To control the change gear ratio up to the infinity in order to carry out the starting of a vehicle smoothly, in a hydrostatic continuously variable transmission furnishing a hydraulic pump in which the inclination of a swash plate is fixed, and a hydraulic motor in which the inclination of a swash plate is variable.
The first distribution valve 55 to communicate the cylinder hole 7 of a hydraulic pump P to a low pressure oil passage 50 and a high pressure oil passage 51 selectively is operated by the first eccentric ring 57 provided to an eccentric weight ring 135. The eccentric weight ring 135 rotates together with an input tube shaft 4, and by moving in the direction inclined 45° to an imaginary trunion shaft line O1 of the hydraulic pump P by a centrifugal force, the phase of the eccentric direction of the first eccentric ring 57 is changed automatically. In a low speed rotating condition, the first eccentric ring 57 is made eccentric to the direction orthogonal to the imaginary trunion shaft line O1 so as to make the speed change ratio infinite, while in a high speed rotating condition, it is made eccentric to the direction along the imaginary trunion shaft line O1 so as to make the speed change ratio at a specific value (LOW).
KARATSU HIROSHI
NAKAMURA KAZUHIKO
