US Patent 7302734 Ground cleaning machine

A mobile floor or ground cleaning machine includes a hydraulic motor for propulsion and/or operating a cleaning brush. Airflow produced by a fan is directed through a housing located adjacent the cleaning brush for creating an area of low pressure adjacent the brush. The housing includes a filter system through which the airflow is directed. Under the influence of the airflow, the closed housing, which preferably is a unitary structure, directs dirt directly into a receptacle and directs dust through the filter system for subsequent deposit in the receptacle. The housing forms a reservoir for oil which drives the hydraulic motor, with the airflow within the housing serving to cool the oil.