Silent Crossbow Cocking Device Using Cam-Based Locking
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Solution Overview
Problem
Conventional crossbow cocking mechanisms rely on user strength and generate mechanical noise due to gear interactions, which can interfere with hunting activities.
Innovation Solution
A silent cocking device comprising a shaft, reels, housing, bushing, covers, rollers, and a clutch wrench system that allows for unidirectional operation without noise, using rollers to pivot freely and reduce friction, enabling effortless string drawing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a unidirectional mechanism (e.g., one-way ratchet) is equipped in the winding device to avoid rope loosening, then the reliability of the cocking mechanism is improved, but mechanical noise is generated during operation
Solution Approach 1:
The patent replaces the traditional one-way ratchet mechanism with a cam-based locking system. The cam structure (with its curved surface and apex) interacts with a follower to provide unidirectional locking without the toothed engagement of a ratchet, thereby eliminating the characteristic clicking noise while maintaining the reliability of preventing rope loosening during the cocking operation.
2Power
If multiple gears are set internally in the winding device to convert driving force, then the mechanical advantage is improved, but the device complexity increases
Solution Approach 1:
The patent extracts and eliminates the complex internal gear train from the winding device. Instead of using multiple gears to achieve mechanical advantage, the invention employs a direct cam-follower mechanism that provides the necessary force multiplication through the geometric shape of the cam and the leverage of the crank, thereby reducing device complexity while maintaining adequate power conversion.
Solution Approach 2:
The patent inverts the traditional approach by using a cam profile (a curved surface) to achieve force conversion instead of using gears. The cam's apex and curved surface create mechanical advantage through their geometry, reversing the conventional method of using interlocking teeth to transfer and multiply force, thereby simplifying the overall mechanism.
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 device reduces user effort and eliminates mechanical noise during cocking, allowing for quiet and efficient crossbow operation.
Implementation Method 1
using rollers to pivot freely and reduce friction
Data Source
AI summary
A crossbow is provided with a silent crank-cocking device including a shaft extending through a positioning sleeve, reels, a housing, a bushing, covers, a shaft sleeve, limiting pieces and a clutch wrench. A crank is connected to an end of the shaft. The reels are connected to two ends of the shaft. The housing receives the bushing, which includes a hole and clutch slots. The covers are connected to both ends of the housing. Rollers are located in the clutch slots. The limiting pieces are arranged on two ends of the shaft sleeve. The clutch wrench includes a portion connected to the rollers in the housing and another portion extending from the housing.