Giant Rubbish Sucker (vacuum cleaner)

These machine will snake throught the streeting in Singapore. Sucking every inch of dirt and rubbish along its path.  A large metal container, either cubic or cylindrical, is mounted on the rear of the truck and is actually a kind of giant vacuum cleaner "bag." Under this container are one or more water tanks feeding into an engine-driven pump and then on to a reeled outlet hose on the front of the vehicle. An engine-driven fan draws air from the container, reducing its air pressure to a level well below ambient (outside) air pressure. The inlet to this container usually has a reinforced hose set, which is used to vacuum up water, gravel, debris or other liquids and solids as desired. Certain nonexplosive petroleum products, such as oil from oil-water separators in urban drain systems, can be removed by this vac truck.