Glass-Reinforced Nylon Rung Lock Frame for Ladders

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Solution Overview

Problem

Conventional rung locks for extension ladders are expensive, fragile, and not sturdy enough to withstand abuse or impact, and they can cause wear to the rungs during operation.

Innovation Solution

A rung lock frame made of glass-reinforced nylon material with a C-shaped or U-shaped opening, triangular aperture, and enhanced structural features such as thicker hook and transition sections for increased strength and stability, allowing for a snap-fit engagement with rungs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If conventional aluminum rung locks are used, then strength and impact resistance are improved, but weight increases and cost increases

Engineering Contradiction:

Improveimpact resistanceVSAvoidrung lock weight

Core Design Contradiction:

StrengthVSWeight of moving object

Solution Approach 1:

The patent applies composite materials by combining glass fibers with nylon polymer to create glass-reinforced nylon. This composite structure provides the strength and impact resistance traditionally associated with aluminum while maintaining the weight advantages of polymeric materials. The glass fibers are embedded within the nylon matrix to create a material that exhibits both high strength-to-weight ratio and durability.

Inventive Principle:

Principle #40Composite materials

2Strength

If conventional aluminum rung locks are used, then strength is improved, but cost increases

Engineering Contradiction:

Improvestructural strengthVSAvoidmanufacturing cost

Core Design Contradiction:

StrengthVSEase of manufacture

Solution Approach 1:

The patent changes the material parameters by transitioning from metallic aluminum to polymeric glass-reinforced nylon. This parameter change allows for alternative manufacturing processes such as injection molding, which can reduce manufacturing costs compared to traditional metal fabrication methods while maintaining structural strength through the composite formulation.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The use of glass-reinforced nylon composite provides a cost-effective alternative to aluminum by utilizing readily available polymeric materials and standard plastic molding processes, while the glass fiber reinforcement ensures the structural strength requirements are met.

Inventive Principle:

Principle #40Composite materials

3Reliability

If conventional aluminum rung locks are used, then impact resistance is improved, but wear on rungs increases

Engineering Contradiction:

Improveimpact resistanceVSAvoidrung wear

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies homogeneity by using a polymeric material (glass-reinforced nylon) that has similar chemical composition to the nylon rungs. This material compatibility creates a homogeneous interaction between the rung lock and rungs, reducing galvanic corrosion and mechanical wear that occurs with dissimilar metal-to-metal contact.

Inventive Principle:

Principle #33Homogeneity

Solution Approach 2:

The patent converts the potential harm of material incompatibility into a benefit by selecting a polymeric rung lock material that is softer and more compatible with nylon rungs. This material choice reduces wear on the rungs while the glass fiber reinforcement compensates for the lower base material strength, providing impact resistance without the wear problems of aluminum.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

4Weight of moving object

If glass-reinforced nylon is used, then weight is reduced and cost is reduced, but strength may be compromised

Engineering Contradiction:

Improverung lock weightVSAvoidstructural strength

Core Design Contradiction:

Weight of moving objectVSStrength

Solution Approach 1:

The patent resolves this contradiction by creating a composite material where glass fibers are embedded in a nylon matrix. The glass fibers provide the necessary structural strength and stiffness, while the nylon matrix provides weight reduction and toughness. This composite structure achieves both light weight and high strength simultaneously.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent applies local quality by concentrating the glass fiber reinforcement in critical load-bearing areas of the rung lock structure. This localized reinforcement ensures that strength is enhanced where most needed while maintaining overall weight efficiency throughout the component.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS10669776B2Rung lock frame for a rung lock assembly for use with an extension ladder

Publication Date: 2020.06.02 LOUISVILLE LADDER GROUP LLC

AI summary

A rung lock frame has an upper rung portion, a lower rung portion integrally formed with the upper rung portion, and a bar member formed between the upper rung portion and the lower rung portion. The bar member defines an opening with the lower rung portion for the receipt of a rung of a ladder therein. The upper rung portion, the lower rung portion and the bar member are integrally formed of a glass-reinforced nylon material.