The present invention relates to an engineering machinery which can simply install the cover which surrounds the embarked machine thereby increasing the assembling operability and maintenance operability, etc. The mosaic holes (21E, 23E) arranged at the lower flange (21D, 23D) of the left and right skirt-type covers (21, 23) are inserted at the head (7A) of the internal hexagonal bolt (7) which is arranged at the perimeter part of the rotating frame (5). On the other hand the upper flange (21c, 23c) which is made into each skirt-type covers (21, 23) are fixed on the structures of the screw seat (11B) of the heat exchanger installing rack (11), the installing bracket (13A) of the battery embarking rack (13) and each installing bracket (19E, 19F) of the operating rod desk (19) by the bolt (22). In this way the lower flange (21D, 23D) can be fixed on the rotating frame (5) only with fixing the upper flange (21C, 23C) of each skirt-shape cover (21, 23) thereby doing installing and detaching operation easily.