Trigger Assembly Captured Roller Reduces Friction
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Solution Overview
Problem
Conventional trigger mechanisms for devices like crossbows and firearms require high and inconsistent trigger pull loads due to high friction between the trigger and sear surfaces, making it difficult to achieve both safety and accuracy in firing mechanisms.
Innovation Solution
A trigger assembly with a captured roller that provides rolling frictional resistance between the sear surfaces, allowing for a consistent and reduced trigger pull load by engaging the roller between the first and second sear surfaces, enabling the trigger to move from a load to a release position with lower effort and maintaining device accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional trigger mechanisms use friction between ticker and sear surfaces to hold the firing mechanism, then the trigger can maintain a loaded position, but the trigger pull load becomes relatively high (2.5-9 lbs)
Solution Approach 1:
A roller element is introduced as an intermediary between the trigger and sear surfaces. The roller replaces direct surface-to-surface frictional contact with rolling contact, significantly reducing the trigger pull load required to activate the firing mechanism while maintaining reliable position control
Solution Approach 2:
The invention substitutes a rolling mechanical system for the conventional sliding friction-based mechanical system. By replacing the sliding contact between ticker and sear surfaces with a roller element, the mechanical interaction changes from high-friction sliding to low-friction rolling, reducing trigger effort
2Measurement precision
If the trigger pull load is reduced to improve shooting accuracy, then the trigger becomes easier to pull, but inadvertent activation becomes more likely
Solution Approach 1:
The invention changes the friction parameter from sliding friction to rolling friction through the roller element. This parameter change reduces the trigger pull load to a consistent, predictable value that is low enough for accuracy but high enough to prevent inadvertent activation
3Ease of operation
If polished surfaces and lubrication are applied to reduce friction, then the coefficient of friction decreases, but the trigger pull load remains relatively high (not less than 2.5 lbs)
Solution Approach 1:
The roller element serves as a mediator that eliminates the need for polished surfaces and lubrication. Instead of relying on surface treatments to reduce friction, the roller provides inherent low-friction rolling contact that is more reliable and consistent
4Ease of operation
If leverage is used to lower forces between ticker and sear, then the trigger pull load decreases, but the trigger pull effort remains relatively high in the prior art
Solution Approach 1:
Rather than complexing the geometry to achieve leverage, the invention uses a simple roller intermediary that provides force reduction through the mechanical advantage of rolling contact. This approach achieves lower trigger pull loads without significantly increasing device complexity
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 trigger assembly significantly reduces the trigger pull load required, providing consistent resistance and preventing inadvertent activation, thus enhancing the accuracy and safety of the firing mechanism.
Implementation Method 1
a captured roller positioned for engagement with the first and second sear surfaces... providing rolling frictional resistance to movement of the first and second sear surfaces relative to each other
Data Source
Figure 1A
Figure 1B
Figure 1C~1D
AI summary
A trigger assembly for activating a firing mechanism. The trigger assembly includes a trigger having a sear arm with a first sear surface, and a firing element including a body portion with a second sear surface and an engagement portion for engagement with the firing mechanism, for activating the firing mechanism. The trigger assembly also includes a captured roller positioned for engagement with the first and second sear surfaces. The trigger is pivotable between a load position, in which the captured roller is held between the first and second sear surfaces, and a release position, in which the second sear surface is disengaged from the captured roller and the firing element is released. The firing element is pivotable between a first position, in which the firing element is held by the captured roller, and a second position, in which the firing element is disengaged from the captured roller.