Straddle Carrier Rocker Steering for Load Distribution

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Solution Overview

Problem

Existing straddle carriers for container terminals face issues with uneven load distribution and potential wheel overloading due to spring-supported chassis, which affects steerability and mechanical robustness.

Innovation Solution

The implementation of a rocker construction that allows each wheel or wheel carrier to be steered separately, with pivot pins at the free end of an intermediate carrier on the traveling beam, enabling even load distribution and eliminating the need for complex spring assemblies and expensive steering components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If spring-supported chassis are used in straddle carriers, then the carrier can absorb terrain irregularities, but significant differences in load distribution occur between individual wheels and wheel overloading cannot be ruled out

Engineering Contradiction:
Improveterrain irregularity compensationVSAvoidload distribution uniformity
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The chassis is divided into multiple independently steerable wheels (first and second wheels on first carriage, third and fourth wheels on second carriage), each capable of separate steering motion. This segmentation allows each wheel to independently adapt to terrain irregularities, preventing load concentration on single wheels while maintaining overall chassis stability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The wheels are equipped with steering mechanisms that enable dynamic adjustment of wheel orientation relative to the chassis. The first and second wheels can be steered separately from the third and fourth wheels, allowing the system to dynamically respond to terrain variations and achieve balanced load distribution across all wheels.

Inventive Principle:
Principle #15Dynamics

2Ease of operation

If complex spring assemblies and steering shafts with toothed geometry are used, then steering functionality is achieved, but the design becomes expensive and mechanically complex

Engineering Contradiction:
Improvesteering functionalityVSAvoidspring assembly and steering shaft complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent extracts and eliminates the complex spring assemblies and toothed geometry steering shafts from the design. Instead, it uses a simplified steering mechanism where the first and second wheels are steered separately from the third and fourth wheels through a more straightforward mechanical arrangement, reducing component complexity while maintaining steering functionality.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent employs simpler, more cost-effective steering components that achieve the required functionality without expensive mechanisms. The separate steering of wheel pairs allows for simpler mechanical linkages compared to traditional synchronized steering systems, reducing manufacturing costs and maintenance requirements.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Data Source

PatentEP2477928B1Straddle carrier for use in container terminals and for general transport tasks
Publication Date: 2016.12.14 PFENNING ELEKTROANLAGEN
  • EP2477928B1 patent drawingFigure 1
  • EP2477928B1 patent drawingFigure 2~3

AI summary

A straddle carrier (1) for use in container terminals and for general transport tasks has a frame (2), a load handling means (4), which hangs between the frame (2) and can be locked together with a load, preferably a container (7), hoisting winches (8), by means of which the load handling means (4) is vertically movable, and carriage beams (3), which are arranged at the lower region of the frame (2) and each have a plurality of wheels (11) arranged in a row; wherein two wheel carriers (12), which are arranged next to or behind each other on a carriage beam (3) and on each of which a wheel (11) of the straddle carrier (1) is mounted, are each mounted on a rocker (13), which is pivotable in relation to the carriage beam (3) about a horizontally arranged pivot pin (16). Each wheel (11) and each wheel carrier is separately steerable on its rocker.