Dynamo for the 12 V charging system, of the Lucas C40 type. The dynamo is belt-driven from the crankshaft pulley and generates direct current directly at the commutator through carbon brushes. Unlike an alternator, it carries no internal rectification or regulation: output is fed to a separate control box, which regulates voltage and current and uses a cut-out relay to connect the dynamo to the battery only once output exceeds battery voltage. Because generation depends on rotational speed, charging output falls away at idle and the system relies on sustained running speed to replenish the battery. A dynamo must always be run with a matched and correctly set control box; a faulty or mis-set box will either undercharge the battery or drive the dynamo beyond its rated output. Brushes, commutator condition and bearing wear are the usual service points on this unit.
