<；P>；PROBLEM TO BE SOLVED: To provide a working machine for mowing grass which automatically removes foreign materials adhered to a filter. <；P>；SOLUTION: In the working machine for mowing grass, a space 9A is installed above the machine chamber 20 of a hammer knife mower and a filter 41 is placed to partition the space 9A from the machine chamber 20. Two or more wipers 42 are attached to the filter 41 to be mutually separated. Each of the wipers 42 is independently constituted. Wiper blades 43 continuously rotate in 360°； by rotary power of a wiper motor and the foreign materials adhered to the outer surface of the filter 41 are removed by pieces 46 of wiper rubber. <；P>；COPYRIGHT: (C)2008,JPO&INPIT
