Patent Publication Number: US-9885535-B2

Title: Compound bows with modified cams

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation in part of U.S. patent application Ser. No. 12/431,435 filed Apr. 28, 2009, the entire disclosure of which is incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     This invention relates generally to the field of compound archery bows. In particular, certain embodiments of the invention relate to single cam type compound archery bows. 
     BACKGROUND 
     Compound archery bows typically have a bowstring, on which an arrow may be flocked, along with one or more portions of cable other than the bowstring extending between the limbs of the bow. Such cable portions, sometimes referred to as “power cables”, are generally located at least partly within or close to an operating plane of the bowstring. The power cables thus interfere with shooting arrows. 
     In order to provide adequate room for the arrow, it is conventional practice to mount a cable guard on the bow to engage the central portions of the power cables and to displace them laterally a sufficient distance to one side of the operating plane of the bowstring to avoid interference with an arrow. One drawback associated with conventional cable guards is that, in displacing the center of a power cable laterally from its straight line position, they introduce a lateral component to the force exerted by the power cable against the limbs. This lateral torque not only decreases the accuracy of arrow flight, but also causes twisting of the limbs, cams, wheels and/or handle, and thereby contributes adversely to shortening their useful life. Conventional cable guards also cause the power cables to feed on and off of the cams and wheels at an angle. This may sometimes lead to the power cables becoming dislodged from the cams and/or wheels. 
     There exist a number of prior art systems, other than cable guards, for preventing the power cables from interfering with the shooting of arrows from compound bows. Examples include U.S. Pat. No. 5,623,915 to Kulacek and U.S. Pat. No. 6,729,320 to Terry, and U.S. patent application Ser. No. 11/968,459 to Evans. 
     The inventor has determined a need for further systems which do not require cable guards to prevent power cables from interfering with the flight of arrows. 
     SUMMARY 
     One aspect of the invention provides a compound bow comprising a handle portion having a first limb and a second limb extending outwardly therefrom, a wide body cam assembly pivotally coupled to the first limb near an outer end thereof, and a dual wheel assembly pivotally coupled to the second limb near an outer end thereof. The wide body cam assembly comprises a main sheave and a collector sheave located on opposite sides of a cable sheave. The main sheave is spaced apart from the cable sheave by a first distance sufficient to permit arrows knocked on a bowstring portion extending between the main sheave and the feed out sheave to be fired from the bow free from interference by a cable extending within a plane defined by the cable sheave without the use of a cable guard. The dual wheel assembly comprises a feed out sheave and a take in sheave separated by a second distance which is larger than the first distance. The feed out sheave is positioned substantially within a plane defined by the main sheave. 
     Another aspect of the invention provides a wide body cam assembly for a compound bow. The wide body cam assembly comprises a main sheave and a collector sheave located on opposite sides of a cable sheave. The main sheave is spaced apart from the cable sheave by a distance of at least a radius of an arrow and its fletching. 
     Another aspect of the invention provides a dual wheel assembly for a compound bow. The dual wheel assembly comprises a feed out sheave and a take in sheave separated by a spacer. The spacer is configured such that the feed out sheave and the take in sheave are separated by a distance of at least twice a radius of an arrow and its fletching. 
     Another aspect of the invention provides a cam assembly for a compound bow. The cam assembly comprises a main sheave and a collector sheave located on opposite sides of a cable sheave. A pair of protrusions extend laterally outwardly from the main sheave and the collector sheave. The protrusions are adapted to be rotatably received in a pair of sockets defined in an end portion of a limb of the compound bow, such that no axle is required for coupling the cam assembly to the bow. 
     In addition to the exemplary aspects and embodiments described above, further aspects and embodiments will become apparent by reference to the drawings and by study of the following detailed descriptions. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       In drawings which illustrate non-limiting example embodiments of the invention: 
         FIG. 1  shows an example of a prior art compound bow; 
         FIG. 2  shows a compound bow according to one embodiment of the invention; 
         FIG. 2A  is a rear schematic view of the wheel assembly of the bow of  FIG. 2 ; 
         FIG. 2B  is a rear schematic view of the cam assembly of the bow of  FIG. 2 ; 
         FIG. 2C  is a rear schematic view of the bowstring and power cables of the bow of  FIG. 2  illustrating how arrows may be knocked on the bowstring; 
         FIG. 3  shows a compound bow according to another embodiment of the invention; 
         FIG. 4  shows the compound bow of  FIG. 3  in a drawn position; 
         FIG. 5  shows a cam assembly according to one embodiment of the invention; 
         FIGS. 6A-6C  are rear views of cam assemblies according to embodiments of the invention; 
         FIG. 7  shows a wheel assembly according to one embodiment of the invention; 
         FIG. 8  is a side view of the wheel assembly of  FIG. 7  attached to a bow limb; 
         FIG. 9  shows a wheel assembly according to another embodiment of the invention; 
         FIGS. 10A-10D  show perspective views of a wheel assembly and a cam assembly according to another embodiment of the invention; 
         FIGS. 11A-11D  show perspective views of a wheel assembly and a cam assembly according to another embodiment of the invention; and, 
         FIGS. 11E-11F  show moveable modules for attaching to the wheel assembly and cam assembly of  FIGS. 11A-11D . 
     
    
    
     DESCRIPTION 
     Throughout the following description specific details are set forth in order to provide a more thorough understanding to persons skilled in the art. However, well known elements may not have been shown or described in detail to avoid unnecessarily obscuring the disclosure. Accordingly, the description and drawings are to be regarded in an illustrative, rather than a restrictive, sense. 
       FIG. 1  depicts an example of a prior art single cam compound bow  10 , such as disclosed in U.S. Pat. No. 5,782,229 to Evans et al., which is hereby incorporated herein by reference in its entirety. Bow  10  has a handle portion  20  to which are attached first and second resiliently deformable limbs  22 ,  24 . Limb  22  is adapted to receive a pulley  26  at its outer end. Pulley  26  is free to rotate about an axis  27 . Limb  24  is adapted to pivotally receive a cam assembly  30  at its outer end. Cam assembly  30  is mounted on an axle  28  and pivots about an axis  29 . Limbs  22  and  24  may be adjustably and removably mounted to handle  20  so that the force required to draw bow  10  (the “draw weight”) can be changed by adjusting the angles at which limbs  22  and  24  extend from handle portion  20  and/or by selecting limbs  22  and  24  which have a desired degree of rigidity. 
     Cain assembly  30  comprises three parallel sheaves (not shown in  FIG. 1 ), which may be referred to as a main sheave, a collector sheave and a cable sheave. The cable sheave is typically located between the main sheave and the collector sheave. Each sheave may comprise a body having varying profiles, as described for example, in U.S. Pat. No. 5,782,229. A cable  40  extends from one or more attachment points  42  near the outer end of limb  22  or on pulley  26  to the front side of the cable sheave of cam assembly  30 . A bowstring  50  has a first portion  50 A extending from the back side of the collector sheave of cam assembly  30  to the front side of pulley  26 . Bowstring  50  also has a second portion  50 B which continues around pulley  26  and extends from the back side of pulley  26  to the back side of the main sheave of cam assembly  30 . To shoot an arrow with bow  10 , an arrow  61  (shown in dashed outline in  FIG. 1 ) may be flocked on bowstring portion  50 B at nock point  60 , drawn back on bowstring portion  50 B, and released. A cable guard  62  extends rearwardly from handle portion  20  to displace bowstring portion  50 A and cable  40  and keep them from interfering with the shooting of arrow  61 . When bowstring portion  50 B is drawn rearwardly at nock point  60 , cam assembly  30  rotates in the direction indicated by arrow  64 . As cam assembly  30  rotates, cable  40  is wound onto the cable sheave thereby drawing the outer ends of limbs  22  and  24  together. At the same time, bowstring  50  is fed out by the collector sheave and the main sheave of cam assembly  30 . 
       FIG. 2  shows a single cam compound bow  100  according to one embodiment of the invention. Bow  100  is similar to bow  10  of  FIG. 1 , except that pulley  26  has been replaced with a dual wheel assembly  110  according to one embodiment of the invention, and cam assembly  30  has been replaced with a wide body cam assembly  130  according to another embodiment of the invention. Bow  100  may also differ from some prior art bows in that end portions  23  and  25  of limbs  22  and  24 , respectively, may be somewhat larger on bow  100  than on some prior art bows to accommodate dual wheel assembly  110  and wide body cam assembly  130 , respectively, as discussed below. 
     Other differences between bow  100  and various types of prior art bows may also exist. For example, an arrow rest portion  21  on handle portion  20  may be somewhat wider on bow  100  than on some prior art bows to accommodate the modified flocking position of bow  100 , as discussed below. 
     As one skilled in the art will appreciate, dual wheel assembly  110  and wide body cam assembly  130 , or variations thereof, could be used with a variety of different types of compound bow. For example,  FIG. 3  shows a compound bow  100 A with split limbs  22 A and  24 A which includes dual wheel assembly  110  and wide body cam assembly  130 .  FIG. 4  shows bow  100 A of  FIG. 3  in a drawn position, wherein bowstring portion  50 B has been pulled back at nock point  60 , causing wheel assembly  110  to be rotated, counterclockwise and cam assembly  130  to be rotated clockwise (from the perspective of a viewer of  FIG. 4 ) from the orientations shown in  FIG. 3 . Other types of compound bows may also be equipped with wheel assemblies and/or cam assemblies according to various embodiments of the invention. 
       FIGS. 2A and 2B  schematically illustrate rear views of dual wheel assembly  110  and wide body cam assembly  130 , respectively. The terms “rear”, “back” and the like are used herein to refer to the direction opposite to that in which an arrow fired from bow  100  travels. Conversely, the terms “forward”, “front” and the like are used to refer to the direction in which an arrow fired from bow  100  travels. 
     As shown in  FIG. 2A , dual wheel assembly  110  comprises a feed out sheave  112  and a take in sheave  114  separated by a spacer  116 . Each sheave  112 ,  114  of wheel assembly  110  comprises a body having a peripheral profile and a groove extending around the peripheral profile. Feed out sheave  112  and take in sheave  114  are preferably parallel to one another. Dual wheel assembly  110  may be mounted on an axle  120  extending through end portion  23  of limb  22  in some embodiments. In other embodiments, dual wheel assembly  110  may be mounted without an axle by providing protrusions  122  (not shown in  FIG. 2A ) on either side thereof which are received in bearings  124  (not shown in  FIG. 2A ) mounted in end portion  23  of limb  22 , as described below with reference to  FIGS. 7 and 8 . 
     As shown in  FIG. 2A , cable  40  may have a split portion at an end thereof, with the two sides of the split portion of cable  40  attached to the ends of axle  120  which may extend outwardly from end portion  23  of limb  22 . In embodiments without an axle, the two sides of the split portion of cable  40  may be attached to other features (not shown) extending outwardly from end portion  23  of limb  22 , or may be attached to housings (not shown) of bearings  124  extending slightly inwardly from end portion  23  of limb  22  on either side of dual wheel assembly  110 . In embodiments where the two sides of the split portion of cable  40  are attached to the bearing housings, cable  40  may have a larger split portion to avoid the sides of the split portion of cable  40  from rubbing against sheaves  112  and  114  of dual wheel assembly  110 . 
     Bowstring portion  50 B may be wound around the back side of feed out sheave  112  and anchored thereto, and bowstring portion  50 A may be wound around the front side of take in sheave  114  and anchored thereto. As shown in  FIGS. 2A and 7 , an intermediate portion  50 C may connect bowstring portions  50 A and  50 B in embodiments where bowstring  50  is continuous. When bow  100  is in its undrawn position as shown in  FIG. 2 , bowstring portion  50 A is only wound around a relatively small portion of the circumference of take in sheave  114  and bowstring portion  50 B is wound around a substantial portion of feed out sheave  112 . In some embodiments, bowstring portion  50 A may, for example, be wound approximately 20 degrees around the circumference of take in sheave  114  when bow  100  is in its undrawn position. The angular extent to which bowstring portion  50 A is wound around take in sheave  114  will typically depend on the draw length of bow  100  and the radius of take in sheave  114 . In some embodiments, bowstring portion  50 B may, for example, be wound approximately 280 degrees around feed out sheave  112  when bow  100  is in its undrawn position. The angular extent to which bowstring portion  50 B is wound around feed out sheave  112  will typically depend on the draw length of bow  100  and the radius of feed out sheave  112 . 
     As dual wheel assembly  110  rotates when bow  100  is being drawn, bowstring portion  50 A winds onto take in sheave  114  and bowstring portion  50 B winds off of feed out sheave  112 , such that when bow  100  is in a drawn position (see  FIG. 4 ), bowstring portion  50 A is wound around a substantial portion of the circumference of take in sheave  114  and bowstring portion  50 B is only wound around a relatively small portion of feed out sheave  112 . Bowstring portion  50 A may, for example, be wound approximately 280 degrees around the circumference of take in sheave  114  when bow  100  is in its fully drawn position. Bowstring portion  50 B may, for example, be wound approximately 20 degrees around the circumference of feed out sheave  112  when bow  100  is in its fully drawn position. Bowstring portions  50 A and  50 B may be separate elements, or bowstring  50  may be continuous with portions  50 A and  50 B connected by an intermediate portion  50 C extending across spacer  116 , as described below with reference to  FIGS. 7 to 9 . 
     As shown in  FIG. 2B , cam assembly  130  comprises a main sheave  132  and a collector sheave  134  and cable sheave  136  are preferably parallel to one another. Each sheave  132 ,  134 ,  136  of cam assembly  130  comprises a body having a peripheral profile and a groove extending around the peripheral profile. Spacers  138  and  139  are provided to separate main sheave  132  and collector sheave  134  from cable sheave  136  by distances D 1  and D 2 , respectively. Cam assembly  130  may be mounted with an axle  140  extending through end portion  25  of limb  24  in some embodiments. In other embodiments, cam assembly  130  may be mounted without an axle by providing protrusions  142  (not shown in  FIG. 2B , see  FIGS. 5 and 6A-6C ) on either side thereof which are received in bearings  144  (not shown in  FIG. 2B , see  FIGS. 6A-6C ) mounted in end portion  25  of limb  24 , as described below. 
     Bowstring portions  50 B and  50 A may be wound around the back sides of main and collector sheaves  132  and  134 , respectively, and anchored thereto. Cable  40  may be wound around the front side of cable sheave  136  and anchored thereto. When the bow is in its undrawn position (see  FIGS. 2 and 3 ), cable  40  is only wound around a relatively small portion of the circumference of cable sheave  136 , and bowstring portions  50 B and  50 A are wound around substantial portions of main and collector sheaves  132  and  134 , respectively. When the bow is in a drawn position (see  FIG. 4 ), cable  40  is wound around a substantial portion of the circumference of cable sheave  136 , and bowstring portions  50 B and  50 A are only wound around relatively small portions of main and collector sheaves  132  and  134 , respectively. 
     As shown in  FIG. 5 , cam assembly  130  may comprise a post  133  located at or near the end of the groove in main sheave  132  for anchoring bowstring portion  50 B in some embodiments. Cam assembly  130  may also comprise a post  135  located at or near the end of the groove in collector sheave  134  for anchoring bowstring portion  50 A and a post  137  located at or near the end of the groove in cable sheave  136  for anchoring cable  40 . In some embodiments, multiple posts (not shown) may be provided near the end of the groove in main sheave  132  for providing a plurality of anchor points for bowstring portion  50 B. Likewise, multiple posts (not shown) may be provided near the end of the groove in collector sheave  132  for providing a plurality of anchor points for bowstring portion  50 A and multiple posts (not shown) may be provided near the end of the groove in cable sheave  136  for providing a plurality of anchor points for cable  40 . In other embodiments, other structures may be provided for anchoring bowstring portions  50 B and  50 A and cable  40 . In some embodiments, cam assembly  130  may comprise a cable anchor system such as disclosed, for example, in U.S. Pat. No. 4,967,721 to Larson, which is hereby incorporated by reference herein. 
     Wheel assembly  110  and cam assembly  130  may be configured such that feed out sheave  112  and main sheave  132  are substantially coplanar. Feed out sheave  112  and main sheave  132  define an operating plane for bowstring portion  50 B. Cable sheave  136  of cam assembly  130  defines an operating plane for cable  40  which may be parallel to the operating plane for bowstring portion  50 B and separated therefrom by distance D 1 . The spacing between main sheave  132  and cable sheave  136  ensures that cable  40  remains far enough away from the operating plane of bowstring portion  50 B to avoid interfering with the shooting of arrows. The need for a cable guard is thus avoided. 
     Distance D 1  is selected such that arrows nocked on bowstring portion  50 B may be fired from bow  100  free from interference by cable  40 , without requiring a cable guard. For example, as shown in  FIG. 2C , for an arrow  61 A having three-vaned fletching with a radius R A , D 1  may be at least 0.5×R A  in some embodiments. Similarly, in some embodiments, for an arrow  61 B having four-vaned fletching with a radius R B , D 1  may be at least 0.707×R B . In some embodiments, D 1  may be at least equal to a radius of an arrow and its notching to be fired by bow  100 , such that the arrow may be knocked on bowstring portion  50 B with the vanes of its fletching oriented at any angle and fired without interference by cable  40 . In some embodiments D 1  may, for example, be at least ⅝″ (1.6 cm). 
     The operating plane of bowstring portion  50 B may thus be offset from the lateral center of bow  100 . As noted above, bow  100  preferably comprises an arrow rest portion  21  which is large enough to extend through the operating plane of bowstring portion  50 B to support an arrow nocked thereon. 
     Take in sheave  114  and collector sheave  134  may also be substantially co-planar. The operating plane of bowstring portion  50 A may thus be separated from cable sheave  136  by distance D 2 . 
     In some embodiments, distance D 2  is selected to be equal to distance D 1 , such that main sheave  132  and collector sheave  134  are equally separated from cable sheave  136  on either side thereof. Similarly, feed out sheave  112  and take in sheave  114  may be symmetrically positioned on wheel assembly  110 . Such a configuration may balance the forces on wheel assembly  110  and cam assembly  130  and thus minimize twisting of limbs  22  and  24 . For example, in embodiments where bowstring portions  50 A and  50 B are part of a continuous bowstring  50 , bowstring  50  tends to “self center”, such that the forces exerted by bowstring portions  50 A and  50 B tend to be substantially equal to each other. 
     In other embodiments, D 1  and D 2  may not be equal. Such embodiments may be suitable, for example, if the forces exerted by bowstring portions  50 A and  50 B are not equal, due to differences in the compositions and/or lengths of bowstring portions  50 A and  50 B or other factors. In such embodiments, D 1  and D 2  may be selected based on the ratio of the forces exerted by bowstring portions  50 A and  50 B to minimize twisting of limbs  22  and  24 . 
     Wheel assembly  110  and cam assembly  130  may also be configured to ensure that nock  60  moves linearly, or at least substantially linearly, as bow  100  is fired (sometimes referred to as a “flat nock”). For example, a flat nock may be achieved by selecting appropriate peripheral profiles for the sheaves of the cam assembly, as described in U.S. Pat. No. 5,782,229. 
       FIGS. 6A, 6B and 6C , show cam assemblies  130 A,  130 B and  130 C, respectively, according to example embodiments of the invention. Each of cam assemblies  130 A,  130 B and  130 C comprises a pair of protrusions  142  extending laterally outwardly therefrom. Protrusions  142  are received in bearings  144  mounted in sockets defined in end portion  25  of limb  24 , such that each cam assembly  130 A/ 130 B/ 130 C is rotatable about an axis  141 . The need for an axle is thus eliminated. In other embodiments, bushings not shown) may be provided in place of bearings  144 . 
     Cam assemblies  130 A,  130 B and  130 C (collectively cam assemblies  130 ) are all the same except for the configuration of cable sheaves  136 A,  136 B and  136 C. As discussed in U.S. Pat. No. 5,782,229, the draw force curve of a compound bow may be altered by changing the configuration of the cable sheave. In some embodiments, removable modules (not shown) similar to those described in the above noted U.S. Pat. No. 5,782,229 may be provided for altering the profile of cable sheave  136  and producing varying draw force curves. In some embodiments, cable sheave  136 , or a portion thereof, may be rotatable with respect to cam assembly  130  in a manner similar to that described in U.S. Pat. Nos. 4,686,955 and 4,774,927 to Larson, which are hereby incorporated by reference herein, in order to produce varying draw force curves. 
     The range of variation of the cable sheave disclosed in U.S. Pat. No. 5,782,229 and other prior art compound bows is limited by the presence of an axle through the cam assembly. By providing protrusions  142  instead of an axle, cam assemblies according to certain embodiments of the invention may be provided with a wider range of cable sheave profiles. For example, cable sheaves of cam assemblies of some embodiments may be configured to be very close to or along axis  141  at some points around the peripheral profile thereof (as illustrated by cable sheave  136 B of  FIG. 6B ), or even configured to be “inside” of axis  141  at some points (as illustrated by cable sheave  136 C of  FIG. 6C ). Cam assemblies  130  may thus provide compound bows with draw force curves having let off values ranging anywhere up to and including 100 percent. However, as one skilled in the art will appreciate, 100 percent let off may not be desirable in many embodiments, but certain embodiments of the invention permit the design of a compound bow having a let off as close to 100 percent as desired. For example, compound bows according to some embodiments may have a let off of at least 99 percent. 
     Dual wheel assembly  110  may also be rotatably mounted to limb  22  without the use of an axle. As shown in  FIGS. 7 and 8 , wheel assembly  110  may comprise a pair of protrusions  122  extending laterally outwardly therefrom. Protrusions  122  are received in bearings  124  mounted in sockets defined in end portion  23  of limb  22 , such that wheel assembly is rotatable about an axis. The need for an axle is thus eliminated. 
     With reference to  FIGS. 7 and 8 , each sheave  112 ,  114  of dual wheel assembly  110  comprises a body having a peripheral profile and a groove extending around the peripheral profile. In the illustrated embodiment, the peripheral profile of each of feed out sheave  112  and take in sheave  114  is partially circular, each having a cut out portion  118  such that the peripheral profile defines a circular arc. In other embodiments, either or both of feed out sheave  112  and take in sheave  114  may have non-circular peripheral profiles. For example, in some embodiments the peripheral profile of either or both of feed out sheave  112  and take in sheave  114  may comprise a cut out potion defining an elliptical arc. 
     In some embodiments, cut out portions  118  of sheaves  112 ,  114  are angularly offset from each other such that the radius of the peripheral profile of each sheave  112 ,  114  remains relatively constant at the point at which each bowstring portion  50 B,  50 A contacts the respective sheave  112 ,  114  throughout the range of motion of dual wheel assembly  110 . For example, in some embodiments, cut out portions  118  may be angularly offset from each other by an angle ranging from 60 to 180 degrees. The angular extent of the arc portion of the peripheral profile of each sheave  112 ,  114  may, for example, range from about 220 to 300 degrees in some embodiments. In some embodiments, the angular extent of the arc portion of the peripheral profile of each sheave  112 ,  114  may, for example, be selected based on the size and shape of main sheave  132 . 
     In the illustrated example, each sheave  112 ,  114  has an inwardly angled portion  112 A,  114 A, respectively, extending into cut out portion  118 . An anchor post  113 ,  115  is located at or near the end of each respective inwardly angled portion  112 A,  114 A, for anchoring the respective bowstring portion  50 B,  50 A. As noted above, bowstring  50  may be continuous or may comprise separate parts. In embodiments where bowstring  50  is continuous, bowstring  50  may comprise an intermediate portion  50 C extending between take in sheave  114  and feed out sheave  112  around or across spacer  116 . In such embodiments, bowstring  50  may wrap around each of posts  113  and  115  to prevent bowstring  50  from slipping relative to wheel assembly  110 , such that intermediate portion  50 C does not move with respect to wheel assembly  110  as the bow is fired. Also, spacer  116  may optionally define a groove (not shown) therein for receiving intermediate portion  50 C of bowstring  50 . In embodiments where bowstring  50  is continuous, bowstring portion  50 A may be anchored to collector sheave  134 , extend upward to and partially around take in sheave  114 , wrap around post  115 , continue across and around spacer  116  as intermediate portion  50 C, wrap around post  113 , continue around feed out sheave  112  as bowstring portion  50 B, and extend down to be anchored to main sheave  132 . In embodiments where bowstring  50  is in two parts, intermediate portion  50 C may be omitted, and bowstring portion  50 A may terminate at post  115  and bowstring portion  50 B may terminate at post  113 , for example. 
       FIG. 9  shows a dual wheel assembly  110 A according to another embodiment of the invention. Dual wheel assembly  110 A is the same as dual wheel assembly  110  of  FIGS. 7 and 8  except that dual wheel assembly  110 A has a single anchor post  117  extending outwardly from a central portion of spacer  116  instead of posts  113  and  115 . Intermediate portion  50 C of bowstring  50  may have two knots  50 D and  50 E tied therein, and the individual strands which make up bowstring  50  may be separated into two groups between knots  50 D and  50 E, and the groups of strands may be placed on either side of post  117 . 
     Dual wheel assembly  110  and wide body cam assembly  130  may be constructed using a variety of techniques. In some embodiments dual wheel assembly  110  and wide body cam assembly  130  may each be machined from a block of metal such as, for example, aluminum. In other embodiments, dual wheel assembly  110  and wide body cam assembly  130  may be formed by injection molding using a high strength plastic or other polymeric material. In still other embodiments, the some or all of the various sheaves and spacers of dual wheel assembly  110  and wide body cam assembly  130  may be individually formed (either through machining or injection molding), and the individually formed parts may then be bolted or otherwise securely fastened together. 
       FIG. 10A  shows a dual wheel assembly  1010  comprising a feed out sheave  1012  and a take in sheave  1014  separated by a spacer  1016 .  FIG. 10B  shows the dual wheel assembly  1010  of  FIG. 10A  from a different angle. Feed out sheave  1012  and take in sheave  1014  are preferably parallel to one another. In the example shown in  FIGS. 10A-B , feed out and take in sheaves  1012  and  1014  each have a peripheral profile defining a circular arc. Wheel assembly  1010  comprises an anchor post  1013 ,  1015  located near the end of the groove in each of the respective feed out and take in sheaves  1012  and  1014  for anchoring the respective bowstring portion (not shown in  FIGS. 10A and 10B ). 
       FIG. 10C  shows a cam assembly  1030  comprising a main sheave  1032  and a collector sheave  1034  located on opposite sides of a cable sheave  1036 , and separated from cable sheave  1036  by spacers  1038  and  1039 .  FIG. 101 ) shows the cam assembly  1030  of  FIG. 10C  from a different angle. Main sheave  1032 , collector sheave  1034  and cable sheave  1036  are preferably parallel to one another. Cam assembly  1030  comprises a plurality of posts  1033  located near the end of the groove in main sheave  1032  for anchoring the bowstring portion (not shown in  FIGS. 10C and 10D ) to be wound around main sheave  1032 . Cam assembly  1030  also comprises a plurality of posts  1035  located near the end of the groove in collector sheave  1034  for anchoring the bowstring portion (not shown in  FIGS. 10C and 10D ) to be wound around collector sheave  1034 , and a post  1037  located near the end of the groove in cable sheave  1036  for anchoring the cable (not shown in  FIGS. 10C and 10D ). 
       FIGS. 11A and 11B  show a dual wheel assembly  1110  comprising a feed out sheave  1112  and a take in sheave  1114  separated by a spacer  1116 .  FIG. 11B  shows the dual wheel assembly  1110  of FIG. HA from a different angle. Feed out sheave  1112  and take in sheave  1114  are preferably parallel to one another. In the example shown in  FIGS. 11A-11B , feed out and take in sheaves  1112  and  1114  each have a peripheral profile defining an elliptical arc, and feed out sheave  1112  is larger than take in sheave  1114 . Take in sheave  1114  is mounted on a side portion of spacer  1116 , and the arc defined by the peripheral profile of take in sheave  1114  has an angular extent of less than 90 degrees. Wheel assembly  1110  comprises an anchor post  1113  located near the end of the groove in feed out sheave  1112 , and an anchor post  1115  located near the end of the groove in take out sheave  1114  for anchoring the respective bowstring portions (not shown in  FIGS. 11A and 11B ). Wheel assembly  1110  also comprises a protrusion having a plurality of holes  1120  defined therein for receiving a removable stop (not shown), which can act to halt rotation of the wheel assembly  1110  when the stop contacts the limb of the bow. Wheel assembly  1110  has a pair of slots  1111  defined in the spacer  1116  for adjustably mounting a removable module  1121 , as shown in  FIG. 11E , for example by screws or the like inserted through holes in removable module  1121  and into slots  1111 . Removable module  1121  has a groove in the peripheral profile thereof, such that when removable module  1121  is mounted on the wheel assembly  1110 , the groove in removable module  1121  extends the take out sheave  1114 , for example to have an angular extent of greater than 90 degrees, or greater than 180 degrees. 
       FIG. 11C  shows a cam assembly  1130  comprising a main sheave  1132  and a collector sheave  1134  located on opposite sides of a cable sheave  1136 , and separated from cable sheave  1136  by spacers  1138  and  1139 .  FIG. 11D  shows the cam assembly  1130  of  FIG. 11C  from a different angle. Main sheave  1132 , collector sheave  1134  and cable sheave  1136  are preferably parallel to one another. Cable sheave  1136  is mounted on a side portion of spacer  1138 , and the elliptical arc defined by the peripheral profile of cable sheave  1136  has an angular extent of less than 90 degrees. Cam assembly  1130  comprises a post (not shown in  FIGS. 11C and 11D , but located in an analogous position with respect to main sheave  1132  as post  1113  is located with respect to feed out sheave  1112  shown in  FIG. 11A ) located near the end of the groove in main sheave  1132  for anchoring the bowstring portion (not shown in  FIGS. 10C and 10D ) to be wound around main sheave  1132 . Cam assembly  1130  also comprises a hole  1135  defined therein near the collector sheave  1134  for receiving a removable anchor post (not shown) for anchoring the bowstring portion (not shown in  FIGS. 11C and 11D ) to be wound around collector sheave  1134 , and a post  1137  located near the end of the groove in cable sheave  1136  for anchoring the cable (not shown in  FIGS. 10C and 10D ). Cam assembly  1130  also comprises a protrusion having a plurality of holes  1140  defined therein for receiving a removable stop (not shown), which can act to halt rotation of the cam assembly  1130  when the stop contacts the limb of the bow. Cam assembly  1130  has a pair of slots  1131  defined in the spacer  1138  for adjustably mounting a removable module  1141 , as shown in  FIG. 11F , for example by screws or the like inserted through holes in removable module  1141  and into slots  1131 . Removable module  1141  has a groove in the peripheral profile thereof, such that when removable mounted  1141  is mounted on the cam assembly  1130 , the groove in removable module  1141  extends the cable sheave  1136 , for example to have an angular extent of greater than 90 degrees, or greater than 180 degrees. 
     While a number of exemplary aspects and embodiments have been discussed above, those of skill in the art will recognize certain modifications, permutations, additions and sub-combinations thereof. For example:
     a) in the illustrated embodiments, the dual wheel assembly is mounted on the “upper” limb of the bow with respect to the orientation of the bow&#39;s handle) and the wide body cam assembly is mounted on the lower limb of the bow. The locations of the dual wheel assembly and the wide body cam assembly could be exchanged in other embodiments.   b) The bodies of the sheaves of the wheel assembly and/or the cam assembly may have a number of openings therethrough, as shown in the illustrated embodiments, to reduce the weights thereof. The bodies of the sheaves could be generally solid in other embodiments.   

     It is therefore intended that the following appended claims and claims hereafter introduced are interpreted to include all such modifications, permutations, additions and sub-combinations as are within their true spirit and scope.