Tie Down Clamp Cam Arm Offset Contact
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Solution Overview
Problem
Existing tie down clamps for securing loads on trailers and vehicles lack the ability to be removably mounted and securely attached to various host surfaces, leading to potential failure under load due to uneven pressure distribution and sharp edge formation.
Innovation Solution
A tie down clamp design featuring two U-shaped pieces connected by roll pins with a pivotally mounted cam arm and double torsion springs, where the hook accommodating bore is beveled and positioned close to the pivot point to reduce moment arm and a protrusion at the bottom for offset contact, enhancing strength and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the hook accommodating bore is positioned farther from the pivot point to facilitate easier hook attachment, then the ease of operation is improved, but the moment arm increases causing higher stress and potential failure at the bore
Solution Approach 1:
The patent changes the position parameter of the hook accommodating bore, placing it close to the pivot point to reduce the moment arm and minimize stress concentration, thereby maintaining strength while still allowing operational functionality
2Force
If the point of contact with the trailer angle iron is positioned directly under the axle roll pin for optimal force transmission, then the force efficiency is improved, but the axle roll pin experiences extra pressure causing premature failure
Solution Approach 1:
The patent introduces asymmetry by adding a protrusion at the bottom of the cam arm that offsets the point of contact from the vertical plane through the axle roll pin, distributing the load away from the roll pin while maintaining effective force transmission to the angle iron
3Device complexity
If a single torsion spring is used to provide the necessary cam arm tension, then the device complexity is reduced, but the force distribution becomes uneven leading to premature failure
Solution Approach 1:
The patent divides the single spring function into two separate torsion springs, each mounted on opposite sides of the cam arm, providing balanced and uniform force distribution that prevents premature failure while maintaining reasonable device complexity
4Manufacturing precision
If the hook accommodating bore has sharp edges to precisely define the hook position, then the positioning precision is improved, but the sharp edges create stress concentration points leading to failure
Solution Approach 1:
The patent applies a localized quality change by beveling the edges of the hook accommodating bore, creating a gradual transition that maintains precise hook positioning while eliminating stress concentration at the bore edges
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design allows for secure attachment and distribution of force across the clamp, increasing the strength rating to withstand higher loads without failure, demonstrated by withstanding 2,000 pounds of force during testing.
Implementation Method 1
A double torsion spring wraps around the axle on both sides of the cam arm with the 'hook' of the spring pressing against the cam arm when engaged
Data Source
AI summary
A tie down clamp comprises two U-shaped pieces interconnected via roll pins or similar mechanisms, wherein a cam arm is pivotally mounted on an axle between the two U-Shaped pieces. A double torsion spring wraps around the axle with the “hook” of the spring pressing against the cam arm when engaged. The cam arm includes a bore sized to accommodate a hook as may be found on a load securing mechanism. The bore may be beveled on each side to prevent “sharp edges” from being formed by the load securing mechanism. The bore is close to the pivot point of the cam arm. The cam arm includes a protrusion at the bottom so that the point of contact with the trailer angle iron, when the cam arm is engaged, is toward the end of the cam arm and offset from the vertical plane that runs through the axle roll pin.