ELECTRIC MOTOR ASSEMBLY AND VEHICLE STARTER

An electric motor assembly, in particular an electric motor assembly of a vehicle starter, is disclosed, which comprises an electric motor and a speed changing mechanism, the electric motor comprising an armature shaft, and the speed changing mechanism comprising an input gear which is fitted onto the armature shaft by splines. The splines comprise male spline keys formed on the armature shaft and female spline keys formed in the input gear for mating with the male spline keys, each spline key including a pair of key flanks, at least one of which is oblique with respect to a central axis of the armature shaft. A vehicle starter comprising the above electric motor assembly is also disclosed. Wear of a commentator and electric brushes of the motor caused by axial displacement of the armature can be avoided.