Road-Rail Excavator Bearing Assembly for Pendulum Rail Axle Stability

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Solution Overview

Problem

Existing road-rail vehicles face issues with rail wheel lifting off the rail due to rail unevenness, leading to unsafe guidance and potential derailment, while suspension elements for pendulum movements compromise stability and load capacity.

Innovation Solution

A road-rail vehicle design with rotatable rail axles mounted on a pendulum axis, coupled to a bearing arrangement that switches between damping and locking modes to compensate for rail unevenness, ensuring continuous rail contact and stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If suspension or damping elements are provided to inhibit pendulum movements of the rail axle, then stability of the running gear is improved, but the maximum permissible load is reduced

Engineering Contradiction:
Improvestability of running gearVSAvoidmaximum permissible load
Core Design Contradiction:
Stability of the object's compositionVSWeight of moving object

Solution Approach 1:

The patent applies a dynamically adjustable bearing arrangement that can switch between damping mode (with lower stiffness for stability during rail travel) and locking mode (with higher stiffness for maximum load capacity during working operations). This dynamic adaptability resolves the contradiction by allowing the system to optimize its mechanical properties based on operational requirements.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The bearing arrangement changes its stiffness parameter between two distinct states: a softer state for compensating rail unevenness and a stiffer state for maximizing load-bearing capacity. This parameter switching enables the system to simultaneously achieve both stability and high load capacity at different operational phases.

Inventive Principle:
Principle #35Parameter changes

2Ease of operation

If the rail axle is designed to oscillate around a pendulum axis to compensate for rail unevenness, then driving dynamics are improved, but stability for working operations is reduced

Engineering Contradiction:
Improvedriving dynamicsVSAvoidstability for working operations
Core Design Contradiction:
Ease of operationVSStability of the object's composition

Solution Approach 1:

The system dynamically adjusts the bearing characteristics to enable pendulum oscillation during rail travel for improved driving dynamics, then locks the bearing arrangement during working operations to provide stable support. This temporal separation of functions resolves the contradiction between motion compensation and operational stability.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The bearing arrangement periodically switches between damping and locking modes based on operational requirements. During rail travel, the damping mode is active for smooth operation over uneven rails; during working operations, the locking mode engages to provide rigid support, creating a periodic cycle that satisfies both contradictory requirements.

Inventive Principle:
Principle #19Periodic action

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 solution provides effective compensation for rail unevenness, maintaining driving dynamics and stability, allowing for safe rail travel and increased load capacity.

Implementation Method 1

the rail axles are mounted relative to a center section so as to be rotatable about a pendulum axis in order to compensate for rail unevenness during rail travel by means of a pendulum movement of the rail axle(s) about said pendulum axis

Methodology Applied
Scientific EffectPendulum movement: Pendulum

Data Source

PatentEP4631821A1Two-way vehicle
Publication Date: 2025.10.15 LEIBHERR HYDRAULIKBAGGER GMBH
  • EP4631821A1 patent drawingFigure 1
  • EP4631821A1 patent drawingFigure 2a~2b
  • EP4631821A1 patent drawingFigure 3a~3b

AI summary

The invention relates to a road-rail vehicle, in particular a road-rail excavator, with an undercarriage which comprises a first chassis for the ground-based movement of the road-rail vehicle and a rail chassis with a front and a rear rail axle for rail travel, wherein the undercarriage comprises a center section on which the first chassis is arranged. The rail chassis comprises actuators by means of which the rail axles can be moved relative to the center section between a first travel position for road travel and at least one second travel position for rail travel. According to the invention, the front and/or rear rail axle is mounted relative to the center section so as to be rotatable about a pendulum axis and is additionally coupled to the center section via at least one bearing arrangement which can be switched between a damping mode with comparatively low rigidity and a locking mode with comparatively higher rigidity.The bearing assembly comprises two separate assemblies, a first assembly providing the higher rigidity and a second assembly providing the lower rigidity. The second assembly can be deactivated to switch to the locking mode. The invention further relates to a bearing assembly for a road-rail vehicle according to the invention.