Crossbow with spiral wound cam system

Abstract

A crossbow includes a frame, first and second limbs, first and second cams, a drawstring, and first and second power cables. The frame includes a first side and a second side. The frame defines a projectile axis. The first limb is coupled to the first side and the second limb coupled to the second side. The first cam is coupled to the first side and configured to rotate about a first cam axis that is substantially parallel to the projectile axis. The second cam is coupled to the second side and configured to rotate about a second cam axis that is substantially parallel to the projectile axis. The drawstring is engaged with the first cam and the second cam. The first power cable is engaged with the first cam and the first limb. The second power cable engaged with the second cam and the second limb.

1 - 20 . (canceled) 
     
     
         21 . A crossbow, comprising:
 a frame including a first frame side and a second frame side, the frame defining a substantially horizontal projectile axis;   a first flexible limb coupled to the first frame side and a second flexible limb coupled to the second frame side;   a first cam operatively engaged with the first flexible limb and configured to rotate about a first cam axis that is non-perpendicular to the projectile axis;   a second cam operatively engaged with the second flexible limb and configured to rotate about a second cam axis that is non-perpendicular to the projectile axis,   a drawstring engaged with the first cam and the second cam; and   a first power cable engaged with the first cam and operatively engaged with the first flexible limb; and   a second power cable engaged with the second cam and the second flexible limb.   
     
     
         22 . The crossbow of  claim 21 , wherein the first cam includes a smaller diameter portion and a larger diameter portion that respectively include a groove configured to receive one of the first power cable and the drawstring. 
     
     
         23 . The crossbow of  claim 22 , wherein the larger diameter portion and smaller diameter portions of the first cam and the second cam are substantially coaxial. 
     
     
         24 . The crossbow of  claim 22 , wherein the first power cable is engaged with the smaller diameter portion of the first cam and the drawstring is engaged with the larger diameter portion of the first cam. 
     
     
         25 . The crossbow of  claim 21 , wherein, during operation of the crossbow as the drawstring moves from an undrawn position to a drawn position, the drawstring is configured to wrap around at least a portion of the first cam and the second cam. 
     
     
         26 . The crossbow of  claim 21 , wherein, during operation of the crossbow as the crossbow moves from an undrawn position to a drawn position, the first power cable is configured to wrap around at least a portion of the first cam and the second power cable is configured to wrap around at least a portion of the second cam. 
     
     
         27 . The crossbow of  claim 21 , further comprising:
 a first pulley rotatably coupled to the first flexible limb; and   a second pulley rotatably coupled to the second flexible limb;   wherein the drawstring is engaged with the first pulley and the second pulley.   
     
     
         28 . The crossbow of  claim 21 , wherein, during operation of the crossbow as the crossbow moves from an undrawn position to a drawn position, the drawstring is configured to wind around the first cam at least one full rotation. 
     
     
         29 . A crossbow, comprising:
 a frame including a frame side and defining a substantially horizontal projectile axis;   a flexible limb coupled to the frame side;   a drawstring operatively engaged with the flexible limb and configured to move along the projectile axis;   a power cable operatively engaged with the flexible limb;   a cam operatively coupled to the flexible limb and configured to rotate about a cam axis that is non-vertical, the cam including:
 a first portion configured to engage the drawstring; and 
 a second portion configured to engage the power cable. 
   
     
     
         30 . The crossbow of  claim 29 , further comprising:
 a limb pulley coupled to the flexible limb and configured to engage the drawstring.   
     
     
         31 . The crossbow of  claim 29 , further comprising a projectile rest positioned at a front end of the frame. 
     
     
         32 . The crossbow of  claim 29 , further comprising a drawstring holder configured to selectively receive and retain the drawstring at a rear end of the frame. 
     
     
         33 . The crossbow of  claim 29 , wherein the first portion and the second portion of the cam are coaxial. 
     
     
         34 . The crossbow of  claim 29 , wherein the first portion includes a first diameter that is larger than a second diameter of the second portion, the first portion and the second portion including each including a groove configured to receive respectively receive a portion of the drawstring and the power cable. 
     
     
         35 . The crossbow of  claim 29 , wherein, during operation of the crossbow as the drawstring moves from an undrawn position to a drawn position, the drawstring is configured to wrap around at least a portion of the cam. 
     
     
         36 . The crossbow in  claim 29 , further comprising:
 a power cable pulley coupled to the flexible limb and configured to engage the power cable.   
     
     
         37 . A crossbow, comprising:
 a frame defining a projectile axis;   a flexible limb coupled to the frame;   a drawstring operatively coupled to the flexible limb and configured to move along the projectile axis between an undrawn position and a drawn position;   a power cable engaged to the flexible limb;   a cam coupled operatively coupled to the flexible limb and configured to rotate about a cam axis that is non-perpendicular relative to the projectile axis, the cam including:
 a first, larger diameter portion configured to engage the drawstring; and 
 a second, smaller diameter portion configured to engage the power cable. 
   
     
     
         38 . The crossbow of  claim 27 , further comprising a projectile rest positioned at a front end of the frame. 
     
     
         39 . The crossbow of  claim 37 , wherein the power cable is engaged with the smaller diameter portion of the cam and the drawstring is engaged with the larger diameter portion of the cam. 
     
     
         40 . The crossbow of  claim 37 , further comprising:
 a first pulley rotatably coupled to the first flexible limb; and   a second pulley rotatably coupled to the second flexible limb;   wherein the drawstring is engaged with the first pulley and the second pulley.