The electric motor of direct current is composed of two magnetic structures the stator (field winding or permanent magnet) and the rotor (winding of armature) Gates BX123. The purpose of the commutator is to invert the current in the appropriate rotation phase so that the developed conjugate is always in the same direction. The rotor windings comprise coils and the two sides of each winding are placed in grooves spaced equal to the distance between two stator poles, so when the conductors on one side are under the north pole, the conductors on the other side are under the pole south. The coils are coupled in series through the blades of the commutator, with the end of the latter connected to the beginning of the first.

The stator is made of a ferromagnetic structure with protruding poles to which the coils forming the field are wound, or a permanent magnet and the rotor is an electromagnet made of an iron core with windings which are fed by a mechanical switching system. This system is formed by a switch, integral with the rotor shaft, which has a cylindrical surface with several blades and fixed brushes, which pressurize the switch, connected to the supply terminals.