Road-Rail Excavator Bogie With Pendulum Rail Axle Compensation

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Solution Overview

Problem

Existing road-rail vehicles fail to adequately compensate for rail unevenness during travel, leading to potential derailment due to rail wheels lifting off the tracks, which is unsafe and compromises guidance.

Innovation Solution

A road-rail vehicle design featuring a wheeled chassis with steerable and drivable wheel axles for road travel and a rail-mounted chassis with pivotable rail axles that can oscillate relative to a center section via a pendulum axis, allowing for effective compensation of rail unevenness by maintaining rail contact through actuators and pivot bearings.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the rail axles are fixed to the vehicle's base steel structure, then the structural simplicity is maintained, but the ability to compensate for rail unevenness is insufficient, leading to rail wheels lifting off the track

Engineering Contradiction:
Improverail contact stabilityVSAvoidaxle mounting structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The rail axles are made dynamically adjustable through a pivot mechanism that allows them to oscillate around a longitudinal pendulum axis. This dynamic capability enables the rail axles to adapt to rail unevenness by changing their angle relative to the vehicle base, ensuring continuous rail wheel contact while maintaining structural simplicity through a single-degree-of-freedom pivot connection

Inventive Principle:
Principle #15Dynamics

2Reliability

If the rail axles are made pivotable to compensate for rail unevenness, then the rail contact stability is improved, but the structural complexity increases

Engineering Contradiction:
Improverail wheel contactVSAvoidpendulum axis mechanism
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The pendulum axis mechanism serves multiple functions simultaneously: it acts as a pivot connection for the rail axle, provides compensation for rail unevenness, and maintains the structural integration with the vehicle base. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in structural complexity while achieving reliable rail contact

Inventive Principle:
Principle #6Universality (Multi-functionality)

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

Ensures consistent rail contact and safe guidance by compensating for rail unevenness, preventing derailment and enhancing operational stability and maneuverability.

Implementation Method 1

the rail axles can oscillate relative to a center section via a pendulum axis, allowing for effective compensation of rail unevenness by maintaining rail contact

Methodology Applied
Scientific EffectPendulum motion: Pendulum

Data Source

PatentEP4631820A1Two-way vehicle
Publication Date: 2025.10.15 LEIBHERR HYDRAULIKBAGGER GMBH
  • EP4631820A1 patent drawingFigure 1
  • EP4631820A1 patent drawingFigure 2a~2b
  • EP4631820A1 patent drawingFigure 3~4

AI summary

The invention relates to a road-rail vehicle, in particular a road-rail excavator, with an undercarriage which comprises a wheeled chassis with at least two wheel axles for road travel and a rail chassis with a front and a rear rail axle for rail travel, wherein the undercarriage comprises a center piece on which the wheel axles are arranged. The rail chassis comprises actuators by means of which the rail axles can be moved relative to the center piece between a first travel position for road travel and at least one second travel position for rail travel. According to the invention, the rail chassis comprises at least one end piece which carries one of the rail axles and is mounted on the center piece so as to be rotatable about a pendulum axis running parallel to a longitudinal axis of the undercarriage in order to compensate for unevenness during rail travel by means of a pendulum movement of the rail axis.The end piece is mounted on the center piece via a first pivot bearing and a second pivot bearing spaced apart from the first pivot bearing along the pendulum axis. The invention further relates to a rail bogie for a road-rail vehicle according to the invention.