Lanyard Locking Arm for Automatic Drop-Distance Control

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Solution Overview

Problem

Existing lanyards for securing tools and equipment at height do not effectively prevent tools from dropping further than a predetermined distance and protect them from damage during falls, and require user interaction to unlock the locking mechanism.

Innovation Solution

A lanyard with a locking/biasing mechanism that automatically disengages when a sufficient pulling force is exerted, allowing the spool to rotate freely without user intervention, and includes a spring-biased ball system to maintain the locked or unlocked position, enhancing safety and ease of use.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a retractable cable mechanism is used to secure tools at height, then the tool can be freely maneuvered during normal use, but the tool may drop further than a predetermined distance if the locking mechanism requires user interaction to engage

Engineering Contradiction:
Improveprevention of excessive drop distanceVSAvoiduser interaction required to unlock
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The locking mechanism automatically engages and disengages based on the force applied to the cable. When the cable is pulled with sufficient force (exceeding spring bias), the cam follower disengages from the cam lobe, allowing automatic unlocking without user intervention. This self-service mechanism ensures the tool can be quickly secured or released based on operational needs.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent replaces manual locking/unlocking operations with an automatic mechanical system using a cam and follower mechanism. The cam profile is designed so that normal cable tension maintains locked position, while excessive force automatically triggers disengagement. This mechanical substitution eliminates the need for user interaction while maintaining reliable control.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If a locking mechanism with cam and follower is used to prevent excessive drop, then safety is enhanced, but the device complexity increases

Engineering Contradiction:
Improvesafety during tool dropsVSAvoidnumber of locking components
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The locking and biasing functions are merged into a single integrated mechanism. The cam profile simultaneously provides the locking action (through its geometric shape) and the biasing force (through its interaction with the spring-loaded follower). This merging reduces the number of separate components needed while maintaining safety functionality.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The cam component serves multiple functions: it provides the locking geometry, stores potential energy through its profile shape, and works with the spring to provide both locking and unlocking forces. This multi-functionality reduces overall device complexity by consolidating several functions into a single component.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Ease of operation

If a spring-biased ball system is used to maintain locked or unlocked position, then ease of extension is improved, but the device complexity increases

Engineering Contradiction:
Improveautomatic position maintenanceVSAvoidnumber of spring components
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The spring-biased ball system automatically maintains the locked or unlocked position based on the force applied to the cable. When the cable is under normal tension, the spring keeps the ball engaged with the corresponding surface, maintaining the position without user intervention. This self-service approach improves ease of operation while using a simple spring-ball mechanism.

Inventive Principle:
Principle #25Self-service

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 lanyard automatically locks and unlocks based on force, preventing excessive drop distance and protecting tools from damage, while allowing easy extension without manual actuation, thus meeting regulatory requirements and enhancing safety.

Implementation Method 1

includes a spring-biased ball system to maintain the locked or unlocked position

Methodology Applied
Scientific EffectSpring biasing: Spring

Implementation Method 2

When the locking mechanism is in the unlocked position, the spool is permitted to rotate without interference from the locking mechanism

Methodology Applied
Scientific EffectMechanical advantage: Mechanical Advantage

Data Source

PatentEP4182252B1Lanyard with locking arm
Publication Date: 2025.07.02 MILWAUKEE ELECTRIC TOOL CORP
  • EP4182252B1 patent drawingFigure 1
  • EP4182252B1 patent drawingFigure 2
  • EP4182252B1 patent drawingFigure 3

AI summary

A lanyard having a locking mechanism is provided. The lanyard locking mechanism actuates between a locked position and an unlocked position. In the locked position, the lanyard spool is restricted from rotating, and in the unlocked position, the lanyard spool is permitted to rotate with reduced interference from the locking mechanism. The locking mechanism includes biasing components that bias the locking mechanism to remain stationary unless sufficient force is exerted.