So great has been the interest in the various electrical mechanisms in the automobile, and so quickly has the public taken up with all these that this has stimulated an entirely new invention, called, by its maker, the Vesta Accumulator Company, Chicago, a centrifugal electric-generating clutch. This name gives a little clue to its action, which is a combination of the usual friction clutch and that of the electric-magnetic drag between armature and fields of any electric machine.
In addition to its clutching feature, its ability to drive when partially clutched makes it, in effect, a transmission, so that it is designed to replace the usual clutch, gearset, flywheel, electric generator and starting motor. It is composed of two parts: an armature, which becomes the flywheel; and a field mounted on the propeller shaft. The former carries an internal commutator, and the latter, brush holders which hold brushes against the commutator. These are mounted so that the centrifugal force of rotation increases the force with which they press against the commutator. Thus there is a variation from practically no contact up to the maximum, at which point the centrifugal force is so great that field and armature revolve as a solid unit.
An automobile built in France - the Ampere - uses this construction exclusively, the master clutch being dispensed with in favor of an individual clutch transmission, the clutches being magnetically operated as just described. In addition, the differential is dispensed with, and in its place is used a pair of magnetic clutches, one for each wheel. The differential action is obtained on curves by decreasing the current to the clutch on the inner wheel up to a certain point, at which it is cut off entirely. This gradual reduction and cutting off of the current is accomplished automatically by the movement of the steering wheel.