Gray & Davis Early Generator Governor & Friction Clutch - Manual Page Figs 15-15B

This scanned page from an early automotive reference manual explains the mechanical regulation method used by early-model Gray & Davis generators, among the first generators designed for automobile use. Unlike magneto-type devices with permanent magnets, this generator used electro-magnetic fields. Three illustrations (Figs. 15, 15A, and 15B) show the clutch of the generator with parts labeled A and B, the governor assembly, and a cutaway of the governor showing the fan, oil points, and adjusting screw. The text explains that maximum output was regulated mechanically by a centrifugal governor that kept machine speed constant, classifying the generator as a "constant-speed constant-current" mechanically regulated machine. Speed variations from the engine were absorbed by an automatic friction-type clutch: the two clutch halves (A and B) slip more or less depending on engine speed, with the amount of slippage controlled by the governor. Once armature speed exceeds the rated number of revolutions, the governor pulls the clutch halves apart, causing them to slip so the armature never rotates faster than the predetermined speed. Readers can learn the operating principle of this early generator regulation system and identify its clutch and governor components from the labeled figures.