Grill Guard Over-Center Latch for Corrosion-Resistant Retention
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Solution Overview
Problem
Existing grill guard latch assemblies for highway tractor trucks rely on springs that can corrode over time, reducing the reliability of the latch mechanism to maintain the grill guard in the upright working position.
Innovation Solution
A grill guard assembly featuring an over-center linkage and a biasing linkage that provides a robust and corrosion-resistant mechanism to retain the grill guard in the closed position, with a clamping jaw and second jaw design to ensure secure engagement and easy operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a simple spring is used to retain the hook in the closed position, then the latch assembly structure is simple, but the reliability decreases over time due to corrosion from road salt and other environmental factors
Solution Approach 1:
The latch assembly is segmented into distinct functional components: the over-center linkage mechanism separate from the hook, the biasing linkage separate from the clamping jaw, and the resilient member as a separate element. This segmentation allows each component to be optimized for its specific function and replaced independently if corroded, improving overall reliability without excessive complexity.
Solution Approach 2:
The over-center linkage acts as an intermediary mechanism between the hook and the biasing linkage, transferring and amplifying the biasing force to create the latching action. This intermediary mechanism provides mechanical advantage and ensures positive engagement, improving reliability while maintaining reasonable structural complexity.
2Reliability
If an over-center linkage with biasing linkage is used instead of a simple spring, then the reliability and corrosion resistance improve, but the device complexity increases
Solution Approach 1:
The over-center linkage utilizes dynamic geometric transformation as the hook moves between open and closed positions. The linkage passes through an over-center position where the geometry naturally provides the latching force, creating a dynamic self-latching mechanism that is more reliable than static spring pressure alone, while the movement-based operation keeps the structure manageable.
Solution Approach 2:
The over-center linkage introduces a rotational dimension to the latching mechanism, moving the hook through a circular arc path rather than linear motion. This dimensional change allows the biasing linkage to apply force more effectively and provides a more secure engagement, improving reliability while the rotational mechanism remains mechanically straightforward.
3Strength
If the clamping jaw is designed to be firmly clamped against the clamping surface, then the grill guard retention is secure, but the ease of operation for maintenance access decreases
Solution Approach 1:
The biasing linkage acts as a counterweight mechanism, using a resilient member (spring) to provide a counteracting force that balances the clamping force. This allows the clamping jaw to maintain strong engagement during normal operation while enabling easy release when the operator applies force to overcome the balanced system, resolving the contradiction between secure retention and ease of maintenance access.
Solution Approach 2:
The biasing linkage pre-loads the clamping jaw against the clamping surface, creating the strong retention force before any external force is applied. This preliminary action ensures secure engagement during vehicle operation, while the pre-stored energy in the resilient member facilitates easy release during maintenance by simply overcoming the pre-loaded condition.
Data Source
AI summary
A grill guard assembly has a vehicle coupling portion mounted to the vehicle forwardly of the vehicle grill. A hinge couples a coupling portion of a grill guard frame on the vehicle coupling portion to pivot between a working position extending primarily upwardly and a lowered position extending primarily forwardly. A latch assembly has a clamping surface and a clamping jaw supported on opposing ones of the vehicle coupling portion and the grill guard coupling portion. An over-center linkage operatively connects the clamping jaw to the respective coupling portion and the second coupling portion such that the linkage is rotated through an over-center position between open and closed positions of the jaw, whereby the clamping force of the jaw acts to urge the jaw to remain closed.