Parallel Cam System for Archery Bow Limb Twist Reduction
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Solution Overview
Problem
Conventional compound archery bow cam systems experience cam lean and limb twist due to unbalanced cable loads, leading to stress on axle components, fatigue, and inconsistent arrow flight, which complicates sight setup and arrow impact.
Innovation Solution
A dual bowstring track cam assembly with laterally separated and parallel tracks, centered power cable tracks, and synchronized cam operation to balance forces and reduce torque, ensuring balanced loads and straight nock travel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a single bowstring track and laterally offset power cable track are used, then the cam system can guide the bowstring and power cables, but unbalanced cable loads cause cam lean and limb twist
Solution Approach 1:
The bowstring track is divided into two separate, laterally spaced tracks (first and second bowstring tracks) that guide different portions of the bowstring. This segmentation allows the bowstring to be routed symmetrically relative to the cam assembly's longitudinal axis, balancing the loads on either side of the cam and eliminating cam lean and limb twist.
Solution Approach 2:
The power cable track is positioned asymmetrically relative to the bowstring tracks, specifically offset laterally from the central plane of the bowstring. This asymmetric positioning, combined with the symmetric dual bowstring track configuration, allows the power cable loads to be balanced against each other while maintaining proper cable routing and mechanical advantage.
2Object-affected harmful factors
If cable guards are employed to protect cables, then cable protection is improved, but cable loads become more unbalanced, exacerbating cam lean and limb twist
Solution Approach 1:
The bowstring is segmented into multiple portions (first and second portions) that are guided through separate lateral tracks. This segmentation allows each portion to be independently routed and protected, with the combined symmetric arrangement balancing loads even when cable guards are present.
Solution Approach 2:
The dual bowstring track configuration creates counterbalancing forces on either side of the cam assembly. The first and second portions of the bowstring exert equal and opposite forces that cancel out the unbalanced loads created by laterally offset power cables and cable guards, preventing cam lean and limb twist.
3Power
If conventional cam systems are used, then the bow can transfer energy from limbs to bowstring, but frequent longitudinal twisting accelerates fatigue and breakage of limbs
Solution Approach 1:
The bowstring track is segmented into two separate lateral tracks that guide different portions of the bowstring. This segmentation creates a symmetric load distribution that eliminates the longitudinal twisting forces responsible for limb fatigue and breakage, while maintaining full energy transfer capability.
Solution Approach 2:
The dual bowstring track configuration provides counterbalancing forces that eliminate the unbalanced loads causing limb twist. By positioning the tracks symmetrically on opposite sides of the cam assembly's longitudinal axis, the system creates equal and opposite forces that cancel out twisting moments, protecting limbs from fatigue.
4Ease of operation
If unbalanced cable loads are present, then the cam system can function, but sight pins must be positioned off center, complicating sight setup and arrow impact consistency
Solution Approach 1:
The bowstring track is segmented into two symmetric lateral tracks that guide different portions of the bowstring. This segmentation centers the overall bowstring path on the cam assembly's longitudinal axis, allowing sight pins to be positioned at the center of the arrow for consistent arrow flight and simplified sight setup.
Solution Approach 2:
The power cable track is positioned asymmetrically relative to the bowstring tracks, which allows the power cable to be routed laterally offset from the central plane while the symmetric dual bowstring tracks maintain central alignment. This asymmetric-power-cable/symmetric-bowstring configuration enables both proper cable routing and centered bowstring alignment for accurate shooting.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution reduces cam lean and limb twist, enhances arrow consistency, simplifies sight alignment, and reduces cable wear, providing a well-balanced and forgiving shooting experience across various bow types.
Implementation Method 1
The function of the cams is to provide a mechanical advantage so that energy imparted to the arrow is a multiple of that required of an archer to draw the bow.
Data Source
AI summary
An archery bow is provided having a cam assembly including a first bowstring track and a second bowstring track laterally separated by a distance, and adapted to guide different portions of a bowstring. The bowstring tracks can be spaced from one another along an axis of rotation of the cam assembly so that the loads exerted by the bowstring portions are substantially balanced. Accordingly, the loads are inhibited from urging the cam to lean out of vertical alignment and/or twisting the limb. The cam assembly can include a power cable track which guides a cable centered on the axis of rotation, and which is within a central longitudinal limb plane. Large, dynamic loads exerted by the power cable through the cam assembly can be centered to inhibit cam lean and limb torque. A related method of inhibiting limb twist, and a split bowstring also are provided.