(31) Passenger boarding bridges. These bridges permit passengers and personnel to walkbetween a terminal building and a parked aircraft, a cruise ship or ferry-boat, without having to go outside. The bridges generally consist of a rotunda assembly, two or more rectangular telescopic tunnels, vertical lift columns with wheel bogies, and a cabin located in the front part the bridges. The include electromechannical or hydraulic devices that are design for moving the bright horizontally , vertically and radially i.e.their telescopic sections, cabin, vertical, vertical, etc., in order to adjust the bridges to the appropriate position to the particular aircraft’s door, or to the port (entrance) of the cruise ship or ferry-boat. The passenger boarding bridges of the type used at seaports can be, furthermore, equipped with a transitional device installed on their foreside which can be extended into the port (entrance) of the cruise ship or ferry-boat. These bridges themselves do not lift, handle, load or unload anything. Appliances for cleaning carpets in situ by injecting a liquid cleaning solution into the carpet, the solution then being extracted by suction, and designed for use in establishments (other than domestic premises) such as hotels, motels, hospitals, offices, restaurants and schools are classified in heading 84.51. The heading also excludes machinery for encapsulation in the assembly of semiconductors (heading 84.86)PARTSSubject to the general provisions regarding the classification of farts (see the General Explanatory Note to Section XVI), the heading also covers parts of the machinery of this heading, including moulds other than those covered elsewhere (in particular, heading 84.80).