Interchangeable Pulley Assembly for Compound Archery Bows

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Solution Overview

Problem

Compound archery bows with existing pulley systems lack versatility in accommodating archers of varying reach, arm span, or stature, as they often require substantial let-off at specific draw lengths, making them difficult for archers with different physical characteristics to use effectively.

Innovation Solution

A pulley assembly with interchangeable power cable pulleys that can be mounted on a draw cable pulley, allowing for either substantial let-off or negligible let-off of draw force, enabling adjustable draw lengths and accommodating archers of different sizes by altering the position and type of power cable pulleys.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a fixed pulley configuration is used in a compound archery bow, then the bow can provide substantial draw force let-off at a specific draw length, but it cannot accommodate archers with different physical characteristics such as reach, arm span, or stature

Engineering Contradiction:

Improveaccommodation of archers with different physical characteristicsVSAvoidpulley system configuration

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The pulley system transitions from a static fixed configuration to a dynamic interchangeable configuration, where power cable pulleys can be swapped to change the let-off characteristics and draw length, allowing the same bow to adapt to different archers' physical characteristics

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The pulley system is segmented into interchangeable power cable pulleys that can be independently replaced. Each pulley type provides different let-off characteristics, and by swapping these segments, the bow's performance is customized for different archers without redesigning the entire system

Inventive Principle:

Principle #1Segmentation

2Adaptability or versatility

If interchangeable power cable pulleys are provided, then the bow can be adjusted for different draw lengths and let-off characteristics, but the device complexity increases

Engineering Contradiction:

Improveadjustable draw lengths and let-off characteristicsVSAvoidpulley assembly structure

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The draw cable pulley is designed as a universal mounting platform that can accommodate multiple types of power cable pulleys. This multi-functional design allows a single pulley assembly structure to support various let-off configurations, reducing the need for multiple complete pulley assemblies

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Ease of operation

If substantial let-off is provided at a specific draw length, then the bow is easier to draw at that length, but it becomes difficult for archers with different draw lengths to use effectively

Engineering Contradiction:

Improveease of drawing the bowVSAvoidusability across different draw lengths

Core Design Contradiction:

Ease of operationVSAdaptability or versatility

Solution Approach 1:

The let-off point and ease of operation are made dynamic rather than fixed. By interchangeable pulleys, the let-off occurs at different draw lengths depending on which pulley is installed, allowing each archer to experience optimal ease of operation at their specific draw length

Inventive Principle:

Principle #15Dynamics

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 pulley assembly allows for easy conversion between configurations with substantial let-off and negligible let-off, making the bow usable by archers of varying reach and stature without requiring disassembly, ensuring consistent ease of use across a wider range of draw distances.

Implementation Method 1

A pulley assembly for a compound archery bow comprises a set of multiple power cable pulleys and a draw cable pulley... Each power cable pulley is arranged to receive the power cable in the power cable journal and to take up the power cable when the bow is drawn

Methodology Applied

Scientific EffectMechanical Advantage: Mechanical Advantage

Data Source

PatentUS8082910B1Pulley assembly for a compound archery bow

Publication Date: 2011.12.27 BOWTECH LLC

AI summary

A pulley assembly for a compound archery bow comprises a set of multiple power cable pulleys and a draw cable pulley. The draw cable pulley is arranged to be rotatably mounted on a bow limb, to let out the draw cable when the bow is drawn, and so as to have interchangeably mounted thereon any one of the multiple power cable pulleys. Each power cable pulley is arranged to take up the power cable when the bow is drawn. At least one of the power cable pulleys is arranged so as to result in substantially negligible let-off of draw force of the bow. At least one other of the power cable pulleys is arranged so as to result in substantial let-off of the draw force of the bow at a corresponding draw length.