A lawn mower is described comprising a load-beaiing body (10), a motor (20) supported by the load-beaiing body (10), a cutting blade (30) connected to the motor (20), a bag (40) for containing the grass clippings applied to the rear of the load-beaiing body (10), a flange (50) provided with a series of vents (56) and applied to the body (10) so as to separate a central chamber (13) from the cutting blade (30), comprising a post-compression blade (7) of air flow (80) coming from the vents (56) arranged in a space (86) between the blade (30) and the flange (50) and adapted to create pressure gradients of the air flow (80) during rotation. (Figure 7).
