This information is part of the Modelica Standard Library maintained by the Modelica Association.
Basic model for Coulomb friction that models the stuck phase in a reliable way.
This procedure is implemented in a "clean" way by state events and leads to a mixed continuous/discrete systems of equations if friction elements are dynamically coupled which have to be solved by appropriate numerical methods. The method is described in (see also a short sketch in UsersGuide.ModelingOfFriction):
Type: AngularVelocity (rad/s)
Description: Relative angular velocity near to zero if jumps due to a reinit(..) of the velocity can occur (set to low value only if such impulses can occur)