Tripod Stepladder Frame Collar Load Distribution

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Solution Overview

Problem

Tripod stepladders face challenges with stability due to minimal structural strength and weight distribution, leading to torsional stresses and instability, especially when users exert forces that cause the ladder to twist or move during use.

Innovation Solution

A tripod stepladder design featuring a front section with angled side rails, a single square tubular rail for the back section, and a frame with a collar that securely engages the back section, distributing loads and reducing torsional effects through a wide base and secure fastening, while minimizing weight and manufacturing costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If the stepladder is designed with minimal weight for portability, then ease of carrying is improved, but structural strength and stability deteriorate

Engineering Contradiction:

Improveladder weightVSAvoidstructural strength

Core Design Contradiction:

Weight of moving objectVSStrength

Solution Approach 1:

The patent employs composite construction by combining multiple materials with different properties. The frame uses a collar receiving the back section rail, creating a composite structural system that optimizes both weight and strength. This allows the ladder to maintain portability while achieving the necessary structural integrity through material combination rather than relying on a single heavy material throughout.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The stepladder is divided into distinct segments: a front section with side rails, a back section with a single rail, and a frame with collar. This segmentation allows each component to be optimized independently for its specific function while contributing to overall structural strength without requiring the entire ladder to be heavily constructed.

Inventive Principle:

Principle #1Segmentation

2Ease of operation

If the stepladder has minimal structural strength for portability, then ease of handling is improved, but stability and resistance to torsional stress worsen

Engineering Contradiction:

Improveease of handlingVSAvoidladder stability

Core Design Contradiction:

Ease of operationVSStability of the object's composition

Solution Approach 1:

The patent incorporates dynamic elements including a pivotally connected back section that can move between folded and extended positions, and a folding brace member that dynamically adjusts to maintain stability. These dynamic features allow the ladder to adapt its structural characteristics based on operational state, providing ease of handling during transport and enhanced stability during use.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The frame with collar and the folding brace member provide preliminary structural support and anti-torsional reinforcement before the ladder is fully deployed. This preliminary anti-action prevents torsional stresses from developing during the transition from folded to extended position, maintaining stability throughout the operational cycle.

Inventive Principle:

Principle #9Preliminary anti-action

3Ease of operation

If the stepladder uses a traditional folding brace design, then ease of folding is improved, but stability and resistance to twisting motion deteriorate

Engineering Contradiction:

Improvefolding capabilityVSAvoidtorsional stress

Core Design Contradiction:

Ease of operationVSObject-generated harmful factors

Solution Approach 1:

The frame with collar acts as an intermediary structure between the back section rail and the front section. This intermediary component provides a stable pivot point and distributes loads, reducing torsional stresses on the individual rails while maintaining the folding capability. The collar receives the back section rail, creating a mediating connection that enhances stability during folding and extension.

Inventive Principle:

Principle #24Intermediary (Mediator)

4Weight of moving object

If the stepladder is designed for portability with reduced weight, then ease of carrying is improved, but the ability to resist user-induced forces and moment couple worsens

Engineering Contradiction:

Improveladder weightVSAvoidresistance to user force

Core Design Contradiction:

Weight of moving objectVSForce

Solution Approach 1:

The patent merges the back section support functions into a unified frame structure with collar that receives the back section rail. This consolidation creates a more efficient load-bearing system that can resist user-induced forces with less material than traditional designs, maintaining portability while improving force resistance through structural integration.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS10767418B2Tripod stepladder

Publication Date: 2020.09.08 LOUISVILLE LADDER GROUP LLC

AI summary

A stepladder assembly has a front section with a pair of side rails and a plurality of steps extending between the pair of side rails, a back section having a rail, and a frame pivotally connected or interconnected to the front section. The frame has a collar receiving an upper end of the rail of the back section therein. A ladder top is affixed to an upper end of the front section. The frame is pivotally affixed to the ladder top. The frame has a horizontal member positioned above the collar, and first and second side members extending from the collar to opposite ends of the horizontal member.