Direct current motor with multiple field windings connected in parallel

Claim 1

IN A DIRECT CURRENT MOTOR HAVING AN ARMATURE, A SERIES WOUND FIELD AND A TORQUE-SPEED CONTROLLER, THE IMPROVEMENT IN SAID CONTROLLER FOR PROVIDING MOTOR TORQUE AND SPEED CONTROL IN A FULL RANGE OF STEPS FROM LOW SPEED TO HIGH SPEED, SAID IMPROVEMENT COMPRISING SAID SERIES WOUND FIELD HAVING A PLURAL NUMBER OF FIELD COILS EQUAL TO THE NUMBER OF TORQUE-SPEED STEPS IN SAID FULL RANGE, AND A MANUALLY ACTUATED SWITCH FOR EACH COIL TO SELECTIVELY DISCONNECT ONE OR MORE COILS FROM THE FIELD OR CONNECT ONE OR MORE OF SAID COILS IN THE FIELD DIRECTLY IN A SERIES WITH THE ARMATURE AND IN PARALLEL WITH ANY OTHER COIL SO CONNECTED SO THAT FOR EACH SAID STEP THERE IS A DIFFERENT NUMBER OF COILS IN PARALLEL WITH EACH OTHER BUT IN DIRECT SERIES CONNECTION WITH THE ARMATURE AND THE RESISTANCE OF THE FIELD DECREASES AND THE VOLTAGE DROP ACROSS THE ARMATURE INCREASES AS SAID SWITCHES ARE SUCCESSIVELY CLOSED.