Two-Stage Rope Cocker for Lower-Effort Crossbow Cocking
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Solution Overview
Problem
Existing crossbow cocking devices require significant physical effort and can be cumbersome, especially for users of shorter stature, and often involve complex mechanisms that are costly to manufacture and maintain.
Innovation Solution
A two-stage retractable rope cocking device with a bowstring carrier assembly and traverse mechanism, utilizing a single cord and two handle assemblies with spring motors, spools, and one-way bearings, providing a reduction in perceived draw force, allowing for easy cocking with minimal effort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a traditional rope cocker with 2 to 1 reduction ratio is used, then the perceived draw weight is reduced in half, but the handles must be pulled a distance twice the power stroke, which limits usability for users of shorter stature
Solution Approach 1:
The cocking process is divided into two distinct stages: first cocking the bowstring to a mid-position, then cocking it to the full cocked position. This segmentation allows the user to reset the handles to a lower starting position between stages, reducing the vertical distance required for the second stage and making the device accessible to users of shorter stature while maintaining the force reduction benefit
2Force
If a 3 to 1 reduction ratio rope cocker is used, then the perceived draw weight is reduced to one-third, but the handles must be pulled three times the power stroke distance, greatly reducing available power stroke and making cocking impossible for many users
Solution Approach 1:
By dividing the cocking process into two stages with a mid-position reset, the invention achieves effective force reduction comparable to or greater than 3 to 1 ratio devices while limiting the maximum handle travel distance to a manageable amount, making the device usable by a broader range of users
3Force
If two separate cords with two handles are used, then force reduction is achieved, but uneven pressure application causes tipping of the bowstring carrier and uneven cord movement about pulleys
Solution Approach 1:
The invention merges the two separate cord systems into a single integrated cord that loops through both handles and connects to the bowstring carrier. This ensures that tension is automatically balanced between the two sides, preventing carrier tipping and ensuring smooth, even cord movement about the pulleys during the cocking process
4Ease of operation
If complex crank cocking devices are used, then adequate strength requirements are eliminated, but the devices are time-consuming and mechanically complex
Solution Approach 1:
The rope cocker is designed to be manually operated without requiring complex mechanical assistance. The system uses simple pulleys, cords, and handles that work together through basic mechanical advantage, eliminating the need for motors, gears, or other complex mechanisms while still reducing the strength requirement for the user
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
Enables crossbow cocking with less than half the perceived effort compared to prior art, facilitating easy operation for users of varying heights and reducing manufacturing complexity.
Implementation Method 1
Each of the handle assemblies preferably include a spring motor, a spool, a spool winding surface
Implementation Method 2
The rope cocker created a pulley system, thereby reducing the overall perceived draw weight in half
Implementation Method 3
Each of the handle assemblies preferably include a spring motor, a spool, a spool winding surface, a one-way bearing
Data Source
AI summary
A two-stage rope cocker for a crossbow includes a bowstring carrier, a midway retainer, at least one handle and a cord. The bowstring carrier is slidably engaged with a rail of the crossbow. The midway retainer is pivotally engaged with the rail. Each handle includes a spring-motor engaged with a spool. A first end of the cord is retained on a first spool and a second end of the cord is retained on a second spool. A length of the cord is retained on the bowstring carrier. First and second spring-motors bias the first and second spools to wind the cord on the first and second spools. Pulling first and second handles translates the bowstring carrier from a distal position to the midway retainer. The first and second handles are pulled to translate the bowstring carrier from the midway retainer to a ready to fire position.