three brush regulator

[rotorwrench]

The 2-stage unit was a cut out with an extra control relay. The control relay would allow the generator to charge until the battery was fully charged. With the battery charged, the system voltage would start to rise. When it reached 8.5 volts, the relay would open and shut down the generator. The caveat to the system was that the generator would not come back on line till the engine rpm slowed down to idle. In stop and go traffic, this worked out OK but in long distance travel, the battery would discharge until the next stop.

These units require both an armature lead (red) and a ground lead (black) to protrude the case in order to connect the unit up. The B-model & V8 generators were set up this way in early 1934 or so and stayed that way till the 3-pole voltage regulators with 2-brush generators came out around 1939.