Abstract
This work develops the kinematic-geometry for ruled surfaces by using the analogy with spherical kinematics. This provides the ability to compute set of curvature functions which define the local shape of ruled surfaces. Hence, the well known equation of the Plucker's conoid has been obtained and its kinematic-geometry are examined in details. Finally, a characterization for a line trajectory to be a constant Disteli-axis is derived, and investigated.