US Patent 7770255 Vacuum cleaner with drive assist

A base has wheels, including a drive wheel, for wheeling the base over a floor. A nozzle is fixed to the base for a fan in the base to draw air from the floor through the nozzle. A handle is connected to the base for propelling the base by manually applying a force to the handle. A drive assist motor, which is not configured to drive the fan, has an output shaft coupled to the drive wheel. The controller is operative in a driving mode to power the motor to rotate the drive wheel in a direction corresponding to a direction of the force applied to the handle. The controller is operative in a non-driving mode to refrain from powering the motor to rotate the drive wheel.