Abstract: A lawn mower includes a mower body and a grass bag provided at the rear of the mower body. The mower body has a cutter deck rotatably accommodating a cutter blade, a carrying passage for guiding grass clippings into the grass bag, and an air return passage for guiding only air from the grass bag into the cutter deck. Cutter deck-facing openings of the air return passage are opened in line with the rotating track of airlifts provided at the opposite ends of the cutter blade. A swirling airflow inside the cutter deck induced by the rotation of the cutter blade is in the same direction as that of air returned via the air return passage, resulting in a smooth airflow inside the cutter deck.

Abstract: A cutter blade for lawn mowers having an airlift curved from a cutting edge formed on a rotationally leading edge toward a rotationally trailing edge. The trailing edge of the airlift is shaped in a waveform comprising a plurality of protrusions and a plurality of depressions. The protrusion closest to an outer end where the centrifugal force is greatest during the rotation of the cutter blade, is greatest in width so as to improve the discharging capability of grass clippings. The depressions limit negative pressure generated rotationally behind the airlift. A plurality of vent holes formed in the airlift is arranged radially in lines.