Technical Reports

Friction and Creep in Rolling Contact

  • 01
  • Nov
  • 1970
AUTHOR: P.R. Nayak, S. Hariharan, Raya Stern, R. Abilock, P.A. March, P.K. Gupta
OFFICE: RPD
REPORT NUMBER: FRA-RT-71-64
SUBJECT: Track/Train Interactions
KEYWORDS: Rolling Contact, Friction, Creep, Vibration, Surface Dynamic Loading
ABSTRACT: Experimental and analytical studies of friction and creep in rolling contact are reported. Factors examined for their influence on friction (adhesion) and creep are (a) surface roughness, (b) surface vibration, (c) surface contamination, (d) dynamic loading due to irregular track, and (e) rolling velocity. The following conclusions are reached. 1. Surface roughness does not influence the creep coefficients at operating loads. However, surface roughness influences the tractive capacity when the wheel and rail surfaces are either very clean or flooded with a contaminant. 2. Surface vibrations affect wheel-rail friction considerably. 3. Surface contamination decreases both friction and creep coefficients. The magnitude of the change in these coefficients depends on the oil viscosity temperature and pressure coefficients, the normal load on the wheel and the surface roughness. 4. Dynamic loads due to suspension resonances do not appear to influence the friction or creep coefficients significantly. 5. Observed decreases in the friction coefficient at increased rolling velocities are probably due to increased surface vibrations, decreased time for the formation of friction junctions, and elastohydrodynamic effects.

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