| 摘要 |
PURPOSE:To secure ample driving force in time of starting, by installing a maximum speed change ratio holding valve, which forcibly brings it to the state of a maximum speed change ratio, till a clutch is connected. CONSTITUTION:In a state that a car is stopped, since the oil pressure of a driving pulley speed signal is zero, there is no force to press a spool 232 to both directions so that this spool 232 is pressed down by a spring 234, that is, in a state of coming up to the left. A driving pulley cylinder chamber 42 is drained via an oil passage 180, a port 230c, a port 230b and an oil passage 200 whereby a stepless speed change gear comes into the state of a maximum speed change ratio without fail. This state is continues till right-handed force by oil pressure in a port 230a acting on the area of a land 232a of the spool 232 overcomes the force produced by oil pressure in a port 230e acting on the areal difference between lands 232b and 232c and also the left-handed force produced by the spring 234. When a driving pulley 6 with rotates beyond the specified speed, a maximum speed change ratio holding valve 120 is changed over to one that is little shifted to the right whereby these ports 230c and 230d are interconnected with each other, and oil pressure is fed to the driving pulley cylinder chamber 42 from a speed change control valve 106, thus the stepless speed change gear comes into a state of being changeable in speed. |
