an electric motor includes a stator and a rotor . the stator includes a motor housing with an open end and an end cover mounted to the open end . the rotor includes a rotor shaft that extends through the end cover . the end cover includes a bearing that supports the rotor shaft . the rotor shaft and motor housing are made of an electrically conductive material and are electrically connected with each other . the motor housing , end cover , bearing and rotor shaft cooperatively form an electromagnetic shield suppressing electromagnetic interference generated by the motor . optionally , the rotor shaft drives a coaxial worm shaft of a gearbox by an insulating member , which further suppresses electromagnetic interference .