Abstract: A compound-motor speed control system for a battery-powered vehicle (86) wherein the series winding (14) and the shunt winding (16) of the motor (12) are magnetically linked in energy transfer relation. A first current switch (18) is connected in series with the series winding (14) and the armature (15) and a second current switch (20) is connected in series with the shunt winding (16). A digitally-implemented speed control system (24) responds to the speed selection settings of an analog device (64) to operate the first switch intermittently while holding the second switch closed over a lower speed range, and to operate the second switch intermittently while holding the first switch closed over a higher speed range.

Abstract: A brush wear indicator includes a first contactor and a second contractor movable relative to the first contactor from an open position to a closed position to connect an electrical circuit to an indicator. The second contactor is maintained in the open position against the resiliency of a leaf spring by a coil spring which urges a brush toward a commutator in response to wear to the brush. When the brush wears away to a preselected length the coil spring will have moved to a position at which the leaf spring is free to bias the second contactor to the closed position.

Abstract: A control system for a compound DC electric motor includes a shunt field winding connected in parallel with a series field winding, with both windings being connected to a power source. A time delay is positioned between the series field winding and the power source for energizing the series field winding a predetermined time period after the energization of the shunt field winding.

Abstract: A DC electrical motor of the form having one field winding connected in series with the armature winding in addition to a shunt field winding connected in parallel with the armature winding is provided with a diode or the like in the shunt field winding circuit. This blocks reversed current flow in the shunt field winding which can otherwise occur during start-up due to an inductive interaction with the series field winding and armature circuit. The diode or the like enables faster magnetization of the stator poles by preventing creation of negative shunt field ampere turns due to the magnetic couple with the series field-armature circuit during the motor start period. Faster starting of the motor results, and adverse effects such as heating, brush deterioration, and commutation problems are reduced.