  A family of solitary waves is constructed in Frenkel-Kontorova model and its
continuum and quasi-continuum approximations. Each solitary waves is
characterised by the number of local maxima in its profile and a relation
between external force and the velocity of wave. Such waves may be interpreted
as a coherent motion, with constant velocity, of two dislocations of opposite
sign or of kink-antikink pair.
