Dual-Stage Spring Caster for Uneven Surface Stability

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Solution Overview

Problem

Conventional casters fail to maintain contact with uneven surfaces, leading to potential damage of goods due to shock absorption issues and misalignment of swivel casters when encountering depressions, which can result in goods falling off or being jarred.

Innovation Solution

A caster design featuring a dual-stage spring mechanism with a wheel stage spring and main stage spring, where the wheel is rotatably mounted to an axle that moves between up and down positions within elongated axle holes, maintaining contact with the surface and allowing the arm assembly to pivot relative to the horn assembly, ensuring the caster remains aligned and stable on uneven surfaces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a standard spring-loaded caster is used, then shock absorption is provided, but the caster loses contact with the surface over deep depressions

Engineering Contradiction:

Improvecaster contact with surfaceVSAvoidsurface condition adaptation

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The invention employs a dual-stage spring mechanism where the first spring (in the horn assembly) and second spring (in the arm assembly) work together to dynamically adapt to varying surface conditions. The springs are configured with different stiffness characteristics to provide progressive suspension, allowing the caster to maintain reliable contact with the surface over both shallow and deep depressions while absorbing shock.

Inventive Principle:

Principle #15Dynamics

2Reliability

If a swivel caster encounters a deep depression, then the spring absorbs the shock, but the caster loses alignment with the direction of travel

Engineering Contradiction:

Improvecaster alignmentVSAvoidshock and misalignment

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The caster is divided into functionally independent segments: the horn assembly with its first spring, the arm assembly with its second spring, and the wheel assembly. This segmentation allows each component to perform its specific function - the first spring handles overall suspension, while the second spring in the arm assembly specifically maintains alignment and reduces misalignment during depression traversal.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The second spring in the arm assembly acts as a preliminary cushioning mechanism that prepares the wheel assembly for upcoming surface irregularities. By providing advance cushioning through the arm assembly's independent spring, the system prevents sudden misalignment and shock transmission to the wheel, thereby maintaining caster alignment during depression traversal.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Productivity

If conventional casters are used on rough surfaces, then the vehicle can move, but goods are subject to damage due to shock

Engineering Contradiction:

Improvevehicle mobilityVSAvoidshock to goods

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The invention merges two spring-loaded caster designs into a single integrated system, combining the first spring in the horn assembly with the second spring in the arm assembly. This merged dual-stage suspension system provides enhanced shock absorption capability while maintaining vehicle mobility on rough surfaces, thereby protecting goods from shock damage without sacrificing productivity.

Inventive Principle:

Principle #5Merging (Combining)

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 dual-stage spring mechanism ensures that the caster maintains contact with the surface over depressions and raised portions, preventing goods from falling or being jarred, thereby reducing damage and maintaining vehicle stability on rough surfaces.

Implementation Method 1

A wheel stage spring is operatively coupled to the axle and configured to bias the axle downwardly in each elongated axle hole

Methodology Applied

Scientific EffectSpring: Spring

Implementation Method 2

When the wheel moves over a raised portion in the support surface, the arm assembly pivots relative to the horn assembly so as to compress the main stage spring

Methodology Applied

Scientific EffectSpring: Spring

Data Source

PatentUS10518578B1Dual-stage spring loaded caster

Publication Date: 2019.12.31 HAMILTON CASTER & MFG CO

AI summary

A dual-stage caster is disclosed. The caster includes a horn assembly and an arm assembly pivotally coupled to the horn assembly. The caster further includes a wheel rotatably mounted to the arm assembly and a mounting plate mounted to the horn assembly and configured be mounted to a transport vehicle. When the wheel is moved along a support surface, the arm assembly is in a neutral position and the wheel is in the up position. When the wheel moves into a depression in the support surface, the wheel stage spring moves the wheel from the up position to the down position and the arm assembly remains in the neutral position. When the wheel moves over a raised portion in the support surface, the arm assembly pivots relative to the horn assembly so as to compress the main stage spring. The caster may be a swivel caster or a rigid caster.