Types.—(i) "Built-in" or stationary type: a powerful motor usually placed in the basement of the building operates an ex haust fan or a suction pump from which metal pipes lead to valved inlets on each floor. A flexible hose of from i o to 20 ft. in length may be attached to these inlets. Suction is applied to the floor or floor covering by means of an extension tube and a nozzle which is normally fitted with a universal joint for ease in handling. The dirt is separated from the air by means of a filter and either drops into a removable receptacle or is directed into a sewerage inlet.
(2) The portable electric type is now supplementing and sup planting many central installed systems. Two distinct types of portable electric vacuum cleaners are in use : the truck type and the light portable type. The truck type is placed on a truck plat form which is mounted on three or four wheels. It employs motors of from -4- to i h.p. which operate an exhaust fan or suction pump. A large flexible hose and nozzle is used similar to that of the permanently installed systems. The light portable type is by far the most popular and represents 95% of all electric vacuum clean ers in use. Although of several distinct types, identified by varied cleaning principles, its main characteristics are lightness, from 10 to 20 lb. in weight, use of exhaust fan principles and use of floor nozzle. The latter is attached to a suction chamber, motor, exhaust fan and cloth bag to trap dust and sift air; and is mounted on small wheels guided by a handle, through which an electric cord runs to motor. The switch is usually in the handle. These cleaners operate from house current at a cost which is generally less than r cent per hour. Motors are of from to horsepower. The attachments which are commonly sold at extra cost generally consist of a flexible hose about 8 ft. in length, which may be connected to the intake of the suction chamber, various cleaning nozzles, a brush attachment and an extension tube which enables the operator to clean any type or contour of surface and without step-ladders reach any part of a room of normal height.
There are three main types of light portable electric vacuum cleaners. The first is the high vacuum type, characterized by sim plicity and paucity of moving parts. Powerful suction is generated because the motor is used for producing suction only. High vacuum is effective in removing deeply embedded dirt. The broom action self-cleaning brush removes surface litter without injury to the nap of the floor covering. The second is the carpet sweeper
type which employs suction for removing embedded dirt and a revolving wheel driven brush for surface litter. The revolutions of the brush are controlled by the speed at which the cleaner is moved across the surface of the floor covering. The brush not being connected to the motor permits the full use of the power of the motor for generating suction. The brush is removable for cleaning. The third is the motor-driven brush and metal drum types which beat the floor covering and cause vibration to dis lodge embedded dirt. Surface litter is effectively removed by this type of cleaner and clinging dog or cat hairs or loose and cut nap are picked up by suction.
Small hand vacuum cleaners, frequently termed vacuum brushes, are sold in limited quantities. These are miniature elec tric cleaners and are of a pattern of all three types of portable electric cleaners explained above. Larger portable electric cleaners which can be suspended by a strap from the shoulder of the operator or carried in one hand while he is using the cleaning nozzle, are designed and powered like the standard portable vacuum cleaners, but have no handle or large floor nozzle. Non electrical vacuum cleaners of current design are generally of the exhaust fan type. A fly wheel weighing several pounds to which the fan is attached is actuated by a slip ratchet gear in mesh with one or two large driving wheels. These wheels also support the cleaner. The speed at which the cleaner is moved determines the amount of suction generated which is never very great. A carpet sweeper type revolving brush is generally used and is the chief cleaning agent. The dust is trapped in a cloth bag. These cleaners resemble electric vacuum cleaners in appearance.
Large tank type vacuum cleaners mounted on horse-drawn wagons, or automobile trucks were the first power-driven vacuum cleaners to appear in America. A motor supplied the power for both exhaust pump and fan types. This type employed flexible tubes, in sections, to reach from the street to the farthest corners of home, office building or hotel. They are practically obsolete to-day. (F. WAR.)