Plastic Caster Tab-and-Groove Structure for Load Transfer
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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-bearing stress, particularly at the arms and axle connections.
Innovation Solution
A plastic yoke and wheel caster design with a weight-transferring tab and groove system, where the yoke and wheel are made from different types of plastic, and the wheel has integral shafts that snap into the yoke, eliminating the need for a separate axle and rivets, allowing weight transfer directly onto the wheel, enhancing structural integrity and reducing material usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metal is used for the yoke to withstand weight and pressure, then strength and durability are improved, but weight and cost increase
Solution Approach 1:
The weight-bearing function is segmented from the yoke arms and transferred to the wheel through the tab-groove mechanism. The yoke is divided into structural support elements while the wheel assumes the primary load-bearing role, allowing the yoke to be made from lighter plastic material.
Solution Approach 2:
The caster combines plastic yoke material with a plastic wheel that has enhanced load-bearing characteristics. The composite structure of yoke with integrated tab and wheel with groove creates a system where weight is distributed to the more suitable component (wheel) for bearing it.
2Reliability
If metal is used for the yoke to withstand weight and pressure, then reliability under load is improved, but manufacturing cost increases
Solution Approach 1:
The tab is integrated as part of the yoke structure rather than being a separate metal component. The wheel includes an integrated groove and shafts molded as one piece, eliminating the need for separate axles and rivets. This merging of components allows universal use of plastic materials and reduces assembly steps.
Solution Approach 2:
The design accepts that plastic components may have shorter service life under extreme loads compared to metal, but achieves cost-effectiveness by using inexpensive plastic materials that can be molded efficiently. The tab-groove design ensures reliable weight transfer within the expected service life of plastic components.
3Strength
If separate axles and rivets are used to attach the wheel to the yoke, then structural integrity is improved, but device complexity and assembly steps increase
Solution Approach 1:
The wheel shafts are molded integrally with the wheel as a single plastic component. The shafts extend through the wheel and snap directly into the yoke's receiving holes, eliminating the need for separate metal axles and rivets. This reduces the total component count and simplifies the assembly process.
Solution Approach 2:
The integral shafts on the wheel serve dual functions: they act as the rotation axis and as the attachment mechanism to the yoke. The shafts are designed to snap into place within the yoke's receiving holes, providing self-contained attachment without requiring additional fastening components.
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.