Designed as dry carpet cleaning machines, CRB (contra-rotating brush) machines are also used by professional carpet cleaners for agitating pre-sprays prior to wet extraction. CRB machines lift and restore the carpet pile, while agitating to thoroughly detach soiling from the fibres.
A good CRB machine gives you much better results. CRB machines take away a lot of the manual work. Extraction is then quick and easy with fewer passes and less water needed, resulting in a drier carpet. After agitating with a CRB machine, the carpet often already looks clean.