Reversible Ratchet Mechanism With Low Reverse Torque Feedback

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Solution Overview

Problem

Existing ratchet mechanisms either have low reverse torque but lack strong haptic and/or tactile feedback, or they have high reverse torque with strong feedback, failing to provide a balanced experience.

Innovation Solution

A reversible ratchet mechanism design incorporating a first spring with a lower spring constant and a second spring with a higher spring constant, along with a linear switch mechanism, to achieve reduced reverse torque while maintaining strong tactile feedback and reducing accidental actuation risk.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a stronger spring is used between pawls to increase haptic feedback, then tactile feedback is improved, but reverse torque increases

Engineering Contradiction:
Improvehaptic feedbackVSAvoidreverse torque
Core Design Contradiction:
Ease of operationVSForce

Solution Approach 1:

The spring mechanism is divided into two separate springs: a first spring with lower spring constant for pawl engagement (reducing reverse torque) and a second spring with higher spring constant for the ball detent mechanism (providing strong haptic feedback). This segmentation allows each spring to be optimized for its specific function without compromising the other.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different regions of the ratchet mechanism have different spring constant requirements. The pawl engagement area uses a softer spring (lower k value) to minimize reverse torque, while the switching mechanism area uses a stiffer spring (higher k value) to provide strong tactile feedback. This local differentiation of spring properties resolves the contradiction.

Inventive Principle:
Principle #3Local quality

2Device complexity

If a simpler switching mechanism is used, then device complexity is reduced, but risk of accidental actuation increases

Engineering Contradiction:
Improveswitching mechanismVSAvoidaccidental actuation risk
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

A ball detent acts as an intermediary element between the user's input and the ratchet mechanism activation. The ball must be deliberately pressed into a recess to actuate the switch, providing a clear tactile confirmation and preventing accidental activation while maintaining relatively simple mechanism geometry.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The switch is pre-configured with recesses that must be deliberately engaged to activate the ratchet mechanism. This preliminary positioning requirement ensures that only intentional actions trigger the mechanism, reducing accidental actuation without significantly complicating the overall design.

Inventive Principle:
Principle #10Preliminary action

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 design provides a reversible ratchet mechanism with reduced reverse torque and enhanced tactile feedback, ensuring secure operation and user control.

Implementation Method 1

a first spring with a lower spring constant between the pawls

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

a second stronger spring within the handle to press a ball detent into a linear switch

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP4385661B1Reversible ratchet mechanism
Publication Date: 2026.05.06 MILWAUKEE ELECTRIC TOOL CORP
  • EP4385661B1 patent drawingFigure 1
  • EP4385661B1 patent drawingFigure 2
  • EP4385661B1 patent drawingFigure 3

AI summary

A tool with a reversible ratchet mechanism is shown. The ratchet mechanism includes a gear structure, pawl structure, and a switching mechanism such that the ratchet mechanism allows tightening in the clockwise and counterclockwise direction. The ratchet mechanism further includes a biasing component for pawl movement and another biasing component engaged with the switching mechanism to provide tactile feedback.