Abstract: A method is described of making a piston crown, the method comprises the steps of making a lower crown portion, the lower crown portion also having piston pin bosses, making an upper crown portion which co-operates with the lower crown portion and joining the lower and upper crown portions together to form an oil retaining chamber. The upper and lower crown portions may be made by a precision casting technique in a ferrous alloy and may be joined by a brazing operation. The piston crown may be part of an articulated piston or may further include integral skirt portions.

Abstract: A method of bonding a component in a piston, involves the steps of coating the component surfaces to be bonded with an oxidation-resistant particulate material, preheating the coated component, placing the preheated component in a casting die and then casting an aluminum alloy around the component. The casting technique may comprise squeeze-casting.

Abstract: Pistons are described comprising a crown having an associated piston ring groove belt and which crown is supported by gudgeon pin bosses connected thereto by two generally axially extending planar webs which are orientated transversely to the gudgeon pin axis and also supported by at least one subsidiary support rib associated with each planar web and pin boss and which support rib extends in a generally axial direction between the crown underside and pin boss and generally transversely to the planar web. The piston may be of either articulated or monometal construction.

Abstract: A cast light metal piston has a plurality of longitudinally extending reinforcing members. These reinforcing members may be disposed at predetermined positions in the piston as cast and are designed to impart a compressive stress to the material of the piston in the regions where the reinforcing members are located. Conveniently, the reinforcing members may be located adjacent the opposite sides of each of a pair of gudgeon pin holes provided in the skirt of the piston.

Abstract: A piston having a crown and a body connected together by bolts. The bolts pass through an annular gap defined by a pair of concentric ring members located between the crown and the body. One of the ring members is relatively resilient and the other ring member is relatively rigid. Such a construction reduces fretting between the crown and the body when the piston is in operation in an engine.

Abstract: A sealing ring assembly for a piston has an outwardly springing carrier ring and an inwardly springing sealing ring which is located in an outer peripheral recess in the carrier ring. The gaps in the two rings of the assembly are displaced one from the other.

Abstract: A deposit of a reinforcing material is formed on an aluminium alloy piston by spraying one or more regions of the piston with a copper-based material from an electric-arc spray gun which produces molten particles of a heat content sufficient to produce an effective metallurgical interaction with the piston alloy so that the copper-based material is bonded to the region or regions of the piston.