Abstract: A joint structure is provided between a crankshaft rotated within a crankcase of an engine and a connecting rod an end of which is jointed to the crankshaft via a bearing and the other end of which is jointed to a piston reciprocated within a cylinder of the engine. The large end of the crankshaft is provided with an aperture for receiving the crankpin at the other periphery of the crankshaft. The bearing is positioned at the inner periphery of the aperture, and comprises a plurality of needle rollers made of a ceramic material having silicon nitride as one of the main ingredients. A cage is provided for positioning and retaining the plurality of needle rollers at equal intervals along its periphery. The bearing is lubricated by a lubricant contained within a gas mixture supplied to the engine. Since the needle rollers of the bearing are composed of a very hard, light, and heat-resistive material, the junction structure is more reliable and runs well under severe conditions over a longer period of time.

Abstract: A cage of a roller bearing including a plurality of pockets formed by punching from the outside, each storing a roller, in the circumferential direction of a barrel, which comprises a first projection for preventing the roller from being disassembled to the outside of the barrel and a second projection for preventing the roller from being disassembled to the inside of the barrel. The first projection is provided at a thin portion of the barrel which is formed between the brims of the pocket. The second projection is provided at a thick portion of the barrel in the axial direction by knurling.