Third-brush dynamo

It was superseded, first by a two-brush dynamo equipped with an external voltage regulator, and later by an alternator.

As the name implies, the machine had three brushes in contact with the commutator.

The other end of the field winding was connected to a switch which could be adjusted (by inserting or removing resistance) to give "low" or "high" charge.

The third-brush dynamo had the advantage of simplicity but, by modern standards, it gave poor voltage regulation.

This led to short battery life as a result of over-charging or under-charging.