Plastic Caster Yoke With Weight-Transfer Tab for Load Support
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Solution Overview
Problem
Traditional metal yoke bed frame casters are heavy and costly, and existing plastic alternatives often fail under weight and pressure due to uneven weight distribution and lack of structural support.
Innovation Solution
A plastic yoke and wheel caster design with a weight-transferring tab and groove system that distributes load onto the wheel, eliminating the need for separate axles and rivets, and using different types of plastic for optimal friction and strength, allowing the yoke to be made from less robust materials like glass-reinforced nylon and impact-resistant polypropylene.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metal yoke is used to withstand weight and pressure, then strength and reliability are improved, but weight and cost increase
Solution Approach 1:
The yoke is divided into multiple arms that collectively support the load, distributing stress across several plastic components rather than requiring a single heavy metal structure. The wheel is segmented with a groove system that distributes contact forces across multiple points on the wheel perimeter.
Solution Approach 2:
The invention uses plastic materials with reinforced properties (such as glass-filled nylon or polypropylene) to achieve the necessary strength-to-weight ratio. The composite plastic structure provides adequate load-bearing capacity while maintaining lightweight characteristics.
2Strength
If metal yoke is used to withstand weight and pressure, then strength and reliability are improved, but cost increases
Solution Approach 1:
Multiple functional components are merged into single molded plastic parts. The yoke integrates the stem mounting structure, arm supports, and wheel mounting features into one piece. The wheel integrates the groove system and shaft mounting features into a single molded component, eliminating the need for separate metal parts and assembly steps.
Solution Approach 2:
The invention changes the material parameter from metal to plastic, fundamentally altering the cost structure while maintaining functional performance. This material substitution enables cost-effective manufacturing through injection molding processes.
3Weight of moving object
If plastic yoke and wheel are used to reduce weight and cost, then weight and cost are reduced, but weight-bearing capacity and reliability worsen
Solution Approach 1:
The design incorporates preliminary structural features during the molding process that pre-position load paths and stress distribution patterns. The groove geometry and arm configurations are designed in advance to optimize force transmission and prevent failure under expected loads.
Solution Approach 2:
The plastic components are designed with varying local densities and reinforcement patterns. Areas subject to high stress (such as the groove contact points and arm joints) are reinforced with material or structural features, while other areas remain lighter. This localized quality optimization ensures reliability where needed without compromising overall weight reduction.
Data Source
AI summary
The invention consists of a caster comprises a yoke having a weight transferring tab and a wheel with groove for receiving the tab. Preferably, the yoke and wheel are made out of plastic, and in some embodiments two different types of plastic. A tab and groove helps transfer the weight of the load on the castor away from the arms of the yoke and onto the wheel. In a preferred embodiment the plastic wheel is molded so as to include a shaft on either side that snap into receiving holes in the yoke, thus avoiding the need for separate axel and rivets.