Abstract: An aluminium or aluminium alloy cast piston has a piston ring carrier of a ferrous material encast therein. The carrier has sides which converge towards their radially inner ends. As a result of this, and as a result of a lesser coefficient of thermal expansion of the ferrous material of the carrier as compared with the aluminium or aluminium alloy of the piston body, solidification of the piston material causes elastic outward expansion of the carrier which is sufficient to prevent any clearance occurring between the two parts, even at operating temperatures. Thus the carrier is not, and need not, be locked to the piston body against radial movement.

Abstract: A method of shaping the gudgeon pin bores formed in gudgeon pin bosses of pistons comprises introducing into the bores portions of a pin-shaped tool before the insertion of the gudgeon pin. A load is applied to the pin-shaped tool and the direction of the load and the shape of the pin-shaped tool are chosen so that areas of bore-defining walls of the bosses subjected to high stresses by the gudgeon pin in use, and therefore liable to crack, are radially outwardly deformed to reduce the incidence of cracks.

Abstract: The manufacture of piston rings for internal combustion engines comprises making a ring blank of which the diameter over the outer periphery is greater, and the diameter within the inner periphery is less than that required in the finished ring. A gap is cut in the ring blank to afford two free ends and the ring blank is held in a closed position by the application of a force only to each of the free ends of the ring blank. One or more ring blanks are then clamped in a closed position and machined so that the inner and outer peripheries are circular. This enables a ring to be produced which conforms very closely to a required shape and which thus, in use, provides a good seal between a piston and the associated cylinder of an internal combustion engine.

Abstract: A piston ring for use in a reciprocating internal combustion engine or in a compressor. The ring has an outer peripheral surface provided with a rotary finish machined curved center portion, rotary finished machined chamfer edges and a final finish plated wear-resistant coating evenly over the complete outer peripheral surface.

Abstract: A Diesel engine piston conventionally has an annular conduit, at the level of the uppermost piston ring, through which lubricating oil circulates. The oil enters and leaves the annular conduit through two longitudinal holes in the piston. According to this invention, a branch conduit extends radially inwardly from the annular conduit to bring oil flow beneath the central part of the piston crown, thereby cooling the latter. The branch conduit is especially useful with a piston having a combustion chamber in its head. The usual discharge hole from the annular conduit is blocked, and a substitute discharge hole, at the end of the branch conduit, opens into the interior of the piston.

Abstract: A piston mainly composed of an aluminium alloy for use in a cylinder of aluminium alloy. The piston is provided with one or more inserts of ferritic steel. The insert or inserts extend across opposed thrust faces of the piston and form part of the running surface of the piston skirt.

Abstract: In a piston and cylinder assembly in which the piston is made of an aluminium alloy, the wall of the cylinder contacted by the piston is formed of a hyper-eutectic silicon aluminium alloy having the composition by weight percentages of silicon (Si) 12-20%; copper (Cu) 0.5-5%; iron (Fe) 1.0-6%; magnesium (Mg) 0.2-2%; nickel (Ni) 0.5-4%; and optionally manganese (Mn) 0-5%; cobalt (Co) 0-3%; chromium (Cr) 0-3%; tin (Sn) 0-8%; titanium (Ti) 0-0.3%; lead (Pb) 0-5%; and molybdenum (Mo) 0-5%, the remainder being aluminium.