The main subject of the paper is to resolve the Ekman layer analytical
ly and to formulate an appropriate set of 3D-geodynamo equations. The
equations are formulated in the mean field approximation where the mea
n valves of magnetic field and velocity over azimuthal direction vanis
h. The's approach should allow the numerical calculation to be perform
ed for small Ekman numbers, down to 10(-12), which are usually conside
red to be realistic in the geodynamo. The solution of the Ekman layer
is also newly interpreted and consequently a new term appears in the u
sual expression for the geostrophic shear. The viscous terms are negle
cted in the main volume of the core and their leading role is assumed
just in the thin Ekman layer. The inner core is not included in these
considerations and no concrete calculations of a model are presented.