Abstract: A d.c. motor control system, intended primarily for use in battery powered vehicles, includes a control switch (RL2a, RL2b) for varying the connections of the motor field winding (24) to determine the mode of operation of the motor and speed interlock means for preventing said control switch being operated to change the motor mode while the motor is actually running. Instead of using a mechanical speed transducer the speed interlock means includes means for supplying current to the motor field winding (24) when current would not otherwise be flowing therethrough and means (BR1, T.sub.1, P.sub.16 etc.) connected to detect the voltage across the armature which occurs in these circumstances if the motor is in motion.

Abstract: A control circuit for an electric vehicle traction motor having separate armature and field windings, includes an armature winding current control, a braking contact which is in series with the armature winding and which is closed or opened in accordance with whether motoring or braking is required, an alternative path being provided for motor current during braking, reversing switch means connected in circuit with the field winding, a field current control and logic circuit means arranged to operate during a change for braking mode to motoring mode so as sequentially to reverse said reversing switch means when the field current is below a predetermined level, commence field current flow in the required direction for motoring and then close the brake contact whereby any residual magnetism in the field structure is reversed before the brake contact is closed.