The on-board system is the core part of a train control system that ensures traffic safety and improves operational efficiency. At present, fault data processing methods for on-board systems do not show the degradation of components, subsystems, or the system over time, but only focus on identifying faults after a failure has occurred, so fault prognosis cannot be realized. This paper applies a multilevel flow model based on system-level failure mode and effect analysis. The model defines the primary and secondary alarms, divides the failure modes into different levels, and ranks the risk priority numbers at different levels. The Balise transmission system is then used as an example to demonstrate the system-level fault prognosis methodology, and the variables from different levels are combined through the component model, subsystem model, and system model. The results are verified according to the actual operation manual.

This paper presents a comparison between the performances of two chemistries of synthetic oil lubricants, polyalphaolefins (PAOs) and perfluoropolyethers (PFPEs) when applied on gold-plated electrical contacts operating at contact loads of 9.8 cN and experiencing fretting-induced degradation. Performance assessment was done using the contact resistance and coefficient of friction behavior and the surface’s response to fretting in the presence of different types of lubricants within the two chemistries. It was found that the PAOs improved the fretting performance of the lightly loaded contacts, and statistically, were at least fifty times more reliable for a longer duration of fretting cycles than the PFPEs, suggesting their suitability for low contact load applications. At low loads, PFPEs underwent contact separation due to hydrodynamic lubrication, and the behavior was more observable among the PFPEs having higher kinematic viscosities. On the contrary, viscous PAOs had improved fretting performance and delayed time to contact failure than less viscous PAOs. The applied lubricant film thickness also contributed to the contact’s performance, and it was found that increasing the thickness of the PFPE films advanced contact failures, while the PAO film postponed contact’s time to failure.

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