Selectorized Dumbbell Weight Selector Continuous Periphery Design
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Solution Overview
Problem
Existing selectorized dumbbells are prone to cross-pinning errors and inadvertent dislodgement during exercise, which can lead to damage or injury, especially in multi-user facilities like gyms, due to the use of magnets and lack of redundancy in weight selector design.
Innovation Solution
A selectorized dumbbell design featuring a weight selector with a substantially continuous periphery that encloses an open interior, including a rear wall to prevent cross-pinning and a flexible central portion that develops a biasing force to resist disconnection, ensuring secure attachment to the handle and preventing unintended dislodgement by contacting the user's hand or forearm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If magnets are used to hold the connecting pin in place, then the pin can be easily retained during exercise, but the risk of cross-pinning errors and inadvertent dislodgement increases
Solution Approach 1:
The patent removes magnets from the connecting pin design entirely, extracting the magnetic retention mechanism that caused reliability problems. Instead, it uses a purely mechanical retention system where the pin is held in place by friction and geometric constraints from the slot and rail interface, eliminating the cross-pinning risk while maintaining ease of operation during exercise.
Solution Approach 2:
The connecting pin is designed with asymmetric features including a rounded end and a flattened end, which must be inserted in the correct orientation. The pin fits into an asymmetric slot configuration where only the correct orientation allows proper engagement with the rail, preventing cross-pinning errors through geometric constraints rather than magnetic attraction.
2Ease of operation
If a U-shaped connecting pin is used, then the weight selector can be easily installed and adjusted, but the pin can be incorrectly installed by inserting prongs on different sides beneath different weight rails
Solution Approach 1:
The connecting pin features asymmetric geometry with a rounded end and a flattened end that must be inserted in a specific orientation. The pin engages with an asymmetric slot and rail configuration where only the correct orientation allows proper engagement, making incorrect installation physically impossible while maintaining ease of operation.
Solution Approach 2:
The slot acts as an intermediary element between the connecting pin and the weight rails. The slot's asymmetric geometry mediates the interaction by allowing the pin to pass through only in the correct orientation, where the rounded end enters first and the flattened end aligns with the rail, ensuring proper installation without requiring user precision.
3Device complexity
If the connecting pin is designed without redundant features, then the device complexity is reduced, but the pin can be inadvertently dislodged during vigorous exercise
Solution Approach 1:
The connecting pin incorporates a rounded end with a curved surface that interfaces with the slot and rail. This curvature creates a larger contact area and distributes forces more evenly during exercise, increasing friction and resistance to dislodgement while maintaining a simple, single-piece design without additional redundant features.
Solution Approach 2:
The pin design utilizes friction as the primary retention mechanism, changing the retention parameter from magnetic attraction to friction-based mechanical engagement. The rounded end geometry and slot configuration are optimized to maximize friction forces during exercise while maintaining simplicity, eliminating the need for magnets or complex redundant retention features.
Data Source
AI summary
A selectorized dumbbell has a plurality of nested weights that provide a stack of left weight plates and a stack of right weight plates. A handle is dropped between the stacks and a selector is inserted into one of a plurality of vertically spaced positions on the handle to couple a selected number of the weights to the handle. The selector has a continuous periphery enclosing an open interior. A user who is exercising with the dumbbell will be alerted to unintended dislodgement of the selector since a portion of the selector's periphery will contact a portion of the user's grip hand, wrist or forearm during such dislodgement. This prevents complete dislodgement and prompts the user to restore the selector to a fully installed position. Side walls of the selector may become curved when the selector is installed to provide an additional frictional force resisting dislodgement of the selector.