Hollow-Through Pulley Block for Arrow Launching
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Solution Overview
Problem
Conventional counteracting block and tackle systems in compact arrow launching devices face issues with friction and wear due to high-density metal pulleys and inadequate protection for razor broadhead arrow tips, leading to premature failure of launching cords.
Innovation Solution
A moveable pulley block with a hollow-through structure and low-density solid pulley sheaves aligned in series, along with captive cable terminals, minimizes friction and wear by providing radial clearance for the arrow tip and reducing fleet angles, while maintaining mechanical stability and shock absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high-density metal ball bearing pulleys are used, then the pulleys are strong enough to operate for thousands of cycles, but they generate significant momentum and friction that causes launching cord failure in 5-10 cycles
Solution Approach 1:
The patent changes the density parameter of the pulley material from high-density metal to low-density solid material (such as solid nylon or solid PTFE). This parameter change reduces the momentum and friction generated by the pulleys, preventing launching cord failure while maintaining operational strength through careful material and design selection.
Solution Approach 2:
The patent employs composite material strategies by using solid low-density materials with specific mechanical properties that combine sufficient strength with low density. The pulleys are designed with specific mechanical responses including low axle friction, shock absorption, and dimensional stability, achieving a composite performance profile that balances strength and low friction characteristics.
2Device complexity
If bridge type pulley blocks with parallel pulleys are used, then the system is structurally simple, but fleet angles are introduced into the serpentine path creating additional friction
Solution Approach 1:
The patent transitions from a parallel pulley arrangement to an in-line series arrangement, changing the dimensional configuration of the pulley path. This dimensional change aligns all pulleys and cable terminals in a single linear plane, eliminating fleet angles and the associated friction losses while maintaining structural simplicity.
3Volume of moving object
If conventional pulley blocks are used, then the structure is compact, but they do not fully surround the exposed edges of razorblade broadhead arrow tips
Solution Approach 1:
The patent implements a hollow-through pulley block structure that completely surrounds and protects the razorblade broadhead arrow tips. The arrow tips are positioned within the hollow-through space of the pulley block, nesting the protective structure around the vulnerable component. This design provides full enclosure protection while maintaining a compact overall size.
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 solution reduces friction and wear, increases the service life of the launching cord, and enhances the efficiency of the counteracting block and tackle system by aligning pulleys and terminals in a single linear plane, eliminating the need for a long arrow support rail.
Implementation Method 1
The high density of metal pulleys generates significant momentum when deployed at high RPMs. These systems rely on the surface friction of the launching cord to arrest the spinning pulleys, which generates enough combined heat and wear that even the toughest launching cords fail in as little as 5-10 launch cycles.
Implementation Method 2
The high density of metal pulleys generates significant momentum when deployed at high RPMs.
Implementation Method 3
a moveable pulley block having a hollow-though structure with an inner radial clearance for the cutting profiles of razor broadheads arrow tips
Implementation Method 4
In-series alignment of cable terminals and pulleys can position bowstring and cable on a single linear plane to minimize bowstring operating friction with virtually no fleet angles.
Data Source
AI summary
Within a counteracting block and tackle system of compact arrow launching devices, a cable-suspended, moveable pulley block structure permits the through clearance of razor-edged arrow broadheads and employs a plurality of low-density, solid sheaves, aligned in series to guide the in-line purchase of bowstring. The moveable pulley block has a hollow-though structure that permits the radial clearance of an arrow broadhead, reducing potential external interference or contact with the razor edges of the broadhead. The pulley block is attached to cable terminals at one end which allow the pulley block to travel in cooperating with cables. The pulley block has low-density, solid sheaves that facilitate high velocity launching cord travel with low rotational momentum for reduced friction and wear. The sheaves and cable terminals, and any launching cord terminals, are aligned in series and share a single linear plane to minimize launching cord fleet angles, reduce friction and increase efficiency.