Compound Bow Cable Yoke Pulley Torque Reduction
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Solution Overview
Problem
Compound archery bows face issues with high torque and friction at pulley axles due to the force/draw characteristics, which affect the performance and stability of the bow.
Innovation Solution
The implementation of a bow cable arrangement with yoke pulleys and idler pulleys mounted on brackets, where the cables extend around idler pulleys and split ends anchor directly to the axles, reducing the load on pulley bearings and distributing the cable load outboard of the pulleys, thereby minimizing friction and torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a power cam is mounted on the bow limbs to control draw force, then the bowstring can be drawn with controlled force characteristics, but high torque and friction are applied to the pulley axles
Solution Approach 1:
A cable arrangement with yoke and idler pulleys is introduced as an intermediary mechanism between the power cam and the bowstring. The yoke pulley system redistributes the cable loads, preventing direct transmission of high torque to the pulley axles while maintaining controlled draw force characteristics
Solution Approach 2:
The cable system is segmented into multiple cables (bowstring cable, first cable, second cable) with separate yoke pulley assemblies. This segmentation distributes the overall load across multiple independent cable paths, reducing the torque burden on each individual pulley axle
2Device complexity
If the bow cable arrangement uses traditional anchoring, then the structure is simple, but the pulley bearings experience high friction and torque
Solution Approach 1:
Idler pulleys mounted on brackets serve as intermediary elements that redirect cable forces. These idler pulleys create additional leverage points that reduce the direct torque load on the main pulley bearings, thereby reducing friction without significantly increasing overall structural complexity
Solution Approach 2:
The yoke pulley assembly introduces a new dimensional arrangement by mounting pulleys on brackets extending from the bow limbs. This spatial reconfiguration changes the force transmission geometry, distributing loads in multiple directions rather than concentrating them on single axles
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
This configuration reduces friction and torque at the pulley bearings, enhancing the bow's performance and stability by distributing the cable load effectively, allowing for a more efficient draw and release mechanism.
Implementation Method 1
The yoke includes an idler pulley mounted on a bracket. The first cable preferably extends around the idle pulley between the first and second ends
Implementation Method 2
reducing the load on pulley bearings and distributing the cable load outboard of the pulleys, thereby minimizing friction and torque
Data Source
AI summary
A compound archery bow includes a bow handle having projection limbs, and first and second pulleys mounted on the limbs for rotation around on axles. A bow cable arrangement includes a bowstring cable extending from a bowstring anchor through a bowstring let-out groove at the first pulley and then toward the second pulley, a first cable extending from a first anchor through a portion of a groove on the first pulley and then toward the second pulley, and a second cable extending from a second anchor through a portion of a groove on the first pulley and then toward the second pulley. The first cable includes a yoke having a first end connected to the first anchor, a split second end connected to the first axle on opposite sides of the first pulley, and a third end extending toward the second pulley. The yoke preferably includes an idler pulley mounted on a bracket. The first cable preferably extends around the idle pulley between the first and second ends, and the third end extends from the bracket toward the second pulley. The second pulley and the bow cable arrangement at the second pulley, including the yoke, preferably are near mirror images of each other at the first and second pulleys.