Shower Door Roller Assembly with Keyed Anti-Lift Tab Locking
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Solution Overview
Problem
Existing roller assemblies for glass shower door enclosures lack an effective anti-lift mechanism, as prior art anti-lift tabs are free to rotate and often adjust out of position, compromising their functionality in preventing the door from lifting off the rail.
Innovation Solution
A roller assembly with a circular face plate featuring an anti-lift tab locked into place with keys on the inner face that mate with keyways in a castellated nut and shaft component, preventing the anti-lift tab from rotating relative to the roller as it moves along a fixed rail, and utilizing stops at the ends of the rail to secure the door in place.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If an anti-lift tab is used without a locking mechanism, then the structure is simple, but the anti-lift tab rotates and adjusts out of position, compromising functionality
Solution Approach 1:
The anti-lift tab assembly is segmented into distinct components: the anti-lift tab itself, the circular face plate with keys, the castellated nut with keyways, and the central bolt. This segmentation allows the locking mechanism to be added as a modular assembly rather than redesigning the entire structure, thereby maintaining relative simplicity while achieving reliable position fixation.
Solution Approach 2:
The keys on the face plate act as intermediary elements that mate with the keyways in the castellated nut. This intermediary mechanism transfers and locks the rotational position of the anti-lift tab relative to the roller assembly, preventing unwanted rotation while maintaining a relatively simple overall structure.
2Reliability
If keys and keyways are added to lock the anti-lift tab, then position stability is improved, but device complexity increases
Solution Approach 1:
The central bolt serves multiple functions: it holds the anti-lift tab assembly together and also acts as the axis around which the castellated nut rotates to lock the keys in place. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity while achieving reliable position stability.
Solution Approach 2:
Instead of adding a complex mechanical locking device to prevent rotation, the invention inverts the approach by using a simple keyed-hole mechanism where the keys fit into keyways. This inverted simple locking approach achieves reliable position stability without significantly increasing device complexity.
3Ease of operation
If the anti-lift tab is free to rotate, then ease of installation is improved, but the door may lift off the rail compromising safety
Solution Approach 1:
The keys are pre-positioned on the face plate at specific angular orientations corresponding to safe operational positions of the anti-lift tab. During installation, the castellated nut is rotated to align its keyways with these pre-positioned keys, thereby preliminarily establishing the correct angular position before the door is put into service. This prevents the door from lifting off the rail while maintaining ease of installation.
Data Source
AI summary
An anti-lift tab of a roller assembly that rides along a fixed rail in use. The anti-lift tab protrudes from the bottom of a face plate having keys molded onto the back face of the face plate which interface with keyways of a castellated nut and shaft component having internal screw threads. A threaded rod is inserted through a bearing seated in the roller assembly. The rod is screwed into the castellated nut and shaft component. A screw attaches the face plate to the castellated nut shaft component and to the roller assembly.