Patent ID: 8615837

Claim:
A drain-cleaning machine comprising: a) a cable, wherein the cable comprises a longitudinal axis; and b) a motor assembly, wherein the motor assembly is in mechanical communication with the cable, wherein the motor assembly is configured to rotate the cable about the longitudinal axis of the cable, wherein the motor assembly comprises i) a motor, wherein the motor is configured to operate at an operating speed, wherein the operating speed may vary within a range of operating speeds, wherein the motor is configured to produce substantially constant torque while operating at varying operating speeds across the entire range of operating speeds, wherein the motor is configured to be powered by DC power, and ii) a motor control device, wherein the motor control device is mounted to the motor, wherein the motor control device is configured to receive AC power from an AC power source, wherein the motor control device is configured to convert the AC power into DC power comprising an input voltage, wherein the motor control device communicates the DC power to the motor, wherein the DC power communicated from the motor control device to the motor comprises an output voltage, wherein the motor control device is further configured to subject the DC power to voltage compensation by adjusting the input voltage of the DC power to correspond to a target voltage prior to adjusting the input voltage of the DC power to the output voltage; and c) a speed control assembly, wherein the speed control assembly is in communication with the motor assembly, wherein the speed control assembly is configured to vary the operating speed of the motor within the range of operating speeds by controlling the output voltage of the DC power communicated from the motor control device to the motor.