  In the present paper, a new type of ruled surfaces called osculating-type
(OT)-ruled surface is introduced and studied. First, a new orthonormal frame is
defined for OT-ruled surfaces. The Gaussian and the mean curvatures of these
surfaces are obtained and the conditions for an OT-surface to be flat or
minimal are given. Moreover, the Weingarten map of an OT-ruled surface is
obtained and the normal curvature, the geodesic curvature and the geodesic
torsion of any curve lying on surface are obtained. Finally, some examples
related to helices and slant helices are introduced.
