Freecoaster Hub Slack Adjustment Without Bearing Side Loads
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Solution Overview
Problem
Standard freecoaster hub designs require disassembly for slack adjustment and suffer from bearing failure due to excessive side loads, limiting their adjustability and durability.
Innovation Solution
A freecoaster hub system with a transmission assembly that includes a drive member with pawls and a ratchet member, and an engagement assembly with a slack adjustment pin, allowing for quick adjustment of slack angle without disassembly, using magnetic pawl retention and a friction-fit ratchet member for engagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the standard freecoaster hub design uses a clutch system with male and female threads, then the bicycle can coast backwards freely, but the excessive side load applied to the hub face causes bearing failure
Solution Approach 1:
The patent replaces the threaded clutch mechanism with a pawl and ratchet system. The pawl engages with ratchet teeth to prevent backward rotation, eliminating the side loading problem inherent in threaded designs. This mechanical substitution maintains the freecoaster function while improving bearing reliability by removing the harmful lateral forces.
Solution Approach 2:
The hub is divided into separate functional components: a stationary ratchet ring with teeth and a rotating pawl mechanism. This segmentation allows the pawl to engage and disengage independently from the hub body, preventing side loads from being transmitted to the bearings while maintaining the ability to coast backwards when disengaged.
2Adaptability or versatility
If the slack adjustment is achieved by inserting washers between the stopper and clutch cylinder, then the slack angle can be adjusted, but the entire hub must be disassembled for adjustment
Solution Approach 1:
The patent extracts the adjustment function from the internal clutch mechanism and places it on the external hub body through an adjustment slot and movable stopper. This allows users to access and adjust the slack angle from the outside without disassembling the hub, while still achieving the desired adjustment range.
Solution Approach 2:
The patent introduces a stopper as an intermediary element between the pawl mechanism and the hub body. By making the stopper movable along the hub body via an adjustment slot, it serves as a mediator that translates user adjustments into changes in engagement timing, enabling slack adjustment without internal disassembly.
3Speed
If the ratchet and pawl system is used with springs holding the pawls in place, then the bicycle cannot coast backwards, but this design provides immediate acceleration response
Solution Approach 1:
The patent creates a dynamic system where the pawl can switch between two states: engaged with the ratchet teeth for immediate acceleration, and disengaged for coasting backwards. The spring provides the force to return the pawl to the engaged position, while the rider's input allows temporary disengagement, combining both immediate response and backward coasting capability.
Solution Approach 2:
The system changes the engagement parameter of the pawl-ratchet interface based on rider input. When the rider pedals forward, the pawl is forced into engagement with the ratchet teeth for immediate acceleration. When the rider stops pedaling or pedals backward, the pawl disengages, allowing the wheel to coast freely in either direction.
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
Enables quick and easy adjustment of slack angle, reducing the need for frequent disassembly and minimizing bearing stress, enhancing the hub's versatility and durability.
Implementation Method 1
using magnetic pawl retention
Implementation Method 2
friction-fit ratchet member for engagement
Data Source
AI summary
A freecoaster hub system for a bicycle allows the bicycle to coast freely in either a forward or backward direction. The freecoaster hub system includes a hub assembly having a hub and an axle, wherein the hub is interconnected to the rim of a wheel of the bicycle by a plurality of spokes. The freecoaster hub system for a bicycle also includes a transmission assembly at least partially mounted in the hub and operatively interconnected to the axle and the hub. The transmission assembly comprising a drive assembly and an engagement assembly, each of which operatively engage the axle and or hub.