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.