CZ/SK verze

LL silent soles for freight wagon brakes under special observation

LL silent soles for freight wagon brakes under special observation
photo: ANSFISA/LL silent soles for freight wagon brakes under special observation
24 / 08 / 2021

A few days ago, ANSFISA (Italian National Agency for Safety of Railways and Road and Highway Infrastructure) issued a note to the subject "Emergency preventive measures following repeated accidents and incidents to freight wagons equipped with brake soles in composite material type LL (Low noise, Low friction).

The events occurred in several European countries and continued despite the first warnings to railway operators in February 2021, also involving wagons carrying dangerous goods, and with an accident in France that could have led to the derailment of the train.

In July, the FerCargo Association had advanced the hypothesis that the alarm thresholds of the bushing temperature detection systems and braked axles installed along the railway network are not able to promptly detect the overheating phenomena of the LL type soles.

ANSFISA has therefore issued a series of prescriptions, both for the wagon keepers and CME subjects, as well as for the Railway Companies and also for the Infrastructure Manager, so that the necessary preventive control and verification measures during the journey are adopted to avoid overheating of the braked axles.

The various recipients of the prescriptions must report to ANSFISA on the evolution of the phenomenon by 15 September 2021.

LL soles have been the subject of a long study and an extensive series of tests in all climatic conditions a few years ago, and they must play an important role in reducing the traffic noise of freight wagons as they offer good results and they do not require the replacement of the entire braking system to adapt the existing wagons. In fact, while the K synthetic soles must work at lower pressures, the LL are compatible with the pressures in use for cast iron blocks.

However, it seems that in the real long-term exercise, some problems still need to be solved.

On the other hand, the overheating of the axles is a potentially very dangerous event, especially on the crossing lines with long descents, and can lead in extreme cases to the encroachment of the wheel rims with a serious risk of detachment and consequent derailment of the wagon.