Two-Part Pusher Assembly for Dry-Fire Fastener Drivers

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Solution Overview

Problem

Existing fastener drivers face power, size, and cost constraints, and often suffer from dry-fire issues due to insufficient fastener supply.

Innovation Solution

A fastener driver with a magazine assembly, nosepiece assembly, and pusher assembly that includes adjustable portions biased by springs, featuring a dry-fire lockout mechanism to prevent operation when a predetermined number of fasteners are left, allowing for efficient use of long and short fasteners.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional fastener driver is used, then it can drive fasteners into workpieces, but it suffers from dry-fire issues when fastener supply is insufficient

Engineering Contradiction:
Improveprevention of dry-fire operationVSAvoidcomplexity of lockout mechanism
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The lockout member is positioned in advance within the magazine assembly to detect when the fastener supply reaches a predetermined low level. Before a dry-fire condition can occur, the lockout member engages the blocking member to prevent further operation, thus preliminarily blocking the harmful action before it happens.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The lockout member acts as an intermediary element between the fastener supply status and the driving mechanism. It translates the physical state of fastener availability into a mechanical blocking action through its engagement with the blocking member, preventing direct transmission of the driving force when fasteners are insufficient.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Adaptability or versatility

If the pusher assembly uses a single rigid structure, then it is simple in design, but it cannot accommodate both long and short fasteners effectively

Engineering Contradiction:
Improveaccommodation of various fastener lengthsVSAvoidcomplexity of pusher assembly
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The pusher assembly is divided into a first portion and a second portion that can move independently relative to each other. This segmentation allows each portion to be optimized for different fastener lengths, with the first portion handling shorter fasteners and the second portion extending to accommodate longer fasteners, thereby achieving versatility without requiring a completely different mechanism for each fastener type.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The pusher assembly transitions from a static rigid structure to a dynamic configuration where the first and second portions can move independently. This dynamic capability allows the assembly to adapt its shape and reach to accommodate various fastener lengths, providing versatility while maintaining a relatively simple overall structure that uses basic mechanical components.

Inventive Principle:
Principle #15Dynamics

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

Ensures reliable operation by preventing dry-fires and accommodating various fastener lengths, optimizing power usage and reducing waste.

Implementation Method 1

A first spring has an end coupled to the first portion. A second spring has an end coupled to the second portion. Each of the first spring and the second spring is configured to bias the first portion and the second portion, respectively, toward the channel independent of each other.

Methodology Applied
Scientific EffectElastic force: Elasticity

Implementation Method 2

a magnet exerting a magnetic force on the lockout member to bias the lockout member toward a first position

Methodology Applied
Scientific EffectMagnetic force: Magnetism

Data Source

PatentEP4126462B1Powered fastener driver
Publication Date: 2026.01.28 MILWAUKEE ELECTRIC TOOL CORP
  • EP4126462B1 patent drawingFigure 1
  • EP4126462B1 patent drawingFigure 2
  • EP4126462B1 patent drawingFigure 3

AI summary

A fastener driver includes a pusher assembly slidably coupled to a magazine assembly. The pusher assembly includes a first portion and a second portion that are selectively movable relative to each other. The pusher assembly is adjustable between a first state in which the first portion and the second portion are configured to move together in unison toward the channel, and a second state in which the first portion moves relative to the second portion toward the channel. A dry-fire lockout assembly includes a blocking member coupled to the magazine assembly or the nosepiece assembly, and a lockout member selectively engageable with the blocking member for moving the blocking member from a first position and a second position. The pusher assembly is configured to transition from the first state to the second state after a predetermined number of fasteners remain in the magazine assembly.