| 摘要 |
PURPOSE:To improve the safety and the reliability in case of a breakdown of a transmission gear by providing a double operating circuit for controlling an actuator which operates a driving condition change-over valve adapted for achiving a parking condition and each driving condition of forward, rear and neutral operations. CONSTITUTION:A gear speed change mechanism (not shown) which offers the operating conditions of forward run, backing, and neutral by appropriately engaging and disengaging a plurality of frictional engagement elements is provided with an operation condition change-over valve 88 adapted for achieving said operation conditions and a parking condition. Revolution of a motor 192 causes a control rod 196 to be reciprocated via a screwed mechanism 190, a shaft 188 and others and when it is reciprocated to the left, a parking mechanism 59 is brought into the active condition and a spool 166 is to be reciprocated via a level 186 and a rod 184 to change-over a change-over valve 88. As an operation circuit for controlling the motor 192, the first and the second electronic controller 112 and 113 are provided. The motor 192 may be controlled by either the controller 112 or 113. |
