Abstract: In a toothed belt including at least one positioning-aiding/position-identifying tooth and a large number of driven teeth engageable with a driving toothed pulley, the positioning-aiding/position-identifying tooth is formed in a predetermined positioning area of the toothed belt and has a different shape from that of each of the driven teeth. The total amount of rubber used in the positioning-aiding/position-identifying tooth is set to equal an assumptive total amount of rubber in one or more imaginary driven teeth that could be formed in the predetermined positioning area if the positioning-aiding/position-identifying tooth was not formed in that area, and the amount of backing rubber used in a portion right behind the positioning-aiding/position-identifying tooth is set to be equal to or greater than an assumptive amount of backing in a portion right behind the imaginary driven teeth.

Abstract: A double-sided meshing type silent chain which permits improvement in service life of the shoe of a chain guide for example, also permits a smooth and high-speed transmission of power, and which has a high durability. A plurality of articular train plates and a plurality of guide train plates are alternately connected together with pins, the plates being formed on the front side with main teeth for engagement with a sprocket located on an inner peripheral side of the chain, and guide plates, whose inner faces are abutted against and guided by side faces of the teeth of the sprocket, are disposed on both outer sides of the plural guide train plates.

Abstract: A transmitting chain is provided which can lower surface pressure between a bushing and a pin, which can well maintain a lubricating state, and which is high in durability so as to be capable of withstanding high load. A groove or a depression, into which lubricating oil, supplied from outside of the chain, is moved, is formed in at least one of a group including an inner peripheral surface of a bushing and an outer peripheral surface of a pin. A difference, space, or clearance, located between an inside diameter of the bushing and an outside diameter of the pin, of portions of the chain not including the groove or depression, is set in a range of from about 0.05 to 0.6% of the outside diameter of the pin.

Abstract: An oil-operated tensioner is constructed with an internal cylinder which receives a rod in such a way that the rod itself serves as a piston, and the diameter of the high pressure chamber formed by the rod and the cylinder is the same as that of the rod. This configuration eliminates changes in the volume of the low pressure oil chamber of the tensioner, maintains substantially constant oil pressure in the low pressure chamber, and substantially reduces the tendency of air to be drawn into the low pressure chamber as a result of flow of oil out of the low pressure chamber when the rod moves in the protruding direction. A piston on the rod in the low pressure chamber, but spaced from the wall of the chamber by a gap, exerts a positive pressure on the oil as the rod moves in the protruding direction to provide further assurance against the entry of air.

Abstract: A camshaft driving mechanism in an internal combustion engine is disclosed. It comprises a crank sprocket, a cam sprocket and an idler sprocket disposed therebetween, a first timing chain entrained on the crank sprocket and idler sprocket, and a second timing chain entrained on said idler sprocket and cam sprocket. The improvement resides in that the first timing chain is sized smaller than the second timing chain.