Reduced length crossbow
A reduced length crossbow with a trigger located near a midpoint of the crossbow and a small included angle of the draw string when in the drawing configuration that creates a space between the draw string and the user's face. The included angle of the draw string when in the drawing configuration may be less than about 25 degrees. The trigger is typically located proximate the midpoint within about 10% of the overall length of the crossbow.
1. A crossbow comprising:
first and second flexible limbs attached to a center rail;
a trigger mounted on the center rail near a midpoint of an overall length of the crossbow;
a first cam assembly mounted to the first flexible limb by a first axle mount and rotatable around a first axis located a fixed distance from the first flexible limb, the first cam assembly comprising a first draw string journal having a first plane of rotation perpendicular to the first axis, and first upper and lower helical power cable journals on opposite sides of the first draw string journal;
a second cam assembly mounted to the second flexible limb by a second axle mount and rotatable around a second axis located a fixed distance from the second flexible limb, the second cam assembly comprising a second draw string journal having a second plane of rotation perpendicular to the second axis, and second upper and lower helical power cable journals on opposite sides of the second draw string journal;
a draw string received in the first and second draw string journals, wherein the draw string unwinds from the first and second draw string journals as it translates from a released configuration to a drawn configuration;
upper and lower power cables received in the upper and lower helical power cable journals on each of the first and second cam assemblies; and
wherein the first and second upper and lower helical power cable journals displace the upper and lower power cables along the first and second axes relative to the first and second planes of rotation, respectively, the upper and lower power cables wrap around the respective first and second upper and lower helical power cable journals, and the first and second axes move continuously toward the center rail as the draw string is moved from the released configuration to the drawn configuration, and the upper and lower power cables unwrap from the respective first and second upper and lower helical power cable journals as the draw string is moved between the drawn configuration to the released configuration.
2. The crossbow of claim 1 , wherein the trigger is located proximate the midpoint a distance about 10% of the overall length of the crossbow.
3. The crossbow of claim 1 , wherein the trigger is located proximate the midpoint a distance about 5% of the overall length of the crossbow.
4. The crossbow of claim 1 , wherein a center of gravity of the crossbow is located proximate the midpoint a distance about 10% of the overall length of the crossbow.
5. The crossbow of claim 1 , wherein the draw string in the drawn configuration comprises an included angle of less than about 25 degrees.
6. The crossbow of claim 1 , wherein the upper and lower power cables comprise:
a pair of first upper and lower power cables having first ends received in the first upper and lower helical power cable journals and second ends attached to attachment points on the crossbow; and
a pair of second upper and lower power cables having first ends received in the second upper and lower helical power cable journals and second ends attached to attachment points on the crossbow.
7. The crossbow of claim 1 , further comprising:
a cocking mechanism captured to slide on the center rail, wherein the cocking mechanism slides into engagement with the draw string in the released configuration;
a rotating member coupled to a flexible tension member attached to the cocking mechanism; and
a cocking handle configured to rotate the rotating member to retract the flexible member, whereby the cocking mechanism slides to a retracted position and moves the draw string to the drawn configuration in response to rotation of the cocking handle.
8. The crossbow of claim 1 , further comprising:
a string carrier captured by the center rail that slides forward to engage with the draw string in the released configuration and slides to a retracted position adjacent a proximal end of the crossbow that locates the draw string in the drawn configuration, the string carrier comprising a catch movable between a closed position that engages the draw string and an open position that releases the draw string; and
a cocking mechanism that retracts the string carrier to the retracted position and the draw string to the drawn configuration, wherein the trigger is configured to engage with the catch when the string carrier is in the retracted position adjacent the proximal end of the crossbow to move the catch from the closed position to the open position.
9. The crossbow of claim 8 , wherein the cocking mechanism composes:
a rotating member mounted to the center rail coupled to a flexible tension member attached to the string carrier, and
a cocking handle configured to engage with and rotate the rotating member to move the string carrier to the retracted position.
10. The crossbow of claim 9 , further comprising a torque control mechanism located in one of the cocking handle or a stock of the crossbow.
11. The crossbow of claim 8 , wherein the cocking mechanism composes:
at least one cocking rope configured to releasably engage with the string carrier to retract the string carrier and the draw string to the drawn configuration; and
a retaining mechanism on the crossbow that releasably retains the string carrier in the retracted position and the draw string in the drawn configuration independent of the at least one cocking ropes.