| 摘要 |
PURPOSE:To make improvements in reliability ever so better, by locking a shift valve to a backward speed position with operating pressure out of a manual value at a time when the manual valve is shifted to an R range. CONSTITUTION:A port 75 to be opened in time of selecting an R range is installed in a manual valve 70, while the said port 75 is connected to each spring chamber of shift valves 80 and 90, and in time of selecting the R range, these shift valves 80 and 90 are locked to a position feeding operating pressure to hydraulic actuators 17a and 36a for backward speed use by operating pressure out of the port 75. With this constitution, if they are shifted to the R range, a backward speed is surely securable regardless of trouble or biting foreign substances in a solenoid-operated device and trouble in a spring, so that reliability in an automatic transmission is improved.
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