HYDRAULIC CONTROL SYSTEM FOR CONTINUOUSLY VARIABLE V-BELT TRANSMISSION

摘要

A continuously variable V-belt transmission has a change-direction gearing upstream of a drive pulley, and a hydraulic control system. The hydraulic control system comprises a shift control valve for controlling the distribution of fluid pressure between the drive and driven pulleys, a pitot tube for generating an engine revolution speed indicative signal fluid pressure, a pitot tube for generating a drive pulley revolution speed indicative signal fluid pressure indicative of not only of a revolution speed of the drive pulley in the forward direction but also of a revolution speed of the drive pulley in the reverse direction, and a shift prohibiting valve for prohibiting the supply of fluid pressure to at least one of the cylinder chambers of the drive and driven pulley until a difference between the engine revolution speed indicative signal oil pressure and the drive pulley revolution speed indicative oil pressure is less than a predetermined value.