This invention relates to a piston with its skirt being cut to locate four sets of bearing pads and circulating roller bearings. Each pad has been milled to have a doughnut shaped groove with half of a roller cross-section to hold the roller bearing in circulation during the piston reciprocating motion. Two lines of roller bearings on each side of a piston pin are in contact with the cylinder liner and share the piston thrust load. Lubrication of the roller bearings is ensured by oil slots through the piston skirt under the oil ring groove to the top of the grooves of the bearing pads and to the exposed roller bearings in rolling contact.
