M60 Rifle Select Fire Trigger Assembly Mechanism

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Solution Overview

Problem

The M60 machine gun lacks a select fire mechanism to allow operation in both fully automatic and semi-automatic modes, leading to unnecessary fully automatic fire when not required.

Innovation Solution

A trigger assembly with a sear pivotally mounted to a trigger housing, including a disconnector and a select fire mechanism with a switch accessible outside, allowing the rifle to be selectively operated in fully automatic or semi-automatic modes by moving the switch between positions, which alters the engagement of the sear with the op rod assembly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the M60 rifle is equipped with a standard trigger assembly for fully automatic fire, then the rifle can operate in fully automatic mode, but it cannot operate in semi-automatic mode

Engineering Contradiction:

Improvefiring mode selection capabilityVSAvoidtrigger assembly structure

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The trigger assembly is designed to perform multiple functions: it can operate in fully automatic mode (original function) and semi-automatic mode (new function). The sear mechanism is configured to work with both the op rod assembly for automatic firing and a separate striker mechanism for semi-automatic firing, making the single trigger assembly universal for both firing modes

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The trigger assembly is divided into distinct functional segments: a first sear for engaging the op rod assembly in automatic mode, a second sear for engaging the striker in semi-automatic mode, and a trigger mechanism that can selectively actuate either sear. This segmentation allows independent control of each firing mode while maintaining a unified trigger assembly structure

Inventive Principle:

Principle #1Segmentation

2Productivity

If the rifle fires in fully automatic mode continuously, then firepower is maximized, but ammunition is wasted when only single shots are needed

Engineering Contradiction:

Improverate of fireVSAvoidammunition consumption

Core Design Contradiction:

ProductivityVSLoss of substance

Solution Approach 1:

The trigger assembly provides dynamic adaptability by allowing the shooter to switch between fully automatic and semi-automatic modes based on operational requirements. The mechanism can transition from continuous firing (high productivity) to single-shot firing (conservative ammunition usage), making the fire rate adjustable rather than fixed

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The firing mode parameter is changed by the shooter's selection through the trigger mechanism. In semi-automatic mode, the parameter changes from continuous cyclic firing to discrete single-shot firing, directly controlling ammunition consumption to match actual tactical needs

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS8453554B2M60 rifle with select fire mechanism for selective fully-automatic semi-automatic operation

Publication Date: 2013.06.04 OHIO ORDNANCE WORKS

AI summary

A trigger assembly for a trigger housing for a, M60 fully automatic rifle is provided having a switch accessible at the outside of the trigger housing for changing the firing of the rifle between semi-automatic and fully-automatic fire.