Municipal Maintenance Machinery

machines owned and run by a municipality for cleaning streets and public facilities, removing and disposing of garbage, and washing and dry-cleaning linens and clothing. The corresponding machines of lower power, capacity, and overall dimensions that are used in the home, such as washing machines, vacuum cleaners, and floor polishers, are classified as household appliances.

The first machines used to perform certain types of municipal work were built in the second half of the 19th century. The first street-sweeping carts, clothes wringers, and mechanical house-flannel holders appeared at the beginning of the 20th century. More significant development of municipal technology, however, occurred in the 1930’s, with the possibility of the wide-scale use of automobiles and tractors, electric energy, and the products of the chemical industry. Plants in Moscow and Leningrad were by that time producing the first machines for garbage removal and street cleaning, and plants at Penza, Volgograd, and Blagoveshchensk were putting out the first washers, driers, and mangles. The construction of municipal maintenance machinery in the USSR developed still more widely in the 1950’s and 1960’s (in particular, after the acknowledgment in 1965 of municipal machine-construction as a specialized branch of industry).

Sanitation machinery for populated areas is designed to collect refuse and sewage and remove them to places where they can be disinfected and, when possible, utilized. The machines, which are constructed on automobile, tractor, and special chassis, are divided into two basic groups: night-soil machinery, for cleaning cesspools and removing liquid domestic waste, and refuse haulers, for collecting and removing trash and solid domestic wastes. Night-soil machines use a hermetically sealed tank. An intake hose and pump are used to fill the tank and evacuate it. The pump is activated by the automobile engine. Refuse haulers are subdivided into body types and container types. The first are used to haul away the refuse collected from trash cans; after loading, the trash in the body of the machine is compressed, thereby increasing the load factor. The second type is used for the transport of refuse in trash collectors, or containers; the machine is equipped with devices for the mechanized loading and unloading of these containers (for example, swiveling cantilever cranes).

Sludge-pumping machines are used to clean out sewerage manholes. These machines have a hermetically sealed tank, a pump, and a hose for sludge intake. Hydrodynamic cleaners are used for the sewer pipes. These machines have a water tank, a pressure pump, delivery hoses, and flushing nozzles.

Special sanitation machinery is used in the summer to wash down and sweep the streets. Brush-plow and rotary snow removers, snow loaders, and sand spreaders are used in the winter.

The problem of the year-round use of sanitation machinery is solved by using easily detachable units and assemblies. New designs for sidewalk cleaners and small all-purpose cleaners are being developed for special or tractor chassis.

The machines used to clean public buildings work by electricity, storage batteries, or internal combustion engines. Floor washers have a tank that feeds the cleaning solution and a tank to collect the dirty water. The working element of the machine consists of one or more rotating brushes. The used solution is drawn up through a nozzle; a vacuum is created by a fan. Brush sweepers or brush-pneumatic sweepers are used to sweep floors and collect the sweepings in a hopper. This is done by a brush, in the case of the former, and with a supplementary vacuum device, providing dust removal, in the latter. Dust can also be removed by moistening the sweepings and delivering them pneumatically to the dust bag.

Vacuum cleaners consist of a dust bag into which dust is sucked through a nozzle and hose by a vacuum created with a fan. The dust is trapped by a cloth filter. Floor polishers buff the floor with mastics. They have attachments to apply the mastic, buff and polish the floor, remove old mastics, and wash floors and carpets.

Machines used in the upkeep of buildings come in a variety of models, differing in size, appearance, and attachments available.

Washing and dry-cleaning machines are divided into machines that wash, wring, dry, and mangle laundry, machines that dry-clean clothing, and machines and equipment that handle the complex of operations that includes transporting, warehousing, loading, and unloading.

Clothes and linens are laundered in washing machines that handle loads of as little as 5 and as much as 200 kg. The working elements of the machines are an outer drum, which is filled with detergents, and a perforated and ridged inner drum with reversible rotation, which is filled with the laundry. The linen is centrifuged or wrung to a moisture content of 45–50 percent. Permanent mechanized laundries are equipped with washer-wringers in which the laundry is successively washed, wrung, and sometimes tumbled, all without reloading.

Once washed and wrung, flat linens are processed in combination drier-mangles or through rollers or calenders. Contoured linens are processed on mangles or dummies. Drier-mangles have one or more successive sets of rollers through which the laundry is continuously passed. All-purpose mangles are made to handle the complete cycle for a wide assortment of linens. Special mangles are also manufactured to handle specific operations. For example, sets of three or four mangles are produced for processing men’s shirts.

The heater in the drier-mangle is a drying tray. The heating element of the mangle is a drying plate. Both are heated to a temperature of 150°-170°C by steam or electricity. Laundry that does not need mangling is processed in a simple drier, which usually has a perforated drum to which a blower delivers air heated to 80°-100°C. Depending on the machine’s design, it can be loaded with from 5 to 25 kg of laundry (dry). Municipal public laundries use production lines that successively wash, wring, tumble, dry, mangle, and fold linens with a minimum of manual labor. Such lines have an output as high as 350–400 kg per hr.

Dry-cleaning machines perform the complete set of laundering operations: degreasing in solvents, wringing, drying, and airing. Dry-cleaning machines have an immobile outer drum and a movable, perforated inner drum. The drums of different machines may hold as little as 5 and as much as 150 kg of clothing. The machines are equipped with devices to purify, to distill, and to extract the solvent from the clothing, so that the solvent can be reused. The solvents used include perchlorethylene, trichlorethylene, naphtha, and fluorinated hydrocarbons. Stains are removed on special machines that use the appropriate solvents and spot removers. The final step is performed using a mangle or steam dummy.

In addition to the machines described, there are a number of other pieces of equipment that help to mechanize the various operations of an urban residential community or municipality. These include extension ladders, the standing maintenance and emergency repair machines for the community’s water-supply, sewerage, gas, heating, and electric systems, machines for the repair of municipal roads and residential buildings, the equipment used in garbage treatment plants, and automatic lawn sprinklers.