To provide a low-cost pulley for belt type continuously variable transmission, which is constructed compactly and sustains the use in the high-torque region by enhancing its resistance against wear of the sheave surface and the rolling fatigue strength of the ball spline.
This pulley concerned comprises a metal belt 6, sheave surfaces 3, 5, 13, 15 to be in friction contact, and ball splines 7, 17 to enable sliding in the axial direction. The sheave surfaces 3, 5, 13, 15 are prepared from chromium casehardened steel subjected to a heat treatment for surface hardening followed by grinding so that a surface hardness of 750-850HV and a 300°C tempered hardness of 625-700HV are obtained. The surface residual austenite amount after grinding of the ball splines 7, 17 should range from 30% to 50%.
MABUCHI YUTAKA
WATANABE YOICHI
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