Crossbow Limb Asymmetry and Cable Routing for Wear Reduction
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Solution Overview
Problem
Existing crossbows face issues with power cable wear, left to right draw string movement, and premature draw string wear due to the design of the limbs and the routing of the power cables, which affects accuracy, efficiency, and safety.
Innovation Solution
The crossbow design features a stock with a unique limb configuration that flexes in a vertical plane, a string let out assembly with a rotatable axis perpendicular to the projectile flight path, and a cable groove system that reduces power cable wear and eliminates left to right draw string movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the limbs are oriented parallel to one another to reduce recoil, then recoil is reduced and safety is improved, but the riser becomes wider and the length and weight of the crossbow increase
Solution Approach 1:
The patent applies asymmetry by orienting the limbs at an angle to each other rather than parallel, creating a V-shaped configuration. This asymmetric arrangement reduces the width of the riser and overall crossbow length while maintaining recoil reduction through the angled limb configuration that still provides opposing force vectors.
2Weight of moving object
If the crossbow is made narrower to reduce length and weight, then portability is improved, but power cable wear increases due to reduced guiding distance
Solution Approach 1:
The patent resolves this contradiction by routing the power cables through a three-dimensional path that utilizes vertical space and angular relationships. The cables are guided along the angled limb structure and through strategically positioned guides that create sufficient friction and wear distribution without requiring a wide horizontal configuration, thus maintaining a narrow crossbow profile while protecting cable durability.
3Volume of moving object
If camming means are used to reduce power cable wear and narrow the crossbow, then compactness is improved, but left to right movement of the drawstring occurs reducing accuracy
Solution Approach 1:
The patent eliminates the traditional camming mechanism entirely, extracting this source of drawstring movement instability. Instead, it uses a direct drawstring path guided by fixed guides and the angled limb structure, which maintains the drawstring in a stable, predictable linear path from the trigger to the limbs, preventing left-to-right movement and ensuring consistent shot accuracy while still achieving a compact design through the angled limb configuration.
4Device complexity
If the drawstring is routed perpendicular to the arrow flight path, then the crossbow structure is simplified, but the drawstring moves aggressively during shooting requiring objects to remain free of the flight path
Solution Approach 1:
The patent inverts the traditional perpendicular drawstring arrangement by routing the drawstring parallel to the arrow flight path. This reversal allows the drawstring to move in the same direction as the arrow, eliminating aggressive lateral movement and hazards to surrounding objects. The drawstring travels forward along with the arrow rather than perpendicular to it, fundamentally changing the motion dynamics to eliminate the hazard while maintaining structural efficiency.
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
This design enhances the accuracy, efficiency, and safety of the crossbow by reducing power cable wear, minimizing left to right movement, and improving the overall structural integrity and balance of the crossbow.
Implementation Method 1
The limb is configured to flex in a substantially vertical plane
Data Source
AI summary
Systems and apparatuses of a crossbow including a stock defining a front end and a rear end, and a limb including: a fixed end affixed to the stock between the front end and the rear end, and a free end positioned between the front end and the rear end. The limb is configured to flex in a substantially vertical plane.