Metal belt for continuously variable transmission

A metal belt for a continuously variable transmission, comprising a metal ring assembly formed by stacking a plurality of endless metal rings one on another, and a number of metal elements supported on the metal ring assembly, the metal belt being wound around pulleys to transmit a driving force, wherein the metal element includes a ring slot which is surrounded on three sides by:

• a main body section abutting on V faces of the pulley,
• a neck section extending to a radial outside from the main body section, and
• an ear section protruding from a radial outside edge of the neck section to a right and left, the ring slot housing the metal ring assembly therein;
• wherein a metal ring contact surface of the neck section which is contactably opposed to a side edge of the metal ring of the metal ring assembly has a surface hardness which is lower at a radial outside portion with respect to the neck section than at other portions with respect to the neck section where a contact frequency of the side edge of the metal ring with respect to the radial outside portion of the metal ring contact surface is higher than that with respect to the other portions, the surface hardness of the metal ring contact surface of the neck section gradually decreasing in a direction extending from the main body section toward the radial outside portion with respect to the neck section,
• wherein a surface hardness of a radial center portion of the metal ring contact surface of the neck section is less than a surface hardness of a radial inside portion of the metal ring contact surface of the neck section, and the surface hardness of the radial outside portion of the metal ring contact surface of the neck section is less than the surface hardness of the radial center portion of the metal ring contact surface of the neck section,
• wherein the surface hardness of the metal ring contact surface of the neck section at the radial outside portion is less than a surface hardness of the metal ring,
• wherein the radial inside portion of the metal ring contact surface of the neck section is located near the main body section, and
• wherein the radial center portion of the metal ring contact surface of the neck section is located between the radial outside portion and the radial inside portion and is located at the vertical center of the plurality of endless metal rings.