Patent attributes
A drain cleaning machine includes a brushless direct current (DC) motor configured to rotate a snake about the snake axis. An electronic processor is configured to control power switching elements to drive the brushless DC motor. In a first operating range when a load experienced by the brushless DC motor is less than or equal to a predetermined load, the electronic processor is configured to control the power switching elements to drive the brushless DC motor at an approximately constant speed regardless of the load experienced by the brushless DC motor. In a second operating range when the load experienced by the brushless DC motor is greater than the predetermined load, the electronic processor is configured to control the power switching elements to drive the brushless DC motor at a decreasing speed as the load experienced by the brushless DC motor increases.