This document establishes definitions and evaluation methods for wheel-rail contact geometry parameters influencing the vehicle running dynamic behaviour:

— the rolling radius difference between the two wheels of a wheelset (Δr-function) which serves as a basis for all further calculations;
— the equivalent conicity function from which are derived:
— a single equivalent conicity value for a specified amplitude which is relevant for the assessment of vehicle running stability on straight track and in very large radius curves according to EN 14363;
— the nonlinearity parameter which characterizes the shape of this function and is related to the vehicle behaviour particularly in the speed range close to the running stability limit;
— the rolling radii coefficient which is used to describe the theoretical radial steering capability of a wheelset in a curved track.

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