HYDRAULIC CONTROL DEVICE FOR BELT TYPE CONTINUOUSLY VARIABLE SPEED CHANGE GEAR FOR VEHICLE

PURPOSE:To optimize the tension of a belt by a method wherein a speed ratio pressure signal responding to a speed ratio is generated from a speed ratio detecting valve worked by means of a second line oil pressure serving as a pressure source, and a second line oil pressure is reduced by a second pressure regulating valve according to the signal. CONSTITUTION:A speed ratio detecting valve 182 generates a speed ratio pressure responding to the speed ratio of a CVT in an oil passage 86 by means of a balance between the force of a spring 194 and a second line oil pressure Pl2 through displacement of a detecting rod 192 making slide contact with a moving rotary body on the input side operated by means of a hydraulic cylinder 54 on the primary side, and feeds it to second and third pressure regulating valves 102 and 220. The second pressure regulating valve 102 regulates a pressure so that the second line oil pressure Pl2 is reduced according to a speed ratio pressure Pe, and feeds it to a hydraulic cylinder 56 on the secondary side. This constitution enables tension of a transmission belt to be always optimized.