This paper investigated the influence of pulley tilting on slip ratio (s) of the commercially available continuously variable transmissions (CVTs). Two types of pulleys (tiltable pulley and untiltable pulley) were prepared to investigate the influence of the tilt of pulley on the slip properties. The tilt of the driving pulley was prevented for simple comparisons when untiltable driving pulley was applied, while tiltable pulleys were conventionally used. The maximum transmitting efficiency (η) and the maximum transmitting torque were increased when untiltable pulleys were used, while slip ratio (s) was decreased. The radial displacement of contacting point due to the tilt of pulley was much affected to the penetration of the belt about max 70 times compared with that by rolling, when pulley surface was tilted. The remarkable penetration was prevented by applying untiltable pulley. In current type of CVT, practical CVT unit for commercial uses was usually driven with the slip in circumferential direction due to the tilt of pulley accompanying with radial displacement of the belt. This paper found that about 33% of slip was counted due to the tilt of pulley in observed total slip between driving and driven pulley by the specific reason where the driving pulley should be tiltable for the motion of the shift in axial direction on the shaft. The observed slip was dominantly caused by the penetration of the belt when the driven pulley was tilted.Keywords : Metal V-belt, CVT, Untiltable pulley, Tilting angle, Radial displacement IntroductionCVTs (Continuously Variable Transmissions) have been installed into many cars in Japan because they can continuously change the speed ratio and provide comfortable driving and low fuel consumption by allowing engines to drive efficiently. The slip should be happened between a metal V-belt and pulleys because the traction force is generated by the friction. The commercially available pulleys for practical uses are unexpectedly tilted to keep the geometrical condition with the clearance between pulley center boss and shaft, so that the pulley is moved on the shaft in axial direction for the shift changing the winding radius of the belt in the V-shaped pulley groove. Fujii, et al, experimentally showed the influence of pulley tilt on the power loss and on the transmitting efficiency of a metal belt type CVT. However, principal factor has not been shown to explain the influence of the tilt of pulley on the transmitting behaviors of the CVT.This study investigated the influence of pulley tilting on slip ratio (s) of the commercially available continuously variable transmissions (CVTs). Two types of pulleys (tiltable pulley and untiltable pulley) were prepared to investigate the influence of the tilt of pulley on the slip properties. The tilt of the driving pulley was prevented for simple comparisons when untiltable driving pulley was applied, while tiltable pulleys were conventionally used. To investigate the radial Okuda, Okubo, Fujii, Sakagami and Yagasaki, Journal of Advanced...

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