Evaluation of Time-Duration Dependent Wheel Load Criteria for Wheelclimb Derailment

The most widely accepted criterion for wheelclimb derailment defines an upper limit for safe operation on wheel/rail contact forces on the climbing wheel, with the limit varying with time duration of the forces. For dynamic wheelclimb processes with significant lateral velocities, lateral forces may be measured for short time durations that are larger than those that may be sustained without derailment in steady state. This paper shows, however, that the JNR and other time-duration dependent criteria based on wheel load measurements alone are unsuccessful in predicting derailment safety. For wheelclimb processes involving negligible lateral velocities, the derailment limit can be estimated from quasisteady analysis of wheel/rail forces. The evaluation of criteria is based on experiments with a single wheelset and a nonlinear theory for dynamic wheelclimb.