TY - GEN
T1 - The effect of friction modifiers on wheel/rail isolation
AU - Lewis, R.
AU - Gallardo, E. A.
AU - Cotter, J.
AU - Eadie, D. T.
PY - 2008
Y1 - 2008
N2 - Train detection, for signalling purposes, is often by means of track circuits. Signalling block occupancy is triggered by the wheelset of the train 'shorting out' the track circuit, i.e. the wheels and axle act as a shunt. Contamination on the track such as ballast dust, rust, oil, or leaves as well as substances designed to improve train operation such as friction modifiers or sand may cause the contact between the wheelsets and the track to be compromised, inhibiting train identification. In previous work a twin disc approach has been used to study the effect of sand (used to improve adhesion) and leaves on wheel/rail isolation. Friction modifiers are of significant current interest in wheel/rail research. Introducing a new material into the tread/top of rail interface can raise questions about the impact on signalling systems. Although no significant effects have been observed in practical operation on a range of railway systems, the intention in this work was to evaluate conductance between wheel and rail in a more controlled and systematic fashion using the previously established methodology. Using the twin disc technique, friction modifier, in the form of a solid stick, was applied using a spring loaded device to the rotating wheel disc to generate a visible film. Tests were run to measure contact impedance at typical loads and slips. Static tests were also carried out using discs pre-conditioned with a friction modifier film. The electrical circuit used was a modified simplified simulation of audio frequency track circuit. No significant difference was observed in the measured impedance for dry conditions with no friction modifier, versus tests where friction modifier was applied, regardless of percentage slip or input voltage. The analysis suggests that the introduction of friction modifier into the existing wheel/rail interfacial film does not result in increased impedance with all other factors being equal.
AB - Train detection, for signalling purposes, is often by means of track circuits. Signalling block occupancy is triggered by the wheelset of the train 'shorting out' the track circuit, i.e. the wheels and axle act as a shunt. Contamination on the track such as ballast dust, rust, oil, or leaves as well as substances designed to improve train operation such as friction modifiers or sand may cause the contact between the wheelsets and the track to be compromised, inhibiting train identification. In previous work a twin disc approach has been used to study the effect of sand (used to improve adhesion) and leaves on wheel/rail isolation. Friction modifiers are of significant current interest in wheel/rail research. Introducing a new material into the tread/top of rail interface can raise questions about the impact on signalling systems. Although no significant effects have been observed in practical operation on a range of railway systems, the intention in this work was to evaluate conductance between wheel and rail in a more controlled and systematic fashion using the previously established methodology. Using the twin disc technique, friction modifier, in the form of a solid stick, was applied using a spring loaded device to the rotating wheel disc to generate a visible film. Tests were run to measure contact impedance at typical loads and slips. Static tests were also carried out using discs pre-conditioned with a friction modifier film. The electrical circuit used was a modified simplified simulation of audio frequency track circuit. No significant difference was observed in the measured impedance for dry conditions with no friction modifier, versus tests where friction modifier was applied, regardless of percentage slip or input voltage. The analysis suggests that the introduction of friction modifier into the existing wheel/rail interfacial film does not result in increased impedance with all other factors being equal.
UR - http://www.scopus.com/inward/record.url?scp=69949175944&partnerID=8YFLogxK
M3 - Contribución a la conferencia
AN - SCOPUS:69949175944
SN - 0791848124
SN - 9780791848128
T3 - Proceedings of the ASME/IEEE/ASCE Joint Rail Conference, JRC 2008
SP - 109
EP - 117
BT - Proceedings of the ASME/IEEE/ASCE Joint Rail Conference, JRC 2008
T2 - ASME/IEEE/ASCE Joint Rail Conference, JRC 2008
Y2 - 22 April 2008 through 24 April 2008
ER -