Abstract: A plunger equipped with a relief valve mechanism is slidably mounted in a tensioner housing. The relief valve mechanism has a valve spring disposed between a valve and a spring retainer plug in a compressed condition. The spring retainer plug has a stopper surface formed on the side which opposes the valve. The maximum displacement of the valve and the maximum amount of compression of the valve spring are defined by the stopper surface so that the maximum shear stress acting in a wire of the valve spring is less than a fatigue limit of the valve spring wire.

Abstract: In a hydraulic tensioner having a relief valve mechanism in which a spring-biased valve element is reciprocable in a bore, hitting sounds produced by collision of the relief valve element with a plug in the bore, and wear and breakage of the biasing spring, are prevented by providing an oil relief hole in a peripheral wall of the relief valve bore at a position where it is closed by the relief valve element when he relief valve element is moved by a rapid increase in oil pressure.

Abstract: A plunger equipped with a relief valve mechanism is slidably mounted in a tensioner housing. The relief valve mechanism has a valve spring disposed between a valve and a spring retainer plug in a compressed condition. The spring retainer plug has a stopper surface formed on the side which opposes the valve. The maximum displacement of the valve and the maximum amount of compression of the valve spring are defined by the stopper surface so that the maximum shear stress acting in a wire of the valve spring is less than a fatigue limit of the valve spring wire.

Abstract: A low noise roller chain includes a rigid roller made of metal and an elastic roller made of elastic material that are arranged end to end and fitted on a bushing between two opposed inner plates so as to jointly form a roller assembly. The width of the elastic roller is 13 to 45% of the overall width of the roller assembly, and the thickness of the elastic roller is larger than the thickness of the rigid roller by 5 to 25% of the thickness of the elastic roller. With the elastic roller thus constructed, noise generated upon abutment of the roller chain with a sprocket can be effectively suppressed without deteriorating the durability of the rigid metal roller. The elastic roller may be arranged in a zigzag pattern in the longitudinal direction of the roller chain.

Abstract: The frictional type connector 10 includes an inner ring 20, an outer ring 30, and bolts 40. The outer surface of the inner ring 20 is formed into a tapered surface 23 which decreases the diameter from a flange portion 21 toward the other end of the inner ring. The outer ring 30 has an inner tapered surface 31, so that the tapered surface can face the outer tapered surface 23 of the inner ring 20. The taper angle .theta.i of the tapered surface of the inner ring 20 is larger than the taper angle .theta.o of the tapered surface of the outer ring 30.