Bowstring cam arrangement for compound long bow or crossbow
First Claim
1. A pulley system for a bow having a riser with at least one limb attached at one end on each side of a medial plane of the riser, the pulley system comprising:
- at least one cam pivotally mounted to a free end of each of the limbs on each side of the medial plane of the riser, each of the cams comprising a bowstring cam groove and upper and lower power cord cams located above and below the bowstring cam groove;
a bow string wound on the bowstring cam grooves and travels in the respective bowstring cam grooves to be wound and unwound therefrom; and
upper and lower power cords having distal ends attached to fixed anchor points on the bow on opposite sides of the medial plane and wound on upper and lower power cord cam grooves of the upper and lower power cord cams, respectively, such that the upper and lower power cords do not extend across the medial plane to the riser,wherein the power cord cam grooves and the bowstring cam grooves are programmed such that the draw weight on the bow string increases from full brace position to full draw position without weight drop-off.
6 Assignments
0 Petitions
Accused Products
Abstract
A compound bow or crossbow employs bowstring cams with bowstring cam grooves and power cord cam grooves. Preferably a pair of generally identical power cord cam grooves are positioned axially above and below the bowstring cam groove. The power cords are anchored to a fixed anchor point, e.g., a pylon, on the near end of the riser or on the near side of the crossbow bar or stock. The power cords do not cross over to the other limb. The reduction in the number of cam wheels and pulleys and in the number of strings or cords results in greater efficiency and higher transfer of energy from the bow to the arrow or bolt. There is no drop-off in pull weight at full draw. The bolt or arrow accelerates throughout the travel of the bowstring, resulting in significantly higher velocity.
142 Citations
22 Claims
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1. A pulley system for a bow having a riser with at least one limb attached at one end on each side of a medial plane of the riser, the pulley system comprising:
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at least one cam pivotally mounted to a free end of each of the limbs on each side of the medial plane of the riser, each of the cams comprising a bowstring cam groove and upper and lower power cord cams located above and below the bowstring cam groove; a bow string wound on the bowstring cam grooves and travels in the respective bowstring cam grooves to be wound and unwound therefrom; and upper and lower power cords having distal ends attached to fixed anchor points on the bow on opposite sides of the medial plane and wound on upper and lower power cord cam grooves of the upper and lower power cord cams, respectively, such that the upper and lower power cords do not extend across the medial plane to the riser, wherein the power cord cam grooves and the bowstring cam grooves are programmed such that the draw weight on the bow string increases from full brace position to full draw position without weight drop-off. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An energy storage system for a bow comprising:
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a riser having a medial plane; at least one limb attached to the riser on each side of the medial plane; a cam pivotally mounted to a free end of each of the limbs on each side of a medial plane of the riser, each of the cams comprising a bowstring cam groove and upper and lower power cord cams located above and below the bowstring cam groove of the cam; a bow string wound on the bowstring cam grooves and travels in the respective bowstring cam grooves to be wound and unwound therefrom; and upper and lower power cords having distal ends attached to fixed anchor points on the bow on opposite sides of the medial plane and wound on upper and lower power cord cam grooves of the upper and lower power cord cams, respectively, such that the power cords do not extend across the medial plane of the riser, wherein the power cord cam grooves and the bowstring cam grooves are programmed such that the draw weight on the bow string increases from full brace position to full draw position without weight drop-off. - View Dependent Claims (8, 9, 10, 11)
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12. A method of configuring an energy storage portion for a bow comprising the steps of:
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coupling at least one limb on each side of a medial plane of a riser; attaching at least one cam to each of the limbs, each of the cams comprising a bowstring cam groove and upper and lower power cord cams located above and below the bowstring cam groove of the cam; attaching distal ends of upper and lower power cords to fixed anchor points on the bow on opposite sides of the medial plane, so the upper and lower power cords are wound on upper and lower power cord cam grooves of the upper and lower power cord cams, respectively, such that the power cords do not extend across the medial plane of the riser; and attaching a bowstring to the bowstring cam grooves in the cams to be wound and unwound in the respective bowstring cam grooves, wherein the power cord cam grooves and the bowstring cam grooves are programmed such that the draw weight on the bow string increases from full brace position to full draw position without weight drop-off. - View Dependent Claims (13, 14, 15, 16)
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17. A bow comprising:
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a riser with at least one limb attached at one end on each side of a medial plane of the rise; at least one cam pivotally mounted to a free end of each of the limbs on each side of the medial plane of the riser, each of the cams comprising a bowstring cam groove and upper and lower power cord cams located above and below the bowstring cam groove; a bow string wound on the bowstring cam grooves and travels in the respective bowstring cam grooves to be wound and unwound therefrom; and upper and lower power cords having distal ends attached to fixed anchor points on the bow on opposite sides of the medial plane and wound on upper and lower power cord cam grooves of the upper and lower power cord cams, respectively, such that the upper and lower power cords do not extend across the medial plane to the riser, wherein the power cord cam grooves and the bowstring cam grooves are programmed such that the draw weight on the bow string increases continuously to full draw. - View Dependent Claims (18, 19, 20, 21, 22)
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Specification