Abstract: This invention pertains to an electrical machine whose excitation is coordinated to the respective rpm in such a fashion that a desired characteristic of induced voltage or delivered output is produced. For that purpose at least one portion of the windings generating or controlling the working flux of the machine or a resistance wired in series before the machine is connected to a rectifier circuit, which is supplied, through a frequency-dependent impedance network, with an a.c. voltage of a frequency proportional to the machine rpm.

Abstract: A brake circuit for a universal motor having an armature and a field winding normally connected in series therewith, the circuit including switch means operable to disconnect the power source and electrically connect the armature in series with the field winding and a brake resistor, with voltage limiting means in parallel with the field winding. The voltage limiting means include biasing diodes for maintaining the voltage across the field generally constant, resulting in a more even deceleration rate and a lower total brake time.

Abstract: A switch for speed control of an electric motor driven vehicle employs a combination of resistance switching, field weakening and voltage switching. A mechanical switch assembly has a speed switch and a voltage switch that are interconnected so that the voltage switch provides 36 volts when the speed switch is in neutral and fifth speed position and provides 18 volts when the speed switch is in first through fourth speed positions. The speed switch has an operator controlled rotor arm that successively engages a neutral contact and five driving speed contacts so that varying resistance is inserted in circuit with the motor armature in the first two speed positions and no external resistance is employed in the third and fifth speed positions. The motor field comprises pairs of first and second oppositely disposed series wound coils with the pairs of coils all connected and energized in series in all but the fourth speed position.