BRUSH INSTEAD OF “TABLETS”
Maintained a constant voltage in the car's electrical system.
In pre-electronic times, the design of relay controllers has not changed for decades, and on many machines of the 30s there was no separate controller at all. Its role was played by an additional third brush of the generator.
The method of adjusting the onboard voltage was based on a simple principle. When the generator’s armature rotates, the field created by the excitation electromagnets shifts more strongly along the armature’s rotation, the higher the speed of the latter. Excitation electromagnets were connected between the negative and additional brushes. With a certain increase in the number of revolutions of the armature and the current strength, the magnetic field was shifted so that the portion of the armature winding, from which the extra brush was drawn, came out of the magnetic flux. The voltage supplied by the brush to the field magnets dropped. The magnetic field strength and, consequently, the voltage excited by the generator armature decreased.
So, if during adjustment the additional brush was displaced in the direction of rotation of the armature, the current strength increased, in the opposite - decreased.
A simple and fairly reliable design was used not only on domestic cars (for example, on the first Muscovites-400). Many veteran motorists remember her for some captured vehicles.
Interestingly, experienced drivers managed to check the results of adjustment without an ammeter, which was usually used by repairmen in large garages. Experienced at times lacked their own instinct and control lamp instrument panel. Even the AMO-3 truck instruction manual indicated a similar diagnostic method. If the lamp lights up when driving in direct gear at a speed of 12-15 (!) Km / h, then the voltage of the on-board network has been adjusted correctly.