Cleaning solution is pumped from solution tank to the brush, which agitates the carpet to create a mechanical cleaning action in addition to water pressure. Vacuum shoe collects dirty water and sends it to the recovery tank. Machines are fully autonomous; no hoses or other accessories to fuss with. However, an optional hose can be fitted on most machines for cleaning upholstery or better reaching corners and other hard-to-reach spots. Brush lifts pile of carpet for quick and effective cleaning, making these machines ideal for larger surfaces. Brush and tank sizes vary. Some models offer encapsulation as well. Choice of single or dual brushes for more effective mechanical action.