Modular Portal-Axle Design for Low-Floor Rail Vehicles
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Solution Overview
Problem
Current portal-axles for low-floor light rail vehicles are limited by poor modularity, high weight, complex assembly, difficulty in automated inspection, and expensive non-standard bearings, leading to increased production and maintenance costs.
Innovation Solution
A modular portal-axle design using standardized, certified bars instead of cast or forged central portions, allowing for easy assembly, weight reduction, and simplified inspection, with the option to use different materials and coupling methods such as welding, keying, or screwing, and the use of cartridge bearings for wheel support.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If conventional cast or forged central portions are used in portal-axles, then structural integrity is ensured, but weight increases and modularity decreases
Solution Approach 1:
The portal-axle is divided into separate modular components: standardized certified bars for the central portion and interchangeable shoulders. This segmentation allows the central portion to be produced through simpler, lighter processes while maintaining structural integrity, and enables easy adaptation by replacing shoulders for different gauge tracks without redesigning the entire portal-axle.
Solution Approach 2:
The standardized certified bars are designed as universal components that can be used across different portal-axle configurations. The modular design with interchangeable shoulders allows the same central portion to serve multiple functions and adapt to various gauge requirements, enhancing versatility without increasing weight.
2Strength
If cast or forged central portions are used, then structural strength is achieved, but manufacturing complexity and cost increase
Solution Approach 1:
The invention replaces expensive cast or forged central portions with simpler, lighter standardized certified bars that can be manufactured through more economical processes. While individual bars may need replacement over time, their standardized nature allows for cost-effective production and easy substitution, reducing overall manufacturing complexity and cost.
Solution Approach 2:
The central portion design transitions from traditional cast/forged construction to standardized certified bars with controlled parameters. This parameter change enables the use of simpler manufacturing processes while maintaining adequate structural strength through proper selection of bar dimensions, materials, and certification standards.
3Adaptability or versatility
If non-standard technical specifications are provided for each customer, then customization needs are met, but production costs and assembly complexity increase
Solution Approach 1:
The portal-axle is segmented into standardized central portions and customizable shoulders. This segmentation allows the majority of the structure to remain standardized for simple, repeatable production, while only the shoulder components need to be adapted to specific customer gauge requirements. This significantly reduces assembly complexity compared to fully customized designs.
Solution Approach 2:
Standardization is applied to the central portion where uniformity provides maximum benefit, while customization is concentrated in the shoulder regions where gauge-specific adaptations are needed. This local differentiation optimizes both production efficiency and customer-specific adaptability.
Data Source
AI summary
A portal-axle of bogies for light rail vehicles, such as for example trams or light rail metros with street running, is described, the light rail vehicles being characterized by a floor, i.e. a walking surface, lowered with respect to the rails. The portal-axle comprises two shoulders equipped with spindles for mounting wheels and with a central portion for structurally connecting the shoulders. Unlike conventional solutions, the central portion is not made by casting or forging, but advantageously is simply defined by at least two bars coupled thereto during the assembly. The bars are easily available on the market at low cost, have lower weight with respect to a traditional forged/cast component and allow modularity and versatility in dimensioning the portal-axle to be obtained.