Step-Adaptive Caster Mechanism for Compact Stage-End Climbing

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Solution Overview

Problem

Conventional stage-corresponding caster devices have a long longitudinal dimension and generate torsion when the main wheel contacts the stage end face with slight inclination, making smooth operation difficult and requiring strong force to overcome the stage end face.

Innovation Solution

A compact stage-corresponding caster device with a holder main body, main and sub wheels, and a slide roller mechanism that allows the sub wheel to contact the stage upper face with strong force, converting reaction forces to push the attached member upward and forward, enabling efficient climbing over the stage end face without additional lifting effort.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If the main wheel is moved greatly back and forth in horizontal directions to move the sub wheel up and down, then the sub wheel can contact the stage upper face, but the longitudinal dimension of the holder main body becomes long

Engineering Contradiction:
Improvelongitudinal dimension of holder main bodyVSAvoidstage climbing function
Core Design Contradiction:
Length of moving objectVSEase of operation

Solution Approach 1:

The patent introduces a slide roller that moves in a direction oblique to the horizontal direction (at an angle of 15-45 degrees), converting part of the horizontal movement into vertical movement. This dimensional change allows the sub wheel to be raised more efficiently without requiring excessive horizontal travel of the main wheel, thereby reducing the longitudinal dimension of the holder main body while maintaining the stage climbing function

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent employs a dynamic mechanism where the slide roller is guided by an inclined guide surface that converts horizontal motion into combined horizontal and vertical motion. This dynamic conversion allows the system to achieve vertical displacement of the sub wheel with reduced horizontal displacement of the main wheel, resolving the contradiction between compact dimensions and climbing capability

Inventive Principle:
Principle #15Dynamics

2Ease of operation

If the main wheel contacts the stage end face with slight inclination, then the caster can move, but torsion is generated making smooth operation difficult

Engineering Contradiction:
Improvesmooth operationVSAvoidtorsion stability
Core Design Contradiction:
Ease of operationVSStability of the object's composition

Solution Approach 1:

The slide roller acts as an intermediary element between the main wheel and sub wheel, providing a guided path that converts inclined contact into controlled motion. The inclined guide surface mediates the force transmission, preventing torsion by directing the contact force along a predetermined oblique path rather than allowing uncontrolled lateral forces

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The use of a cylindrical slide roller with a circular cross-section provides smooth rolling motion that naturally accommodates slight inclinations without generating torsion. The curved surface of the roller allows it to roll along the inclined guide surface, converting angular misalignment into rotational motion rather than torsional stress

Inventive Principle:
Principle #14Spheroidality (Curvature)

3Force

If strong force is applied to overcome the stage end face, then the carriage can get over the stage, but the user must run and lift up the attached member with strong force

Engineering Contradiction:
Improveforce to overcome stage end faceVSAvoiduser effort
Core Design Contradiction:
ForceVSEase of operation

Solution Approach 1:

The mechanism enables self-service by using the motion of the main wheel itself to generate the force needed to raise the sub wheel. As the main wheel moves forward and contacts the stage end face, the inclined guide surface automatically converts this horizontal motion into vertical motion of the sub wheel, eliminating the need for the user to apply additional lifting force

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent converts the harmful effect of the stage end face (which normally creates resistance and requires strong lifting force) into a beneficial force. By positioning the sub wheel to contact the stage upper face and using the inclined guide surface, the resistance encountered by the main wheel is transformed into the driving force that raises the sub wheel, enabling the carriage to climb the stage with minimal user effort

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

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 device achieves stable and smooth stage climbing with reduced longitudinal dimension, allowing easy and lightweight traversal of stage end faces by converting reaction forces to push the attached member upward and forward, minimizing torsion and requiring minimal user effort.

Implementation Method 1

an elevation guide having a guiding inclined face to guide the slide roller and fixed to a front portion of the holder main body

Methodology Applied
Scientific EffectInclined plane: Inclined Plane

Implementation Method 2

the attached member such as carriage, walking frame, shopping cart, etc. and the main wheel can be pushed up by making the sub wheel contact the stage upper face with strong force

Methodology Applied
Scientific EffectReaction force: Reaction (physics)

Data Source

PatentEP3722105B1Step adaptive caster device
Publication Date: 2025.08.06 YUEI CO LTD
  • EP3722105B1 patent drawingFigure 1
  • EP3722105B1 patent drawingFigure 2
  • EP3722105B1 patent drawingFigure 3

AI summary

To provide a stage-corresponding caster device being entirely compact, able to smoothly and stably work, and able to easily get over a stage end face, a holder main body 1 attached to an attached member B and having a pair of left and right side wall portions 10, a main wheel supporting member 2 in which the main wheel 7 is pivoted to a lower portion 2b and an upper portion 2a is pivoted to the holder main body 1, a sub wheel supporting member 3 in which the sub wheel 8 is pivoted to a front portion 3c and a rear portion 3d is pivoted to the main wheel supporting member 2 coaxially with the main wheel 7, and a slide roller 30 attached to the sub wheel supporting member 3 on a forward position to the main wheel 7, are provided; and the holder main body 1 has a guiding groove 13 inclined backward and downward in side view on the side wall portion 10 to guide the slide roller 30, the front portion 3c of the sub wheel supporting member 3 is oscillated downward by contact of the main wheel 7 with the stage end face Ja, the sub wheel 8 is pressed to the stage upper face Jb, and the main wheel 7 climbs over the stage end face Ja.