AR Trigger Assembly With Retractable Pins for Quick Removal
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Solution Overview
Problem
AR-type firearms require triggers that can be easily removed and installed for maintenance without specialized knowledge, without losing parts, and without requiring disassembly of other firearm components, while preventing pin rotation and axial movement, and without using threaded studs or adhesive.
Innovation Solution
A trigger mechanism with hollow shafts and bearing journals secured by a positive locking mechanism, using a threaded spindle with a Torx® drive, allowing quick installation and removal by retracting the journals into the shafts, and featuring anti-rotation and anti-falling-out mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If standard pins are used to secure the trigger, then the trigger can be mounted in the lower receiver, but the pins rotate during firing causing pin holes to widen and trigger play to increase
Solution Approach 1:
The patent employs asymmetric features including a non-circular pin cross-section and corresponding asymmetric recesses in the trigger housing. This prevents the pin from rotating during firing, maintaining consistent clearance and eliminating trigger play while preserving secure mounting.
2Ease of repair
If the trigger is removed for cleaning, then maintenance access is improved, but disassembly requires specialized knowledge and results in loss of small parts
Solution Approach 1:
The trigger assembly is segmented into modular components that can be independently removed. The trigger body separates from the lower receiver as a complete unit through simple pin removal, eliminating the need to disassemble internal components or handle small parts separately, thus reducing complexity while maintaining accessibility.
Solution Approach 2:
The trigger assembly is extracted as a complete functional unit from the lower receiver. This allows full cleaning access without requiring the user to disassemble internal trigger components or manage small parts, simplifying the maintenance procedure while achieving complete cleaning capability.
3Reliability
If cylindrical pins are used for mounting, then the trigger can be secured in the lower receiver, but the pins must be driven out with tools and the safety mechanism must be removed
Solution Approach 1:
The mounting system transitions from a static permanent installation to a dynamic removable configuration. The pins are designed to be easily inserted and removed without tools, allowing the trigger to be quickly detached from the lower receiver while maintaining secure mounting during operation.
Solution Approach 2:
The pins are extracted from the traditional cylindrical form that requires driving tools. Instead, they use a push-button or snap-fit mechanism that allows tool-free removal, eliminating the need to disassemble the safety mechanism or use specialized tools while maintaining secure mounting during firing.
4Reliability
If threaded studs with adhesive are used, then pin axial movement is prevented, but additional fastening methods increase complexity and maintenance difficulty
Solution Approach 1:
The patent replaces permanent adhesive-bonded threaded studs with reusable mechanical retention features. The pins use simple mechanical stops or interference fits that provide adequate positioning without requiring adhesive, reducing fastening system complexity and eliminating maintenance issues associated with adhesive degradation.
Data Source
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AI summary
A trigger is described which can be quickly removed and installed from the lower housing section of AR-type weapons, wherein the trigger (24) has a trigger housing (27) which has two hollow shafts (36), and wherein a hammer (25) is rotatably mounted on one of the two hollow shafts (36a) and a trigger (26) is rotatably mounted on the other of the two hollow shafts (36b), and wherein each of the two hollow shafts (36) has an opening in which a left-hand bearing pin (31) and a right-hand bearing pin (32) are displaceably guided, which are connected to one another by means of a threaded spindle (39).