  The phenomenon of so-called break-away forces, as maximal actuation forces at
which a sticking system begins to slide and thus passes over to a steady
(macro) motion, is well known from engineering practice but still less
understood in its cause-effect relationship. This note analyzes the break-away
behavior of systems with nonlinear friction, which is analytically
well-described by combining the Coulomb friction law with rate-independent
presliding transitions and, when necessary, Stribeck effect of the
velocity-weakening steady-state curve. The break-away conditions are harmonized
with analytic form of the system description and shown to be in accord with a
relationship between the varying break-away force and actuation force rate --
well known from the experiments reported in several independently published
works.
