Abstract: A piston for internal combustion engines, preferably made of aluminum or its alloys, having freely suspended piston pin bosses connected by first ribs to the piston head at points of zero moment and by second ribs to the piston skirt. The piston skirt has apertures in register with the bores in the piston pin bosses. The piston head is separated from the piston skirt by a transverse slot through at least a part of the circumference of the piston head and the ribs which connect the piston pin bosses to the piston skirt extend at an angle of 0.degree.-45.degree. to the boss plane.

Abstract: A piston and cylinder for two-cycle engines wherein the fuel-air mixture is precompressed in the crankcase and flows to the combustion chamber through transfer passages formed in the cylinder wall and under the control of the piston movement. The piston skirt is formed with windows or openings adjacent the end faces of the piston pin, the latter being mounted in piston pin bosses carried by bearing brackets depending from the piston head and, when the piston is at its lower dead center, the windows or openings register with the inlet openings of the transfer passages so that the precompressed fuel-air mixture then flows through the interior of the piston, the openings in the piston skirt and the transfer passages and into the combustion chamber itself which contains a depression volume.