Abstract: Protrusions formed on an inner peripheral surface of at least an innermost metal ring of a belt for a continuously variable transmission are initially worn. An average contact width w of the protrusions, measured in a direction perpendicular to a direction of travel of the metal ring, is equal to or less than 16 ?m. The development of pitching at a top of the protrusion in a depthwise direction is inhibited. Shallow pitching is eliminated due to the contact between the protrusion and a metal element, which prevents the generation of cracks. When the metal ring and the metal element are conformed to each other, the average Hertz's surface pressure is lowered, whereby the pitching is difficult to occur. Also, the top of the protrusion is worn, leading to an improved surface roughness, whereby the lubrication is enhanced, resulting in an enhancement of metal ring durability.

Abstract: A free-state diameter (a diameter in a state in which a residual stress has been released by cutting) of each of metal rings in a continuously variable transmission) is determined so that a predetermined compression stress and a predetermined tensile stress are applied to outer and inner surfaces of the metal ring in an endless state in which the metal ring is not cut, respectively. When the metal ring is cut in order to measure the free-state diameter, the metal ring is cut at least at two points so that cut ends do not interfere with each other in the free state, and the free-state diameter is then measured. Thus, the free-state diameter of the metal ring in a continuously variable transmission can be accurately measure.

Abstract: Protrusions formed on an inner peripheral surface of at least an innermost metal ring of a belt for a continuously variable transmission are initially worn. An average contact width w of the protrusions, measured in a direction perpendicular to a direction of travel of the metal ring, is equal to or less than 16 &mgr;m. The development of pitching at a top of the protrusion in a depthwise direction is inhibited. Shallow pitching is eliminated due to the contact between the protrusion and a metal element, which prevents the generation of cracks. When the metal ring and the metal element are conformed to each other, the average Hertz's surface pressure is lowered, whereby the pitching is difficult to occur. Also, the top of the protrusion is worn, leading to an improved surface roughness, whereby the lubrication is enhanced, resulting in an enhancement of metal ring durability.

Abstract: A free-state diameter, upon cutting each metal ring, is set so that when the ratio of a continuously variable transmission is a value in a TOP state and a metal ring receives a severe load, a corrected amplitude of a stress on an outer peripheral surface of the metal ring calculated from an amplitude and a middle value of the stress on the outer peripheral surface of the metal ring is equal to a corrected amplitude of a stress on an inner peripheral surface of the metal ring calculated from an amplitude and a middle value of the stress on the inner peripheral surface of the metal ring. Therefore, an appropriate free-state diameter is set in consideration of a stress based on a tensile load of the metal ring and a stress based on the bending load of the metal ring.

Abstract: A free-state diameter, upon cutting each metal ring, is set so that when the ratio of a continuously variable transmission is a value in a TOP state and a metal ring receives a severe load, a corrected amplitude of a stress on an outer peripheral surface of the metal ring calculated from an amplitude and a middle value of the stress on the outer peripheral surface of the metal ring is equal to a corrected amplitude of a stress on an inner peripheral surface of the metal ring calculated from an amplitude and a middle value of the stress on the inner peripheral surface of the metal ring. Therefore, an appropriate free-state diameter is set in consideration of a stress based on a tensile load of the metal ring and a stress based on the bending load of the metal ring.

Abstract: A free-state diameter (a diameter in a state in which a residual stress has been released by cutting) of each of metal rings in a continuously variable transmission) is determined so that a predetermined compression stress and a predetermined tensile stress are applied to outer and inner surfaces of the metal ring in an endless state in which the metal ring is not cut, respectively. When the metal ring is cut in order to measure the free-state diameter, the metal ring is cut at least at two points so that cut ends do not interfere with each other in the free state, and the free-state diameter is then measured. Thus, the free-state diameter of the metal ring in a continuously variable transmission can be accurately measure.