Crossbow Crank Safety Wrist Strap Preventing Uncontrolled Spinning
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Solution Overview
Problem
The mechanical advantage of crossbow winch mechanisms can lead to uncontrolled spinning of the crank handle, causing damage to the crossbow and potential injury to the user, especially when the clutch is disengaged or the user's hand slips off during drawing or decocking.
Innovation Solution
A safety wrist strap with a crank aperture that secures the crossbow crank's shaft but not the handle, preventing uncontrolled spinning by restraining the handle against the user's palm, thus preventing the winch mechanism from spinning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the clutch is disengaged or the user's hand slips off the crank handle during drawing or decocking, then the winch mechanism can operate freely, but the crank handle spins uncontrollably causing damage and potential injury
Solution Approach 1:
A wrist strap is introduced as an intermediary safety device between the user's hand and the crank handle. The strap includes a retention loop that mechanically couples to the crank handle, ensuring continuous control even when the user's hand slips or releases the handle. This intermediary device prevents uncontrolled spinning by maintaining a physical connection to the crank mechanism throughout the drawing and decocking operations.
2Ease of operation
If the crank handle is designed to be easily grasped and released, then the user can quickly operate the winch mechanism, but the handle can slip off or be accidentally released causing uncontrolled spinning
Solution Approach 1:
The wrist strap is donned and positioned around the user's wrist before the drawing operation begins. The retention loop is pre-configured to engage with the crank handle, establishing a safety mechanism in advance. This preliminary action ensures that even if the user's hand slips or accidentally releases the handle during operation, the wrist strap maintains control of the crank mechanism, preventing uncontrolled spinning.
3Object-affected harmful factors
If the wrist strap completely restrains the crank handle, then uncontrolled spinning is prevented, but the user cannot quickly release the handle when needed
Solution Approach 1:
The wrist strap retention loop is designed with dynamic engagement characteristics. The loop can be easily engaged with the crank handle by simple insertion or snapping motion, and can be quickly released when needed by pulling the handle away from the loop. During normal operation, the loop maintains a secure mechanical connection that prevents uncontrolled spinning. When the user needs to release the handle, they can do so rapidly by manipulating the handle relative to the loop, which opens or disengages the retention mechanism.
Data Source
AI summary
A safety device for a crossbow includes a wrist strap with a crank aperture in a palm portion thereof, and is secured around a user's wrist with the crank aperture over the palm of the user's hand. The crank aperture allows passage therethrough of a shaft of a crossbow crank, but prevents passage of a handle; wearing the wrist strap, the user can grasp the handle with the shaft extending through the crank aperture away from the palm of the user's hand. The wrist strap can be divided at its dorsal-wrist portion and include a closure to allow the wrist strap to be secured around or removed from the user's wrist as desired. Restraint of the crank handle by the crank aperture prevents uncontrolled spinning of the crossbow crank.