The invention discloses a grass
trimmer having the semi-balance
deflection angle and provided with a parabolic wing blade LPG (
liquefied petroleum gas) engine and solves the problem of axial movement for the original taper of a magnetic
flywheel. According to an equation for arcs of blades, the bending angle is 18 degrees, the chord length b is 20, the ratio of a to b is 0.45, and a refers to the maximum deflection point on the bow; an intermediate
technician can make a mold module for the
wing section contour line. Outer ends of the blades are sharp ends and have
cutting edges, so that entangled materials can be
cut off conveniently. The balance
deflection angle (phi) exists between an angle bisector of the central angle from two sides of an opening, where a C-shaped ring (56a) of a
crankshaft valve (56) is mounted, of a
crankshaft (57) to a circle center of the
crankshaft and a central connecting line from the circle center of the crankshaft to a large-end circle center of a connecting rod and is in the range of 2-22 degrees, and the single-cylinder semi-balance is improved. A cutter is provided with an outer protecting cover (73) mounted on an inner protecting cover (60), and a long grass pressing wheel (74) with the roller length equal to the grass trimming
diameter is arranged on the outer protecting cover of the cutter, so that grass pressing
water retention and
grassland pattern pressing are facilitated; multiple sharp edges (54a) are arranged on a
buttress cutting and grass trimming steel wire (54b) of a grass trimming head (54) of the cutter and
cut out on the steel wire by a sharp flat-ended
chisel under hammering.