7 Machine parts, not for land vehicles, having wear resistant oxide surfaces, namely, transmission gears, cam sprockets and chains, drive sprockets and chains, axles, engine bearings, shaft couplings, brake linings, clutches, crank shafts for engines, cylinders for motors and engines, joints and joint parts for connecting sliding strips, plates, guides and shafts, cylinder linings, journals for machines, journal boxes, pistons for engines, piston rings, pulleys, reels for machines, ball rings for bearings for machines, sleeves for bearings, transmission shaft bearings, turbine blades, valves for engines and compressors, and valve seats; and journals, pistons, piston rings, pulleys, reels, ball rings, sleeves, for land vehicles