| 摘要 |
PURPOSE:To prevent the occurrence of a belt slip by a method wherein an arm to close a shift lock valve only during reduction of a Pitot pressure at a high speed stage is mounted between the shift lock valve and a sensor shoe. CONSTITUTION:When shift to a low speed stage is effected by a change gear ratio control valve 100, a normally ordinary speed change is ensured through engagement of an arm 165 of a shift lock mechanism 160 with a sensor shoe 95. When the Pitot pressure of a sensor 73 is reduced abnormally in a state to carry out up shift to a high speed stage, the occurrence of tire lock during brake in a low mu passage is decided, a shift lock valve 84 is closed by the arm 165, and a primary pressure is held at a high value. When a pulley and a belt are rotated rapidly due to release of brake, especially a primary pulley and a belt are held by means of a press force produced by a high primary pressure, and are rotated without the occurrence of a belt slip. Through the motion of a plunger 161 or the sensor shoe 95 created by the restoration increase of the Pitot pressure, the shift lock valve 84 is opened through the arm 165, resulting in return to a normal state. |
