The bar screen starts and stops automatically according to the water level difference between upstream and downstream by means of level sensor or by timer clock. The bar screen includes a screen frame, a bar rack (grid) a back dead plate, a series of chain driven rakes and a drive unit. All bearings and critical parts are above liquid level at all times to facilitate lubrication and improve machine life.  The number of rakes de? pends on the screen length and type of effluent. When the screen is started, the 2 chains on the sides pull the rakes towards the top of the screen. When passing in between the bar rack, the rakes collect the screenings waste and lift them to the top where an ejector system pushes the screenings waste into the conveying or compacting system. The bar screen is a mechanical fully automatic screen used for liquid/solid separation in the pre-treatment stage of wastewater treatment plants, pumping station, Sewage treatment plant, etc;