Crossbow Crank With One-Way Bearing for Controlled De-Cocking
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Solution Overview
Problem
Existing crossbow systems face challenges in safely and efficiently transitioning the bowstring between drawn and undrawn positions without complex mechanical components or risking damage and injury, particularly with higher draw weights.
Innovation Solution
A crossbow de-cocking system incorporating a sled with a stop mechanism and a crossbow crank that allows controlled movement of the bowstring between drawn and undrawn modes, including a safety mechanism to prevent interference with the trigger assembly and a one-way bearing for secure operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a winch is used to draw the crossbow to improve speed and reduce manual effort, then the draw weight capability is improved, but the operational complexity and risk of operator error increase
Solution Approach 1:
The patent introduces a sled as an intermediary component between the winch and the bowstring. The sled includes a cord engagement element that connects to the winch cord and a bowstring engagement element that engages the bowstring. This intermediary sled mechanism simplifies the operation by providing a clear, controlled interface for both cocking and de-cocking operations, reducing operator error while maintaining the winch's force multiplication capability.
2Ease of operation
If the sled is used to de-cock the crossbow by engaging the bowstring, then the de-cocking operation is simplified, but the risk of interfering with the safety mechanism increases
Solution Approach 1:
The patent makes the sled's engagement characteristics dynamic by providing different engagement elements for different operational modes. The sled includes a first engagement element for cord engagement and a second engagement element for bowstring engagement. During de-cocking operations, the sled is designed to engage the bowstring in a controlled manner that does not interfere with the safety mechanism, while still providing the necessary force to release the bowstring. The dynamic design allows the same sled to perform different functions safely in different contexts.
3Productivity
If the trigger mechanism is used to release the bowstring, then the firing function is achieved, but the stored energy can cause damage or injury during de-cocking operations
Solution Approach 1:
The patent extracts the de-cocking function from the trigger mechanism by introducing a separate sled-based de-cocking system. The sled engages the bowstring directly and provides a controlled release path that is independent of the trigger mechanism. This separation allows the bowstring to be safely released without relying on the trigger's complex safety interlocks, thereby eliminating the risk of stored energy causing damage during de-cocking operations while preserving the trigger's firing function.
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
Facilitates safe and efficient cocking and de-cocking of crossbows, reducing the risk of operator error and damage, while simplifying the operation of winches and ensuring reliable transition of the bowstring.
Implementation Method 1
a one-way bearing that allows rotation of the drive shaft and spool in a first direction, and impairs rotation of the drive shaft and spool in a second direction
Implementation Method 2
a brake that axially compresses the drive shaft and sleeve to lock the drive shaft and sleeve together, preventing relative rotation
Data Source
AI summary
A crossbow crank can comprise a drive shaft selectively coupled to a one-way bearing that allows rotation of the drive shaft and an associated spool in a first direction, and impairs rotation of the drive shaft and the spool in a second direction. The drive shaft can be automatically locked and unlocked relative to the one-way bearing, allowing the bearing to control operation of the drive shaft, via a brake. The brake can be axially compressible along the drive shaft to automatically lock the drive shaft and a sleeve so they are fixed relative to one another and rotate in unison when the drive shaft is rotated in the first direction. The brake can be deactivated by operation of a crank so that the drive shaft can rotate freely relative to the sleeve and thus the bearing in a second direction. A related method of use is provided.