Abstract
Free coning motion of axi-symmetric spinning bodies around their fixed angular momentum vectors, called free precession, have already been explaned using body/space cones in the 19th century. It is very easy to describe their motion of the radial angular momentum vectors as circles on a horizontal complex plane, if the total angular momentum vectors are large enough and nearly vertical. As a result, a linearized equation of motion of spinning tops including both horizontal components of frictional torques and the gravitational one could be derived easily. As an example, trochoid model of horizontally suspended spinning tops is shown using a rolling wheel and a rail.
