Abstract: A sintered body assembly having an inner section and an outer section is formed from independent inner and outer compacts corresponding to the inner and outer sections, respectively. The inner and outer compacts are so shaped that a predetermined clearance is provided therebetween. The outer compact is larger in shrinkage percentage at the time of sintering than the inner compact such that the clearance is filled by the compacts at the time of sintering thereby allowing the compacts to be formed into a single sintered body or an integral unit.

Abstract: A rocker arm comprises a main body section made of ceramics and a protective member section covering the outer surface of the main body section. The protective member section is in the form of a film or layer and made of a ductile material so that upon breakage of the ceramic main body section the protective member is plastically deformed to hold the broken pieces of the ceramic main body together.

Abstract: An internal combustion engines comprises at least one exhaust valve made of ceramics per each engine cylinder and a pluarality of intake valves made of steel. The relation in number and valve head diameter between the intake and exhaust valves is designed so as to give Pe<Pi and De>Di where Pe is the number of exhaust valves per each engine cylinder, Pi is the number of intake valve per each engine cylinder, De is the valve head diameter of the exhaust valves and Di is the valve head diameter of the intake valve.

Abstract: A mechanical part comprises a sliding section and a sleeve section which are prepared separately. The sliding section is made of a wear resisting material such as ceramics and formed with a planar sliding surface at one of the sides thereof. The sliding section is further formed with a joining portion at the outer periphery thereof. The sleeve section is made of metal and formed with a joining portion at the inner periphery thereof. The joining portions of the sliding section and the sleeve section are joined by interference fit or the like, whereby to allow the sliding surface of the sleeve section to be formed into a crowned shape.

Abstract: An end of a rocker arm proper is formed into a stepped shape and includes a base section and a mounting section projecting outwardly from the base section. A ceramic tip and a soldering or brazing metal have the same plane figure as the mounting section. The ceramic tip is soldered or brazed to the mounting section by means of a continuous furnace. During conveyance by a conveyor to and from the continuous furnace, the ceramic tip and the soldering or brazing metal are held in place on the mounting section by a jig. The jig is in the form of a framework and adapted to be installed on the base section and fittingly receive therein the mounting section. The jig is also adapted to fittingly receive therein the ceramic tip and the soldering or brazing metal.

Abstract: A piston pin made of ceramics is journalled in piston bosses of a piston made of aluminium alloy. Intermediate members are installed in bearing bores to receive therein terminal end portions of the piston pin. The intermediate members are made of metal which is intermediate in thermal expansion coefficient between the aluminium alloy forming the piston and the ceramics forming the piston pin.

Abstract: A piston boss is formed with an oil inlet hole for collecting oil flowing downward along a piston and allowing it to flow toward a snap ring and an end of a ceramic piston pin in contact with the snap ring. The oil having lubricated the snap ring and the end of the piston pin is collected by an oil outlet hole formed in the piston boss and allowed to flow downward therethrough.