Pivot Pin Aperture Design for Controlled Detent Installation
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Solution Overview
Problem
The installation of pivot pins in AR-pattern firearms is challenging due to the susceptibility of retention detents to fall out of place or be expelled from the lower receiver, especially when using specialized tools that are often not readily available outdoors, and existing solutions fail to provide sufficient control over the detent orientation and require significant force to overcome spring bias.
Innovation Solution
A pivot pin design featuring a shaft with an installation aperture that allows a tool to guide the detent into the lower receiver's recess, reducing the likelihood of detent escape and enabling installation with reduced force, while also providing increased control through a retention portion and ramp configurations to facilitate smooth transition between locked and unlocked configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a spring-biased retention detent is used to retain the pivot pin in the lower receiver, then the pivot pin can be retained securely in the locked configuration, but the detent becomes susceptible to falling out of place or being expelled from the lower receiver during installation
Solution Approach 1:
The pivot pin is segmented into functional zones: a head portion, a shaft portion with channel, and a detent-retention recess. This segmentation allows the detent to be retained separately in the recess during installation, preventing expulsion while maintaining secure retention in the locked configuration.
Solution Approach 2:
The detent-retention recess is prepared in advance in the pivot pin shaft. This preliminary structural feature allows the detent to be positioned and retained securely before the pivot pin is fully installed, preventing the detent from falling out of place during the installation process.
2Manufacturing precision
If specialized tools are used to aid in the installation of the pivot pin, then control over the detent orientation can be improved, but the tools are not readily available outside of a workshop
Solution Approach 1:
The pivot pin design incorporates self-aligning features including the detent-retention recess and channel geometry that guide the detent into the correct orientation during installation. This self-service mechanism eliminates the need for specialized alignment tools, allowing installation with common tools while maintaining precise control over detent orientation.
3Ease of operation
If force is applied to the pivot pin to cause the detent to jump out of the recess and translate into the lower receiver, then the detent can be transitioned from the recess to the channel, but the pivot pin suddenly moves and increases the likelihood of mistakes causing detent expulsion
Solution Approach 1:
The transition mechanism utilizes dynamic interaction between the pivot pin and detent. As the pivot pin is inserted, the detent naturally transitions from the retention recess to the channel through controlled movement along a ramp surface, eliminating sudden jumps and reducing the risk of expulsion.
Data Source
AI summary
Embodiments are directed toward a pivot pin for a coupling an upper receiver of a firearm to a lower receiver of the firearm. In some embodiments, the pivot pin includes a head and a shaft that extends from the head. In some embodiments, the shaft defines a detent-retention channel and an installation aperture opposite the channel from the head. In some embodiments, the channel is configured to receive a detent and to enable the pivot pin to slide between a locked configuration and an unlocked configuration. In some embodiments, the installation aperture is configured to receive a tool that extends through the shaft, thereby urging the detent into a detent recess in the lower receiver while the shaft covers the detent recess in the lower receiver. Accordingly, the installation aperture facilitates reducing the likelihood that the detent escapes from the detent recess during installation of the pivot pin.