUND 
     Various types of devices for launching projectiles are already known, both for sports and amateur uses, and for professional uses. Among these, we can identify, in particular, crossbows, generally consisting of a bow (in wood, metal, or plastic or composite material, e.g. including glass or carbon fiber) apt to accumulate elastic energy to return it to the projectile to be launched, a propulsive wire for pushing the projectile, a fastening system to keep said wire in the load position and then release it, a stock secured at one end to said bow and comprising a support-guide for the projectile. 
     The modern devices for launching a projectile usually have a bow divided into two bending members (or flexing members, also called limbs) which are identical (left and right) and secured to a central handle member or to an end of a stock of the device. 
     In some devices (e.g. U.S. Pat. No. 3,854,467; U.S. Pat. No. 3,923,035; U.S. Pat. No. 3,987,777), there are pulleys pivoted to the free ends of the bending members and pulleys pivoted to a central member; the pulleys include tracks on which a propulsive wire is partially wound; under the most common arrangement a propulsive wire is connected to one pulley and to its symmetrically opposite one on the other side; each one of said pulleys is integral to a smaller pulley, which holds one end of another wire whose other end is connected to the opposite limb. Some of the pulleys may have an eccentric profile. 
     The traction of the propulsive wire turns the pulleys, unwinding the propulsive wire from some pulleys, while at the same time the other wires are wound around other pulleys; this causes the flexing of the bending members and the accumulation of elastic energy. Thanks to an adequate profiling of the pulley tracks and an appropriate eccentricity of the same, in these devices it is possible to reduce the maximum force which must be exerted by the user during the loading of the device and to increase the ratio between the stroke of the projectile (also called “draw length”) and the movement of the ends of the bending members. 
     Other devices for the launching of projectiles comprising pulleys or the like for a similar purpose are disclosed, for example, in U.S. Pat. No. 5,388,564, U.S. Pat. No. 5,499,618, U.S. Pat. No. 5,967,132. 
     Crossbows comprising pulleys are disclosed, for example, in U.S. Pat. No. 5,630,405 and U.S. Pat. No. 6,155,243. 
     One of the main disadvantages of the devices of known art and, in particular, of crossbows of known art, is that during the launch phase, the bending members, the propulsive wire and any pulleys arrive at the end of the stroke with a high residual kinetic energy, proportional to the masses in movement; because of the very structure of the device, this energy must be dissipated in a very short space or even in no space, as the components in motion have already reached the end of their possible stroke. The stopping of the components in motion after the launch is, therefore, quite sudden and subjects the entire device to an end of stroke shock which involves very high stresses, discharging the residual energy on the wires and stressing the pivots of the pulleys and the bending members. Indeed, in the case of dry firing (that is, no projectile is fired), there is no transfer of energy to a free mass and the stresses may be so high as to break the device. 
     This dictates structural constraints in the dimensioning of the device, imposes practical limits on the mass that can be launched safely and imposes very high levels of attention and expertise on the part of the user who, in case of dry firing or of using too light a projectile, could damage the crossbow or even get injured. 
     In the case of said more advanced devices, the problem is actually accentuated by the presence of the pulleys at the ends of the bending members, as this considerably increases the masses, the kinetic energy and the moments of inertia in play. In addition, the sudden stop at the end of the stroke is the main cause of the noise produced by the use of these devices for launching a projectile. 
     Another disadvantage of the devices of known art is the fact that, even when the device is unloaded, the bending members are in a pre-tensioned state; among other things, this makes it necessary to use specific tools, such as a press, in order to carry out maintenance operations such as the replacement of the propulsive wire. 
     Finally, it must be noted that possible differences, even slight ones, in the elastic characteristics of the right and left bending member may be the cause of asymmetries in the thrust exercised on the projectile and, therefore, compromise the launch precision. 
     On the other hand, not even the pulleys manage to compensate for any such differences in the elastic characteristics of the bending members. 
     Also note that the crossbows of known art usually take the form of a device which allows little or no possibility of adapting it to the requirements of the user: once a crossbow of known art has been built to certain specifications, the maximum power or the force required for the loading are substantially fixed and can no longer be varied, except with laborious replacements of components which, in any case, are beyond the common user&#39;s skill. These interventions, in fact, are dangerous and also void the warranty provided by the manufacturer. 
     An archery crossbow  1001  according to the known art (U.S. Pat. No. 6,155,243) is shown in  FIG. 1 . It has a stock  1002  with a butt  1003 , bending members  1010  connected to said stock  1002 , a propulsive wire  1031  for pushing a projectile, a fasten and release system (not shown, but located near the butt  1003 ) for said propulsive wire  1031 , a shooting trigger (not shown). The free ends of the bending members  1010  support eccentric pulleys  1009 , so that the propulsive wire  1031  passes at these and connects them to the bending member opposite. During the loading phase, shown in  FIG. 1 , the propulsive wire  1031  is drawn towards the butt  1003 , causing the eccentric rotation of the pulleys  1009 , the bending of the bending members  1010  and the accumulation of elastic energy in these. During the launch phase, the same movements take place in the opposite direction, with the transfer of energy to a projectile (not shown) which slides in a suitable guide track  1008 . This type of known-art crossbow  1001  has the disadvantages mentioned above. 
     SUMMARY 
     The present disclosure, therefore, starts from the position of the technical problem of providing a device for launching a projectile or a launch object in general which makes it possible to overcome the disadvantages specified above with reference to the known art. 
     As defined in independent claim  1 , this is obtained by providing a device for launching a projectile or a launch object in general, comprising: a stock having a longitudinal development direction between a rear or proximal end and a front or distal end, at least two bending members associated to said stock on opposite sides of it and having a preferential development direction, said bending members being apt to be subjected to bending in order to accumulate and supply energy usable to launch said projectile, and released in a rest condition, tensioning means of said bending members, pushing means of said projectile apt to cooperate with said bending members, wherein said tensioning means comprise at least two cams arranged on opposite sides to the stock, each of which is pivoted at a respective first axis of rotation and is associated to at least one corresponding bending member, so that an angular displacement of said cam around said first axis of rotation determines a bending action on said at least one corresponding bending member, and said pushing means comprise at least two arms arranged on opposite sides of the stock and connected to each other through a flexible member, wherein each of said arms has a first end pivoted at a second axis of rotation and a second end apt to support a portion of said flexible member, each of said arms being operatively connected to a respective cam, so that a rotation of each arm in a first rotation direction determines a bending of said bending members by means of the cam during a loading phase of the device and that during a launch phase of said projectile a return of the bending members towards said rest condition determines, by means of the cam, a rotation in the opposite direction of each arm. 
     Secondary characteristics of the subject of the present disclosure are defined in the corresponding dependent claims. 
     The subject of the present disclosure provides certain significant advantages. A main advantage lies in that the device permits a reduction in the stresses acting on the structure in the end-of-stroke arrest, thanks to the gradual absorption of the inertia and kinetic energy of the parts in movement in a braking run which follows the propulsive run. Furthermore this braking run is especially long as can be seen from the drawings. Also the braking run does not cut short the useful run of the limbs or bending members, for example by elastically intercepting the propulsive wire some distance before their neutral position as conceivable in devices of known art, that is, while they are still partially under tension; on the contrary, the braking run intervenes when the bending members have exhausted all the stored energy and when they have crossed the neutral, zero energy state while flexing in the opposite direction. The device can thus handle higher energies while also featuring smoother and more silent action and higher safety levels for the user particularly in case of dry firing, compared to known-art devices. 
     A second advantage lies in that the device makes it possible to load higher energies compared to known-art devices. In fact the use of a solid body (i.e., said cams) as the primary mover acting on the bending members (rather than a wire) allows for the application of greater force and the use of more rigid bending members, thereby increasing the maximum energy that can be transmitted. 
     Another advantage lies in that the device makes it possible to vary the specific use characteristics and it has a simpler maintenance. In fact said bending members are released in the rest condition, i.e. they do not present accumulated elastic energy and are non-deformed, so they can easily and safely be replaced with other bending members of same or different characteristics. Also the bending members do not present the risk of seeing their performance degraded in warmer storing conditions. 
     A further advantage lies in that said device makes it possible to synchronize the rotation of the left and right pushing means or pushing arms, in order to compensate for asymmetries in the elastic properties of left and right bending members. This determines a uniform distribution of the force acting on the projectile during the launch phase, eliminating the components of the acting force which are orthogonal to the launch direction, which benefits the launch accuracy. 
     In one embodiment, the bending members are arranged so that their preferential development direction is substantially parallel to the longitudinal development direction of the stock. This benefits the compactness of the device, reducing the lateral dimensions. Preferably, the bending members are positioned close to the stock. 
     In one embodiment, the bending members, the cams and the arms are arranged in a manner substantially symmetrical with respect to the stock. This configuration is advantageous as the symmetrical arrangement favors a symmetrical and balanced distribution of the forces acting on the stock. 
     In one embodiment, the axes of rotation of the cams move together with a portion of at least one bending member, in a direction orthogonal to the development direction of the bending member. This movement takes place at the same time as the rotation of the cam, thanks to the fact that the cam has an eccentric profile which cooperates with a respective cam positioned symmetrically. This makes it possible to load the device by means of a rotation of the cams around their axes of rotation and launch the projectile with a rotation movement in the opposite direction. 
     More specifically, the cams are pivoted using a connection element which comprises at least one “U”-shaped or “C”-shaped housing which houses a portion of the respective bending member. 
     In one embodiment, the movement of each cam is synchronized with a respective cam positioned symmetrically with respect to the stock. This allows for a uniform distribution of the force acting on the projectile during the launch phase, even in the presence of asymmetries in the elastic characteristics of the bending members, and also makes it possible to eliminate the components of the acting force which are orthogonal to the launch direction; this benefits the launch precision. 
     In one embodiment, the cams have an edge with teeth, so that each cam can engage the respective symmetrical cam by means of these teeth. This makes it possible to synchronize the movement of each cam with the respective symmetrical cam. 
     In one embodiment, there is a slide positioned between one cam and the respective symmetrical cam; said slide may slide in the device stock in a direction parallel to the longitudinal development direction of the stock and is engaged by the edges of the cams. In this way, the motion of the cams is synchronized thanks to the fact that they both engage the slide and make it slide along the stock. 
     To be more specific, the slide may have toothed edges in order to engage the toothing of the cams. 
     Alternatively, the synchronization between the cams is obtained by hinging together one cam and the respective symmetrical cam, which are pivoted to each other using a pivot body which is slidingly associated to the stock and may slide within it parallel to its longitudinal development direction. 
     In one embodiment, each pushing arm forms a single part with a respective cam and the axis of rotation of the arm is the same as the axis of rotation of the respective cam. This solution has the particular advantage of requiring a lower number of parts and being of simpler construction. 
     In one embodiment, each pushing arm is operatively connected to a respective cam using at least one connection rod pivoted to the arm and to the cam. This solution makes it possible to reduce the maximum lateral dimensions of the device and allows for greater design flexibility. 
     In one embodiment, each pushing arm is operatively connected to a respective cam using a guide member (for example, a rotating wheel) joined to the arm and which engages slidingly a guide track provided in an appendix of said cam. This solution allows, for same lateral dimensions, higher device power and a longer stroke for the flexible member. 
     In one embodiment, the second end of each pushing arm supports a pulley rotationally associated to the respective arm; said pulley rotates around an axis of rotation which, therefore, performs translation movements together with the second end of the respective arm; the pulley is further apt to wind on to itself at least partially the flexible member during a rotation movement around its axis. Preferably, the pulley has an eccentric profile with respect to said axis of rotation. 
     Even more preferably, the rotation of the pulley is synchronized with the rotation of a respective cam around the respective axis of rotation. More specifically, the pulley includes a pivot integral to it and having a longitudinal axis which is coincident to said axis of rotation of the pulley; said pivot also includes at least one toothed portion; the respective cam is firmly joined to at least one appendix having a guide track, said guide track comprising an edge with toothing apt to be engaged by said toothed portion of said pivot. 
     These solutions presenting a pulley supported at the end of each arm offer a first advantage consisting of not leaving the flexible member slack at the end of the launch. In addition, the possibility of selecting the eccentricity of the pulley, the magnitude of the angle of rotation of the pulley, and an opportune dimensioning and relative positioning of the parts makes it possible to obtain various different force-draw curves. A further advantage is the cancelling out of the residual forces acting on the device and of the inertia of the pulleys, thanks to the movement of these in opposite directions. 
     In one embodiment, the pushing arms may rotate between a first position of maximum loading and a second position of maximum discharge. Between said first and second positions, there is a neutral position at which the bending members do not present accumulated elastic energy. In particular, in said first position of maximum loading the pushing arms are rotated towards the proximal end of the stock, and in said second position of maximum discharge they are rotated towards the distal end of the stock. 
     To be more specific, said second position corresponds to the maximum advance of the arms towards the distal end, in the braking stroke after the launch stroke, where with launch stroke it is meant the run of the arms between said first position of maximum loading and said neutral position, while with braking stroke it is meant the run of the arms between said neutral position and said second maximum discharge position. 
     Therefore, with the device loaded, the bending members are initially in a bent configuration; during the launch phase, the bending members reduce the bending gradually, they pass the rest position (corresponding to said neutral position) and continue their movement by bending in the opposite direction, until they get to a configuration of maximum counter bend corresponding to said second position of maximum discharge. One advantage of this solution is that it allows for a gradual and non-sudden stopping of the components at the end of the launch phase, thereby reducing the stresses at the end of the stroke and the risk of damaging the device. 
     Contrast means operating when the arms are between the neutral position and the position of maximum discharge may also be provided. 
     In addition or in alternative to the contrast means, the device may include auxiliary pushing means including at least one elastic member apt to accumulate energy during the device loading phase and apt to supply energy to the pushing means during the projectile launch phase. This makes it possible to increase the power of the device for same overall dimensions. 
     Further advantages, characteristics and the modes of employment of the subject of the present disclosure will become apparent from the following detailed descriptions of preferred embodiments thereof, presented for exemplificative and not limitative purposes. 
     It is however evident that each embodiment described in this disclosure may present one or more of the advantages listed above; in any case, it is not required that each embodiment presents at the same time all the advantages listed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Reference will be made to the figures of the drawings attached, in which: 
         FIG. 1  shows a plan view of an embodiment of a crossbow according to the known art; 
         FIG. 2A  shows a perspective view of a first embodiment of a device for launching a projectile according to the present disclosure; 
         FIG. 2B  shows a perspective view of the device in  FIG. 2A , in which different operative positions are shown; 
         FIG. 3  shows an enlarged detail of the device in  FIG. 2A  in a loading phase; 
         FIG. 3A  shows a further enlarged detail of the device in  FIG. 2A ; 
         FIG. 4  shows again a detail of the device in  FIG. 2A  in a launch phase; 
         FIG. 5  shows a construction detail of the device in  FIG. 2A ; 
         FIG. 6  shows a perspective view of a component of the device in  FIG. 2A ; 
         FIG. 7  shows an exploded perspective view of another component of the device in  FIG. 2A ; 
         FIG. 8  shows a perspective view of a second embodiment of a device for launching a projectile according to the present disclosure; 
         FIG. 8A  shows a construction detail of the device in  FIG. 8 , from which some components have been removed; 
         FIG. 9A  shows a perspective view of a third embodiment of a device for launching a projectile according to the present disclosure; 
         FIG. 9B  shows a perspective view of the device in  FIG. 9A , in which a different operative position is shown; 
         FIG. 10  shows a perspective view of the device in  FIG. 9A , from which some components have been removed; 
         FIG. 11A  shows a perspective view of a fourth embodiment of a device for launching a projectile according to the present disclosure; 
         FIG. 11B  shows a perspective view of the device in  FIG. 11A , in a different operative position; 
         FIG. 11C  shows a plan view from below of the device in  FIG. 11A , from which some components have been removed, in a further operative position; 
         FIG. 11D  shows a perspective view of an enlarged detail of the device in  FIG. 11A , from which some components have been removed; 
         FIG. 12A  shows a perspective view of a fifth embodiment of a device for launching a projectile according to the present disclosure, in a first operative position; 
         FIG. 12B  shows a perspective view of the device in  FIG. 12A , in a second operative position; 
         FIG. 12C  shows a plan view of the device in  FIG. 12A , in a third operative position; 
         FIG. 13  shows a perspective view, partially in cross-section, of an enlarged detail of the device in  FIG. 12A , from which some components have been removed; 
         FIG. 14A  shows a perspective view of a sixth embodiment of a device for launching a projectile according to the present disclosure, in a first operative position; 
         FIG. 14B  shows a perspective view of the device in  FIG. 14A , in a second operative position; 
         FIG. 14C  shows a perspective view of the device in  FIG. 14A , in a third operative position; 
         FIG. 15  shows a perspective view, partially in cross-section, of an enlarged detail of the device in  FIG. 14A , from which some components have been removed; 
         FIG. 16  shows a side perspective view of an enlarged detail of the device in  FIG. 14A ; 
         FIG. 17A  shows a perspective view of a seventh embodiment of a device for launching a projectile according to the present disclosure, in a first operative position; 
         FIG. 17B  shows a perspective view of the device in  FIG. 17A , in a second operative position; and 
         FIG. 17C  shows a perspective view of the device in  FIG. 17A , in a third operative position. 
     
    
    
     DESCRIPTION OF EXAMPLE EMBODIMENTS 
     A first embodiment of a device for launching a projectile, an arrow, a bolt, or a launch object in general, created according to the present disclosure, is shown in  FIGS. 2A to 7 , where it is indicated with the reference number  1 . Hereinafter in the description, particular reference will be made to an archery crossbow, although the same principles of the subject of the present disclosure could similarly be applied to other launch devices, such as for example a bow or a catapult. 
     The crossbow  1  comprises a stock  2  with a longitudinal development direction  201 , comprised between a rear or proximal end  205  and a front or distal end  206 . The other components are connected to the stock  2 . The portion of the stock  2  which is closest to a user during use, that is, the rear or proximal end  205 , comprises, in fact, a butt  3 , a handle  4 , a system  5  for positioning and holding a projectile or a bolt or an arrow (not shown in the figures), a system  6  for fastening a flexible member  31  for pushing a projectile, a trigger  7  which makes it possible to open the fastening system  6  in order to release the flexible member  31  when launching the projectile. The components listed so far can be considered to be substantially known-art components and, therefore, will not be described in greater detail. 
     The crossbow  1  also comprises at least two bending members  10 , which have an elongated shape along a preferential development direction  202 , for example, with a parallelepiped shape. They may be made of wood, metal, fiberglass, plastic or composite material, e.g. including glass or carbon fiber, or other suitable material. The bending members  10 , from the structural and functional point of view, may be considered to be substantially identical to the bending members used in known-art crossbows. 
     The bending members  10  are suitable for being subjected to bending in order to accumulate the elastic energy required to launch the projectile and to supply it subsequently during the launch itself. At the end of the launch of the projectile, the bending members  10  are released in a rest condition. 
     In the embodiment represented here, the bending members  10  are positioned substantially adjacent to the stock  2  and in a symmetrical manner with respect to it, so that their preferential development direction  202  is substantially parallel to said longitudinal development direction  201  of the stock  2  itself; to be more specific, there are four bending members  10 , as there are two on each side of the stock  2 . 
     The bending members  10  are associated to the stock  2  on opposite sides of it. To be more specific, the bending members  10  are connected and/or may be connected (in other words, associated) to the stock  2  using supports  11  positioned at the ends  101 ,  102  of the bending members  10 . Said supports  11  are pivoted to the stock  2  and have a housing  12  substantially with a “C”-shape which houses said end, in any case allowing the bending member  10  a limited translation movement along said preferential development direction  202 ; the bending member  10  can, in fact, slide in said housing  12  along that direction. This is beneficial during the loading phase of the bending members  10 , as it allows them to take on a simply arched shape, preventing the creation of longitudinal stresses. In addition, the bending members  10  may be removable, said supports  11  being made so as to allow the extraction of the bending members  10  when it is necessary to replace them. 
     The bending members  10  might, however, have said support  11  only at one end, while the other end might be constrained in a rigid manner to the stock  2 . They might also be secured with different methods, e.g. using a ring wire which surrounds and tightens a bending member  10  and its corresponding bending member on the other side of the stock  2 ; this solution will be illustrated below. 
     Alternatively, each end  101 ,  102  of a bending member  10  is closed off at the side between a first sidebar, e.g. with a cylindrical shape, constrained to the stock  2  and a second sidebar, e.g. a support which is preferably cylindrical, positioned outside the bending member  10  with respect to the stock  2 , as illustrated in  FIGS. 11A to 11D  for another embodiment. 
     As an alternative, at least one portion of a bending member  10  can be constrained in a rigid manner to the stock  2 . In other words, a portion or tract of a bending member  10  can be tightly joined to the stock  2 , so as to substantially prevent any movement (translation, rotation and/or flexion movement) of the tract itself with respect to the stock  2 . 
     It is also possible to combine these methods to associate a bending member  10  to the stock  2 ; for example, a bending member  10  could include a first end constrained using said support  11  and a second end constrained using said cylindrical sidebars. Similarly, different bending members  10  may have different association methods. 
     The crossbow  1  comprises tensioning means  20  for said bending members  10 , that is, means apt to bring them to a bent position during said loading phase. The tensioning means  20  comprise at least two cams  21  positioned in opposite sides of the stock  2 , symmetrical with respect to said stock  2 . Each cam  21  is pivoted at a respective first axis of rotation  22  and is associated to at least one corresponding bending member  10 , so that an angular displacement of the cam  21  around said first axis  22  creates a bending action on the corresponding one or more bending members  10 . 
     In the embodiment illustrated, the overall structure is such that each side of the stock  2  has at least two bending members  10  opposite to each other with respect to a plane on which the cams  21  lie and on which their rotation movement takes place, in order to create, overall, a group of at least four bending members  10  symmetrical with respect to the longitudinal development direction  201  of the stock  2 . 
     The cams  21  have an edge  23  having an eccentric profile with respect to said first axis of rotation  22 , said edge  23  also having, at least partially, a toothing  24 . 
     In addition, there is a slide  25  associated to the stock  2  and positioned between the cams  21 . 
     Said slide  25  has a substantially elongated shape and has toothed edges  26 , by means of which it is in engagement on opposite sides with the teeth  24  of the cams  21 . The slide  25  slides in the stock  2  substantially parallel to said longitudinal development direction  201  and, during said sliding movement, coordinates the angular displacement of the cams  21 . In addition, the slide  25  can be removed from the stock  2 . 
     The crossbow  1  also comprises connection elements  27  between cams  21  and bending members  10 . Each connection element  27  comprises at least one connection member apt to move a portion of a bending member  10 . To be more specific, said connection member includes a housing  28  substantially “U”-shaped or “C”-shaped apt to house said portion of bending member  10 ; the connection element  27  also comprises a cylindrical collar  29 . 
     In this embodiment, each bending member  10  is fixed with respect to the corresponding connection element  27 , that is, a translation movement of the connection element  27  with respect to the bending member  10  along its preferential development direction  202  is prevented; the connection element  27  and the bending member  10 , therefore, move together. 
     The connection element  27  represented in  FIG. 3A  comprises two of said connection members, each with a “U”-shaped housing  28 , positioned symmetrically with respect to a plane and connected to each other by said cylindrical collar  29 ; this connection element  27  is, therefore, apt to be associated with two bending members  10  and each of said connection members is apt to move a portion of a respective bending member  10 . 
     There are suitable guides for limiting the movements of the connection element  27  with respect to the stock  2 . To be more specific, one of said “U”-shaped housings  28  has a first groove  191  on a face facing the proximal end  205  and a second groove  191 , parallel to the first groove, on a face facing the distal end  206 . Each of these grooves  191 , which extend on a plane orthogonal to an axis of the cylindrical collar  29 , is engaged by a rail  190  which extends laterally from the stock  2  and orthogonally to the longitudinal axis  201 . As a result, the connection element  27  is constrained to move, with alternate motion, parallel to the plane defined by these rails  190  and orthogonal to the longitudinal axis  201 . 
     The connection element  27  and, in particular, the collar  29 , is positioned idle in a slot  211  in a respective cam  21  at the respective first axis of rotation  22 . To be more specific, the slot  211  is a hole. 
     This way, the cam  21  is pivoted at the connection element  27  and its axis of rotation  22  is substantially the same as the axis of said cylindrical collar  29 . Thanks to the connection element  27  and the pivoting methods, a portion of each bending member  10  is associated idle to the respective slot  211  so as to allow said portion of bending member  10  to make a translation movement together with the slot  211 ; in particular, said translation movement takes place in a direction substantially orthogonal to the preferential development direction  202  of the bending member  10 . 
     Therefore, the first axis of rotation  22  may make translation movements together with a portion of the respective bending members  10 . Note that this portion of the bending members  10  corresponds to the region positioned about half way along their length. However, in another possible embodiment, this portion might correspond, for example, to an end region of the bending members  10 ; in this case only the other end of the bending members  10  would be constrained to the stock  2 . 
     The crossbow  1  also comprises pushing means  30  for said projectile apt to cooperate with the bending members  10 . They include a flexible member  31 , such as, for example, a propulsive wire for pushing a projectile, and at least two lever arms  32  positioned on opposite sides of the stock  2  and connected to each other by the flexible member  31 . 
     Each of the arms  32 , i.e. the pushing arms, has a first end which is pivoted to the stock  2  at a second axis of rotation  33  and a second end  34  apt to support, and in particular to hold, a portion of said flexible member  31 . The flexible member  31  may be secured to the stock  2  or to the arms  32  using a suitable securing device  35 . In the case where the flexible member  31  is secured to the stock  2 , it will be held by said second end  34  so that it may slide somewhat with respect to the end  34  itself. If, on the other hand, the flexible member  31  is secured to the arms  32 , it may further be secured also to said end  34 . 
     During a rotation movement with respect to said second axis of rotation  33 , the arms  32  are apt to cooperate with the tensioning means  20  to realize a transfer of energy to said bending members  10  during the loading phase of the crossbow  1  and a transfer of energy from said bending members  10  to said pushing means  30  during the projectile launch phase. 
     In a first embodiment, each arm  32  forms a single part with a respective cam  21 ; in this case, said first axis of rotation  22  of the cam  21  is the same as said second axis of rotation  33  of the arm  32 . 
     As illustrated in  FIG. 2B , the arms  32  can be rotated between a first maximum loading position, corresponding to a maximum bending of the bending members  10 , and a second maximum discharge position following the launch of the projectile. Between said first and second positions, there is a neutral position, at which the bending members  10  do not have accumulated elastic energy, as they are in a rest condition in a non-deformed state, as illustrated in  FIG. 2A . 
     To be more specific, in the present embodiment said first rotation direction during the loading phase is directed towards said proximal end  205  of the stock  2 , and said rotation in the opposite direction during the launch phase is directed towards said distal end  206  of the stock  2 . 
     For the sake of clarity, note that  FIG. 2B  intends to show these possible positions through a single drawing; it is intended, obviously, that, in a crossbow  1  according to the present disclosure, the right and left arms  32  will move in a substantially synchronized manner and the two arms  32  will be in the same position at the same time. 
     To be more specific, in the neutral position, the flexible member  31  passes at said second axes of rotation  33  of the arms  32  intercepting them. 
     Contrast means  50  may also in case be provided, associated to the stock  2  and operatively connected to the cams  21 , in order to dampen the motion of the arms  32  and the cams  21 ; said contrast means  50 , for example, include a cylinder  51  with a small hole  52 , a piston  53 , a spring  54  and a rod  55 . The contrast means  50  are connected to the slide  25  by the rod  55  (slotted in, for example) which, therefore, follows its movement parallel to the longitudinal development direction  201  of the stock  2 . Depending on the extent of the counter bending permitted for the bending members  10  (also related to their rigidity) and the choices for the dimensioning of the components of the crossbow  1 , the contrast means  50  may also dampen the motion of the bending members  10  by means of the interaction with the arms  32  and with the cams  21 . 
     The contrast means  50  are loaded so as to apply a force against the cams  21  when the arms  32  are past said neutral position towards said second maximum discharge position. In fact, when the arms  32  have passed the neutral position, the rod  55  is inserted in the piston  53  and pushes against a special recess (not shown) with a cone-shaped terminal; this way, the piston  53  is pushed inside the cylinder  51  and, thanks to a ring-shaped collar  56  on the outer surface of the piston  53 , compresses the spring  54  and pushes the air towards the outside of the cylinder  51  through the small hole  52 . This way, a slowing down of the motion of the arms  32  is obtained thanks to the transfer of energy to the spring  54  and thanks to the compression action on the air in the cylinder  51 ; the fluid dynamic resistance related to the flow of air through the small hole  52  contributes to the dissipation of the kinetic energy possessed by the moving parts. 
     When the arms  32  are between said first maximum loading position and said neutral position, the rod  55  is not in contact with said recess with cone-shaped terminal, of the piston  53  and, therefore, the contrast means  50  do not have any influence on the motion of the arms  32  themselves. 
     These same elastic means represented by the spring  54  can bring the arms  32  back towards the neutral position, so that, at the end of the launch phase, they are in this position again. 
     The crossbow  1  may comprise a cover  61 , positioned at the slide  25  and pivoted to the stock  2  at one end  62 , which makes it possible to protect the internal members and to access them only when necessary; to be more specific, this makes it possible to proceed to the replacement of the slide  25 . For safety reasons, it is possible to open the cover  61  only when the crossbow  1  is not loaded and the flexible member  31  has been removed. In addition, the cover  61  includes at least one tooth  65  (preferably, a pair of teeth  65 ) coming out of the cover  61  near its distal end, said at least one tooth  65  having the function of stopping the run of the flexible member  31  at the end of the launch phase in order to prevent the flexible member  31  from falling beyond the cover  61 . 
     Covering members  63  with a “U”-shape (upside down with respect to the corresponding housing  28 ) may be secured in a reversible manner to said connection elements  27  and cooperate with these in order to keep the bending members  10  in position. 
     In addition, there is a perimeter protective structure  64  which substantially limits the region in which the arms  32  move, in order to assist the user with preventing interference with any objects present nearby and to avoid getting struck by the arms  32  themselves. 
     During a loading phase of crossbow  1 , the user pulls the flexible member  31  towards the proximal end  205  of the stock  2 , until the flexible member  31  is engaged in the fastening system  6 . During this operation, the arms  32  and the cams  21  rotate in an initial direction around the respective axes of rotation  33 ,  22 ; thanks to the edges  23  with eccentric profile on the cams  21  which push against the slide  25 , the slot  211  on each cam  21  (and, therefore, the axis of rotation  22 ) moves orthogonally to the development direction  201  of the stock  2 , thereby causing a bending of the respective bending members  10  through the cam  21 . The bending members  10 , therefore, are in the bent configuration illustrated in  FIG. 2B  and in  FIG. 3 . At the same time, the slide  25  slides towards the distal end  206  of the stock  2 . When the maximum loading position is reached and a projectile is placed in a suitable track  8  on the stock  2 , the crossbow  1  is ready for launching. 
     Pressing of the trigger  7  starts a projectile launch phase, during which the flexible member  31  is released from the fastening system  6 . The bending members  10  tend to return to the rest position, that is, the non-deformed neutral position, and therefore push on the cams  21  making them rotate in the opposite direction with respect to the loading phase. Through the cams  21 , the arms  32  in turn rotate towards the distal end  206  of the stock  2  and pull the flexible member  31 , which transfer energy to the projectile. At the same time, the slide  25  moves towards the proximal end  205 . 
     When the neutral position is reached, the inertia of the arms  32 , the cams  21  and the bending members  10  has them continuing their run past the neutral position tending towards the maximum discharge position; in this portion of the stroke, the bending members  10  are in a bent position towards the longitudinal axis  201  of the stock  2  (that is, in a counter bent configuration with respect to the loaded position) and the flexible member  31  is no longer tensioned. In case of an especially high residual kinetic energy (for example, in case of a very light projectile or of dry firing), the arms  32  may reach said maximum discharge position, in which they are rotated towards the distal end  206 , for example, by 25° with respect to the neutral position. 
     In this portion of the stroke, the movement of the cams  21  and the arms  32  is opposed by the contrast means  50 , which also dissipate part of the kinetic energy; according to the methods described, these contrast means  50  only operate starting from the neutral position. 
     Thanks to the combined action of the bending members  10  and the spring  54 , which tend, obviously, towards the respective non-deformed positions, the entire system is then brought back to the neutral position, where it stops. 
     Note that the toothings  24  and  26  and the slide  25  are made so that they are mutually engaged even in the stroke between the neutral position and the maximum discharge position; to be more specific, there may be a particular portion of toothing, for example, with deeper teeth and/or possibly with a non-straight profile, to make sure that there is no accidental disengagement. This is especially advantageous for preventing the cams  21  from disengaging the slide  25  when, with the crossbow  1  unloaded and the bending members  10  in the rest condition, the arms  32  are pushed by the user towards the maximum discharge position. Note, in fact, that, with the crossbow  1  unloaded, this movement towards the maximum discharge position may be executed without this involving the deformation of the bending members  10 . 
     From the above description it is understood how the end of stroke shock is, therefore, substantially eliminated, since the stopping of the components at the end of the useful run is not sudden as with the known art, but takes place within the stroke between the neutral position and the discharge position, and return. This enables a major reduction in the structural stresses, the noise and the risks related to the use of too light a projectile or no projectile at all. To the same end also the better distribution of the masses of the components, as they are much closer to the center of mass and to the longitudinal axis  201  of the stock  2 . A crossbow according to the present disclosure will be lighter than a known-art crossbow and the center of mass will be closer to the handle  4  for same power. 
     Note that, because of the eccentric profile  23  of the cams  21 , when the bending members  10  are in a non-deformed position, the arms  32  can rotate towards the maximum discharge position without this determining the deformation of the bending members  10  themselves. In this case, the spring  54  has the additional function of bringing back and maintaining the arms  32  in the neutral position when the crossbow  1  is unloaded, pushing them towards that position. 
     The slide  25  allows for the synchronization of the motion of the cams  21  and, therefore, of the arms  32 : this way, even in case of asymmetries in the elastic characteristics of the bending members, the force acting on the projectile through the flexible member  31  is in any case balanced and does not have any component orthogonal to said track  8 . The synchronization of the motion of the cams  21  one with the other and of the arms  32  one with the other guarantees a balanced pull on the flexible member  31  and this absolves a condition necessary for the purpose of precision. 
     This configuration makes it possible to considerably increase (with respect to the known art) the ratio between the stroke of the projectile and the extent of the shifting of the masses of the bending members  10 , thereby increasing the efficiency of the conversion between potential and kinetic energy; an adequate profiling of the edges  23  of the cams  21  and, in case, of the edges  26  of the slide  25  also makes it possible to obtain a more marked reduction in the maximum loading force with respect to the known art. 
     The fact that the slide  25  is removable also makes it possible to easily vary the characteristics of the crossbow  1 , adapting them to the use requirements. It can, in fact, be replaced by another slide  25  having profiles  26  which are not straight and/or not parallel (e.g. concave, convex, divergent or convergent), so that, with equal loading stroke, the bending members  10  have a higher or lower degree of deformation, a different level of stored energy and a different force-draw curve. 
     It is also possible to modify the characteristics of the crossbow by replacing the bending members  10  with other bending members of different elastic characteristics. 
     Note that the possibility of easily taking apart the crossbow  1  and replacing its components is linked to the fact that, in the neutral position, there are no members in elastic tension; therefore, the taking apart and the assembly do not require either special tools (e.g. presses) or special caution on the part of the user. 
     The embodiment described above lends itself to several variants. For example, the slide  25  may not be present and the cams  21  may be engaged to each other directly through edges with toothing  24 ; in this case, these edges could also be smooth, without toothing, but with eccentric profiles. Or both the cams  21  and the slide  25  could have edges partially smooth and without toothing, but be able to transfer movement by friction. 
     The cams  21  themselves could be pivoted to the bending members  10  with methods different from the described slot  211 : more generally, said portion of each of the bending members  10  may be associated idle to a portion of a respective cam  21 . 
     For example, each cam  21  may rotate around a pivot which is part of the respective bending members  10  themselves (which could also be just one in number per side of the stock  2 ). 
     As a further possibility, the cams  21  could be pivoted to the stock  2  so that said first axis of rotation  22  is fixed with respect to the stock  2  and the cams  21  could also not have an eccentric profile: in this case, each cam  21  would include at least one tooth (or an edge) apt to engage and/or cooperate with a respective bending member  10 , in order to push it orthogonal to the longitudinal development direction  201  away from or close to the stock  2  itself during the rotation of the cam  21  itself, in order to create a reciprocal transfer of energy between cams  21  and bending members  10 . 
     As a further hypothesis, each cam  21  could cooperate with the bending members  10  positioned on the opposite side of the stock  2 . 
     The cams  21  might be more than two in number (for example, two per side, for a total of four, or one for each bending member  10 ), and the arms  32  might be more than two in number. 
     There may also be auxiliary pushing means (not shown) in order to further increase the power of the crossbow  1 , these auxiliary pushing means including at least one member with elastic behavior (spring or hydraulic and/or pneumatic device or other) apt to accumulate elastic energy during the loading phase of the crossbow  1  and return it to said pushing means  30  during the projectile launch phase. Said auxiliary pushing means may be connected to said slide  25  and, in particular, be housed to the front of the stock  2 , that is, in a position which is substantially opposite to said contrast means  50 ; in effect, the action of these auxiliary pushing means would be similar to the action exercised by the spring  54 , but directed in the opposite direction and active in the phase in which these contrast means  50  are not operative. 
     These auxiliary pushing means may also be side by side to said contrast means  50 , for example, by making that the spring  54  is joined in a stable manner to the cylinder  51  and to the rod  55  so that it may accumulate elastic energy when the arms  32  are brought from the neutral position to the maximum loading position and return it in the opposite direction. 
     A second embodiment of a device for launching a projectile, indicated with number  70  and illustrated in  FIGS. 8 and 8A , comprises further technical characteristics which may, however, be present alone or in combination. Parts having the same function and structure maintain the same reference number as in the embodiment described previously and, therefore, are not described again in detail. 
     The device  70  includes a stirrup  210  secured to the stock  2  at the distal end  206 . Said stirrup  210  is apt to house a user&#39;s foot: in this way, during the device loading phase, the user can push the stirrup  210  (and, therefore, the device  70 ) towards the ground with a foot and, at the same time, use the hands to apply force to the flexible member  31  to bring it to the loaded position, managing to apply more force than when the stirrup  210  is not used. 
     As in the embodiment already described, the cover  61  includes a pair of teeth  65  which come out of the cover  61  near to its distal end, in order to arrest the run of the flexible member  31  at the end of the launch phase in order to prevent the flexible member  31  from falling beyond the cover  61 . 
     The second ends  34  of the arms  32  have a groove  36  apt to receive a portion of the flexible member  31 . To be more specific, said groove  36  is shaped so as to support the flexible member  31 , preventing it from being disengaged from the ends  34 . 
     The contrast means  50  and, in particular, the cylinder  51 , are positioned in the region delimited by the bending members  10 , that is, further away from the proximal end  205  than as shown for the first embodiment ( FIGS. 2A to 7 ). This allows for a greater compactness of the device  70 . 
     Finally, in this second embodiment, the upside down “U”-shaped covering members (indicated with number  63  in the first embodiment, only one of them being represented in  FIG. 4 ) to be secured to the connection elements  27 , are not present, as the connection elements  27  are by themselves able to constrain the cover  61 , making it only possible to open it in the neutral position. 
     A third embodiment of a device for launching a projectile according to the present disclosure is indicated with reference number  71  and is illustrated in  FIGS. 9A to 10 , in which only the essential components are shown in order to understand its functioning with respect to the previous embodiments. Parts having the same function and structure maintain the same reference number as in the embodiments described previously and, therefore, are not described again in detail. 
     The crossbow  71  also comprises a stock  2  with a longitudinal development direction  201 , to which the other components are connected. As well as the handle  4 , the fastening system  6  for a flexible member  31 , and the track  8 , it also, obviously, comprises other components not shown, such as a projectile positioning system, a trigger and other accessories, as with the previously described embodiment. 
     The bending members  10 , entirely similar to the ones already described, are represented here with a different method for connection to the stock  2 . Their ends, in fact, are in contact with sidebars  75 , which are preferably cylindrical, connected to the stock  2  and each bending member  10  is pressed against these sidebars  75  by a wire  76  or similar flexible holding means which envelops the bending member itself and its corresponding member on the opposite side of the stock unit  2 . The bending methods for the members  10  are, when all is said and done, similar to those already described, even if they use a simpler solution for their connection to the stock  2 . Note, however, that this connection method is in no way limitative for the crossbow  71 , just as, the pivoted supports  11  for the bending members  10  are not limitative for the crossbow  1 : these solutions may, in fact, be used indifferently in the embodiments shown here as examples. 
     The crossbow  71  has cams  81  which are constrained and pivoted to the bending members  10  in a manner similar to that described above, and they can also rotate around an axis  22 . In this case, no slide is present, but a first and a second cam  81  are hinged on a pivot body  82 , which is slidingly associated to the stock  2  in order to run parallel to said longitudinal development direction  201 . The cams  81  rotate around a determined axis  83  of the pivot body  82 ; the axis  83  moves with the pivot  82 . 
     The already described contrast means (not shown here) may in case be connected to said pivot body  82 . Similarly, the auxiliary pushing means already previously described may also be connected to the same pivot body  82 . 
     Arms  84  are pivoted to the stock  2  at axes of rotation  33 , which are distinct from the axes of rotation  22  of the cams  81 . In this case, in fact, each arm  84  and the respective cam  81  do not form of a single part, but are separate from each other. The transmission of the rotation movement from one cam  81  to the respective arm  84  (and vice versa) is realized through a connection rod  85  which is pivoted to said cam  81  and to said arm  84 . The connection rod  85  might be replaced by more than one connection rods  85 , in case pivoted to each other. 
     The methods of loading and of launch of the crossbow  71  are substantially similar to those already described for the previous embodiments and, therefore, are not repeated here. 
     Also note that the cams  81  may have a particular “L” shape as illustrated in  FIG. 10 , which ensures that, with opportune dimensioning of these, the crossbow  71  allows an operative position with the bending members tensioned, the system for the fastening and releasing the flexible member  31  not tensioned, and arrow in place, from which operative position the crossbow  71  can be practically brought back to the launch position with a manual action. 
     In fact, a further movement of the arms  84  beyond a position of maximum loading ensures that a plane containing both the axes of rotation  22  intersects the longitudinal axis  201  of the stock  2  in a region between said axis  83  of the pivot  82  and the proximal end  205 . In this position, the recall force exercised by the deformed bending members  10  on the cams  81  tends to cause a rotation of the cams  81  in the loading direction instead of in the launch direction: there is, therefore, no danger of an involuntary activation of the crossbow  71 . In order to launch, it will then be necessary to first spread the arms  84 , so that the axis  83  may pass over said plane containing both axes of rotation  22 , getting closer to the proximal end  205 . 
     Obviously, the reciprocal pivoting methods for the cams  81 , their shape and the separation between cams  81  and arms  84  so that they rotate with respect to axes which are not coincident are technical solutions which, individually or in combination, could also be used in a crossbow similar to the other embodiments described here. 
       FIGS. 11A to 11D  show a fourth embodiment of a device for launching a projectile, indicated with reference number  72 . Parts having the same function and structure maintain the same reference number as in the embodiments described previously and, therefore, are not described again in detail. The device  72  is shown in the rest position in  FIG. 11A  and in the loaded position in  FIG. 11B . 
     The arms  84  include teeth  86  positioned on the top surface  87  of the arms  84  themselves, said teeth  86  having the function of stopping the run of the flexible member  31  at the end of the launch phase in order to prevent the flexible member  31  from falling beyond the arms  84 . 
     Also in this embodiment, as in the previous one, the “L”-shaped cams  81 , dimensioned in an appropriate manner, make it possible for the crossbow  72  to be transported by the user in total safety, even when it is in the loaded position. As illustrated in  FIG. 11C , the further movement of the arms  84  beyond a position of maximum loading makes it possible that a plane  92  containing both axes of rotation  22  of the cams  81  intersects the longitudinal axis  201  of the stock  2  in a region between the axis  83  of the pivot  82  and the proximal end  205  of the stock  2 . In this position, the recall force exercised by the deformed bending members  10  on the cams  81  tends to cause a rotation of the cams  81  in the loading direction instead of in the launch direction. 
     In other words, in this position, the moment of force exercised by the bending members  10  on each cam  81 , with respect to the axis  83 , rotates the cam  81  in the direction indicated by the respective arrow  95 . As said, then, there is no danger of involuntary activation of the crossbow  72 . In order to launch, it is necessary, in fact, to first spread the arms  84 , so that the consequent rotation of the cams  81  makes the axis  83  pass over the plane  92  containing both axes of rotation  22 , getting closer to the proximal end  205 . 
     This embodiment  72  illustrates a further method for associating the bending members  10  to the stock  2 . 
     Each end  101 ,  102  of a bending member  10  is associated to the stock  2  by means of a first sidebar and a second sidebar, in turn associated to the stock  2 . The first sidebar and the second sidebar are in a spaced relation in order to define a housing for said end  101 ,  102 , so that they touch opposite sides of the bending member  10  and, in particular, of said end  101 ,  102 . 
     In the example, the first sidebar consists of a cylindrical stem  15 , constrained to the stock  2  close to it; in the example, the second sidebar consists of a support  14 , preferably cylindrical, positioned to the outside of the bending member  10  with respect to the stock  2 . 
     The end  101 ,  102  of the bending member  10  is enclosed at the sides between the support  14  and the stem  15 , in particular, in order to be slightly jutting out in a longitudinal direction  202  with respect to the stem  15 . 
     The first and the second sidebars also both have a curved profile (in the example, a cylindrical profile) in order to permit, during the bending of the bending member  10 , a partial rotation of said end in the housing defined by these. 
     To be more specific, the cylindrical supports  14  are pivotably mounted to the stock  2  in order to be able to make angular displacements around their central axis  214 , so as to rotate following the movement of the end of the bending member  10  when the latter, bending, varies its tilt with respect to the stock  2 ; the stems  15  also act as spacers, in order to keep the bending member  10  slightly displaced from the stock  2 . 
     The embodiment described, as well as permitting the connection of the bending members  10  to the stock  2 , allows the bending member  10  to easily bend towards the outside during the loading phase and to counter bend towards the stock  2  in the stroke towards the maximum discharge position. 
     Note that, if it is required by particular construction requirements, said first and second sidebars can be positioned at a tract of the bending member  10  not corresponding to an end of it, but instead positioned at a certain distance from the end. In addition, a first tract of the bending member  10  may be associated to the stock  2  using these sidebars, while a second tract of the bending member may be associated using different methods (for example, using the supports  11  already described). 
     A fifth embodiment of a device for launching a projectile according to the present disclosure is indicated with reference number  73  and is illustrated in  FIGS. 12A-12C  and  13 . Parts having the same function and structure maintain the same reference number as in the embodiments described previously and, therefore, are not described again in detail. 
     The device  73  comprises levers  160 , each of which has a cam  161  with an appendix  162 . The appendix  162  has a guide track which, in the example, consists of a slit  163  which extends into the body of the appendix  162  along the appendix itself. 
     Each cam  161  is associated to the bending members  10  in a manner substantially similar to the methods described previously. In fact, the cam  161  and, therefore, the lever  160 , is pivoted to the bending members  10  using a connection element  27  with “C”-shaped housings and it can, therefore, rotate around an axis  22 . 
     The cam  161  extends from the axis of rotation  22  towards the longitudinal axis  201  of the stock  2 , while the appendix  162  extends in the opposite direction. 
     To be more specific, the device  73  comprises a pair of levers  160  arranged symmetrically with respect to the stock  2 . 
     The cam  161   a  of a first lever  160   a  is pivoted to the cam  161   b  of a second lever  160   b  at a pivot body  82 , which is slidingly associated to the stock  2  to run parallel to the longitudinal development direction  201  of the stock  2  itself. The cams  161   a  and  161   b,  then, also rotate around an axis  83  which moves with the pivot  82 . Again in this case, as for the embodiments already described, contrast means and/or auxiliary pushing means may be used, possibly connected to the pivot body  82 . 
     The device  73  comprises arms  132 , positioned substantially symmetrical with respect to the stock  2 . Each arm  132  has a first end which is pivoted to the stock  2  at a respective axis of rotation  33 , which is distinct from the axes of rotation  22  of the cams  161 . Each arm  132  includes a second end  34  apt to support and retain a portion of a flexible member  31 , in a manner similar to the ones described previously. 
     The arm  132  is provided with a guide member  135 , for example, including a tooth or a wheel, which extends orthogonal to a plane on which said arm  132  lies in the direction of the plane on which the levers  160  lie. Said member  135  is, to be more specific, associated with a side appendix  134  of the arm  132  which, in the embodiment illustrated, is envisaged in a region between the axis of rotation  33  and the second end  34 . 
     The member  135  is apt to engage the guide track  163  provided in the appendix  162  of the respective cam  161 ; to be more specific, in the embodiment illustrated, the member  135  is a wheel apt to slide in said guide track  163 . This way, each arm  132  is operatively connected to a respective cam  161 . The wheel  135  is rotationally pivoted to the arm  132  and has a diameter less than the transversal width of the respective guide track  163 , so that it can slide in said track  163  remaining in contact with just one edge of the track  163  itself. 
       FIG. 13  shows a detail of the particular method for pivoting the cams  161  to the stock; this method may be also applied in the same way to the other embodiments for the device presented here. In a manner similar to what has already been described, each cam  161  has a hole  211  in which the collar  29  of the respective connection element  27  is housed idle. 
     The stock  2  includes, on each side, appendices  250  which extend substantially orthogonal to the longitudinal development direction  201 . Each appendix has a rail  251  which also extends in a direction which is substantially orthogonal to said longitudinal direction  201 . Each appendix  250  may also include an end portion at which a respective arm  132  is pivoted. 
     On each side of the stock  2 , there is a slide  252  which, on a first face, includes means for engaging a respective rail  251 . The slide  252 , guided by the rail  251 , can, therefore, move along the appendix  250 . Preferably, the rail  251  and said engagement means are made so that the slide  252  can only make a translation movement along the rail  251  and, therefore, along a direction orthogonal to the longitudinal direction  201 , while the slide  252  is prevented from making movements along said longitudinal direction  201 . For example, the rail  251  and said means have a dove tail transverse cross section. 
     A second face of said slide  252 , opposite the first face and facing a respective cam  161 , has a concave slot, with a cylindrical sector shape, apt to house a corresponding cylindrical portion  165  of the cam  161 . The angle described by said cylindrical sector is less than the angle described by said cylindrical portion  165 . This way, when the cylindrical portion  165  is housed in the cylindrical sector, the cam  161  can make an angular displacement, of a preset maximum amplitude, with respect to the slide  252 ; this angular displacement takes place between a first position in which a first edge  167  of the cam  161  is touching a first edge  253  of the slide  252 , and a second position in which a second edge  168  of the cam  161  is touching a second edge  254  of the slide  252 . 
     From said second face, a slit extends into the body of the slide  252 , orthogonal to this second face and facing the first face. Said slit is apt to house part of a plate portion  166  integral to the cam  161  and positioned outside said cylindrical portion  165  and transversal to it. 
     The slit and the plate portion  166  are made so that they cooperate with each other in order to prevent relative translation movements between the cam  161  and the slide  252  along the axis  22 ; they are also made so that they do not impede said angular displacement, of preset maximum amplitude, of the cam  161  with respect to the slide  252 . 
     Therefore, during the loading and launch phases, the cam  161  rotates around the axes  22  and  83 , both mobile: the axis  83  moves along the longitudinal direction  201 , while the axis  22  moves along a direction orthogonal to the longitudinal direction  201 , parallel to the rail  251 , together with the slide  252 . To be more specific, the slide  252  moves towards the axis  201  during the loading phase and moves away from it during the launch phase. 
       FIGS. 12A ,  12 B and  12 C illustrate, respectively, the crossbow  73  in a neutral (rest) condition, in a loaded condition, and in a maximum discharge condition. 
     Before a projectile is launched, the crossbow  73  is initially in the neutral condition ( FIG. 12A ). During the loading phase, the pull on the flexible member  31  causes the rotation of the arms  132  around the axes  33  and the movement of their ends  34  towards the proximal end  205  of the stock  2 . 
     The wheels  135 , also moving towards the proximal end  205 , sliding in the guide tracks  163 , apply force to the arms  162 , which causes the rotation of the levers  160  around the axes  22 . The sliding of the wheels  135  in the guide tracks  163 , then, makes it possible that the cams  161  rotate around the axes  22  and bend the bending members  10 , thereby accumulating energy which can be used to launch a projectile. The loaded condition is illustrated in  FIG. 12B . 
     Note that, unlike the embodiments described previously, in this embodiment, the bending members  10  bend towards the stock  2  during the loading phase and counter bend towards the outside in the launch phase: this is due to the different position of the axis  83  with respect to the plane on which the axes  22  lie in relation to the rotation movements described by the levers  160 . 
     It is evident, in any case, that this bending method for the bending members  10  may also be used for the embodiments described previously ( FIGS. 9A to 11D ), and vice versa. In fact, the bending method away from or closing to the stock  2  during the loading phase may be selected through an opportune dimensioning and assembly of the cams, and is substantially unrelated to the other specific characteristics of the embodiments described; it is, therefore, “interchangeable” between the embodiments described. 
     During the launch phase, the bending members  10  tend to return to their non-deformed configuration and, therefore, apply a force to the cams  161 , causing the rotation around the axes  22  towards the distal end  206  of the stock  2 . As a result of the force transmitted through the wheels  135 , the arms  132  also rotate around the axes  33  towards the distal end  206  of the stock  2  and pull the flexible member  31  which, in turn, transmits energy to the projectile. 
     Due to the inertia of the moving parts, the arms  132 , the levers  160  and the bending members  10  pass the neutral position and reach a maximum discharge position, shown in  FIG. 12C , in which the bending members  10  are deformed towards the outside of the stock  2 . 
     Subsequently, the bending members  10  return of their own accord to the non-bent (neutral) position, also bringing the arms  132  and the levers  160  back to the initial position ( FIG. 12A ). 
     A sixth embodiment of a device for launching a projectile according to the present disclosure is indicated with reference number  74  and is illustrated in FIGS.  14 A- 14 C,  15  and  16 . Parts having the same function and structure maintain the same reference number as in the embodiments described previously and, therefore, are not described again in detail. 
     The device  74  comprises levers  170 , each of which has a first portion including a cam  171  constrained and pivoted to bending members  10  in a manner substantially similar to the methods described previously, and a second portion including two appendices  172  integral to the cam  171 . 
     The appendices  172  are substantially identical and parallel to each other and are also positioned on planes parallel to the plane on which the respective cam  171  lies. To be more specific, said second portion includes a block  179  which separates the planes on which said cam  171  and said appendices  172  lie. 
     Each of these appendices  172  has a guide track, which consists of a first edge  174  with toothing  176 ; said first edge  174  is optionally facing, at least in part, a second edge  175  with a groove or a rib  177 , thereby defining a region  173  between the first edge  174  and the second edge  175 . 
     In a manner similar to the previous descriptions, the cam  171  and, therefore, the lever  170 , is pivoted to the bending members  10  using a connection element  27  and it rotates around an axis  22 . 
     The device  74  comprises a pair of levers  170 , arranged in a symmetrical manner with respect to the stock  2 , one on each side of it. 
     The cam  171   a  of a first lever  170   a  is pivoted to the cam  171   b  of a second lever  170   b  at a pivot body  82 , which is slidingly associated to the stock  2  and can run parallel to the longitudinal development direction  201 . The pivot body  82  has a housing apt to slidingly receive a guide  180  joined to the stock  2  and positioned parallel to the longitudinal development direction  201 . 
     The cams  171   a  and  171   b  also rotate, then, around an axis  83  which moves with the pivot body  82 . Again in this case, as for the embodiments already described, contrast means or auxiliary pushing means may be used, connected to the pivot body  82 . 
     The device  74  comprises arms  142 , each having a first end pivoted rotationally with respect to the stock  2  at a respective axis of rotation  33 , which is distinct from the axis of rotation  22  of the respective cam  171 . The second end  143  of each arm  142  supports a pulley  145  which, in turn, supports the flexible member  31 . The arm  142  and the pulley  145  lie on planes which are parallel to each other. The side edge of the pulley  145  has a groove  147  in which one end  311  of the flexible member  31  is secured and in which the flexible member  31  itself winds. Note that it is not required that the pulley  145  has a side edge which defines a closed line: in fact, the figures show a pulley which has an interrupted side edge. 
     To be more specific, the pulley  145  has a pivot  146  which rotates jointly with it and which extends orthogonal to the surface of the pulley and is positioned close to a portion of the edge of the pulley  145 , so that the pulley has an eccentric side edge with respect to a longitudinal axis  150  of the pivot  146 . 
     The pivot  146  is housed in a slot, or in a hole, in the second end  143  of the arm  142  and may rotate in this hole with respect to the axis  150 . The axis  150  makes translation movements together with the second end  143  of the respective arm  142 . 
     To be more specific, the arms  142  are two in number and they are arranged symmetrically with respect to the stock  2 , one on each side of it. 
     Each arm  142  is placed in spaced relation from the appendices  172  of the respective lever  170 , but so that the respective pulley  145  is inserted in a space defined between the same appendices  172 . 
     The pivot  146  has two toothed portions  148  (preferably, cylindrical portions), positioned, respectively, at one face of the pulley  145  and at the opposite face, that is, above and below the pulley  145 . 
     Each of these toothed portions  148  engages the guide track of a respective appendix  172  and, in particular, the edge  174  with toothing  176 . 
       FIGS. 14A ,  14 B and  14 C illustrate, respectively, the crossbow  74  in a neutral condition, in a loaded condition and in a maximum discharge condition. 
     The crossbow  74 , before a projectile is launched, is initially in the neutral condition ( FIG. 14A ), in which the bending members  10  are in the non-deformed configuration and the flexible member  31  is partially wound on the pulleys  145 . 
     During the loading phase, the pull on the flexible member  31  towards the proximal end  205  causes the unwinding of the flexible member  31  from the pulleys  145  and the rotation of each pulley  145  around the respective axis  150 ; the toothed portions  148  of the pivot  146  rotate together with the respective pulley  145  and, engaging the toothed edges  174  of the guide tracks of the respective appendices  172 , move along said guide track, in turn causing the rotation towards the proximal end  205  of the arms  142  and of the levers  170  around the respective axes of rotation  33  and  22 . 
     The rotation of the pulley  145  around the respective axis of rotation  150 , that is, around the translating axis  150  of the pivot  146 , is, therefore, coordinated with a respective cam  171  for a synchronized rotation of the cam  171  itself around the respective first axis of rotation  22 . In other words, the pulley  145  moves synchronized with the respective cam  171 , with a combined translation and rotation movement. 
     The rotation of the cams  171 , joined to the levers  170 , bends the bending members  10  towards the stock  2 , thereby accumulating energy which can be used to launch a projectile. The loaded condition is illustrated in  FIG. 14B . 
     During the launch phase, the bending members  10  tend to go back to their non-deformed configuration and therefore apply a force to the cams  171 , causing the rotation of the levers  170  towards the distal end  206  of the stock  2 . 
     The toothed edges  174  have a profile apt to push the pivots  146  towards the distal end  206 , causing the rotation of the same (thanks to the engagement of the toothed portions  148  of the pivots  146  on the toothed edges  174  of the appendices  172 ) and their movement towards the end of the region  173  and towards the longitudinal axis  201  of the stock  2 . The pulleys  145  move together with the pivots  146  and, therefore, have both a translation motion towards the distal end  206  and towards the stock  2  (in particular towards the longitudinal axis  201 ), and a rotation motion around the axis  150  in a direction opposite to that of the loading phase. The combination of the translation motion and the rotation motion of the pulleys  145  draws the flexible member  31  and also winds it in the grooves  147  of the pulleys  145 . The flexible member  31 , hence, transmits energy to the projectile. 
     Due to the inertia of the moving parts, the arms  142 , the levers  170 , the pulleys  145  and the bending members  10  pass the neutral position and reach a maximum discharge position, shown in  FIG. 14C , in which the bending members  10  are deformed towards the outside. In this position, there is the maximum winding of the flexible member  31  on the pulleys  145 , which are almost in contact with each other. 
     Subsequently, the bending members  10  return of their own accord to the non-bent (neutral) position, also bringing the arms  142 , the levers  170  and the pulleys  145  to the initial position ( FIG. 14A ). 
     This embodiment, that is, the crossbow  74 , shows certain further advantages with respect to the forms previously described. First of all, the winding of the flexible member  31  on the pulleys  145  permits a reduction of the lateral dimensions of the device when it is in the neutral position for same loading stroke with respect to the other embodiments. In addition, the winding itself also prevents the flexible member  31  from going slack in the stroke from the neutral position to the maximum discharge position. 
     The use of pulleys  145  rotating with respect to the arms  142  allows for greater design freedom in order to obtain the desired force-draw curve. In fact, the shape of this curve may be adapted to the requirements by envisaging an opportune profile and rotation angle for the pulleys. 
     By modifying the diameter of the pivot  146  and, therefore, the number of teeth  148 , it is also possible to vary the number of rotations carried out by the pulley  145  and the number of windings of the flexible member  31  on it for equal shift along the guide track (in particular along the toothed edges  174 ), thereby making it possible to vary the stroke of the flexible member  31  for same maximum lateral dimensions of the device. 
     Finally, in the launch phase, the rotation movement of the pulleys  145  combined with their movement towards the longitudinal axis  201  of the stock  2  makes it possible that the moments of inertia of these are substantially cancelled out and, therefore, the structure of the crossbow  74  and the user are subject to lower stresses. 
     Also, the provision, on each side, of two appendices  172  with two toothed edges  174 , engaged by two toothed portions  148  placed on opposite faces of the pulley  145  insures that the movement of the pulley  145  with respect to the arm  170  is more regular, that their interaction is more efficacious, and that the forces acting on the pulley  145  in directions not parallel to its plane are balanced out. However, in principle, there could be just one appendix  172  with toothed edge  174  and a pivot  146  with just one toothed portion  148  which engages said edge  174 . 
     A seventh embodiment of a device for launching a projectile according to the present disclosure is indicated with reference number  80  and is represented in  FIGS. 17A-17C . Parts having the same function and structure maintain the same reference number as in the embodiments described previously and, therefore, are not described again in detail. 
       FIGS. 17A ,  17 B and  17 C show the crossbow  80  in a neutral condition, in a loaded condition and in a maximum discharge condition, respectively. 
     With respect to the crossbows described in the previous embodiments, in the crossbow  80 , the cams  171  are associated to the respective bending members  10  at one end of these. 
     To be more specific, each bending member  10  has a proximal end  101  connected to the stock  2  using an already described support  11 , and a distal end  102  associated idle to a cam  171  by means of a connection element  27 . 
     The fixed support  19  holds a tract  103  of the bending member  10  in a suitable housing, blocking its translation movements orthogonal to its preferential development direction  202 , that is, away from or close to the stock  2  in a direction  203 . 
     At most, the opposite internal walls of the fixed support  19  may, if required, have a plan view profile which is curved and divergent to each other, in order to allow said enclosed tract  103  to assume a certain degree of bending. 
     Therefore, the bending of the bending member  10  as a result of the action of the cam  171  causes the distal end  102  to move away from or close to the longitudinal axis  201  of the stock  2 , while the tract  103  remains steady. 
     Note that, in this case, the bending member  10  is allowed, at least partially, a degree of freedom of translation, along the preferential development direction  202 , with respect to the respective connection element  27 . 
     This latter embodiment is advantageous from the point of view of the reduced overall length and the rearing of the center of mass for same loading length. 
     To summarize the various different methods presented to associate a bending member  10  to the stock  2 , means for associating a bending member  10  to the stock  2  are generally envisaged, these associating means being apt to prevent a translation of a first tract of the bending member  10  in a direction  203  orthogonal to the stock  2 . 
     In certain embodiments, the associating means additionally allow this first tract to bend, and/or to make an angular displacement (that is, a rotation) with respect to the stock  2 , and/or a translation in the preferential development direction  202  of the bending member  10 . 
     In other embodiments, at least one tract of a bending member  10  is constrained in a rigid manner to the stock  2 , that is, a portion or tract of a bending member  10  is tightly joined to the stock  2 , so as to substantially prevent any movement (translation, rotation and/or flexion movement) of the tract itself with respect to the stock  2 . In other words, in said embodiments the associating means are apt to join a tract of a bending member  10  to the stock  2  in such a way as to prevent said tract from translating, with respect to the stock  2 , along said preferential development direction  202  and along a direction  203  orthogonal to said preferential development direction  202 , and from performing an angular displacement with respect to the stock  2 . 
     In the embodiments illustrated in  FIGS. 2A to 8A , these associating means comprise supports  11  pivoted to the stock  2  and block both a first and a second tract of the bending member, preventing them from carrying out said translation in a direction  203  orthogonal to the stock  2 ; to be more specific, said first and second tracts coincide with the ends  101 ,  102  of the bending member  10 . 
     In another embodiment, illustrated in  FIGS. 9A to 10 , said associating means comprise a wire  76  or other flexible retaining member, which in case, cooperates with sidebars  75  joined to the stock  2  in order to block two end tracts  101  and  102 . 
     In yet another embodiment, illustrated in  FIGS. 11A to 11D , the associating means comprise a first sidebar and a second sidebar, associated to the stock  2  which, in the example, are a stem  15  constrained to the stock  2  near the latter and a support  14  positioned on the outside of the bending member  10  with respect to the stock  2 . These means may be envisaged to block end tracts  101 ,  102  or an intermediate tract  103 . 
     Obviously, it is possible to combine these associating means in order to associate a same bending member  10  to the stock  2 . 
     In a further embodiment illustrated in  FIGS. 17A to 17C , a fixed support  19  is envisaged, apt to block a translation movement of a first tract  103  of the bending member  10  in a direction  203  orthogonal to the stock  2 , and also block an angular displacement (that is, a rotation) of said first tract  103  with respect to the stock  2 . However, the fixed support  19  may permit the bending of the tract  103 . 
     In this latter embodiment, it is further envisaged that a second tract  102  of the bending member  10  is associated idle to a respective cam  171 , in particular, by means of a connection element  27 . 
     The principles at the basis of the present disclosure may be applied not just to a crossbow, but also to a bow, to a catapult, or to an apparatus for launching model aircraft or unmanned aerial vehicles or for devices for experimental purposes. 
     The examples set forth above are provided to give those of ordinary skill in the art a complete disclosure and description of how to make and use the embodiments of the device for launching a projectile or a launch object in general, and are not intended to limit the scope of what the inventors regard as their disclosure. Modifications of the above-described modes for carrying out the disclosure may be used by persons of skill in art, and are intended to be within the scope of the following claims. All patents and publications mentioned in the specification may be indicative of the levels of skill of those skilled in the art to which the disclosure pertains. All references cited in this disclosure are incorporated by reference to the same extent as if each reference had been incorporated by reference in its entirety individually. 
     The entire disclosure of each document cited (including patents, patent applications, journal articles, abstracts, laboratory manuals, books, or other disclosures) in the Background, Summary, and Description is hereby incorporated herein by reference. 
     It is to be understood that the disclosure is not limited to particular devices, which can, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the content clearly dictates otherwise. The term “plurality” includes two or more referents unless the content clearly dictates otherwise. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the disclosure pertains. 
     A number of embodiments of the disclosure have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the present disclosure. Accordingly, other embodiments are within the scope of the following claims.