| 摘要 |
PURPOSE:To prevent the slippage of a transmission belt caused on the leakage of the working oil by providing an unilateral bypath between an oil path of the working oil flowing out from a speed change control valve for controlling respective hydraulic cylinders which modifies the effective diameters of a pair of variable pulleys and the hydraulic cylinder. CONSTITUTION:In a hydraulic control circuit for a continuously variable transmission 14 where a transmission belt 24 is entrained about the primary and secondary variable pulleys 20, 22 having the effective diameters being modified by the hydraulic cylinders 26, 28, a pressure regulation valve for regulating the pressure of the working oil flowing out from the hydraulic cylinder 28 to the second line oil pressure lower than the first line oil pressure is provided. A speed change control valve 44 for feeding the working oil to one of said hydraulic cylinders 26, 28 and regulating the speed ratio of the continuously variable transmission 14 is also provided. Furthermore, an unilateral bypaths 112, 116 for allowing the oil flow only in the direction toward said hydraulic cylinders 26, 28 are provided between the oil paths 29, 30 for leading the working oil flowed out from said cylinders 26, 28 through the speed change control valve 44 and respective hydraulic cylinders 26, 28. |
